Air Compressor Pressure Relief Valves: Purpose & Testing

What Are Pressure Relief Valves, And How Do They Work?

A compressed air pressure vessel and its operator must be protected from an over-pressure situation—the set pressure of the pressure relief device must not exceed the maximum allowable working pressure (MAWP) marked on the air pressure vessel. A pressure relief valve is used to control and limit the pressure build-up in a system.

With a pressure relief valve, the pressure can be automatically relieved by a spring-loaded valve, actuated by the static pressure upstream of the device. The valve opens in proportion to the increase in pressure over the opening pressure.

The minimum relieving capacity of the pressure relief device must meet the requirements of the American Society of Mechanical Engineers (ASME) Code. ASME is the international leader in developing and revising codes associated with mechanical engineering.

Pressure relief valves are designed to protect a system during a condition which would cause pressure in a vessel or system to increase beyond the specified design pressure or MAWP. These valves are normally very durable and long lasting and are important in protecting life and property from overpressurized vessels. It is important to compare the pressure relief device data (set pressure and relieving capacity) with the air pressure vessel nameplate and compressor output data to ensure the pressure relief device is adequate for the installation.

Typically, the method of operation of safety valves for compressed air applications is direct-acting. A disc seal is pushed up by the pressure from the system against a spring, which is holding the valve closed. If the opening compressed air force exceeds the force exerted by the spring, the valve disc is lifted off the valve seat and the valve discharges the compressed air to atmosphere. In accordance with the requirements of the ASME relief valve standard, the full discharge capacity of the valve typically will be achieved when the system pressure climbs to no more than 10% above the set pressure of the valve. Full shutoff must be achieved if the system pressure falls to below the set pressure value, usually set at 90%. A set pressure function test should be carried out at least once per year. The test procedure is performed by the user, and test instructions should be supplied by the air compressor manufacturer.

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How to test your pressure relief valve

VMAC recommends the inspection of the pressure relief valve for signs of corrosion or loss of functionality. VMAC’s manuals include test instructions to perform a pressure relieve valve inspection:

“To test the pressure relief valve functionality, turn the system on and bring it up to operating pressure. Pull the ring on the pressure relief valve to depressurize the system. Turn the system off, and ensure the system comes back to operating pressure when the system is restarted. If the pressure relief valve is showing loss of functionality, contact your local, authorized VMAC dealer for a replacement part. Relief valve failure can result in air/oil tank overpressurization leading to system failure or rupture.”

If you are operating a system that is not a VMAC air compressor, check your manual or contact the manufacturer for detailed instructions on how to test your pressure relief valve.

Visit VMAC’s Support page for technical information, troubleshooting, manuals, service kits, and more.

Related blogs:
Components of your VMAC mobile rotary screw air compressor system
The purpose and functions of compressed air storage tank
Why is my air compressor shutting off? Temperature sensors and switches

VMAC Gas Driven Air Compressors Work Smarter, Not Harder

Work Smarter, Not Harder, With VMAC’s G30 Gas Driven Air Compressor

VMAC Gas Driven Air CompressorWe all know in the industry that time is money, but how much is your time really worth? How much is your employees’ time worth, or the value of your entire fleet’s services each day? How ever you decide to quantify the cost of wasted minutes and hours, it’s clear that to be successful, waste must be minimized.

This is where the VMAC G30 air compressor comes in. This rotary screw gas driven air compressor is your equipment MVP for getting jobs done faster. Get on-demand air in the time it takes to walk from your truck to your tool; no more waiting around for the air pressure to build. And with 30 CFM at 100% duty cycle, you can get through your jobs in less time and with no interruptions.

Whether your goal is to finish work faster to get home and relax, or squeeze in a few extra jobs before the end of the day, the VMAC G30 air compressor is able to handle your on-demand air requirements, every time. This gasoline powered air compressor was designed with functionality and convenience in mind—here are the facts:

