Best Service Truck Air Compressors For 2020

Best Service Truck Compressor

Discovering the best service truck air compressors for the upcoming year can be tough, but your fellow service truck operators are here to help!

A  poll on Facebook in the Service Trucks group, which has 17,000 members, asked what service truck operators across the United States and Canada think are the best service truck air compressors.

In today’s article, we’re going to take a closer look at your top picks.


VMAC is top of the list and we can think of more than a few reasons why… But the most common reasons people choose VMAC over other air compressor brands include:

  • High performing rotary-screw design
    • 100% duty cycle
    • No air tank needed
  • Limited lifetime warranty
  • 30 to 140 CFM ranges
  • Lightweight & compact designs
  • Numerous options for power sources
  • Manufactured in North America

UNDERHOOD Air Compressor

VMAC’s flagship product, UNDERHOOD™, revolutionized the way air compressors are mounted to a vehicle. By placing the individual air compressor components within the engine compartment, VMAC frees up space and ditches unnecessary weight.

After UNDERHOOD™ took the industry by storm, VMAC released several additional vehicle-integrated and stand-alone air compressors, all of which are built specifically for service trucks and vans.

VMAC continues to be the leader in compressed air innovation and has six lines of air compressors on the market today. The VMAC air compressors we predict will be most popular in 2020 are:

UNDERHOOD air compressors banner

2. Harbor Freight with Warranty

Central_PneumaticIf you’re looking for something a little less sophisticated, with lower power and a price tag to match, buying an air compressor from Harbor Freight is a decent option. It’s important to note that Harbor Freight doesn’t actually make air compressors—rather, they’re a reseller of a few inexpensive, low output (under 20 CFM) brands.

Harbor Freight’s air compressor brands include:

  • Ingersoll Rand
  • Central Pneumatic
  • Fortress
  • Pittsburgh Automotive

Harbor Freight’s Extended Service Protection (ESP) is what makes these air compressors so desirable for the casual air user. Harbor Freight will replace, repair, or refund your purchase with the purchase of a 1- or 2-year coverage plan. This warranty program is a great way to get piece of mind when buying lower price-point air compressors with a shorter lifespan.

3. Champion

Champion is best known for its reciprocating air compressor models and, as far as recips go, Champion tends to make a version that’s higher quality than most on the market; Champion doesn’t make the toss-away reciprocating air compressors that get thrown off the back of trucks when they die.

ChampionOf course, this superior quality is reflected in a higher price tag that puts Champion in the same price range as some rotary screw air compressors, including VMAC’s G30, but without the rotary screw benefits…

Champion’s air compressors are also backed by a standard 3-year warranty for the air compressor pump, with the option to purchase a premium extended warranty for an additional three years. Other package components are covered for one or two years, respectively.

If you’ve decided that a reciprocating compressor is right for your service truck, Champion is a great option to consider.

4. Build-My-Own Monster Garage Style

Here’s to all the innovators! Building a new machine out of nothing isn’t for the faint of heart, but it makes sense that daring, mechanically-inclined individuals would build their own systems. DIY air compressors can be a great solution for those who are on a shoestring budget, need lower CFM outputs, and are happy with a machine that will only last a few years.

Of course, it would be irresponsible not to mention that compressed air is a dangerous and sometimes deadly form of power. If you’re going to make your own “monster” compressor, ensure you know exactly what you’re doing and always follow strict safety practices to protect anyone in the vicinity – including yourself!

5. Miller EnPak

Miller EnpackMiller’s EnPak isn’t really an air compressor—it’s a multi-power system, which puts it into an entirely different category. Multi-power systems combine several pieces of equipment into one single package and typically include an:

  • Air compressor
  • Generator
  • Welder (optional)
  • Hydraulic pump (optional)

Multi-power systems are a great way to eliminate extra standalone pieces of equipment, reduce GVW, and free up space, while still carrying all the equipment needed to get the job done. If you’re interested in learning more about multi-power systems, we recommend the following resources:

6. Speedaire

Speedaire Air CompressorSpeedaire is an air compressor brand sold exclusively by Grainger, an industrial distributor that’s become relatively well known across North America. However, it’s not the actual manufacturer of the systems—instead, Speedaire is a rebrand of a variety of existing air compressors and operators have suspected Champion, Campbell Hausfeld and overseas brands in their catalog.

Because of Speedaire’s medley of manufacturers, it’s a bit tough to talk about Speedaire as a collective brand, but the brand does have a good reputation for decent-quality reciprocating air compressors and excellent customer support.

Speedaire is best known for its portable gas and electric shop compressors, but also includes a small line of air compressors that can be properly mounted to a vehicle. These reciprocating air compressors are gas powered with a Honda engine, and offer up to 24 CFM of compressed air.

Here’s a quick overview of Speedaire air compressors for service trucks:

  • 10-24 CFM air compressors
  • Gas-engine powered
  • Reciprocating air compressors
    • 1- and 2-stage options

The Speedaire line also falls under Grainger’s standard warranty, which backs its equipment and products for 1 year from the date of purchase. This isn’t a great warranty, but it’s better than nothing.

At the end of the day, Speedaire is a potential option for operators who only need low-output bursts of air or for operators who need a shop compressor that can be easily moved between two or more locations.

VMAC Gas Drive Air Compressor

Additional Air Compressor Resources

Learn more about buying air compressors for service trucks with these resources:

Easy Guide To Rotary Screw Air Compressors (2020 Edition)

G30 Gas Driven Air Compressor

G30 Gas Driven Air Compressor

Updated: Jan 9, 2020.

Rotary screw air compressors operate by trapping air between two meshed rotors and reducing the volume of that trapped air as it moves down through the rotors. This reduction in volume results in compressed air, which can then be used to power air tools, inflate tires, or in numerous other applications.

In this guide to rotary screw air compressors, we tell you everything you need to know, including:

Intro to Rotary Screw Air Compressor?
Oil-Injected vs. Oil-Free Rotary Screws
Air Compressor Components
Basic Functions & Operation
Power Sources For Mobile Air Compressors
Advantages of Rotary Screw Air Compressors
Disadvantages of Rotary Screw Air Compressors
Types of Rotary Screw Air Compressors
Manufacturing Rotary Screw Air Compressors

Intro to Rotary Screw Air Compressor?

When most people think of air compressors, they picture reciprocating air compressors (also known as piston air compressors.) These air compressors physically push air into a small space, using pistons, and then collect that compressed air in an air receiver tank. Reciprocating air compressors are relatively inexpensive and have been around for decades.

Rotary screw air compressors are a newer, improved type of air compressor. They are more expensive than traditional reciprocating models but have numerous benefits that are quickly making rotary screw air compressors the system of choice for service truck and van fleet managers around the world.

Rotary screw air compressors operate by trapping air between two meshed rotors and reducing the volume of that trapped air as it moves down through the rotors. This reduction in volume results in compressed air, which can then be used to power air tools, inflate tires, or in numerous other applications.

You can learn more about rotary screw versus other types of air compressors in these articles:

Oil-Injected vs. Oil-Free Rotary Screws

Rotary screw air compressors used on trucks and vans are oil-injected, which means oil is used to lubricate and seal the rotors in the air end. This allows the rotors to create high pressures quite quickly and compress air in a single stage. The oil then gets separated out from the air before the air exits the system and is recycled back into the air end for reuse. Oil-injected rotary screws allow the compressor systems to provide high CFM and psi on a continuous basis.

Oil-free rotary screw models are used in industrial, production or medical applications when absolutely no oil can enter the airflow, like for food packaging or medical oxygen. Oil-free rotary air compressors are more expensive, as they require 2 stages of compression to reach the same pressures of an oil-injected rotary system. Most companies only use oil-free rotary screw air compressors when they absolutely need to so oil-free air compressors aren’t usually found on vehicles.

This guide is dedicated to rotary screw air compressors used on vehicles and therefore focuses on oil-injected rotary screws by default.

Air Compressor Components


Many components make up an air compressor, but the heart of the system is the “air end.” The air end is the part of a rotary screw air compressor system in which the air is compressed. An oil-injected air end looks like this:

Air enters the air end through an inlet valve, where it is mixed with oil while being compressed. The oil is then separated from the air, which exits the system. Learn more about how the air compressor system works in the Basic Functions & Operations section below.

While the air end is where air compression actually happens, there are many additional components required to make a rotary screw air compressor work.

Other Common Components

air filter

Air filter

Air filter

The quality of air entering your compressor will affect the longevity of your system. Using an air filter suited for the environment and the air flow required is a necessity.

That air filter can either be mounted directly to the compressor or remotely mounted and connected with an air intake hose. Cool, clean air should be considered when choosing the location of the filter.

Primary Separator Tank

Primary separation filter

Primary separation filter

When compressed air leaves the air end it is mixed with compressor oil. This mixture enters a primary separator tank where the first steps in separating the oil from the air happens. The primary separator tank uses mechanical separation and centrifugal force to drive oil molecules together, which form droplets that eventually fall to the bottom of the tank. A large amount of oil is removed from the air in this stage. Often, the separator tank also acts as an oil reservoir.

Secondary Separation Filter

Secondary separation filter

Secondary separation filter

Once the compressed air leaves the primary separation tank it is close to being oil free. The remaining oil mist mixed with the air will enter the secondary separation filter, which is a coalescing filter. This filter includes a membrane material that gathers the remaining oil particles and circulates the oil back into the main oiling system. The air leaving the coalescing filter is considered oil free.

The secondary separation filter can be attached to the primary separation tank or mounted remotely on its own filter manifold. Figure 5 above includes both the primary separation filter (labelled Stage 1) and the secondary separation filter (Stage 2).

Oil filter

Oil filter

Oil filter

As a rotary screw compressor has a closed loop oiling system, the installation must include an oil filter. The oil filter’s job is to collect any loose particles that have collected in the oil and shouldn’t re-enter the air compressor system. The oil filter can be located on the compressor, the separator tank or mounted remotely on a filter manifold.

Oil Cooler

Oil cooler

Oil cooler

The process of compressing air generates heat—and lots of it! This heat warms up the oil, which must pass through a cooler before it is circulated back to the compressor. A liquid to liquid cooler can be used in conjunction with an engine’s cooling system or a stand-alone air to liquid cooler can be used; each has its own benefits.

The liquid to liquid version will need sufficient cooling capacity to cool the compressor oil combined with the engine cooling. The air to liquid cooler will need clean, cool air to keep the oil within an optimal temperature range.

Air compressor hose

Air compressor hose


Moving oil and air between various air compressor components requires the use of hoses. The hoses must meet the requirements of heat, pressure and the chemical components of the compressor oil. Incorrect hose selection will result in premature failure of those hoses, which can be expensive and dangerous.

VMAC hydraulic system control

VMAC hydraulic system control


Air compressors will use mechanical or electrical controls in the form of a button, switch, or lever. These controls will turn the air compressor off and on and may also provide important diagnostic or service information. The location and type of components used in the controls should reflect the environment the air compressor will be in.


High performance synthetic oil

High-performance synthetic oil

Oil is a critical component of an oil-injected rotary screw air compressor, performing many important jobs at once. Oil lubricates the system, protects components from wear, keeps the system cool, and helps trap and remove contaminants. Without the right type of synthetic oil, oil-injected rotary screw air compressors would not function.

The components listed above are necessary, in some form, for a rotary screw air compressor system. There are many more options for filter manifolds, coolers, oil separators, and so forth. Each system is a bit different, which means the required components are as well.

Encapsulated Air Ends

Encapsulated air end

Encapsulated air end

Some manufacturers use encapsulated air ends, which combine several components within the air end’s metal casing, including the rotors, intake valves, and separators in a seemingly convenient package. However, encapsulated air ends are bulky and restrictive, which can present design challenges for air compressor manufacturers, vehicle upfitters, and OEMs. The combined pieces result in an awkward, inflexible shape that must be accommodated.

When manufacturers choose not to combine multiple components within an encapsulated air end, they have the freedom to design smaller systems with more efficient designs, without compromising on power or efficacy.

Basic Functions & Operation

Rotary screw air compressors are pressurized systems, comprised of many interconnected components that work together to compress air.

Air and oil are both important aspects of a rotary screw air compressor system. Compressed air is the end goal, which requires the use of atmospheric air, but the oil is just as important. Oil is used to lubricate the system and is the not-so-secret weapon that makes rotary screws so efficient at a lower price-point.

But the use of oil also makes the air compressor systems more complex. In addition to requiring a mechanism for producing compressed air, rotary screw air compressors also need to circulate, filter, and recycle oil.

In a sense, there are two separate systems working together: one makes air and the other circulates oil. Combined, the systems look something like this:

Air compressor system flow

A step-by-step guide to the system flow can help explain how the air and oil processes flow together within a single cohesive system:

System Flow Process

Step 1: Atmospheric air enters the inlet valve.
Step 2: Air flows through the system pressure line to a valve on the regulator, which sets the pressure for the entire system.
Step 3: Air is mixed with oil and compressed via the rotors in the air end.
Step 4: Air mixed with oil exits the air end via the air discharge hose.
Step 5: Air mixed with oil enters the primary oil separator tank, which separates most of the oil from the air.
Step 6: Air enters the second separation filters, which catches remaining oil mist in the air.
Step 7 – A: Oil-free air exists the system; if an air receiver tank is used, the air collects in the tank.
Step 7 – B: Oil is moved into the oil cooler, cooled down, and then sent to an oil filter.
Step 8: The oil filter catches any debris remaining in the oil.
Step 9: The recycled oil is returned to the air end, via the scavenge line.

Note that visualizing the process as steps makes it easier to understand the overall flow, but these steps operate concurrently. As soon as the air compressor is turned on, all the steps outlined above occur simultaneously and continuously.

Power Sources For Mobile Air Compressors

Air compressors need a power source to run. Fortunately, vehicle mounted air compressors have several options: a separate air compressor engine, using a truck or van’s existing engine, or tapping into an auxiliary power source like a PTO or hydraulic port.

For example, here is a breakdown of VMAC’s rotary screw air compressors and their power sources:

VMAC Air Compressor/Multi-Power System Power Source
G30 Gas Driven Standalone Gas Engine
D60 Diesel Driven Standalone Diesel Engine
Multifunction 6 in 1 Standalone Diesel Engine
H40/H60 Hydraulic Driven Hydraulic Port
Direct-Transmission Mounted™ PTO
UNDERHOOD™ Gas or Diesel Vehicle Engine


In summary, there are a lot of power options for mobile air compressors. The right one depends on a vehicle’s existing power options and whether they will work with an air compressor that provides enough CFM and psi. Vehicle engine mounted and hydraulic air compressors are convenient, while standalone engines are efficient and cost-effective.


Air power is typically measured in CFM and psi. CFM or “Cubic Feet per Minute”, is the amount of air that’s being delivered. Meanwhile, psi or “Pounds per Square Inch” is the amount of force behind that air. Together, CFM and psi determine how much air is being delivered and at what pressure. Air tools require the right psi and the right CFM to operate efficiently.

Rotary screw air compressors tend to produce lower psi than reciprocating air compressors, but this isn’t a problem for most mobile air applications. Most air tools run at 80 to 110 psi, which is well within the capabilities of rotary screw air compressors.

Find out more about CFM and psi in these two articles:

Advantages of Rotary Screw Air Compressors

Rotary screw air compressors have many benefits that make them ideal for both mobile and standalone applications. As a result, you’ll find rotary screw air compressors on vehicles and trailers, as well as in industrial, production and medical facilities, where high quality equipment is required.

The benefits of rotary screw air compressors over other compressor types include:

  • Continuous airflow/100% duty cycle
  • Larger quantities of air
  • Higher CFM per hp
  • Longer lifespan
  • Better warranties
  • Quieter
  • Energy efficient

Most people appreciate the longevity, reliability, and easy access to instant air. Because rotary screw air compressors can run continuously, there’s no need to wait for an air receiver tank to fill before you can start using the air. Those tend to be the most popular benefits of rotary screw air compressors.

Many operators also appreciate the limited lifetime warranties that come with some rotary screw air compressors, like VMAC’s. These types of warranties are available because the rotors and air ends are proven to stand the test of time—or, more specifically, the life of a modern service truck. This longevity makes rotary screw compressors a drama-free option.

For example, the very first VMAC rotary screw air end outlived the truck it was installed on. The rotors were returned to us and now have a permanent home in our trophy case.

VMAC's first rotors

VMAC’s first rotors, which outlived the truck

Rotary screw air compressors’ lengthy lifespan is a huge advantage over reciprocating air compressors, which are jokingly referred to as “throw-away air compressors” because they’re expected to fail after 3 to 5 years.

Disadvantages of Rotary Screw Air Compressors

Rotary screw air compressors have a lot of advantages, but they aren’t the right choice for everyone. Common rotary screw air compressor disadvantages are:

  • Upfront cost
  • Skilled maintenance required

The number one reason people choose a reciprocating air compressor over a rotary screw is the initial cost. Rotary screw air compressors often cost twice as much as reciprocating air compressors, but it’s a situation where you genuinely get what you pay for.

Rotary screw air compressors may be 2x the cost, but they last at least 4x longer, on average, and produce more air. That makes them a solid investment for any business that plans to use compressed air over the long term.

The other disadvantage to rotary screw air compressors is that they require skilled maintenance. Every type of air compressor needs regular servicing, but rotary screw systems require a higher level of expertise due to their complex nature. Fortunately, detailed manuals and manufacturer tech support team can help alleviate any inconvenience.

Types of Rotary Screw Air Compressors

There are many types of rotary screw air compressors used on vehicles in mobile applications. VMAC’s air compressor systems demonstrate the range of rotary screw compressor options for vehicles:

UNDERHOOD™ Air Compressors

UNDERHOOD™ air compressor systems are one of the coolest options out there, as the air compressor components are integrated with existing truck or van components. The air end is mounted within the engine compartment and the compressor system is powered by the vehicle’s existing engine. UNDERHOOD air compressors are super light, weighing in at 62 to 200 lbs (depending on the system), which saves precious GVW and their integrated location frees up cargo space.

Installed UNDERHOOD air compressor

Installed UNDERHOOD™ air compressor


DTM on 3D-printed Transmission Model

Direct-Transmission™ Mounted Air Compressors & Multi-Power Systems (DTM)

The Direct-Transmission Mounted air compressor uses a vehicle’s PTO to drive the air compressor. Like the UNDERHOOD, the DTM is a lightweight “out of sight” option that integrates with a vehicle’s existing components.

G30 Gas Driven Air Compressor

G30 Gas Driven Air Compressor

Gas Driven Air Compressor (G30)

The G30 gas driven air compressor has a separate Honda GX390 gas engine, like you’d find in a ride-on lawn mower or other small vehicles. This style of air compressor is mounted to a truck or van and can be easily accessed by any operator with a key.

Diesel Driven Air Compressor (D60)

Similar to the G30, VMAC’s D60 is a diesel driven air compressor with its own Kubota diesel engine. These air compressors are also easily mounted to a work vehicle.

D60 Diesel Driven Air Compressor

D60 Diesel Driven Air Compressor

VMAC Hydraulic Air Compressor

VMAC Hydraulic Air Compressor

Hydraulic Driven Air Compressor (H40, H60)

Vehicles that have existing hydraulic systems can tap into those systems to power their air compressor. The VMAC hydraulic driven air compressor makes sense for operators with hydraulic cranes and other hydraulic-powered equipment.

Multifunction Power Systems

Multipower or multifunction systems are a popular option now being offered by some manufacturers. Multipower systems combine air compressors with other vehicle-mounted equipment, such as welders, generators, and boosters, in one convenient system. VMAC’s Multifunction Power systems are powered by a Kubota diesel engine.

MF-CAT Air Compressor

VMAC Multifunction with Cat® engine

Manufacturing Rotary Screw Air Compressors

Rotary screw air compressors are made up of numerous parts that need to be assembled into a highly efficient system. True air compressor manufacturers will create these parts within their facilities, using an in-house foundry, CNC machines, and other specialized equipment to make the required components. Individual components are then assembled on-site into an air compressor system.

Crucible & furnace in VMAC's foundry

Crucible & furnace in VMAC’s foundry

One of VMAC's CNC machines

One of VMAC’s CNC machines

VMAC’s coordinate measuring machine

Design Tolerances

When engineering and manufacturing parts for any system or machine, there is an acceptable margin of error, called tolerance.

The required dimensions for air ends in rotary air compressor systems are so precise that these tolerances are incredibly low. Computer Numerical Control machines—CNC machines, for short—allow manufacturers to meet the exact tolerances needed for rotary screw air compressors.

For example, these are the maximum tolerances VMAC allows for parts made with CNC machines in comparison to the parts made using manual machines:

  Maximum Tolerance Suggested Tolerance
CNC Mills ±0.0003 ±0.005
CNC Lathes ±0.0003 ±0.005
Manual Mills ±0.001 ±0.005
Manual Lathes ±0.001 ±0.005

A stringent quality control process ensures the required tolerances for each machine are met. If a machine fails to produce parts within the acceptable tolerance, those parts are melted back down or otherwise recycled. In that scenario, the designs and machines will also be evaluated and adjusted, as needed.

Fortunately, manufacturers using modern quality control technology can usually predict when a CNC machine will need to be adjusted well in advance, and plan for that maintenance accordingly.

True Manufacturers vs. Assembly Companies

One major advantage to making parts on-site is that the parts can be modified at will. Instead of being restricted by existing component shapes and sizes, true manufacturers have the freedom to innovate on individual parts on their own desired schedule, creating more efficient, powerful and compact air compressor systems.

A more common type of air compressor manufacturer will purchase existing parts from suppliers or, less often, contract their creation out to external companies. If a custom part is required, these air compressor companies have to book a space with third-party foundries, machinists, and other specialists, and then rely on their general expertise for modifications. This style of air compressor manufacturer essentially assembles pre-purchased pieces into air compressors before shipping them out to customers.

VMAC is one of the only true rotary screw air compressor manufacturers in North America.

How To Size An Air Receiver Tank

Many air compressor applications can benefit from the installation of one or more air receiver tanks. An air receiver tank increases the amount of air available on demand, allowing for higher duty cycles and more powerful applications.

Air receiver tanks are sized in gallons, and can range from small 5- and 10-gallon tanks to massive tanks that hold thousands of gallons of air. The ideal size of an air receiver tank will depend on the type of air compressor and the application.

Air Receiver Tanks For Portable Air Compressors

Tanks for Reciprocating Air Compressors

Reciprocating air compressors use an air receiver tank to store air and eliminate pulsation before it can be used. Once the tank is filled with enough air, the tool or equipment can run. In many applications, using the tool will drain the tank, and operators will need to wait for it to fill back up before more air can be used. Properly sizing the air receiver tank that’s used with a reciprocating air compressor can help reduce interruptions and time wasted waiting for the tank to refill.

A simple and straightforward rule for sizing an air receiver tank for a reciprocating air compressor is to take the tool with the highest CFM requirement (at the required PSI), multiply that CFM requirement by 1.25 or 1.5, and then round up to the closest gallon size.

CFM Requirement1.25 Multiply1.5 MultiplySuggested Tank Size
20253030 gallon
40506050-60 gallon
6581.2597.590-100 gallon
80100120100-120 gallon

While these calculations may not completely eliminate the waiting time between tank fills, it will help minimize them.

Tanks for Rotary Screw Air Compressors

It can be trickier to size an air receiver tank for a rotary screw air compressor, as many applications don’t require an air tank at all. Rotary screw air compressors are designed to supply a continuous stream of air without interruption and pulsation. Therefore, if your tool requires less CFM than the air compressor produces, an air receiver tank shouldn’t be required.

However, smart operators may choose to use an air receiver tank to give their compressor a little boost for higher CFM tools. For example, if an operator routinely uses a 1” impact wrench that requires 40 CFM, but only has a 30 CFM air compressor, he may choose to add a 12-gallon air receiver tank to compensate for the difference. By the time the air receiver tank is empty, the task will be complete. Operators can sometimes save money or “make do” with a smaller system using this savvy strategy.

Air Receiver Tanks For Stationary Air Compressors

Properly sizing an air receiver tank for custom stationary applications is more complex and should typically be done by a qualified engineer. These air receiver tanks should be sized according to the volume and pressure variations in air consumption (ie: demand), air compressor size, pipe or hose size and length, and the control system strategy (ie: modulation or on-off control.)

A commonly used formula to find a receiver size is:

t = V (p1 – p2) / C pa


  • V = volume of the receiver tank (cu ft)
  • t = time for the receiver to go from upper to lower pressure limits (min)
  • C = free air needed (scfm)
  • pa= atmosphere pressure (14.7 psia)
  • p1 = maximum tank pressure (psia)
  • p2 = minimum tank pressure (psia)

Formula Sizing Example

Let’s look at an example, using an air compressor system with the following specifications:

  • mean air consumption = 20 cfm,
  • maximum tank pressure = 175 psi,
  • minimum tank pressure = 90 psi, and
  • time the tool will run = 1 minute

The approximate ideal volume of the receiver tank can be calculated by modifying the sizing formula to:

V = t C pa / (p1 – p2)
= (1 minute) (20 cfm) (14.7 psi) / ((175 psi) – (90 psi))
= 3.46 ft3
= 25.9 gallons

However, this formula tends to work best for large reciprocating air compressor systems.

Calculating Maximum Air Consumption

Identifying the maximum consumption of an air compressor system is critical when sizing an air receiver tank. Ideally, the air receiver tank will provide enough air to meet or exceed maximum consumption.

In the t = V (p1 – p2) / C pa formula, maximum air consumption is measured in SCFM and represented by “C”.

To calculate the maximum consumption in the system, summarize the air demand of each air tool or consumer that will be used at the same time. The summarized consumption must then be multiplied with a utilization factor for each consuming item.

Utilization Factor

The utilization factor is the way in which a tool is used and how that use affects air flow.

Let’s say you have an air tool like an impact wrench, which is rated by the manufacturer for a consumption of 20 CFM at 100 PSIG. This wrench may be turned on for only 20 seconds at a time to tighten an individual nut to its required torque value.

Initially, the tool will consume the full rated 20 CFM as it tightens the nut against almost no resistance but as the torque rises on the nut, the tool will consume less air until the final torque is achieved. The tool also won’t consume air when it isn’t being used, in between nuts.

The tool’s air consumption under load is not uniform throughout the process of torquing the nut, and the interval between applying the tool between individual nuts varies—this difference in CFM load and time interval becomes the utilization factor.

In other words, just because the tool is rated at 20 CFM, this does not mean that the tool requires the full rated CFM for each full minute nor the full minute to complete the job.