  • VMAC’s G30 offers up to 30 CFM, 100% of the Time, Every Time
    • 50% more powerful – VMAC’s patented rotary screw air compressor has been engineered to produce full air power, on demand at 100% duty cycle. Typical gas driven reciprocating air compressors produce approximately 20 CFM and can only operate at 50% duty cycle.
    • With a 100% duty cycle, the VMAC G30 will be able to handle the entire job, without interruption, for maximum efficiency.
  • VMAC’s G30 is the Smallest Gas Air Compressor in the World
    • 50% lighter – the G30 air compressor weighs just 205 lbs (93 kg), while typical gas driven reciprocating compressors weigh a massive 410 lbs (186 kg)
    • 50% smaller – the G30 air compressor saves you up to 15 cubic feet, allowing you to fit more tools in your truck. Measurements: 33.5” (l) x 20.3” (w) x 20.7” (h)
  • VMAC G30 is the Most Affordable Gas Driven Rotary Screw Air Compressor Available
    • The VMAC G30 price is competitive and affordable to fit your budget
  • VMAC G30’s Warranty is the Best Available
    • VMAC Lifetime Warranty (Limited) – the G30 air compressor comes with the industry’s first lifetime warranty
    • 5 Year Subaru Engine Warranty – the 14 HP Subaru engine comes with an industry leading warranty. Most engines are under warranty for just 2 years

See the full VMAC G30 gas driven air compressor,  plus specs and components, including the cold climate kit for temperatures hitting -25­°F (-32°C). Watch VMAC’s G30 demo video to see this powerful and compact compressor in action.

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Read more about the VMAC G30 rotary screw gas drive air compressor here:

VMAC G30 Gas Drive Air Compressor Installation Best Practices
Gas Engine Driven Air Compressors for Tire Service: Tech Advancements
Learn the New Features & Benefits of the Gas Drive Air Compressor

For more information, contact [email protected].

VMAC LEAN Manufacturing: 5S

VMAC LEAN Series: 5S Program

Welcome to our VMAC LEAN Blog Series. Here we’ll share various aspects of LEAN and how we specifically apply them to our everyday operations. LEAN Enterprise is part of VMAC’s continuous improvement culture—driven by the goal of maximizing value and minimizing waste. The advancements and improvements make for a healthier organization and allow us to pass additional value on to our customers. See an intro to VMAC LEAN Enterprise.

The first blog in our LEAN series is on VMAC’s 5S Program. The 5S methodology is a valuable tool in VMAC’s LEAN culture, developed to improve organizational efficiency through 5 different steps. The term 5S originates from five Japanese words starting with the letter S: Seiri, Seiton, Seiso, Seiketsu, and Shitsuke. Translated, Seiri means tidiness, Seiton means orderliness, Seiso means cleanliness, Seiketsu means standardization, and Shitsuke means discipline. To stay consistent with the five S’s, the English terms have been modified to Sort (Seiri), Set in Order (Seiton), Shine (Seiso), Standardize (Seiketsu), and Sustain (Shitsuke).

Step 1: Sort (Seiri)

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The Electrical Department’s Red Tag items.

The first step in the 5S methodology is to Sort. Getting a workspace sorted is important as it helps spot and address any problems with efficiency right away. This means sorting through each item in the area, keeping only what is needed. Each item should be inventoried and classified—it’s important to be honest about each item’s purpose as it can be a slippery slope to save items just because one day they might be needed. At VMAC, each coworker is responsible for sorting their workspaces, and teams work together to tidy shared spaces.

While sorting, it’s routine to “red tag” items that are not needed in the area or have no home. Each department at VMAC has its own Red Tag Area where these items are left for 30 days. During this 30-day period, potential owners are welcome to review the item to see if it can be repurposed. After 30 days, the items are recycled or disposed of.

Step 2: Set In Order (Seiton)

Now that an area’s items have been sorted, it’s time to Set the workspace in order, and find a

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An example of a shadow board in VMAC’s Quality Department. Note the outlines for each tool, as well as the labels.

specific place for each item. Items should be identifiable, easy to access, and set so that anyone can tell where to return something. Items that are not frequently used can be stored out of the way.

At VMAC, a combination of labels and tool shadow boards are used to keep items organized. Labels are placed on the outside of cabinets so that coworkers are able to see where items are stored without having to search through shelves and storage areas. In the shops, tool shadow boards provide a visual aid to quickly identify missing items, and show where items should be returned.

Step 3: Shine (Seiso)

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Floors are swept clean every day in the shops.

After a workspace has been sorted and set in order, it’s now time to Shine it up. This means keeping the area clean and in ready-to-use condition at all times. At the end of the day each area should be returned to the clean state it was in at the start of the work day. While cleaning, VMAC coworkers take the time to inspect machines, equipment and tools to ensure everything is in good condition.

In the shops and offices, each coworker is responsible for keeping their own work space clean as well as common areas and shared equipment.