Because of this utilization factor, some air receiver tanks can meet heavy, short time demands of certain equipment at volumes that exceed the supply capabilities of the installed compressor. The minimum receiver capacity for certain applications may also be calculated, but experience and judgment are important at this point.

Pressure Band / Differential

The pressure band (differential) should also be considered when calculating the ideal air receiver tank size.

If the consumption process requires 100 psig and the compressor is set to deliver 100 psig, there is no storage and no buffer. Any increase in demand will result in a tank pressure drop below 100 psig until the compressor responds by increasing the air volume compressed to refill the tank and restore the 100 psig.

If the compressor is set to deliver 110 psig, the difference between 110 psig and 100 psig accounts for the air stored in the receiver.

If the 100 psig demand increases, the tank pressure can drop 10 psig before the minimum set pressure requirement is met. Keep in mind that the discharge piping and hoses also form part of the storage volume.

Pressure and flow controllers can be used after the receiver tank for stabilizing downstream pressure to 100 psig and flattening demand peaks.

When Does Exact Sizing Matter?

Even with the knowledge above, properly sizing an air receiver tank is a complicated and time-consuming process. Operators using straightforward tools and air compressors can default to simple CFM recommendations, and choose a receiver tank using a 1 CFM to 1.25-1.5 gallon ratio. Meanwhile, engineers developing complex and custom systems will need to determine more exact sizing requirements and need to put in the work.

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Why does hose size affect my compressor airflow?

It’s important to consider appropriate sizing of all components of your air system.  If you are investing in an air compressor system, restricting the flow anywhere in your system could make it significantly underperform or cost you a lot more in energy costs to run that compressor over its lifetime.

As air travels from the compressor head to your tool it travels through components such as hoses, fittings, valves, and tanks. Each of these will restrict the flow of air in some way depending on the geometry of each component and the magnitude of the flow passing through it.

For example, a long small hose feeding a high air demand tool can result in a high-pressure drop. The result of this will mean either your compressor is working harder and using more power to keep up with your air demands, or—if it can’t keep up—your tool performance will be reduced.  In some cases, where torque or power at the tool is important, you may not be able to complete your work.

Quick calculators or charts can be referred to for calculating the pressure drop in any of your components. The following components should be considered for proper sizing.

  • Hose reels
  • System piping/tubing
  • Filters
  • Regulators
  • Lubricators
  • Quick connect fittings
  • Fittings

Components such as filters will have pressure drop ratings at different flow rates. Be sure to check the documentation and specifications to match them to the system you are installing the components on.

When considering fittings and quick connects, work with your suppliers to make sure they are rated for the maximum pressure your compressor system is rated for and will not cause excessive pressure drop at the required flow rates.

90° fittings like this may restrict airflow

90° fittings like this may restrict airflow

How Fittings Cause Pressure Drops

Pressure drop is due to the restriction created by the pipe or fitting.  Anyone who has tried to breathe through a drinking straw can tell you that trying to force a large flow of air through a small hole can be difficult. This is because the smaller the diameter, the higher the velocity is required for the air to travel through the hole.

Higher velocities result in more friction created. due to boundary layers at the walls of the pipe or fitting creating more losses. With pipes and hoses, the loss is multiplied by the length of the pipe.

It can be surprising how small the flow diameter is in some fittings.  A quick connect fitting is one of the worst culprits.  Next time you are looking at a quick connect, look inside to see how small the actual flow area is.

Calculating Pressure Drop of Fittings

Pressure drop can be calculated for some components and is made even easier by online tools such as this one.  Note that this calculator is for hard pipe as it is a well-defined shape. Flexible hose in actual use typically contains many bends and loops and as such it is not possible to create an accurate generic calculator. While flexible hose will have more losses than a pipe with an identical inside diameter we can still use the pipe loss calculation to get an estimate and see the influence diameter has on pressure loss.

Let’s look at some examples.

To illustrate the dramatic difference pipe/hose diameter makes on pressure loss, let’s use this tool to compare 100ft long pipes with internal diameters of ½”, ¾”, and 1” for 70CFM FAD (free air delivery) of compressed air delivered at 100 PSI gauge pressure (equivalent to 114.7 PSI absolute pressure*) at the upstream hose entrance.

The approximate pressure loss from end to end for the three pipe sizes is:

1″ x 100’: ~1.4 PSI pressure loss

3/4″ x 100’: ~5.7 PSI pressure loss

1/2″ x 100’: ~44 PSI pressure loss

Your compressor would actually have to be operating at ~134 psi gauge pressure† to maintain 100 psi at the tool with the ½” pipe.

Increasing Pressure vs. Increasing Supply Line Size

Increasing the pressure of your compressor to compensate for flow losses can have a dramatic impact on the amount of work your compressor system is doing. Conversely, increasing the size of the supply lines can provide the following benefits:

  • Less fuel/energy used by your compressor
  • Less heat generated by the compressor
  • Longer oil life and service interval
  • Lower noise output from the compressor
  • Improved safety due to lower operating pressures and lower temperatures
  • Lower load on drive system components
  • Less wear and longer life of your compressor

Each restrictive fitting, hose, accessory, bend etc. you add to your system results in cumulative pressure drop and can have negative results on the performance of your tool or equipment.  Recognizing this and planning and sourcing the right sized components will enable your air system to perform better.

As always, keep in mind that formulas and calculators like the one used above are just a guide.  Real life scenarios depend on many factors and each will affect your individual results.  Using larger diameter hose may cost more but it can result in long-term savings and may even allow for a lower pressure or output compressor, saving money up front.

*Absolute pressure is the pressure relative a perfect vacuum.  Gauge pressure is relative to atmospheric pressure. Standard atmospheric pressure is 14.7 PSI so for a calculation, such as this one, that requires the use of absolute pressure, atmospheric pressure (14.7 psi) needs to be added to your gauge pressure.

† Note that it may seem at first glance that the entrance pressure would need to go up by the same pressure as the loss in the pipe from the first calculation but it’s actually slightly less. As the pressure goes up the volume flow and flow velocity goes down for the same mass flow of gas and therefore so does the pressure drop.

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Power Requirements For Your Industrial Engine Powered Air Compressor

So, you’ve decided you are in the market for an air compressor to add to your existing industrial engine or to include as part of a new piece of equipment you are designing.

Maybe you or your customers are tired of having to haul another separate piece of equipment around to job sites, or maybe you’re looking to open up new markets with a product that does it all. In any case, you are going to have to figure out what your needs are so you can start looking for the right piece of equipment.

To get started you need to consider the following:

  • What tools would you like to use?
    • What are their air requirements?
    • What duty cycle will they be used at?
  • How will your air requirements vary depending on the job at hand?
  • Will you be using an air receiver tank and what is the tank volume?
  • Are you willing to wait for the air pressure to build between tool use?
  • What other loads are going to be imposed on the engine?
  • Will these other loads be running concurrently with air compressor use?

How To Determine Your Tools’ Air Requirements

Each air tool should have a published air requirement specification. Often this is included in the owner’s manual or documentation that came with the tool and is typically stated in airflow (CFM – cubic feet per minute) at a specific pressure. Many air tools are designed to operate in the 90-130 psi range which is a requirement that almost all air compressors can meet.

Where it can get a little interesting is when looking at the airflow specification. Commonly this is stated as an “average airflow consumption” but this can be misleading as it assumes you will only be using the tool intermittently.

Some tools will specify both an average and actual consumption. For example, a popular ½” impact gun states a 4.2 CFM average air consumption and 22CFM during actual use. A quick calculation shows us that this particular tool manufacturer has assumed that this tool will typically only be used an average of 20% of the time.

The amount of time a tool is used is referred to as duty cycle and, in the small air tool industry, it’s commonly based on a cycle time of a minute. Therefore, a 25% duty cycle would refer to using a tool for 15 seconds out of a minute.

For larger or specialized tools, the duty cycle may be quite different. A pneumatic angle grinder or sander might consume 18 CFM under load and be used continuously for five minutes and then put aside for an hour. While this works out to only an 8% duty cycle, because of the longer on time it would require a larger compressor or larger air receiver tank (more on this later) than the impact gun mentioned above.

If possible, find out the actual air requirements for everything you want to power with compressed air and apply the duty cycle that you will actually use each for. It will make the selection of your compressed air system more accurate.

How To Figure Out Everyday Air Needs

Once you have an idea what the air requirements are for each tool and piece of equipment, you need to determine how these air needs might overlap during a typical day. This is an important factor to consider as it has a major impact on the size and type of the compressor and requirements of an air receiver tank.

For example, if the compressor system is part of a mechanic’s service truck, it might only be used to power one tool at a time at a duty cycle of 10-30% in a time span of a minute or two a few times per hour. Contrast this with a compressor system used for the application of spray foam insulation where there are multiple operators each with a spray guns operating at a duty cycle of 60-90% in a time span of an hour.

Do You Need An Air Receiver Tank?

The next important thing to consider is the use and size of an air receiver tank. A receiver tank stores compressed air and acts as a buffer between compressor output and surges in air demand due to heavy tool use.

An appropriately sized tank will allow the compressor to run at its designed duty cycle while still allowing the system to provide a steady supply of air. A larger tank will typically allow a higher intermittent air consumption with a smaller compressor as long as the compressor’s rated duty cycle is not exceeded. In other words, the time to fill the tank from cut-in to cut-out pressure doesn’t overheat the compressor. The duty-cycle and rated maximum run time should be provided by each compressor manufacturer.

Although the rule of thumb of four gallons per HP is sometimes used, it makes many assumptions that may not reflect your particular situation. Instead, use this simple equation to determine the minimum recommended size of your air receiver tank if your demand is occasionally more than the compressor can continuously output. Note this assumes you will not exceed your compressor’s duty cycle when refilling the receiver tank.


V=required minimum receiver tank volume ( US gallons)
Pmax = Compressor cut-out pressure (PSI)
Pmin = Compressor cut-in pressure (PSI)
CFMtools = Max total air consumption possible at one time (CFM)
CFMcompressor = continuous output of the compressor (CFM)
T = Length of time high air consumption will be in demand (minutes)

This equation can be used to find a balance between compressor output and tank size that best suits your needs, for example if you occasionally require 45 CFM at a minimum pressure of 90 psi for one minute out of every 10 minutes, you could meet this need with a compressor that can output 45 CFM and not require a receiver tank at all, or you could use a compressor that outputs only 10 CFM coupled with a 100-gallon tank with a cut-out pressure of 130 PSI.

Properly sizing a receiver tank and air distribution system is beyond the scope of this article, but you can learn more in our How To Size An Air Receiver Tank blog.

How To Determine Your Power Requirements

Now you have an idea what your air consumption needs are and have decided on a compressor size and receiver tank. The next step is to determine the power requirements of running the compressor, commonly specified as CFM per HP.

An important factor in determining a compressor’s CFM/HP ratio is its thermal efficiency. This is fundamentally a measure of how efficient the compressor can turn the engine power into compressed air. There are many factors that influence the isothermal efficiency of an air compressor; compressor type (i.e. piston vs rotary screw or multiple vs single stage compression), discharge pressure, cooling method, etc.

Each compressor manufacturer should be able to supply a CFM/HP curve at different pressures but if not the following table shows how actual output can vary with pressure and isothermal efficiency.
If this information is not available, we can approximate a typical compressor’s performance using the following table at about 3-4 CFM per HP:


Now that you have a ballpark power requirement for compressor operation, you need to add in the other loads to arrive at a total load demand on the engine.

Engine manufacturers will commonly specify a gross and net rated power. Gross power refers to the engine power without any loads (i.e. no water pump, alternator, oil pump, or cooling fan), a situation that you will typically never experience. The Net power rating is the one to use but you may still need to factor in the power required to run the cooling fan and alternator.

You will want to work with your engine supplier to determine what has been accounted for in the net power rating specification.

Torque Curves Under Operating Conditions

Once you have some engines to consider, you can look at comparing the torque curves under the operating conditions you will be running at.

A typical industrial engine has a hill-shaped curve with a peak somewhere is the upper-middle rpm range while a compressor’s drive torque curve at a particular operating pressure can be almost flat or slightly U shaped.

These curves should be plotted to compare the engine’s ability to drive the compressor (and any other concurrent loads) at different operating RPMs. You are going to want to source an engine that can provide the torque you require with some reserve as a safety margin for situations where the engine is not able to produce rated power. A basic graph showing this comparison is shown below.


Some factors that may reduce the available power include: low-quality fuel, extreme high or low ambient temperatures, high altitude, turbo or charge air cooler not working properly, clogged air filter, exhaust restrictions, or simply an engine that is worn out or in need of servicing.

Your engine supplier should be able to provide you with conversion tables to help calculate some of these effects which can lower the engine’s torque by 30 % or more.

Similar factors also apply to the compressor drive torque and should be discussed with your compressor manufacturer to ensure that, even under the worst-case scenario, there is still enough torque available to meet the demand of the compressor.

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There are many factors to consider when sourcing an appropriate engine to power your compressor. Hopefully, this article has helped prepare you to be able to better discuss your options with your chosen engine and compressor supplier.

What’s the difference between PSI and CFM?

The difference between PSI and CFM are what they measure. PSI measures pressure, while CFM measures volume. PSI and CFM are often used as performance specifications for air compressors. Together, they indicate the maximum air volume and pressure produced by an air compressor to power air tools. To better understand the difference between PSI and CFM, let’s learn what PSI means and what CFM means.

What Does PSI Mean?

The initials PSI stand for Pounds per Square Inch. PSI measures how many pounds of pressure (force), is in an area, specifically in one square inch. The force of the air is what gives compressed air its power. For example, an air compressor’s output could be rated for 100 psi*, which means that 100 pounds of pressure is delivered per square inch.

*PSI is typically written in lower case letters, psi, in air compressor specs.

What does CFM mean?

CFM means Cubic Feet per Minute. CFM measures the volume of air in cubic feet for each minute it moves. In the case of an air compressor, CFM indicates how much air can move per minute. For example, an air compressor’s output could be rated for 30 CFM, which means 30 cubic feet of air is flowing per minute.

How Do CFM and psi Relate?

CFM and psi relate to each other in an important way that ensures the proper operation of an air compressor. For a tool to operate and perform optimally, both CFM and psi must be sufficient.

Let’s look at a real-life example to help understand how CFM and psi relate:

garden-hoseImagine you have a garden hose, and you turn it on. Water will flow out, and it might reach a few feet past the end of the hose, perfect for filling up your bucket or watering can. If you take the garden hose and restrict the space at the end of the hose with your thumb to create less room for the water to flow out the water will shoot out with much more pressure than before. Even though the hose is producing the same amount of water, the extra pressure will allow the water to travel faster and further, perfect for having a water fight!

Hopefully this hose example is relatable, and even though the example used water to describe the relationship between CFM and psi, the concept is the same with air.

Consider this second real-life air example. There’s a tunnel with wind blowing through it, and the tunnel gets smaller and smaller. As the wind blows into the tunnel, it travels through the shrinking space, and starts to feel stronger and stronger. This is because even though the volume of air (CFM) remains the same throughout the tunnel, the air is being squeezed into a tighter space, resulting in the pressure (psi) increasing.

In both examples we shared how psi relates to CFM. While having a sufficient volume of air to power air tools is important, it’s also crucial to ensure there’s enough psi (pressure) to give the air power.

What Size Air Compressor Do I Need To Run My Air Tools?


Now that you understand the difference between psi and CFM, you might be wondering how to be sure you have the right air compressor to run your air tools. The easiest way to do this is to check the air requirements of your air tools (both CFM and psi) and then ensure the air compressor you choose meets those requirements.

But it’s more than simply matching the CFM and psi of your tools to your air compressor. It also matters whether you have an air receiver tank, a rotary screw air compressor or reciprocating air compressor, and even what your application is.

To continue your research into psi and CFM, check out these helpful articles:

9 Reasons To Keep Your Tow-Behind Air Compressor

[This is a fun satirical response to VMAC’s article: 9 Reasons to Ditch Your Tow-Behind Air Compressor.]

Tow-behind air compressors have been popular in many industries, including construction and utilities, for decades. This equipment made it easy for contractors and operators to ensure they were able to take their air compressor with them to the job site.

Today, owners, operators, and fleet managers have more options for mobile compressed air than just tow-behind air compressors. Manufacturers continue to innovate with a variety of options, from hydraulic, gas, and diesel powered above-deck air compressors, UNDERHOOD™ air compressors, and underdeck PTO-driven air compressor systems. But even with these innovative air compressor solutions, which pack a lot of power into compact packages, many people still have a problem letting go of their trusty tow-behind air compressors. Here are 9 reasons to keep your tow-behind air compressor:


Your experience towing your bulky air compressor has given you the skills of a precision driver! You’ve successfully merged onto busy freeways, reversed without jack-knifing, and managed to find parking in even the most crowded job sites. You have a sense of pride in the skills you’ve honed over the years of navigating your truck and trailer in all sorts of tricky (and frankly, stressful!) situations.


Trailers can hinder your access to job sites, especially mobile service work in remote or off-road areas. If you enjoy taking extra time and care to navigate your way to hard-to-reach job sites, then it’s best to stick with your tow-behind.


tow-behind-on-hitchYour truck came with a tow hitch for a reason, so you’re going to use it! Now you can always use your tow hitch for your air compressor. If you need more equipment, then you will have to have another vehicle and driver sent out to bring all the required equipment to the same spot. That means the second truck will have the opportunity to use its hitch too.

If you feel like doing it all yourself, you can make two trips to the job site—one to drop off your air compressor, and one to drop off the rest of your equipment. Driving around is fun!


Every service job will present you with the opportunity to guess: will I need my air compressor for this job? You can bet on the odds of whether you’ll need to bring your tow-behind with you to the job site or not. Keep track of how many times you guess right, and how many times you must turn around to go back and collect your trailer.


We hope everyone is passionate about workplace safety, and if you have a tow-behind air compressor, you’ll get to indulge this passion practically every day. Tow-behind air compressors have a lot of parts to check frequently. You’ll need to ensure the hitch, taillights, and tires are all in working condition. If any of these parts are failing, then you’ll get to spend part of your day fixing them, instead of actually getting down to work. If you’re a procrastinator, this is the best!

It also takes vehicles pulling heavy tow-behind air compressors longer to stop. To be able to stop quickly and safely, you’ll have to drive at reduced speeds whenever you’re towing your air compressor. You can learn and observe tow bar regulations and adjust your driving to make up for a larger blind spot.

In addition to all the safety checks you’ll enjoy doing, you’ll also have the opportunity come up with safety measures to ensure thieves don’t steal your tow-behind. It’s much easier to steal a tow-behind than to steal an above-deck air compressor, or a vehicle integrated compressor, like an UNDERHOOD or a transmission-mounted PTO drive air compressor. But since you like a challenge, and you’re passionate about safety and security, you’ll enjoy taking extra precautions to ensure your tow-behind is not stolen. Channel your inner Kevin McCallister in Home Alone and have some fun setting up booby traps every time you need to park your vehicle.


engine-tow-behind-air-compressorTow-behind air compressors come with their own engine, in addition to the engine that’s part of the service truck or van that’s doing the towing. This means that you’ll have two engines to maintain, and you’ll spend more time and money making sure both engines are in tip-top shape.

Several mobile air compressors use the vehicle’s existing power sources to run, such as gas and diesel vehicle engines, transmissions, or PTOs that run hydraulics, but where’s the fun in only maintaining one engine?


Tow-behind air compressors take time to position properly and set up on the jobsite. They require a lot more prep work than a vehicle-mounted mobile air compressor. If you enjoy spending additional time each day setting up your equipment before you actually start to work, then a tow-behind is a great option.


Tow-behind air compressors are beasts. They’re thirsty monsters when it comes to fuel, when you account for the extra consumption to run the tow-behind, as well as the extra fuel your truck will use to lug a 1,000+ lb air compressor. Your local gas station attendants will love seeing your truck and trailer chugging into the station for another big sale!

Speaking of weight, do you like adding extra weight to your truck? If so, you’re in luck—even though the Atlas Copco XAS 110 is considered to be a smaller sized tow-behind air compressor, producing up to 110 CFM, it still weighs 1,100 lb. It’s much heavier than the UNDERHOOD™ 150 air compressor, which weighs in at only 200 lb.


tow-behind-air-compressorAnd the number one best reason to keep your tow-behind air compressor is that you are a traditionalist! You enjoy the nostalgia of using the tow-behind. All the extra time spent driving around, setting it up, maintaining it, and keeping it safe is time well spent! The challenges driving, maneuvering, and parking build up your character. And of course, you love utilizing your truck hitch to carry around your 1,000+ lb tow-behind.

Do you have second thoughts about keeping your tow-behind air compressor? There’s another option. Vehicle mounted air compressors are the right choice for people who:

  • Need mobile air regularly
  • Have light to medium duty applications
  • Want more space for cargo, tools, and other equipment
  • Prefer less weight on their vehicles
  • Want to minimize maintenance
  • Desire the freedom and convenience of trailer-free driving

If this sounds like you, then consider our sister article: 9 Reasons To Ditch Your Tow-Behind.

Rotary Screw Air Compressor Oil – Answers To Your Top 8 FAQs!

What is air compressor oil?

High performance synthetic oil

Air compressor oil is standard or synthetic oil made specifically for air compressors. Unlike motor oil, air compressor oil does not contain detergent, and typically has lower amounts of carbon, sulphur and other contaminants that can cause build-up.

Generally, rotary screw air compressors use synthetic oil, while recreational compressors may use standard oil. Air compressor oil varies in composition and colour, but is often yellow or light brown, and becomes darker as it becomes contaminated over time.

Why do rotary screw air compressors need oil?

Air compressor oil plays several important roles within a rotary screw air compressor system:

  • Lubricates moving parts
  • Creates a seal between rotors to trap air
  • Prevents premature wear on parts
  • Helps cool air during compression

Rotary screw air compressors are sometimes referred to as “oil flooded”, which is a dramatic description of the way oil is injected into the rotor housing. The oil mixes with the air during compression but is separated back out before the compressed air leaves the system.

Some rotary screw air compressors don’t require oil at all. However, these designs tend to be louder and more expensive. Oil-free rotary screw air compressors are typically only used in industrial applications in which oil contamination absolutely can’t occur, such as food processing or medical oxygen.

What kind of oil does an air compressor take?

Some air compressors require a very specific type of oil, while others may not be as specific. Before deciding on a type of oil for your rotary screw air compressor, check your manual and warranty details to determine whether a specific oil is required.

If a manufacturer specifies a specific type of oil, always use that oil. For example, all VMAC air compressors require VMAC’s high performance synthetic rotary screw oil to perform properly and maintain the limited lifetime warranty. We have tested all our systems with this oil and know it has the perfect chemical composition to lubricate and protect components, create proper seals between our two rotors, prevent overheating, and ensure optimal air output.

Manufacturers who don’t specify an exact brand of oil may still recommend a 20 weight or 30 weight non-detergent oil. 20 weight oil is typically used in colder environments, while 30 weight oil is better suited for warm climates. Some operators will switch between these oils for the summer and winter seasons.

When should I change air compressor oil?

Maintaining proper service intervals will keep your air compressor running in tip-top shape and help ensure the warranty in maintained. You should always check and follow your air compressor manufacturer’s service maintenance schedule, when applicable.

For example, here is a breakdown of VMAC’s air compressor oil service intervals:

SystemCompressor TypeOil Service Intervals
G30Gas Powered200 Hours / 6 Months
D60Diesel Powered500 Hours / 6 Months
H60Hydraulic Driven500 Hours / 1 Year
DTM70PTO Driven200 Hours / 6 Months
UNDERHOOD 70Engine Mounted200 Hours / 6 Months

As you can see, the service hours and periods range quite significantly between different air compressors—even when designed by the same manufacturer. Therefore, it’s strongly recommended that you check your air compressor’s manual when determining when to change the compressor oil for your system. If you can’t locate a manual for your system, contact the manufacturer directly.

How do I check the air compressor oil level?

Check Oil-level

Your air compressor oil level should be checked daily or every time you use the air compressors. To check the oil level, follow these simple steps:

  1. Ensure the vehicle is parked on level ground and that the compressor system is depressurized and cool to the touch.
  2. Check the oil level in the sight glass. On VMAC systems, ensure the oil is between the “MAX” arrow and the “ADD arrow.”
  3. If the level is below the required level, remove the fill cap on the tank and use a funnel to pour oil into the fill fitting. Use the sight glass to achieve the desired oil level and avoid overfilling.
  4. Replace the fill cap and tighten securely.

If the air compressor does not have a sight glass, remove the oil fill cap and look inside for a dipstick. Pull out the dipstick and look for the “min” and “max” lines at the bottom tip of the stick, then use these lines to determine whether more oil is needed.

How to change air compressor oil?

When the time comes to change your air compressor’s oil, follow the instructions in your air compressor’s manual. Although the basics of an oil change are simple—drain the old oil, and then pour in new oil—the individual steps can be significantly more detailed.

As an example, here are the steps required to change the oil in VMAC’s G30 gas driven air compressors:

  1. Clean the area around the air compressor’s WHASP tank and oil filter to prevent contamination.
  2. Remove the oil drain plug and drain the oil into a container with a capacity of at least 1 gallon (4L).
  3. Inspect the Viton O-ring on the oil drain plug for damage, hardness or defects and replace if necessary.
  4. Install and tighten the oil drain plug.
  5. Remove the oil filter.
  6. Ensure the threaded nipple did not unscrew with the oil filter.
    1. If the nipple came out with the oil filter, remove it from the filter, being careful to avoid damaging the threads.
    2. To reinstall the nipple, thoroughly clean the threads and apply Loctite 242 (blue) to the end with the short threads and replace it in the air oil separator tank.
  7. Clean the gasket sealing surface on the front of the tank and inspect it for damage. The surface must be free of old gasket material and smooth to ensure a good seal.
    change filter
  8. Apply a thin coat of compressor oil to the rubber gasket on the oil filter.
  9. Spin the filter onto the threaded nipple until the gasket contacts the sealing surface on the tank, then tighten the filter an additional 3/4 to 1 turn to seat the gasket.
  10. Remove the filler cap on the WHASP Tank. Fill the WHASP Tank with VMAC compressor oil until the oil in the sight glass reaches the “MAX” mark. The air compressor system holds approximately 1 gallon (4L) of oil.
    filler cap
  11. Check the oil level at the sight glass on the front of the WHASP Tank. Continue adding oil until the level is correct.
  12. Reinstall the fill cap.
  13. Start the engine and check for oil leaks.
  14. Allow the system to build to pressure (factory setting 145 psi) and for the engine speed to decrease to base idle.
  15. Turn off the engine.
  16. Once the system has sat for 5 minutes, check the oil level through the sight glass. The level must be between the “MIN” and “MAX” level indicators.
  17. Verify there are no oil leaks.