Step 4: Standardize (Seiktsu)

Now that the area has been organized and cleaned, it’s time to Standardize—maintain uniformity and follow best practices in the workplace. Visual aids, simple work instructions, and documentation help ensure standardization. For example, every VMAC department has a 5S schedule posted to show who’s in charge of keeping communal areas clean and tidy. The schedule also specifies if each task is to be completed daily, weekly, bi-weekly, or monthly.

At VMAC, standardization is ongoing as best practices evolve with experience and changing requirements.

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Step 5: Sustain (Shitsuke)

Sustain

This photo shows a drawer of tools, each with their own space. There’s also a photo included for reference, which shows how the drawer is supposed to look.

The 5S methodology is an ongoing commitment to organization and efficiency, and the final step involves Sustaining progress made, even as new equipment, products, and policies are implemented. Continuing to review systems helps prevent new challenges from occurring. For example, a common challenge is maintaining a clutter-free workspace. Once an area has been 5S’d, there’s often lots of free space which can attract new clutter. For this reason, constant vigilance is the key to 5S at VMAC.

5S-Audit

This document is a recent example of the Marketing Department’s recent 5S Audit.

As part of the Sustain step, VMAC coworkers perform monthly 5S audits. What’s more, coworkers audit departments that are not their own, to allow for a fresh set of eyes to identify opportunities. LEAN coaches are also available to help guide coworkers in this exercise.

 

LEAN is part of each VMAC coworker’s individual performance evaluation; this encourages everyone to make LEAN and 5S a priority. 5S wins are celebrated as well, with before and after photos posted to show off each department’s progress. Success stories are shared in the monthly VMAC newsletter as well, inspiring coworkers to continue their commitment to LEAN.

Learn more about VMAC and our company culture, or lean manufacturing. Interested in our line of compact and powerful air compressors? Visit our air compressors page.

Why Is My Compressor Shutting Off? Temperature Sensors and Switches

Temperature Sensors and Switches

Temperature switches and sensors are used on applications which require a solution to a temperature control situation. Often less complicated than most electronic controls, temperature sensors and switches are relatively easy to set up.

Temperature sensors are often used for monitoring compressor coolant, oil and air inlet temperatures as well as discharge air temperatures and logging the variations.

Temperature switches are slightly more complex, and include a sensor plus the ability to send signals. A temperature switch senses temperature levels. When the temperature passes a set point the switch sends a signal to a controller to do something to the application, like cut the power, sound an alarm, turn on a light, or disengage the clutch.

Some immersion temperature switches are appropriate for applications that require an inexpensive solution to simple temperature control. These types of switches activate with a specific rise in temperature and are available with a wide range of temperature pre-set values as well as a set point range, set point tolerance, maximum temperature cut-out setting, and probe length.

On-off controllers

An on-off controller is the simplest form of temperature control device. The output from this type of device is either fully on or off, with no middle state. An on-off controller will cut power or disengage the clutch when the temperature passes the set-point. On-off control is usually used where a precise temperature control is not necessary.

A limit controller is an on-off controller used for alarm indication. This type of controller uses a latching relay, which must be manually reset, and is used to shut down a process when a certain temperature is reached.

VMAC temperature sensors, switches, and controls

VMAC air compressors are equipped with a switch which includes an oil temperature sensor. If the compressor oil gets too hot, the switch sends a signal to the on-off controller to disengage the air compressor’s clutch. This shuts down the system and prevents high temperature related damage.

Why is my compressor shutting off?

If your compressor trips on over temperature, it could be for any of the following reasons:

  • Ambient temperature too high or not enough ventilation
  • Too low oil level
  • Wrong type of oil being used
  • Dirty oil cooler
  • Thermostatic valve not working
  • Dirt / obstruction in oil lines
  • Plugged oil filter
  • Restricted air flow over the air to liquid cooler
  • Too high an engine liquid coolant supply temperature in a liquid to liquid cooler
  • Faulty temperature switch

Excessive oil temperatures can cause damage to your air compressor including premature lubricant degradation, high oil and moisture carryover, and varnishing of the compressor internals and system components (such as the oil filter, cooler, and separator filter). Lubricant flash points also present a fire hazard.

The costs related to rectifying these issues through the use of temperature switches and controls can result in significant cost-savings, as risks of down-time and injury are minimized.

Interested in learning more about air compressor components and accessories? Browse our collection of air compressor accessory blogs here.

 

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