How much air compressor oil do I need?

There is a significant range in how much oil air compressors require, with no clear standard across manufacturers. VMAC air compressors hold approximately 1-2 gallons (4-9 litres) of compressor oil, depending on the VMAC system, but other systems may hold more or less oil. Read your air compressor’s manual or contact the manufacturer directly to find out how much oil your air compressor system will require.

Where can I buy air compressor oil?

Air compressor oil can be bought from air compressor dealers, hardware stores, and some auto shops. VMAC air compressor oil can be purchased through any authorized VMAC dealer.

How To Calculate Vessel Depressurization Time With Quick & Simple Logic

VMAC recently received a message from a process engineer in London who had a great question after reading our How to Work Out ‘Time To Fill’ Type Questions Using Simple Logic article. The process engineer asked:

“I was wondering if you have a similar calculation that you could share for “How to Calculate the Depressurization Time”? For instance, I have a pipe section at a certain pressure and I depressurize it to certain lower pressure through a 1″ hole (via a 1″ valve). How long would it take the pipe section to reduce pressure from P1 to P2?”

Continue reading “How To Calculate Vessel Depressurization Time With Quick & Simple Logic”

The Big Problem With Online Gas Powered Air Compressor Reviews

SearchResultsIf you’re like a lot of people, you do at least some of your research online. We rely on search engines, such as Google, to show us the best results for our searches and, when we search a term like “best air compressors”, we assume the results are mostly accurate.

Unfortunately, this isn’t always the case. There has been a significant and worrisome rise in fake gas powered air compressor reviews, and these fake reviews exist for one simple reason: affiliate sales.

Affiliate programs pay a commission to online salespeople who sell their product. And while the concept is similar to traditional commission structures, there’s one very big difference—anyone can become an affiliate salesperson. There is no interview or qualification process, and online sales people can promote literally any product that catches their fancy, air compressors included.

Review Sites Don’t Share The Best Air Compressors

As a result, affiliate-funded websites aren’t sharing the best air compressors—they’re sharing the best paying air compressors. Every time someone buys an air compressor through one of their links, they get a payout of up to 8%.

This is a big problem. Affiliate sales people limit their reviews to the products available in the affiliate catalogue. As a result, many of the best air compressors will never be considered for these review sites, because they aren’t listed on Amazon or the like. In fact, many quality air compressor manufacturers only sell through authorized dealers and would never list their products for direct sales on an affiliate website.

Who’s Writing These Reviews Anyway?

Let’s look at this from another angle: the people who are the most successful at affiliate linking are marketers, content writers, and SEO experts who know how to drive traffic to their websites. They may know a little bit about air compressors, or they may know nothing at all, because actual product knowledge isn’t a requirement for successful affiliate sales.

It’s highly unlikely that most content marketers earning about $50 to $200 per sale are purchasing and using the air compressors they are reviewing. Instead, it’s common practice in affiliate sales to rehash product descriptions, spec sheets, and other information found online, to try to entice buyers into purchasing any one of the available affiliate products.

Top “Recommended” Air Compressors

We looked at the top 10 sites that appeared in Google for “best gas air compressors” and cross-referenced their recommended products. Without fail, every single one of them was a product from Amazon’s affiliate program.

BrandExample ImageProduct(s)Amazon Affiliate?
Industrial Airindustrial air CTA5090412Industrial Air Contractor CTA5090412Yes
Ingersoll-RandIngersoll-Rand air compressorIngersoll-Rand SS3J5.5GH-WB
Ingersoll Rand IRTC2475F13GH
ROLAIR/Rol-Airrolair air compressorROLAIR 4090HK17 5.5 HP
Rol-Air Air Compressor GX200
Rol-Air Air Compressor 6590Hk18
Pumapuma air compressorPuma Gas Powered Air Compressor PUK-5508GYes
NorthStarnorthstar air compressorNorthStar Air Compressor – 8 Gallon
NorthStar Portable Gas Air Compressor – 20 Gallon
NorthStar Portable Gas Air Compressor – 30 Gallon
Makitamakita MAC5501GMakita MAC5501G 5.5 HP Gas Air Compressor
Makita MAC2400 Big Bore
DeWaltdewalt air compressorDeWalt DXCMTB5590856 Honda Powered Wheelbarrow Compressor
Dewalt Subaru Wheelbarrow Gas Air Compressor
DEWALT D55154 | 4 Gallon Electric Air Compressor
DeWalt DXCMTA5090412
Hitachihitachi air compressorHitachi EC2510E 8 Gallon Gas Powered Air CompressorYes

All of the gas powered air compressors listed above are part of Amazon’s affiliate sales program. Does that mean they’re bad air compressors? Who knows! …But that’s exactly the problem.

Affiliate programs make it impossible to know whether a suggested product is “the best” or if it’s just being promoted that way because it’s an easy pay cheque. Because of this bias, reviews for affiliate products are useless to the buyer who is trying to find legitimate information.

Why Gas Powered Air Compressors Are Popular Targets

Gas powered air compressors and small portable air compressors have fallen victim to the affiliate game, but we don’t see the same problem with PTO driven, vehicle-integrated or hydraulic air compressors. Why?

It’s because gas powered air compressors can be installed without a professional upfitter and fall into a lower price point. These two factors make it easier to buy and sell gas powered air compressors online, while more sophisticated air compressor systems rely on a true expert to help.

How Affiliate Air Compressor Sales Works

The affiliate sales process is a fairly simple concept that almost anyone can execute. Here are the 5 steps it takes to sell air compressors through an affiliate program.

  • Step 1: An internet savvy salesperson signs up for an affiliate program, such as Amazon’s.
  • Step 2: Once registered, the salesperson searches the database for products they can promote:

  • Step 3: The salesperson then adds a link to their site, writes some info about the product, and creates an article around the products they want to sell. They position these products as “the best” and provide a few different options to hook buyers.
  • Step 4: Buyers find the site and purchase the product through the affiliate link.
  • Step 5: The salesperson earns a commission.

The most challenging part is getting people to their site in the first place. But, as proven by all the affiliate links on the search results page for “gas powered air compressors”, it’s not that hard.

People are willing to create entire websites around the products they are hoping to sell and those websites can be pretty convincing.

Best Gas Air Compressors

How To Find Legitimate Air Compressor Reviews

Now that we’ve established there’s some inaccurate, self-serving information on gas powered air compressors, how do you find trustworthy reviews?

First, you need to know what to protect yourself against. The following are some tell-tale signs of an affiliate product:

  • Button that says, “Buy Now”, “Click For Price”, or similar
  • Links to products on Amazon or eBay
  • Disclosure about affiliate products

Affliate ProductDisclosures add some transparency (and legal protection) but a lot of sites don’t bother with them. For example, none of the top 10 articles analyzed for gas powered air compressors included an affiliate product disclosure.

Next, you need to find reputable sources of air compressor information. Let’s discuss a couple of options for gathering reputable air compressor reviews.

Ask Expert Air Compressor Dealers

The best way to find an honest opinion about air compressors is through local air compressor dealers. Find a couple of experts in your area and then visit them in person to ask about your options and get their feedback.

If a Dealer has got your back, they’ll listen to what you need first and then provide a solution that works for your industry and application.

Ask Your Colleagues & Peers

Peers in the industry you work in are another great source of air compressor information. Ask what they’re using and what they think of it. Just ensure you ask around, as personal opinions can vary greatly.

A few places you can get peer feedback include:

  • In-person / on-the-job
  • Facebook groups
  • Tradeshows & conferences

Most people are perfectly happy to help a fellow expert out and share their genuine opinion with you.

If you’re in the market for a gas drive air compressor, skip the online affiliate reviews and talk to someone who will give you a more objective opinion. You’ll thank yourself in the long run.

Additional Resources & Articles

You may also be interested in:

The VMAC Diesel Driven Air Compressor’s Helpful Control Box Features & Functions

D60 control box

D60 Control Box

The control box is essentially the brain of the VMAC diesel driven air compressor system. It tells the system what to do and makes decisions based on the programmed settings. The control box is also the communication hub for the air compressor, relaying important information to the operator on an “as needed” basis.
Continue reading “The VMAC Diesel Driven Air Compressor’s Helpful Control Box Features & Functions”

VMAC Direct-Transmission™ Mounted Air Compressor & Multipower System Control Box Features

The control box plays an important role in the Direct-Transmission™ Mounted air compressor and multipower systems (DTM), as it’s used to power the system and communicate with operators and service techs. In addition, the control box monitors the air compressor system on an ongoing basis to ensure its in proper working order.
Continue reading “VMAC Direct-Transmission™ Mounted Air Compressor & Multipower System Control Box Features”

9 Reasons You Should Ditch Your Tow-Behind Air Compressor

Tow-behind air compressors took the world by storm a few decades ago when they met a simple need: available compressed air, wherever you want it. It was a game-changer for a lot of industries.

But once the novelty of tow-behind air compressors wore off, their limitations became apparent. Manufacturers began to look at innovative ways to solve these problems and, in the 1980’s, companies began to invent new air compressors that would revolutionize mobile air once again.

Today, workers who need compressed air have a medley of compressor options, many of which make more sense than a tow-behind. Let’s talk about 9 reasons you may want to ditch your tow-behind air compressor:

9. Enjoy hassle-free driving and parking

If you have a tow-behind air compressor, chances are you’ve become a bit of a pro at dragging your trailer through busy freeways, reversing without jack-knifing, and circling job site lots until you find a suitable parking spot. This might even seem normal to you. But there’s a better way!

When you ditch your tow-behind air compressor and switch to a vehicle mounted air compressor instead, you’ll feel liberated. You’ll suddenly have more freedom! Driving, reversing, and parking all become second nature again, and you won’t be restricted by your trailer’s capabilities or driving expertise.

If you’re a business owner, you’ll have peace of mind knowing your staff aren’t trying to negotiate your expensive equipment in heavy traffic, park in precarious situations, or backup in environments where space can be highly limited.

Speaking of which…

8. Improve your access to job sites

Dropping your tow-behind can also improve your access to important job sites, as tow-behind compressors are clunky and can limit your work opportunities. A lot of mobile service work is in remote or off-road areas, requiring vehicles that can navigate the challenging terrain. Trailers don’t tend to do well in tricky environments, requiring additional time and care to get to the work site—if accessible at all.

7. Free up your hitch for other equipment

Tow-behind compressors take up a seriously underrated asset on your vehicle: the tow hitch! Many workers have equipment that can only be transported by a hitch, while others simply prefer to tow a trailer with their tools. If your air compressor is taking up that spot on the hitch, you’ll need to make other compromises to get your equipment where it needs to be.

In some cases, business owners send out an extra vehicle and driver just to get all the right equipment in one spot. In others, favorite pieces of equipment are left behind or require extra trips to retrieve. When you mount your air compressor to the truck itself, you free up your hitch and improve your productivity.

One fantastic example of this improved productivity is with asphalt crack sealing, where cracks need to be blown out before they can be sealed. A truck-mounted air compressor can be used to blow the dirt out of the cracks, as the hitch pulls the asphalt applicator immediately behind.

6. Have an air compressor that’s always with you

Imagine this: you’ve just arrived at your next job only to realize it needs the air compressor you left behind. You have to actively plan for every trip with your tow-behind compressor, and decide whether it’s worth bringing along. What a hassle!

Alternative mobile air compressor systems have the compressor mounted to the truck itself, which means it goes everywhere the truck goes. If you need air, it’s there. You’ll never have to experience the frustration of needing the air compressor that’s halfway across town.

5. Need fewer safety checks & measures

You probably already know that there’s more than just physical baggage with a tow-behind, and they carry the need for extra safety precautions everywhere they go. The hitch, taillights, and tires all need to be checked frequently and, if any of these parts are failing, you’re not going anywhere until they’re fixed.

In addition, tow-behind air compressors make it harder for vehicles to stop quickly and safely. That means you need to reduce your speed whenever you’re towing your compressor, wasting valuable time that could be spent on the job or with your family. Throw in tow bar regulations, a larger blind spot, and the need to monitor the compressor itself, and you’ve got a lot of extra safety checks in your day.

And let’s not forget about thieves. Tow-behind compressors are often targeted by thieves because the units can be stolen in just a few minutes. By contrast, compressors that are mounted directly to a vehicle are significantly harder to take, while UNDERHOOD air compressor systems are practically impossible to steal.

When you stop towing your air and upgrade to a mounted air compressor, a lot of these safety concerns are instantly eliminated. Your compressor becomes a part of your truck or van, requiring fewer checks and precautions, and driving becomes safer.

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4. Less engine maintenance

Tow-behind air compressors require their own engine, in addition to the engine that’s included in the vehicle that’s doing the towing. That means two engines need to be maintained for every tow-behind compressor. This maintenance takes up valuable time and money that could be used elsewhere.

While some mobile air compressors require their own engine, many don’t. Recent air compressor innovation has been highly focused on utilizing existing energy sources to power mobile air compressors. For example, gas and diesel vehicle engines, transmissions, and PTOs that run hydraulics can all be used to power an air compressor.

3. Finish your jobs fasters

Time is money. The faster you finish your work, the more time you have to wrap up your “to do” list, take on more jobs, or even just enjoy an extra long break or two. Tow-behind compressors take time to properly position, set up and use.

When you upgrade a tow-behind to an UNDERHOOD, underdeck or abovedeck mobile compressor, you’ll be amazed at how quick and easy it is to get a job done. In some cases, the prep is as fast as flipping the “on” switch and grabbing the tool, while the job itself can be just as quick.

If you’d like more time in your day (and who wouldn’t), it might be time to give your tow-behind the boot.

2. Enjoy fuel & weight savings

Tow-behind air compressors are beasts. They’re notorious for being overweight monsters and they got that reputation for a reason… The Atlas Copco XAS 110 is a relatively small tow-behind compressor that can produce 110 CFM and weighs in at 1100 lbs. By contrast, the UNDERHOOD 150 air compressor provides similar air power and weighs about 200 lbs. That’s a huge difference! Choosing a lightweight air compressor means you’ll be able to add more tools and equipment to your truck, carry more materials, or take advantage of better fuel economy.

1. Discover more innovative alternatives

One of the best reasons to ditch a tow-behind air compressor is because there are much better options out there! Tow-behinds have the luxury of being overweight space-hogs, while other compressor styles have continually adapted to market demands with fresh innovations. For example, vehicle-mounted compressors can deliver more than enough air for light to medium duty applications, and do so in a system that’s significantly smaller, lighter and more compact than a tow-behind.

With modern compressor technology, you can enjoy all the benefits of having mobile air, while also freeing up cargo space, reducing gross vehicle weight, and working more efficiently. These benefits are why you’ll see onboard air compressors mounted to the vehicles of hard-working people like construction workers, military personnel, public works and utility workers, and fleet managers.

Vehicle mounted compressors are the smart choice for people who:

  • Need mobile air regularly
  • Have light/medium-duty applications, such as
    • Post pounding
    • Pressurizing gas lines
    • Road repair & crack sealing
    • Pavement breaking
    • Sandblasting
    • Sprinkler irrigation
    • Fiber optic cable shooting
    • Utility servicing
  • Want more space for cargo or other equipment
  • Prefer less weight and strain on their vehicles
  • Have the budget to make a long-term investment

At the end of the day, you deserve equipment that helps you get your job done quickly, easily, and safely. Tow-behind air compressors are necessary for some types of work, but there are a lot of downsides that you may have to endure. If you have the option to upgrade to a modern mobile air solution, then it’s time to ditch your tow-behind air compressor!

View this post as a shareable infographic here!

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Top 3 Challenges Caused By Over-Weight Heavy Duty Pickup Trucks

Gross vehicle weight ratings (GVWR) and payloads can differ from vehicle to vehicle and it’s important to know what you’re working with when specifying or upfitting a specific heavy duty pickup truck. Before we get into the details on why it’s important to pay attention to vehicle weight ratings, let’s go over some important concepts: GVWR and Payload.

Continue reading “Top 3 Challenges Caused By Over-Weight Heavy Duty Pickup Trucks”

Compressed Air Filtering Basics – Contaminants, Filters & More!

Take a deep breath. Breathe out. Breathe in… Now, let’s talk about all the contaminants in that air you’re breathing!

Atmospheric air is naturally contaminated. In addition to oxygen, air also contains water vapor, dust and dirt, and a medley of other filthy particles depending on the surrounding environment. The average metropolitan area, for example, contains approximately 4 million dirt particles per cubic foot of air.

When air is compressed, some of those contaminants need to be filtered out. Contaminated atmospheric air can cause damage to air compressors and air tools, and isn’t acceptable for certain medical and industrial applications.

But atmospheric air isn’t the only source of contamination for compressed air. Air compressors contribute their own share of pollution from wear particles and, if the compressor is oil-lubricated, carbonized compressor lubricant.

Between atmospheric air contamination and air compressor system contamination, there’s a lot of particles dirtying up our compressed air. Fortunately, we have compressed air filtering to save the day.

A Bit of Dirt Never Hurt Anyone…

Don’t worry about that dirty air you’re breathing. Your lungs act as your body’s filtration system, removing contaminants after they’re inhaled. Air compressor systems obviously don’t have lungs, but they do filter out air contaminants in other ways. Better still, a little contamination is usually okay.

Contaminated particles are measured in microns. The bigger the particle, the bigger the micron. Most fine particle tests use 0.3 micron as the standard to measure liquid or solid particle filtration. If a filter tested on this particle size proves to be 100 % efficient, then it’s fairly safe to say this filter can remove any particle above this size.

Many compressed air applications can handle contamination levels well above 0.3 microns. Tire service, construction, and most other mobile air compressor applications tend to tolerate quite a bit of contamination without problem. Operators with these types of jobs can get away with a more basic filtration system, such as an intake filter, which eliminates contaminants in the 30 to 40 micron range.

Industrial air compressor applications tend to be less tolerant of contamination than mobile applications and up to 80 % of industrial contamination is smaller than 2 microns. Therefore, many industrial air compressors need better filtration than mobile air compressors. Industrial air compressor systems often utilize advanced dry particulate and coalescing filters that can clean air down to 0.01 microns. For applications that require super-clean air for OSHA purposes, an additional charcoal activated filter may also be used.

However, these industrial applications are the exception. Outside of massive factories and industrial enterprises, most people use mobile-style air compressors that can tolerate quite a bit of contaminants and don’t need to think twice about their air compressor’s filtration capabilities.

What Contaminants Are In Compressed Air?

Now that you realize just how contaminated our air is, let’s talk about what it’s contaminated with.

Compressed air contains three types of contaminants:

  • Dry particulates
  • Vapors
  • Aerosols

Dry particulates are exactly what they sound like: dirt and other tiny solid particles. Vapors are the gas-forms of particles that condense into liquids at lower temperatures—for example, water. (The gas state is what allows these “liquids” to exist in air.) Meanwhile, aerosols are very fine solid particles that get trapped in air or gas, becoming suspended. Airborne dust is one familiar example of an aerosol.

Each type of contaminant has its own unique characteristics and properties, requiring their own filtration methods.

There are two primary types of filtration that are used in compressed air systems:

  1. Dry Particulate Filtration
  2. Vapor & Aerosol Filtration

In the next couple sections of this article, we’ll talk about these filtration types and the filters used to eliminate dry particulates, vapors, and aerosols.

The Principles of Dry Particulate Air Filtration

Here’s where we get technical. We already know that most contamination in a compressed air system can be removed simply by filtration. However, it’s important that your air compressor systems use the correct type of filtration for the particles being filtered.

Dry particulate filters rely on three principles to separate contaminants from the air:

  • Direct interception
  • Inertial impact
  • Diffusion & Brownian movement

Direct interception affects the larger particles in an air stream, which are literally sieved out through a filter.

Inertial impact occurs when a particle traveling in an air stream is eventually unable to negotiate the torturous path between the filter fibers and cannot change direction as quickly as the air stream. The contaminants then collide with a fiber and become attached to it.

Diffusion or Brownian movement affects fine particles. With diffusion, small particles merge with other gas particles and begin to move erratically. This erratic movement is called Brownian movement. As these particles move separately from the compressed air flow, they are more likely to become trapped in the filter.

Air Filtering though diffusion

All three of these principles work together in a dry particulate filter to capture and trap contaminants from the compressed air.

If you’re interested in reading more about the principles and physics behind air filtration, check out this “Mechanism of Filtration For High Efficiency Fibrous Filters” report by TSI.

Vapor & Aerosol Filtration for Compressed Air

Vapors and aerosols slip past dry particulate filters, which may require their own filtration systems. In this case, there are two options that may be utilized:

  • Coalescing
  • Adsorption

Coalescing filters trap moisture and oil. The compressed air enters through the inlet port and travels down into the filter, passing through a filter media before it leaves through the discharge port. Moisture and oil droplets bond together during this process, forming larger droplets that then drip into a moisture trap below.


Coalescing filters are commonly used in oil-injected air compressors, such as rotary screw air compressors. In VMAC systems, these filtration methods include a couple types of dry particulate filters, as well as a coalescing filter.

Adsorption filters help eliminate vapors and lubricants, using activated charcoal or similar chemicals to bond with the vapor molecules. Adsorption comes into play when vapors must also be eliminated from a system. Adsorption filters are typically only used in specific industrial applications.

Filtration Systems of Rotary Screw Air Compressors

Reciprocating air compressors that don’t use oil can often get away with just a dry particulate filter. That’s because the contaminants in atmospheric air are negligible for most construction and automotive applications, travelling through the air compressor without causing much problem.

However, oil-injected rotary screw air compressors require additional levels of filtration. The oil used to lubricate the rotors is necessary for this style of air compressor, but that same oil needs to be cleaned and separated from the air.

Therefore, rotary screw air compressors require two types of filtration systems:

  • Dry particulate filters
  • Coalescing filters

In a typical VMAC air compressor, you’ll find both types of filters throughout the system:

  1. Air filter: atmospheric air entering the system goes through a dry particulate air filter.
  2. Coalescing filter: Air that leaves the rotors, now mixed with oil, goes through a coalescing filter, which separates the oil from the clean air. The oil gets recirculated while the air exits the system.
  3. Oil filter: The separated oil then goes through the oil filter, which is another dry particulate filter that separates particles from the oil.filters

It’s these same filters that occasionally need to be replaced and will be included with VMAC’s service kits. Replacing the air filter, oil filter and coalescing filter ensures the air compressors continue to trap contaminants and keeps your air compressor in tip-top shape.

FAQ: Air Compressor Regulations in California

California has some of the toughest regulations in the United States across many industries and air compressors are no exception. Further, California’s legislation often pioneers the laws adopted by the rest of the nation. From anti-idling laws to air receiver tank sizes, we’ll help you understand all of California’s current air compressor regulations in this FAQ.

Who sets air compressor regulations in California?

Regulations are typically set by the U.S. government or state governments. California’s clean air regulations are currently determined by the California Air Resources Board, which has 12 members appointed by the Governor and formalized through the Senate. Other regulations, including air compressor regulations, are currently decided by the California government’s Department of Industrial Relations.

Can I idle my diesel truck to run an air compressor in California?

The short answer is “yes.” California has some of the toughest anti-idling laws out there, restricting the idling of heavy-duty diesel vehicles over 14,000 lbs for more than five minutes. Light- and medium-duty diesel trucks under 14,000 lbs are currently excluded from the restrictions.

However, even heavy-duty vehicles can idle if they are operating a power take-off device. Direct-Transmission Mounte air compressors and hydraulic air compressors are both examples of power take-off devices. In addition, the UNDERHOOD™  70 Green Series has intelligent digital controls that turn your truck engine off when air isn’t needed and turn the engine back on when air is needed again, giving you yet another option in spirit with California’s clean air regulations.

Can I idle my gasoline truck to run an air compressor in California?

Yes, there are currently no idling restrictions for gasoline vehicles. However, proposed legislation suggests expanding the anti-idling regulations to all vehicles that are allowed on highways. This includes both gasoline and diesel trucks, vans, and cars. If you’re planning for the future, it’s safest to assume anti-idling laws will apply to your vehicle in the coming years.

Do I need a permit for my air compressor?

You don’t need a permit for an air compressor but you may need one for your air compressor’s air receiver tank. A permit is required if you have an air receiver tank that exceeds 1.5 cubic feet (11.2 gallons) or 150 psi.

Fortunately, air receiver tanks over 1.5 cubic feet that don’t exceed 25 cubic feet (187 gallons) or 150 psi will receive a one-time permit called an “indefinite permit” at their first inspection. Indefinite permits don’t need to be renewed. Most mobile air compressors will fall into this one-time-permit category.

Because the permits are for the receiver tanks, air compressors without an air receiver tank don’t require a permit. Therefore, many operators avoid air receiver tank regulations by choosing a rotary screw air compressor that can meet their CFM requirements without an air receiver tank.

Do I need inspections for my air compressor?

If your air compressor has an air receiver tank that requires a permit, you will need to have the receiver tank on your portable air compressor inspected every 3 years. Air receiver tanks that aren’t portable but require permits must be inspected once every 5 years.

However, air compressors with air receiver tanks that are 25 cubic feet (187 gallons) or less and have a maximum pressure of 150 psi, are given an “indefinite permit” when first installed. These permits are always in effect, which means your air receiver tank doesn’t need to be inspected.

Air compressors that don’t require a permit are never inspected.

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What air compressors help me avoid permits, inspections, and regulations?

The current California regulations for air compressors are focused on air receiver tanks, not the compressors themselves. Therefore, choosing a rotary screw air compressor without an air receiver tank is your simplest bet, as there is no need for permits or inspections. (By contrast, all reciprocating air compressors need an air tank.)

If you do need an air receiver tank, the next simplest option is an air compressor with an air tank that holds up to 1.5 cubic feet (11.2 gallons) of air and operates at 150 psi or less. These air receiver tanks do not require permits. VMAC has several air compressor and receiver tank options that meet these requirements, including air compressors that don’t require an air receiver tank at all, and air compressors with a recommended 6-gallon (150 psi) or 8-gallon (150 psi) low profile air receiver tank.

If you need even more air, you can minimize the need for permits and inspections by choosing an air compressor with an air receiver tank that has a maximum working pressure of 150 psi and holds less than 25 cubic feet (187 gallons) of air. These air receiver tanks will need an inspection before going into service but are given an indefinite permit at that inspection, which eliminates the need for future inspections or permits. VMAC air compressor systems with a 12-gallon (150 psi) low profile air receiver tank fall within this category.

How Clean Air Regulations Impact Vehicles With Air Compressors

Federal and state air regulations play an important role in keeping communities safe and healthy and have driven significant innovation in the clean energy sector. But what does this mean for the mobile air compressor industry, which often requires an idling engine to power the air compressor?

In this article, we’ll break down the major players in air regulations, including California state and U.S. federal governments, and talk about how they impact you and your business.

The Federal Clean Air Act

The Federal Clean Air Act was first enacted in 1970 and later revised in 1990. This Act sets out guidelines and requirements for the Environmental Protection Agency (EPA) and individual states to protect people’s health and the environment.

The objectives of the Clean Air Act include:

  • Improve air quality
  • Improve visibility
  • Protect the ozone layer
  • Reduce common & toxic pollutants
  • Reduce acid raid

The EPA works with individual states to enact different aspects of the Clean Air Act. Some objectives give states more autonomy than others.

Improve air quality & visibilityStates are responsible for implementing enforceable plans to reduce pollutants in protected areas; the EPA provides guidance
Protect the ozone layerEPA issues & enforces rules for the use and disposal of chemicals known to deplete the ozone
Reduce common pollutantsEPA develops standards, states are responsible for creating enforceable plans to meet the standards
Reduce toxic pollutantsEPA controls national limits for major sources, while states can elect to take on partial or complete enforcement of the limits
Reduce acid rainEPA implements, tracks & monitors compliance with the federal Acid Rain Program

California Air Regulations Set A Higher Bar

California has struggled with air quality for decades and, in 2002, became the first state to set clean air standards that go above and beyond the Clean Air Act. Over the next decade, another 13 states followed California’s lead and created state-based legislation that requires higher standards.

This legislation has resulted in more efficient vehicles that produce fewer emissions. California essentially forced the auto-makers to create lower emission cars and, interestingly, the auto industry complied with little fuss.

However, a change in political perspective disputes California and other states’ autonomy over cleaner air. On August 2, 2018, the acting EPA chief Andrew Wheeler announced that California will no longer be allowed to set their own rules; instead, the state will only need to follow the federal requirements. California is expected to challenge this decision in court.

United States Anti-Idling Laws

The federal government has not issued anti-idling laws. Instead, the majority of states have implemented their own anti-idling regulations. Because California set the initial bar for environmental regulations, many states have followed their example in anti-idling:

California Anti-Idling Rules

  • No idling longer than 5 minutes
  • Minimum $300 fines
  • Exceptions include:
    • Service or repair vehicles
    • Work trucks using power takeoff (PTO)
    • Certified Clean Idle vehicles
    • Emergency or health & safety vehicles

Individual cities within a state can set additional regulations on idling, including specific rules and fine amounts. To see the regulations in your county or state, check out the American Transportation Research Institute’s Compendium of Idling Regulations.

Fortunately, most states let vehicles idle if they are performing work-related tasks. Operators who use air tools are typically allowed to use air compressors that utilize the vehicle’s engine, such as an UNDERHOOD™ air compressor, or PTO-drive systems like a Direct-Transmission Mounted air compressor.

Air Compressor Manufacturing Regulations

Reputable air compressor manufacturers have regulations and procedures that should be followed in the creation, assembly and installation of their air compressors. However, most of these regulations are focused on safety and engineering, and don’t pertain to air quality.

However, there is one notable exception: The EPA’s “Clean Air Nonroad Diesel Rule” requires manufacturers to meet exhaust emission standards for all small diesel engines, including those used in air compressors. This regulation has been in full effect for all nonroad diesel engines since 2015.

Similarly, truck manufacturers are also required to follow strict regulations and guidelines when developing their product lines. For example, California’s Air Resources Board recently passed regulation to increase the greenhouse gas emissions standards for medium- and heavy-duty engines and vehicles within that state. These changes need to be taken into account when designing engine-driven air compressors, like the UNDERHOOD™ air compressor.

While it’s unreasonable to expect consumers and operators to be aware of the regulations developed for manufacturers, operators can help protect themselves by purchasing their products from a reputable air compressor manufacturer that is committed to implementing a high degree of standard and quality control.

How Do Clean Air Regulations Impact Air Compressor Operators?

Fortunately, clean air regulations don’t tend to impact workers who are operating vehicle mounted air compressors. Reputable air compressor manufacturers ensure their products stay up to date with federal emissions regulations, while even the strictest states, like California, have anti-idling exceptions that allow operators to run their vehicles for the sake of their work. At the end of the day, most jurisdictions give a free pass to pneumatic tool operators including tire techs, construction workers, and other roadside operators.

How Many CFM Do I Need To Run Air Tools? – CFM Chart

pneumatic-toolsIt can be tough to know how many CFM you need in an air compressor to operate your air tools. Too little CFM and you won’t be able to run your tools continuously—or at all!—and too much CFM could mean you’ve overspent on your air compressor.

To help you find the compressor that’s right for you, we’ve developed this helpful air tool consumption chart. But before we get into the CFM consumption chart, let’s talk a little bit about why CFM matters to you…

Jump To The Air Tool Chart

Pneumatic Tool CFM Requirements

Every pneumatic tool is rated for CFM, or “Cubic Feet Per Minute”, and the same goes for air compressors. CFM represents the volume of air that is produced by your air compressor or required by your air tool.

Your tools’ CFM requirements give you an idea of what you need your air compressor to do, but it’s not enough to simply match the air tool’s rating and the compressor’s rating 1:1. In this article, we’re going to help you better understand how many CFM you need to run your air tools.

Continuous vs. Intermittent Use

Air tools need a CFM that matches the manufacturer’s guidelines, but what air tool you have and how you use them matters. For example, if you’re using an impact wrench, are you:

  1. continuously holding the trigger down while you work, or
  2. are you using it in quick bursts with short breaks in between use, allowing the air compressor to catch up?

Do you use tools for lengthy periods of time? Or are all of your tools only used for a few seconds here and there? These are the types of questions you need to ask yourself when you start to determine your CFM needs.

If your application requires you to run air tools for an extended length of time, an air compressor with a 100% duty cycle is recommended so you can operate your tools continuously.

By contrast, tools only used intermittently may be able to get away with a less powerful air compressor that uses an air receiver tank, which may save you money.

Multiple Tools

Another common scenario that impacts CFM requirements is using multiple tools at once. Running more than one tool at a time can be a highly efficient way to get things done, especially when you have two or more people working on a single job. However, if you’re running multiple tools at the same time, you’ll need to combine the CFM requirements of each of the tools that will be running to determine your total CFM requirement.

For example, let’s say your team uses the same air compressor to power a ½” drill that requires 30 CFM, and a grinder that requires 60 CFM. If you use these tools at the same, you would add 30 CFM + 60 CFM for a total demand of 90 CFM. When choosing equipment, you would likely need an air compressor that can reliably produce 90 CFM of air.


6-gall-tankAir Receiver Tanks

Air receiver tanks are another factor you should consider when determining your CFM needs. Many air compressors require an air receiver tank—in fact, this is always the case with reciprocating air compressors. “Recips” need an air receiver tank and can only run at 100% duty cycle until the receiver tank runs out of stored air (or the compressor overheats from working too hard – but that’s another story…)

In some scenarios, air receiver tanks can help a lower CFM air compressor keep up with a higher CFM demand, and can be a good strategy when you don’t want to invest in a higher CFM air compressor. These air receiver tanks can vary in size from 5 gallons to over 100 gallons.

Air Tool Consumption Chart

Still wondering what this means for you? We’ve put together a handy air tool consumption chart to help give you an idea of how many CFM you need to run your air tools. We’ve also included 6 tips for choosing an air compressor, the average CFM at load (100% duty cycle), the suggested air compressor CFM, and our recommended rotary screw air compressor based on your CFM needs.

Here’s a sneak peek:

30-40 CFM Air Compressor60-70 CFM Air Compressor150 CFM Air Compressor
¾” impact wrench1” impact wrenchTrenchless piercing tools
Chipping hammersSandersPneumatic saws
2” horizontal grindersLarge (3”+) vertical & horizontal grindersPost-pounders
Tire inflationOTR tire inflationRock drills
Die grinders60lb jackhammer90lb jackhammer
Backfill tampersBackfill tampersAir knives

To view the rest of the info, download our full air tool consumption chart here!

VMAC’s Rotary Screw Advantage

Depending on the product, VMAC air compressors deliver anywhere from 30 to 140 CFM at 100% duty cycle, which means you’ll never have to wait for air. VMAC air compressors also don’t require a bulky air receiver tank, thanks to the rotary screw technology, which allows them to operate at max efficiency 100% of the time. Not only are VMAC air compressors lighter and smaller, you’ll get jobs done faster, improve productivity, and be more profitable.

Explore your air compressor options

Learn more about choosing a mobile air compressor

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Air Tool Pressure + 5 Reasons To Use The Right PSI For Air Tools

If your air tools struggle to live out their warranty or require more maintenance than the manufacturer’s guidelines state, there’s a good chance you are using too much air pressure. This is extremely common and many service operators over-pressurize their pneumatic tools as a standard operating procedure.

The assumption is you get more power out of a tool if you apply more pressure. While this is true some of the time, it doesn’t apply all of the time and—in almost all cases—leads to tool breakage or worse…

In this article, we’ve put together a list of reasons you should always use the proper pressure for your air tools:

5. Reduce Expensive Tool Repairs

Using too much pressure can cause your air tools to wear out or break a lot sooner than they should. Here are the most common pneumatic tool repairs caused by excessive air pressure:

Blown seals: The more pressure you use, the bigger the opportunity for blown seals. You might as well use your shop-vac to suck the extra cash out of your pockets if you don’t protect yourself from blown seals because they result in VERY expensive repair bills.

Anvil breakage: There couldn’t be a better example of “cutting off your nose to spite your face” than anvil breakage, and it’s far too common. Guys apply more pressure to their impact wrench to get more torque, which works. Everyone is happy, the job gets done faster. But then the anvil sees higher stresses and can crack or break and the tool is down for repairs, wasting any time you saved with extra torque and resulting in significant costs for repairs.

Bearing failure: In addition to blown seals and anvil breakage, using too much pressure is one of the most direct causes of bearing failure. If you’ve worked with air tools for awhile, you know bearing failure is an expensive repair and you probably also know that if the bearings go, you already have many more damaged parts to repair. It’s not a good situation!

Vane motor breakdowns: As little as 20 psi of excessive pressure in a vane motor system can half the life of an air tool. Most tools are rated at 90 or 100 psi, so using 120 psi regularly ensures you will be replacing expensive air tools in half the time you should have to.

4. Maintain Your Tools’ Efficiency

In many cases, a broken tool doesn’t happen in an instant. Instead, tools wear down over time until they reach a point of failure. The more a tool is worn down, the less efficient seals and other components become, even if it’s still working. This results in leaked air, which essentially means the tool needs even more air to run than it normally would.

By using the right pressure for your tools, you reduce wear and improve tool efficiency. If you care about getting the best performance out of your tools, stop using too much pressure.

3. Stop Overpaying For New Tools

Tools that break or fail and can’t be repaired will need to be replaced, and we don’t need to tell you that new tool costs add up quickly! It’s an unnecessary expense that could have been reinvested elsewhere.

Consider this: when you buy an air tool from a manufacturer or dealer, they give you a price, and you either agree to pay the price or negotiate a discount. You never ask them to take more money from you. Yet, if you don’t take proper care of your air tools, you might as well do exactly that.

Treat your tools with respect and save your money for better purchases.

2. Prevent Dangerous Accidents

Let’s put the financial impacts aside because you won’t be thinking about expenses when you or one of your employees suffers a devastating or fatal injury. It’s easy to shrug off safety regulations and assume a serious injury would never happen to you or your team, but pressure safety warnings exist in manufacturers’ guidelines for a reason.

We’ve heard stories about tool technicians being killed when an over-pressured grinder explodes, because it’s operating at speeds much higher than the manufacturer’s safety ratings. You don’t want your team to be the one that proves these urban legends are true.

But even if the stories are false, the pneumatic tool manufacturers are concerned enough to include pressure rating warnings in their manuals. For example, here’s what Central Pneumatic says in their ¼” air angle die grinder manual:

“Over pressurizing the tool may cause bursting, abnormal operation, breakage of the tool or serious injury to persons. Use only clean, dry, regulated compressed air at the rated pressure or within the rated pressure range as marked on the tool. Always verify prior to using the tool that the air source has been adjusted to the rated air pressure or within the rated air-pressure range.”

Protect your team and your business by keeping everyone safe. Follow the pressure guidelines and you can prevent serious consequences.

1. Lower Your Fuel Consumption

Last but possibly not least, using the proper pressure will lower your fuel consumption.

The higher the pressure, the higher the volume of air that’s consumed. This is a problem because higher air volumes require more energy, which means you are spending a lot of extra horsepower on wasted air. Further, higher horsepower equals higher fuel consumption, which increases operating costs and throws low emission targets in the trash.

The Real Reasons Your Tools Aren’t Performing

Manufacturing engineers create and test tools using the same psi ranges they publish in the tools’ manuals. If your tool isn’t performing as well as you think it should, the pressure rating isn’t the problem. Instead of cranking up the pressure, take the following steps:

  1. Reflect on your expectations: Is it possible that you simply want a tool that performs better than it’s supposed to? If so, it may be time to consider why you want more power and whether it’s something you really need…
  2. Check the power management switch: If your tool has a power management switch, you wouldn’t be the first person to overlook it. Double-check whether your tool has this switch and ensure it’s on the proper setting.
  3. Check the pressure at the tool: Attach a pressure gauge between the end of your hose and your air tool to confirm whether the air pressure is at the maximum recommended pressure. Each air compressor design is different, and some systems can lose pressure before the air reaches the tool. If the air is losing pressure before it meets the tool, you can try turning up the pressure a bit, but only until it reaches the manufacturer’s psi recommendation.
  4. Check the hose size: A hose that’s too small can cause pressure drops that are easily remedied by an upgrade. Make sure you’re using the right hose size for your application. We talk more about how hose size impacts airflow in this article.
  5. Check the size of everything else: Hoses aren’t the only air compressor component that might be too small. Also check the size of your connectors, fittings, filters, regulators, and lubricators, and ensure they are big enough to handle the task at hand.
  6. Confirm the air compressor’s CFM: An air tool needs the right psi and the right CFM to operate properly. Double-check that the CFM capabilities of your air compressor match the needs of your tools. You can learn more about the CFM needs for your air tools here.
  7. Consider your air compressor type: A reciprocating air compressor has to build up air and then quickly loses pressure. But if you require higher pressure because you’re trying to hit hard and fast to beat the clock, your air compressor type is likely the problem. Instead, upgrade to a rotary screw air compressor that can maintain CFM and PSI for significant periods of time. Find out more about rotary screw vs. reciprocating air compressors here.
  8. Call the tool manufacturer: If everything above checks out, call the manufacturer. Their support team will be able to help you troubleshoot performance issues with your tool.
  9. Upgrade your tool: If you’ve gone through the list above and your tool isn’t getting the job done, it’s likely time for an upgrade. Tools that have enough air and are powerful enough for a job will work properly and efficiently at their recommended psi setting. If your tool isn’t performing under the proper conditions, you need a better tool.

One last tip—don’t use sound when determining if a tool is working. We’ve met operators who think their tool or air compressor is too weak because their tools get quieter after the air has run for a few seconds, even when the tools are operating just fine! Instead of listening, look at how the tool is performing to determine whether it gets the job done in a normal amount of time.

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Use The Proper Pressure For Your Air Tools

At the end of the day, too much pressure for your air tools can be a costly mistake. From equipment failure and repair costs to health and safety risks for your team, there are a lot of reasons you should simply use the right pressure.

It’s unlikely all the terrible things in this article will happen to your team and equipment if you use too much pressure. However, it’s probable you’ll encounter at least some of the issues, including the frustration that goes along with them.

By contrast, eliminating the issues caused by too much pressure is easy to do. Use the proper pressure for your air tools and rest assured you’re getting the most out of your tools.

You may also be interested in:

How to Choose A Mobile Air Compressor For Your Work

Mobile air compressors are a beautiful thing. They make life easy by offering mobile air on demand, wherever you are, and can power high-quality pneumatic tools. But choosing a mobile air compressor can feel overwhelming, with an abundance of information and decisions to consider.

Fortunately, we’re going to make it easy for you to narrow down your options. In this blog, we’ll talk about the simple steps you should follow to choose the best mobile air compressor for the jobs you do.

1: Determine your CFM and PSI requirements

The very first thing you should do is determine your air needs. Pneumatic tools all require different amounts of air and these needs vary quite a bit, even within a single type of tool, which is why you should find out what your tools need as your first step.

Air power is typically measured in two metrics: CFM and PSI. CFM or “Cubic Feet per Minute”, is the amount of air that’s being delivered. PSI or “Pounds per Square Inch” is the amount of force behind that air.

Most tools are rated to run optimally at 80 to 110 PSI, so you’ll want to find an air compressor that can deliver the right CFM at the PSI your tools require. The best way to determine your PSI and CFM requirements is to review all the tools you will be using and check with the manual or manufacturer. If you plan to use more than one air tool at the exact same time, you’ll need to add the CFM requirements of each tool together to determine your total CFM requirements.

For now, you can get a general idea of your CFM requirements here.

2: Decide on a Rotary or Reciprocating Air Compressor

The next step is to determine what type of compressor you need. VMAC exclusively manufactures rotary screw air compressors because they last significantly longer, are a higher quality, can provide air instantly while maintaining constant air flow, and are smaller and lighter. But let’s take a quick look at the pros and cons of both types of air compressors:

Rotary Screw Pros:

  • Continuous airflow / 100% duty cycle
  • Longer lifespan
  • Larger quantities of air
  • Higher CFM per hp
  • Quieter
  • Smaller
  • Lighter

Rotary Screw Cons:

  • More expensive up front
  • Requires skilled maintenance

Reciprocating Pros:

  • Capable of high pressures
  • Less expensive
  • Easier maintenance

Reciprocating Cons:

  • Interrupted flow rates
  • Low life expectancy
  • Maintenance costs
  • Excessive heat
  • Louder
  • Heavy
  • Bulky
In a nutshell, if you’re looking for a cheap way to get your jobs done for the next year or two, a reciprocating air compressor is probably the way to go. But if you need reliable mobile air for the next 5 to 10 years and are willing to pay more for a better-quality solution, rotary screw air compressors are your best bet.

You can read more about reciprocating air compressors versus rotary screw air compressors in this blog.

3: Consider Tow-Behind or Vehicle-mounted

Now it’s time to think about how you want to move your air compressor around. There are two major contenders that you can consider:

  • Tow-Behind Air Compressors
  • Vehicle-mounted Air Compressors

Tow-behind air compressors are air compressors that are mounted onto a trailer and towed by the hitch of your vehicle. They’re not our favorite option and we outline the reasons why don’t love tow-behind air compressors in this blog. However, if you need high CFMs, plan to leave your air compressor in the same spot for weeks or months at a time, or you simply love towing things around, a tow-behind air compressor may be worth considering.

Otherwise, you’re looking at vehicle-mounted air compressors as your best bet. There are two common ways that air compressors are mounted to a vehicle:

1. The simplest way to mount an air compressor is to simply attach a compressor with its own diesel or gas engine onto the back of a truck (or in a van’s cargo hold). Here’s a photo from TiNik Inc. that shows off this style perfectly:


Mounting air compressors in this way is relatively easy and inexpensive, which is why a lot of operators love this style.

2. The other way to mount an air compressor is to intertwine the air compressor components with a vehicle’s existing components. These installs are sophisticated and most people can’t even see the air compressor because it’s tucked away in the engine compartment. Take a look:


Engineers at companies like VMAC work with vehicle manufacturers to determine the best way to install these air compressors, ensuring the vehicle warranties are always still in effect. However, whether an air compressor can be mounted in this manner depends on the specific vehicle. You can see if your vehicle is compatible here!

4: Determine Your Power Source

Air compressors can be powered by many different sources. If you’ve decided on a tow-behind air compressor, you’ll be limited to gas or diesel engines. In this case, it makes sense to just go with an air compressor that uses whatever type of fuel your vehicle already takes, for simplicity.

But if you’re going ahead with a vehicle-mounted mobile air compressor, you have options! Some air compressors have their own gas or diesel engines, while others can integrate into a truck’s existing engine or hydraulics. Air compressors that mount under the hood use these existing systems, which makes them convenient.

As one example, here are the product lines that VMAC offers for various power sources:

VMAC Systems table

Consider what type of power sources you already have available and think about whether they will work for your air compressor. Using your vehicle’s engine or existing hydraulics can be a highly convenient way to power an air compressor. However, if that doesn’t work for you or your vehicle isn’t compatible, air compressors with their own gas engine or diesel engine can be just as effective in getting the job done.

5: Find An Upfitter That Knows Air Compressors

By this point, you should have an idea of what you’re looking for in an air compressor and be able to answer some simple questions. Let’s break them down:

  • How much CFM do you need?
  • Rotary screw or reciprocating?
  • Tow-behind or vehicle-mounted?
  • What is the power source?

Now you’re ready to talk about specific brands and options. If you’ve decided to go ahead with a vehicle-mounted rotary screw air compressor, your next step will be to find an upfitter. The upfitter will be able to share the specific options available to your vehicle and provide you with quotes for purchasing and installing the air compressor. Check out our Dealer Locator to see our favorite upfitters!

If you’d rather have a reciprocating compressor or a tow-behind air compressor, there are numerous options available. Again, we recommend working with an upfitter who knows air compressors well and can help you choose the best compressor for your individual needs.

Curious what other operators are using? Find out in these posts:

The Big Benefits of Rotary Screw Air Compressors In Texas

Not all air compressors are created equal. Performance, quality, safety, and adherence to local laws all vary between manufacturers and even individual air compressor models. Rotary screw air compressors do an excellent job of performing under the Texas heat, while also following local bylaws and regulations. In this article, we’ll break down 6 reasons you should choose a rotary screw air compressor for your work in Texas.

Improved Performance & Function

1. Prevent air compressor failure

You don’t stop work when the temperatures hit the high 90’s and your air compressor shouldn’t either! Air compressors already generate a lot of heat, which is tackled by cooling systems, but when the summer sun combines with the air compression process, some air compressors get too hot to handle—or function!

Hot air compressors cause many problems, including:

  • Lower air flow & efficiency
  • Excessive water vapor
  • More energy & fuel required
  • Unsafe for workers
  • Air compressor failure

Air compressors are comprised of many moving parts that cause heat to increase rapidly. Reciprocating air compressors can reach temperatures of up to 500°F on a regular basis. Compare that to a rotary screw air compressor, which uses an oil injection system to operate at half that temperature, and it’s clear which compressor has the advantage right out of the gate. If you need your air compressor to work 100% of the time, rotary screw is the way to go.

2. Minimize water vapor

As Texas temperatures and humidity rise, the amount of water in the compressed air increases as well. Increased water volume can lead to higher maintenance costs due to air compressor rust, breakdown, and component failure. The hotter the air, the more water you have in your system.

Because rotary screw compressors don’t run as hot as other compressor types, the amount of water created during air compression in minimized, reducing the water that can get into your air compressor, tools, and final application. This smaller volume of water is easier to remove, giving rotary screw air compressors a big advantage over reciprocating air compressors.

When handled properly, most people don’t see the extra water in recip compressors. That’s because reciprocating compressors always require an air receiver tank, which helps capture and drain most of the visible water from the compressor. But even if you don’t see it, that water is still there.

3. Work at 100% Duty Cycle

While this isn’t Texas specific, it is a big deal: rotary screw air compressors supply air on demand, which means you can get to work within seconds of turning it on. The convenience of instant air is why so many workers have become loyal to rotary screw air compressors, always choosing them over the reciprocating/piston-style air compressors.

4. Reduce weight & save space

Rotary screw air compressors are smaller than reciprocating compressors, resulting in trucks that are lighter and have more available space. For example, VMAC’s G30 gas driven air compressor weighs only 205 lbs, while similar-CFM reciprocating-style air compressors easily weigh 400 – 500 lbs and take up twice the amount of space (because they require a large air receiver tank.) They’re hogs!

Choosing a lightweight rotary screw air compressor means you’ll be able to add more tools and equipment to your truck, carry more materials, or take advantage of better fuel economy.

Adheres to Texas Regulations & Bylaws

5. Circumvent vehicle idling restrictions

Essentially all Texas cities have signed a memorandum that prohibits trucks lighter than 14,000 pounds from idling more than five minutes at a time. Operators working with light-duty trucks, such as the Ford F250 and F350, aren’t allowed to idle within most Texas cities—including Austin, Dallas, Houston, and Fort Worth.

Fortunately, clever system designs eliminate the issue. Above-deck air compressors like the G30 gas drive and D60 diesel drive allow operators to utilize a powerful rotary screw option that doesn’t require idling. Because these air compressors are mounted to the vehicle itself, they are always with you and ready to work—no idling needed!

For those who can’t go without an air compressor that uses the vehicle’s engine, there’s also the UNDERHOOD™  70 Green Series air compressor, which uses intelligent digital controls to turn your truck off when you’re not using air and then back on when you are.

6. Avoid noise complaints

Busy urban areas are already littered with noise and some Texas bylaws forbid workers from making more of it. For example, Fort Worth doesn’t allow noise in a commercial area to exceed 80 decibels between the hours of 7 am to 10 pm. Residential areas are even more restricted, with a maximum 70 dBA during the day.

Mobile air compressors are loud. That’s just a fact. But rotary screws are known to be quieter than their reciprocating counterparts, because the two rotating screws don’t actually touch one another while they compress air. As a result, rotary screw air compressors are more likely to fall within noise bylaws.

But even when they don’t, the neighbors are much less likely to file a complaint when you’re in and out within minutes. Rotary screw air compressors are faster and more convenient than other compressor types, allowing you to quickly complete your jobs and minimize any disturbance.

The Right Air Compressor For Texas

To sum it all up, there are a lot of benefits to using a rotary screw air compressor in Texas, including:

  • Better heat performance
  • Working at 100% duty cycle
  • Reducing discharge air temperatures
  • Minimizing water vapor
  • Circumventing idling restrictions
  • Avoiding noise complaints

The right air compressor makes your job easier by ensuring you can get your work done quickly, efficiently, and safely. Rotary screw air compressors do all of these things, while holding up in the tough Texas environment.

If you’d like to read more about the advantages of rotary screw air compressors, check out some of our other blogs on this topic: