air compressor tank safety valve free sample

You may not worry often, if at all, about whether or not your air compressor is running safely. And you really don’t have to, because compressor manufacturers do. From the pressure rating on the air storage tank to emergency stop buttons, air compressors are designed with safety in mind.

But that doesn’t mean you should never think about your compressor’s safety features. In most cases, they need to be inspected regularly to make sure they’re working properly. One key safety feature that should be inspected regularly is the air pressure relief valve (PRV), sometimes called a safety relief valve.

The pressure relief valve is a safety valve that protects the compressor component that it’s attached to from being exposed to a pressure above its rated maximum operating pressure. This rating, called the maximum working pressure (MWP), is the pressure that the vessel has been certified to continuously operate at safely.

So when a compressor is running at or below its maximum working pressure—in other words, when it’s running “normally”—the relief valve doesn’t do anything.

However, when the air pressure inside a compressor exceeds its MWP, the pressure relief valve will activate to “blow off” the excessive pressure within the compressor. Without a relief valve, the storage tank could rupture from the excessive pressure, damaging the compressor itself, possibly other property near it, and even causing injuries (or worse) to anyone standing nearby.

Before we can talk about how the air pressure relief valve works, we first need to look at how air pressure inside a compressor is managed when everything is running normally.

Under normal circumstances, the air pressure in a compressor is controlled by a pressure switch in an electro/mechanical control system or, in the case of an electronic controller, a pressure transducer and controller settings. When the cut-out set pressure for the pressure switch is reached, the compressor will stop compressing air (unload) until the cut-in set pressure is reached, at which time it will start compressing air again (load). If the pressure switch fails, the compressor would not be able to start compressing air again, or potentially worse, not be able to stop. Most compressors also have a high-pressure safety switch that should stop the compressor if the pressure exceeds the unload set point.

A pressure relief valve is a straightforward safety backup to the pressure switch and high-pressure switch, or the controller set points, should any of these components fail with the compressor running. The safety relief valve is set above the high-pressure safety switch and generally at or below the vessel’s maximum operating pressure. Inside the valve is a spring, and the pressure created by the spring’s tension keeps the valve closed under normal operating conditions. However, as the air pressure increases in pressure vessels (like the storage tank), it eventually exceeds the rated pressure of the relief valve, causing the relief valve to open and the excess pressure to be “blown off” to the atmosphere.

If the pressure relief valve fails open, air will continually vent to the atmosphere, preventing the air stream from becoming fully pressurized. The compressor should be shut down and the relief valve replaced before the compressor is restarted. The open relief valve will likely cause a loss of production and possible danger to personnel as a result of the flow of high-pressure air with flying debris and an unsafe sound level.

A pressure relief valve failing closed presents a potentially more dangerous situation. As noted earlier, the relief valve exists to allow excessive pressure to be “blown off” so that the air pressure inside the compressor’s pressure vessels don’t exceed their rated specifications. If the valve fails closed, this pressure venting can’t happen. Unless compressed air demand matches the compressed air supply, the pressure inside the compressor will continue to build. Eventually, the pressure increase would cause the storage tank to rupture, damaging the compressor and possibly causing additional damage and injury to property and people nearby.

If the relief valve is opening because the air pressure in the compressor has exceeded the valve’s pressure set point, that means the valve is working and doing what it was designed to do. But because this indicates the MWP of the compressor has been exceeded, the condition that’s causing excessive pressure should be diagnosed and corrected.

If the relief valve opening wasn’t caused by excessive pressure inside the compressor, then the valve is most likely “failing open”. Most likely, this is because the valve has become “soft” over time, i.e. the valve spring is providing less counterpressure, so it’s opening at a lower pressure than it should.

Whether the valve opened because of excessive pressure in the compressor or because the valve is failing, you should have your local air compressor distributor inspect your compressor before running it again for two reasons:

First, your distributor can determine whether the valve opened due to a failing relief valve or excessive compressors pressure and perform any needed maintenance or service to get your compressor running efficiently and safely again.

Second, regardless of why the pressure relief valve opened, replacing it may be recommended to ensure safe compressor operation, depending on the valve manufacturer. (Replacement is recommended for Sullair compressors.)

Important: Running the compressor after the relief valve has opened, regardless of the reason why it opened, can put both your property at risk of damage and people at risk of injury (or worse). While this may be obvious if the compressor is building up excess pressure, it also applies if the valve failed open. As noted above, even a valve that fails open poses some risk, and next time it could fail closed.

Given how critical a working air pressure relief valve is to the safe and efficient operation of your air compressor, you may wonder whether you need to do any regular inspecting or testing of the valve to make sure it is working. Because this can vary by manufacturer, you should consult your owner’s manual or contact your local air compressor distributor for frequency and type of inspection needed. For most Sullair compressors, inspection for damage or leakage is recommended, but testing is not recommended, as doing so may compromise the valve’s performance.

However, one thing you should do is schedule regular maintenance with your local air compressor distributor. As part of regular maintenance, a service technician can inspect the PRV and let you know it’s at an age or in a condition at which the manufacturer recommends replacement. Also, problems with the compressor’s performance, e.g. not reaching normal operating pressure, may help the service technician identify a failing relief valve after ruling out other possible causes.

When a pressure vessel like a receiver, sump tank or other storage vessel is purchased separately from the compressor, it may not be supplied with a pressure relief valve. To ensure its safe operation, you should add a PRV.

When selecting a PRV to add to the pressure vessel, you must choose a valve with a pressure set point set at or below the maximum working pressure of the vessel. You will find the MWP (and other useful information) on a tag welded to the pressure vessel. Also, flow capacity of the PRV must meet or exceed the total compressed air supplied to the vessel.

For example, if you have two compressors with capacities of 500 and 750 cfm (14.2 and 21.2 m³/min), and a pressure vessel with a maximum working pressure of 200 psi (13.8 bar), the minimum settings for a pressure relief valve would be 1250 cfm (35.4 m³/min) and a set point 200 psi (13.8 bar) or less.

Finally, when attaching the valve to the vessel, the porting must not be reduced to a size less than the size of the inlet port of the pressure relief valve.

Because the pressure relief valve is critical to the safe operation of your compressed air system, if you’re not sure how to select the correct PRV and properly and safely add it to the pressure vessel, contact your local air compressor distributor. They have the experience and expertise to ensure that the PRV is sized and installed correctly.

An OSHA COMPRESSED AIR SAFETY SHUT-OFF VALVES should be placed immediately after the air control shut off valve and before the hose on a compressor, and after each discharge port that a hose is connected to.

Before starting the compressor the air control valve should be closed completely. When the compressor unloads, open the air shut off control valve very slowly. Full port ball valves tend to work better than gate or butterfly type valves.

The air shut off control valve must be fully open for the OSHA COMPRESSED AIR SAFETY SHUT-OFF VALVES to work. Some portable air compressor manufacturers recommend start-up with the air control valve slightly open. In this case you may have to close the valve and reopen it slowly to the full open position, or wait for the safety shut-off valve to reset itself.

If the OSHA COMPRESSED AIR SAFETY SHUT-OFF VALVES fails to operate despite meeting all condi-tions, check the hose line for obstructions or a hose mender restricting normal air flow.

• Turn on air supply slowly (to avoid tripping OSHA safety valve). Prior to fully reaching operation conditions, the OSHA COMPRESSED AIR SAFETY SHUT-OFF VALVES should suddenly activate and stop air flow.

• If the OSHA COMPRESSED AIR SAFETY SHUT-OFF VALVE is not activated the unit should be disconnected and the lower flow range OSHA COMPRESSED AIR SAFETY SHUT-OFF VALVES should be used. This means you need to use a different valve with a lower scfm range.

• At temperatures below 40°F ensure that OSHA COMPRESSED AIR SAFETY SHUT-OFF VALVES are not subject to icy conditions which may prevent proper functioning.

We are a leading manufacturer of high quality valves serving the compressed air, pressure washer, automotive, fluid power, fire protection, specialty gas, and pneumatic industries.

The Model “ST” safety valve is our standard safety valve for small air compressor systems and related applications. Even though the size is compact, flow capacities are high.

Resilient rubber pad, offered in silicone or flourocarbon, insures valve is bubble-tight to within 10% of set pressure. Three inlet sizes are available: 1/8″ NPT, 1/4″ NPT, and 3/8″ NPT.

Model “SV” ASME safety valves are designed for systems where large flow capacities are needed. Resilient pad insures valve is bubble-tight to within 10% of set pressure. Inlet size: 1/2″ NPT.

Model “SB” safety valves offer Control Devices value to users of high capacity ASME safety valves. Unique O-ring seal insures valve is bubble-tight to within 10% of set pressure. 1/2″ NPT and 3/4″ NPT inlets available.

The model “SW” valve is our highest capacity ASME safety valve. Unique O-ring seal insures valve is bubble-tight to within 10% of set pressure. 1″ NPT and 1¼” NPT inlets available.

The Super-Chek® design has been proven over the last 15 years to be the standard for air compressor in-tank check valves. One-piece brass bodies, stainless steel springs, and glass-filled fluoropolymer poppets all add up to long term reliability, while the eight discharge holes insure quiet operation.

Valves may be disassembled for cleaning or repair. Valves are 100% tested for backflow leakage performance. 450 PSI max pressure, 400 deg. F max temperature.

These cast-brass check valves have been specifically designed for installation into air compressor discharge lines. Extra-heavy walled cast brass bodies, glass-filled fluoropolymer poppets, and stainless springs resist corrosion and insure long life.

Conventionally when we talk about oil lubricated screw air compressor maintenance, it is mostly about replacing consumables such as filters and lubricant on time. While these consumables have a defined usable life and have a direct effect on the efficiency and the life of the air compressor itself when not replaced on time, there are a few critical valves in the air compressor that require maintenance as well. Compressor valves directly affect the efficiency, safety, and the functionality of the screw air compressor. Let us understand some of the commonly available valves in a screw air compressor, why they need maintenance, and discuss some of the frequently asked questions about screw air compressor valves.

A screw air compressor is very similar to a human heart. While a human heart has tricuspid, pulmonary, mitral, and aortic valves, a screw air compressor has four critical valves namely air inlet, minimum pressure, blow down, and safety valves.

Air inlet valve is also commonly known as the ‘Intake valve’ which is typically assembled on the airend’s intake. The air inlet valve of a conventional fixed speed screw air compressor controls the air intake into the compressor. It remains closed when the compressor starts to lower the starting load on the main motor and when the desired working pressure is attained in the compressed air circuit and thus enabling the compressor’s motor to run without any load. In some compressors that are capable of providing a variable output by modulating the amount of air it sucks in, the inlet valve holds various opening positions to regulate the volume of air entering the compressor. The effective performance of the inlet valve directly affects the compressor’s capacity and its power consumption during load and no-load conditions.

The minimum pressure valve is typically assembled on the exit of the air-oil separation tank of a compressor. The minimum pressure valve acts as a check valve preventing back flow of compressed air into the airend, retains a minimum pressure in the compressor system for lubrication, offers a restriction to avoid a collapse of the air-oil separation filter, and ensures a suitable velocity of flow across the air-oil separator that ensures efficient air-oil separation. The effective performance of the minimum pressure valve directly affects the compressor’s lubrication, air-oil separation efficiency, and power consumption during load and no-load conditions.

The blow down valve is typically found on a dedicated exhaust line from the air-oil separation tank. The blow down valve evacuates the compressed air in the air-oil separation tank each time the compressor runs on a no-load and when the compressor shuts down to ensure there is no back pressure when the compressor starts to load next time. The blow down valve of a conventional screw compressor is typically actuated by a solenoid valve. The effective performance of the blow down valve affects the compressor’s power consumption during un-load, capacity of the compressor when running on load, and the life of the motor.

The safety valve is typically mounted directly on the air-oil separator tank. The only function of the safety valve is to blow off the compressed air in the air-oil separation tank when the pressure in the air-oil separation tank exceeds the set pressure of the safety valve and there by prevents the tank from cracking under high pressure. A malfunctioning safety valve affects the safe operation of the air compressor or results in leakage of compressed air continuously.

Though each compressor manufacturer has their own unique valve design, compressor valves in general contain moving parts such as springs, valve plates, and plungers that affect the opening and closing of the valves and rubber seals / seats that offer perfect sealing when the valves remain closed. These moving parts wear or lose their mechanical properties over a period of time and the sealing components typically ‘age’ over time and lose their effectiveness and will need to be replaced.

Compressor manufacturers typically design these components to operate efficiently for several thousand or millions of operation cycles. However, several factors such as variability in the demand pattern, sizing of the air compressor against a certain air demand, the environment in which the air compressor operates, promptness of preventive maintenance, etc. determine how long these valves efficiently operate.

Many times, it is difficult to identify a malfunctioning valve or a valve operating with worn-out parts as the compressor continues to generate air. The typical symptoms of a malfunctioning valve are loss in compressor"s capacity, increase in power consumption during load or/and unload, drop in discharge pressure, increase in oil carry-over and more load on motor. These symptoms are either difficult to notice or have other frequently common assignable causes such as air leak before suspecting the compressor valves.

Case studies show that operating a screw air compressor with a worn-out / malfunctioning valve could increase its overall power consumption by 10 - 15%. Power cost contributes to more than 75% of the compressor’s total life cycle cost over ten years and hence this is a significant impact. Unserviced valves also lower the life span of downstream accessories by half. In some cases, a malfunctioning safety valve may result in a catastrophe.

Air compressor manufacturers typically offer convenient valve maintenance kits for customers that contain the internal parts of the valve that wear or age out. Changing the valve kits is a much more sensible and economical option than changing the complete valve.

It is difficult or almost impossible to identify a malfunctioning valve unless it is opened for inspection. Hence it is absolutely mandatory that these valves are inspected for effectiveness every year and the internal moving parts replaced as a part of preventive maintenance once every year or two depending on the operating conditions of the air compressor. It is typical for compressor manufacturers to mandate a valve kit replacement once every two years as a proactive measure.

In particular, the safety valve must be inspected and certified every year per the local safety laws to ensure they are functional and efficient. Sometimes, replacing the safety valve entirely with a valid certificate for one year is more economical as the certification procedures could be equally expensive on an existing valve.

As stated before, it is challenging to identify a valve that is worn out unless it is opened and inspected, but there are a few indicators that a qualified compressor technician can use to deduct a malfunctioning valve.

Low duty cycle operation: A sophisticated screw air compressor in today’s day and age carries a convenient microprocessor-based human-machine interface that keeps track of operating hours of the compressor under load and un-load conditions and the number of load/unload counts the compressor is subjected to over a period of time. A higher un-load hours and load/unload count indicates that the air compressor is oversized against the actual air demand. This in turn indicates the air compressor ‘cycles’ frequently between load and un-load mode as opposed to running continuously on load. Every time a compressor ‘cycles’, the inlet valve, blow down valve, and minimum pressure valve is brought into play where their internals ‘actuate’. Frequent actuation of these valves results in a faster wear of the internals and hence results in shorter life.

High operating temperature: A compressor that runs on a high operating temperature affects the life of the valve’s sealing components, which causes them to ‘age’ fast.

Compressor not building pressure: If the air demand has not changed over time and the facility is relatively free of any air leakage, the air compressor is probably not delivering the rated output. There is a high probability that there is a malfunctioning valve.

Increase in compressor’s power consumption: An increase in the air compressor’s power consumption profile over a period of time where there has been no abnormal change in the air demand and usage pattern indicates an increase in either the load or un-load power. There is a high probability that this is because of a malfunctioning valve.

Based on the design philosophy adopted by the air compressor manufacturer, the oil lubricated screw air compressors could have a few more valves that are critical to functional performance that must be maintained as well. Some of the other valves frequently used in an air compressor are as follows:

Temperature control valve (also known as thermal valve) is used to regulate the flow of oil through the oil cooler based on the operating temperature.

Drain valves are used to drain lubricant at the time of lubricant change over or cleaning. Air compressors equipped with a moisture trap at the outlet of the after cooler also has a drain valve (automatic or timer based) to discharge water collected.

The presence or absence of one of these valves and the type of actuation of these valves (electronic / mechanical) depends on air compressor’s design architecture. The Operation and Maintenance Manual (OMM) and the Piping and Instrumentation Diagram (P&ID) supplied by the air compressor manufacturer are excellent resources that explain the purpose, functioning, and maintenance requirements of these valves.

Many of the air compressor valves are highly specialized and exclusive. Their designs are usually complex and some even need special tools to service them. The internal components" build quality and material selection are extremely important and proprietary. Hence it is highly critical that only genuine valve kits issued by the air compressor manufacturer are used to maintain the valves. An inferior after-market replacement will most certainly compromise the performance of the entire compressor, void the original manufacturer"s warranty of the compressor, cause consequential damage to other parts of the compressor, and above all, be a safety hazard.

In conclusion, while it is important to change the screw air compressor"s filters and lubricants on time, it is equally important to perform preventive maintenance on these critical valves in a screw air compressor as recommended by the air compressor manufacturer. While the intake valve, minimum pressure valve, safety valve, and blowdown valve are critical to the performance and safety of the compressor, there could be other valves in the compressor that are critical and need maintenance. The air compressors sizing and the environment in which it operates are crucial factors that affect the life of the air compressor. Finally, it is critical to proactively service these valves using genuine kits issued by the compressor manufacturer to enable the air compressor performs efficiently and safely.

Gershom Joel has over 15 years of experience in the compressed air field and specializes in helping industries such as Pharmaceuticals, Textile, Electronics, and Food and Beverage find compressed air solutions to meet their unique requirements.  Gershom holds a Mechanical Engineering Degree from Anna University and a Masters in Business Administration from University of North Carolina.

ELGi North America, headquartered in Charlotte, NC, is a subsidiary of ELGi Equipments Limited, a leader in compressed air solutions for over 60 years. Established in 2012, ELGi North America, in conjunction with its subsidiaries, Pattons, Pattons Medical, and Michigan Air Solutions, offers a comprehensive range of compressed air products and services. Our product offering includes oil-lubricated and oil-free rotary screw and reciprocating compressors, dryers, filters, and ancillary accessories. ELGi and its subsidiaries serve multiple industry verticals spanning medical applications, pharmaceuticals, food & beverage, construction, manufacturing, and infrastructure. For more information, visit https://www.elgi.com/us/.

Before youbuy compressed air receiver tank, take some time to learn about the device itself. Our guide to compressed air receiver tanks explains how they work, what they do, and how you can use them to maximize the efficiency of your compressed air system.

An air receiver tank (sometimes called an air compressor tank or compressed air storage tank) is what it sounds like: a tank that receives and stores compressed air after it exits theair compressor. This gives you a reserve of compressed air that you can draw on without running your air compressor.

An air receiver is a type ofpressure vessel; it holds compressed air under pressure for future use. The tanks come in a range of sizes and in both vertical and horizontal configurations.

An air receiver tank provides temporary storage for compressed air. It also helps your air compression system run more efficiently. The air receiver tank has three main functions in your compressed air system:

The primary role of an air receiver tank is to provide temporary storage for compressed air. Storing compressed air allows the system to average the peaks in compressed air demand over the course of a shift. You can think of your air receiver tank as a battery for your compressed air system, except it stores air instead of chemical energy. This air can be used to power short, high-demand events (up to 30 seconds) such as a quick burst of a sandblaster, dust collector pulse, or someone using a blowgun to dust themselves off. The air in the tank is available even when the compressor is not running. Storing compressed air reduces sudden demands on your air compressor, prolonging the life of your system. Using an air receiver tank may also allow you to use a smaller horsepower compressor for larger jobs.

The air receiver tank provides a steady stream of air to compressor controls, eliminating short-cycling and over-pressurization. Uneven compressed air utilization causes uneven demand on the air compressor, resulting in rapid cycling of the compressor controls as the compressor turns on and off to meet moment-by-moment demand. Each time the system turns on and off (or loads/unloads) is called a “cycle”; it is better for the compressor motor to keep these cycles as long as possible. Over time, frequent short cycling will lead to premature failure of switches and other compressor components. Rapid cycling can result in excessive wear of the motor contactor or even a direct motor short because of winding insulation. The air receiver tank eliminates short cycling and provides more consistent system pressure to controls.

As air is compressed under pressure, its temperature increases; this is a simple law of physics known as thePressure-Temperature Law. Depending on the type of air compressor you are using, the air discharged from the compressor may be as hot as 250 – 350°F. This is too hot for most air-operated equipment to use directly. Hotter air also contains more moisture, which will result in excess water vapor that will condense in control lines and tools if it is not removed. The condensed air must be cooled and dried before it is utilized. Aheat exchangeris used to remove excess heat caused by compression. The air receiver tank acts as a secondary heat exchanger; as air sits in the tank or slowly flows through it, it naturally cools over time. The air receiver tank supports the work of a primary heat exchanger; lowering the temperature of the air an additional 5 – 10°F is not uncommon.

As the air compressor cycles on and off, compressed air can be wasted. Every time arotary screw air compressorunloads, the sump tank (oil tank) is vented. Compressed air is released during the venting. Over time, this adds up to the loss of thousands of cubic feet of compressed air that could otherwise have been used to power processes in your facility. A properly sized air storage tank reduces frequent cycling and venting.

Compressed air storage also allows you to reduce the pressure at which your air compressor operates. Without a store of compressed air to draw on, the system will have to operate at higher pressures, so it is always ready to meet peak demands. In essence, you are asking your system to operate as if your facility is always running at maximum demand. This leads to increased energy use and wear and tear on the system. On average, for every 2 PSI that you increase the pressure of your system increases the energy demand by 1%. This can lead to hundreds or thousands of dollars added to your energy bills annually. As explained above, adding an air receiver tank to your compressed air system will even out these peaks in demand, allowing you to meet intermittent periods of high demand without increasing the overall pressure of your system.

The heat exchanger function of the air receiver tank helps to improve the efficiency of your air dryer. As air passes slowly through the receiver tank, it cools. Cooler air can’t hold as much moisture as warm air, so excess moisture condenses and falls out of the air as a liquid. The water drains out of a valve at the bottom of the tank. By removing some moisture in advance, the air receiver tank reduces the amount of work the air dryer needs to do. This improved efficiency translates to additional energy savings for your system.

When shopping for an air receiver tank, you may be asked whether you want “wet” or “dry” compressed air storage. The difference is in the location of the air storage tank in your compressed air system; there is no difference in tank construction or design.

“Wet” storage tanks are locatedbeforethe air drying system. Air flows through the tank in this configuration, entering through the bottom port from the compressor and exiting out the top to the dryer.

“Dry” storage tanks are locatedafterthe air dryers to store compressed air that has already been dried and filtered. It is not necessary to flow the compressed air through the tank for dry storage.

With wet air storage, the receiver tank is positioned in between the air compressor and the air dryer. Wet air enters the receiver tank from the air compressor through the lower port in the tank and exits through the upper port to enter the air drying system. A wet air receiver tank has several benefits.

As explained above, wet storage increases the efficiency of your air dryer by allowing excess water and lubricant to condense out of the air before it hits the dryer.

A wet air storage tank also prolongs the life of the pre-filter element, which is located in between the wet storage tank and the dryer. Since the air going through the filter is cleaner and dryer than it would be directly out of the air compressor, slugging of the filter with liquids is minimized, along with resulting pressure drop on the air dryer side of the system.

The compressor does not experience backpressure because the air does not go through filtration before entering the tank. This results in a steadier pressure signal to the compressor controller.

Without a dry air tank, air from the wet tank will have to go through the air dryer before it is used. During periods of high demand, the dryer is at risk of becoming over-capacitated as the system tries to pull air through at higher volumes than the dryer is rated for. If the dryer cannot keep up with the demand, drying efficiency is reduced, potentially leading to unwanted water in the air lines.

The ideal ratio of compressed air storage is1/3 wet to 2/3 dry capacity. For example, if you have a total of 1,200 gallons of compressed air storage, 800 gallons should be dry storage, and 400 gallons should be wet. Dry air is ready to use on-demand. The wet air tank increases the efficiency of the dryer and acts as a secondary reserve when dry air is exhausted. Dry air storage needs to be greater than wet storage to minimize the risk of over-capacitating the air dryer during periods of high demand.

An exception to this rule is for applications that have steady airflow without sharp peaks in demand. In this case, there is no need for a dry storage tank because air will simply flow through it without being stored up. This is often the case in robotic manufacturing facilities where airflow is consistent and predictable.

A good rule of thumb for most applications is to havethree to five gallons of air storage capacity per air compressor CFM output. So if your air compressor is rated for 100 CFM, you would want 300 to 500 gallons of compressed air storage. As explained above, 1/3 of the total storage capacity should be wet storage, and 2/3 should be dry storage.

While the standard rule works well for many applications, you will also want to consider other variables in determining your compressed air storage needs. Flow consistency has a large impact on storage requirements.

Facilities with very steady airflow, such as robotic facilities, typically don’t need as much stored air. That’s because they don’t have frequent high bursts of demand that rely on stored air. In this case, air storage can be reduced to 2 gallons per CFM of air compressor capacity. All storage should be wet storage in this case, as explained above.

Facilities with high variability in airflow and large peaks in demand may require larger volumes of stored air. This extra capacity will ensure that the system will be able to keep up with periods of high demand. Testing to determine CFM at peak demand will be needed to calculate air storage requirements.

The final consideration in determining compressed air storage requirements is the size of the pipework in the system. The pipes also store air for your compressed air system, and the larger the pipes, the more storage they provide. For systems with pipework of 2” or greater diameter, it may be worthwhile to consider that volume into the calculation.

Compressed air receiver tanks can be bulky, so many compressed air system owners would prefer to store them outside. Outdoor storage saves precious floor space in the facility.

It also helps to reduce strain on your HVAC system in warm weather. The compressed air storage tank radiates heat as hot air from the compressor cools within the tank, raising temperatures in the compressor room. Storing your tank outside avoids excess heat buildup in the compressor room and also helps the storage tank perform its secondary job as a heat exchanger more efficiently.

However, outdoor storage only works in milder, non-freezing climates. Make sure your climate is suitable for outdoor placement of your compressed air tank.

Outdoor storage of the air receiver tank is only appropriate for environments that stay above freezing year-round. In freezing temperatures, outdoor tanks can ice up and even rupture—a costly and potentially dangerous outcome. If your area experiences freezing temperatures during part of the year, it is safest to keep your tank indoors.

If you are storing your air receiver tank outdoors, be sure to conduct frequent inspections to monitor for corrosion. Any signs of corrosion should be addressed immediately to maintain the integrity of the tank.

If your area is subject to cooler temperatures with occasional risk of icing, take special care of your tank in cooler weather. The tank will generate some heat on its own. However, if temperatures drop too far, the tank is still at risk of freezing. Insulating your tank and providing auxiliary heating during cold weather may be necessary to prevent damage.

The majority of air receiver tanks are bare steel on the inside with a primer coating on the outside to reduce corrosion. The exterior paint is commonly matched to the compressor equipment. A basic steel tank works well for most applications and is the least expensive option. However, they may be prone to corrosion if too much liquid is allowed to build up inside the tank.

Epoxy coatings are sprayed onto the interior as a liquid and then cured into a tough, anti-corrosive coating. Epoxies work by creating a moisture-proof barrier between the air and the base metal of the tank.

Galvanized tanks are treated with a protective zinc coating that halts the formation of rust. Zinc protects the base metal by reacting chemically with corrosive agents before they can reach the base.

Both methods provide long-lasting protection for the interior of the tank, but they do add to the cost and lead time. Coated or galvanized tanks are better at maintaining air purity because they reduce the risk of particulates caused by corrosion entering the airstream. Applications needing higher purity air, or users concerned about the longevity of their air tanks, may want to consider one of these options.

Stainless steel air receiver tanks are primarily used for specialty applications where very high-purity air is required. They are the most expensive option, but they are highly durable and corrosion-resistant and maintain exceptional air purity. Hospitals, labs, electronics manufacturers, and other applications requiring high-purity air should consider a stainless steel tank.

Air receiver tank accessories are essential for tank safety and operation. While the tank itself is just a large sealed metal tube, all tanks must have at a minimum:

Automatic drain valves eliminate the need for daily manual draining of liquid inside the air receiver tank. Anelectric automatic drain valveis programmed to open at set intervals to let accumulated liquid drain out.

Zero air-loss condensate drainsalso provide automatic drainage of the tank. Instead of draining at set intervals, they use a float mechanism to control drainage. The drain will only open when needed, saving energy and reducing air loss from the tank.

The pressure gauge provides a visual indicator for the interior pressure of the air in the tank. You need the gauge to monitor pressures and ensure that the tank is not under stress from over-pressurization.

A pressure relief valve is required for all air receiver tanks per OSHA and ASME guidelines. The pressure relief valve opens automatically to release some air if pressures in the tank are too high. This safety mechanism is essential to minimize the risk of a dangerous rupture due to over-pressurization. The relief valve is typically set to 10% higher than the working pressure of the compressed air system but never more than the rated pressure of the tank’s ASME certification.

Vibration pads are not required for all applications, but they are recommended if the air compressor is mounted on top of the tank. Vibration pads absorb vibrations from the compressor motor and reduce fatigue on the tank.

Many buyers wonder if ASME certification is important for air receiver tanks—and the answer is yes. All air receiver tanks used in industrial applications must be certified by ASME for safety and performance.

The American Society of Mechanical Engineers, or ASME, is an organization that sets engineering codes and manufacturing standards for a variety of machines, parts, and system components. ASME acts as an independent quality assurance organization to ensure the safety and quality of manufactured items. An ASME certification stamp means that the manufacturer has met all safety and engineering standards for their product.

ASME has developed a set of codes and standards for pressure vessels, including air receiver tanks. The ASMEBoiler and Pressure Vessel Certification Programsets rules governing the design, fabrication, assembly, and inspection of pressure vessel components during construction. These rules include engineering standards for the thickness of the tank body, welds and joints, connections, and other components of the tank. Tank manufacturers must conform to all of the rules to obtain ASME certification.

Some big box stores carry non-code air receiver tanks. While these may be cheaper, they have not undergone the rigorous manufacturing processes and quality testing needed to ensure that they are safe and reliable. Using a non-code air receiver tank could put your life and the lives of your coworkers at risk.

If you are not sure whether or not your air receiver tank meets code requirements, you should have it inspected. Your local Fire Marshall may provide this service. They will stop in and test your tank with ultrasonic metalthickness testing technology. If your air receiver tank does not pass the inspection, it should be decommissioned and replaced immediately.

All air receiver tanks must also be inspected periodically once they are installed. OSHA does not mandate a specific testing interval, but it is recommended that all air receiver tanks be inspected at least annually. Your insurance company or local governing board may have different requirements. OSHA requires that formal inspections be performed by an inspector holding a validNational Board Commissionand in accordance with the applicable chapters of the National Board Inspection Code. Manufacturers are required to keep records of formal inspections and make them available to OSHA representatives upon request.

In between formal board inspections, manufacturers should conduct frequent visual inspections of the air receiver tank to look for signs of corrosion, damage or weld failure. Check drains daily and pressure relief valves quarterly to make sure they are operating correctly. Contact your manufacturer or compressed air system installer immediately if you see any signs of problems with your air receiver tank.

Pressure vessels must be built to withstand high internal pressures over a long period of time. Over time, corrosion, stress, and fatigue can make tank failure more likely. The most common causes of air receiver failure are:

The high internal pressures within an air receiver tank make failure extremely hazardous. Cracking or weld failure can cause the tank to burst with explosive force, projecting large pieces of metal or fragments of shrapnel at high speed. Air receiver tank failure may result in extensive damage to the facility and nearby equipment and severe injury or death for nearby workers.

An appropriately-sized air receiver tank will improve the efficiency of your system—and can even reduce your operating costs for your compressed air system. Your air receiver tank reduces energy consumption and saves wear and tear on your system.

Your compressed air receiver tank is like a battery for your facility, providing an extra reservoir of compressed air you can draw on during periods of high demand. This lets you reduce the overall operating pressures for your system, resulting in lower energy costs. You may also be able to purchase a smaller air compressor with lower CFM capacity by relying on your air receiver tank for high-demand events.

As explained above, the air receiver tank reduces cycles counts for your air compressor by evening out peaks in compressed air demands. Lower cycle counts add up to lower energy use and less wear and tear on other system components, extending the life of your air compressor.

The air receiver tank functions as a pulsation dampening device, absorbing vibrations from the air compressor motor and pulsations in the air stream. This reduces fatigue on piping and other system components.

As the air cools in the air receiver tank, the excess liquid condenses and falls out of the air. This results in less work for the air dryer and less energy consumption.

Particulates can enter the airstream due to corrosion within the system, motor exhaust from the air compressor, or particulates in facility air. Many of these particulates will fall out of the air along with condensate within the air receiver tank. The excess dirt is then simply drained away with the liquids. As a result, the air entering the air dryer is both cleaner and drier than air directly from the air compressor.

Your air receiver tank is an essential component of your compressed air system. Having a properly sized air receiver tank ensures the safe and efficient operation of your system and provides a reservoir of extra power for use during periods of peak demand.

If you’re not sure how much air storage capacity you need, or if you have questions about maintaining your tank for safe operation, the experts at Fluid-Aire Dynamics can help. We will perform an assessment of your compressed air usage patterns and recommend an air receiver tank that will fit your needs. We can also help you inspect, repair, or upgrade your current storage system.

Before youbuy compressed air receiver tank, take some time to learn about the device itself. Our guide to compressed air receiver tanks explains how they work, what they do, and how you can use them to maximize the efficiency of your compressed air system.

An air receiver tank (sometimes called an air compressor tank or compressed air storage tank) is what it sounds like: a tank that receives and stores compressed air after it exits theair compressor. This gives you a reserve of compressed air that you can draw on without running your air compressor.

An air receiver is a type ofpressure vessel; it holds compressed air under pressure for future use. The tanks come in a range of sizes and in both vertical and horizontal configurations.

An air receiver tank provides temporary storage for compressed air. It also helps your air compression system run more efficiently. The air receiver tank has three main functions in your compressed air system:

The primary role of an air receiver tank is to provide temporary storage for compressed air. Storing compressed air allows the system to average the peaks in compressed air demand over the course of a shift. You can think of your air receiver tank as a battery for your compressed air system, except it stores air instead of chemical energy. This air can be used to power short, high-demand events (up to 30 seconds) such as a quick burst of a sandblaster, dust collector pulse, or someone using a blowgun to dust themselves off. The air in the tank is available even when the compressor is not running. Storing compressed air reduces sudden demands on your air compressor, prolonging the life of your system. Using an air receiver tank may also allow you to use a smaller horsepower compressor for larger jobs.

The air receiver tank provides a steady stream of air to compressor controls, eliminating short-cycling and over-pressurization. Uneven compressed air utilization causes uneven demand on the air compressor, resulting in rapid cycling of the compressor controls as the compressor turns on and off to meet moment-by-moment demand. Each time the system turns on and off (or loads/unloads) is called a “cycle”; it is better for the compressor motor to keep these cycles as long as possible. Over time, frequent short cycling will lead to premature failure of switches and other compressor components. Rapid cycling can result in excessive wear of the motor contactor or even a direct motor short because of winding insulation. The air receiver tank eliminates short cycling and provides more consistent system pressure to controls.

As air is compressed under pressure, its temperature increases; this is a simple law of physics known as thePressure-Temperature Law. Depending on the type of air compressor you are using, the air discharged from the compressor may be as hot as 250 – 350°F. This is too hot for most air-operated equipment to use directly. Hotter air also contains more moisture, which will result in excess water vapor that will condense in control lines and tools if it is not removed. The condensed air must be cooled and dried before it is utilized. Aheat exchangeris used to remove excess heat caused by compression. The air receiver tank acts as a secondary heat exchanger; as air sits in the tank or slowly flows through it, it naturally cools over time. The air receiver tank supports the work of a primary heat exchanger; lowering the temperature of the air an additional 5 – 10°F is not uncommon.

As the air compressor cycles on and off, compressed air can be wasted. Every time arotary screw air compressorunloads, the sump tank (oil tank) is vented. Compressed air is released during the venting. Over time, this adds up to the loss of thousands of cubic feet of compressed air that could otherwise have been used to power processes in your facility. A properly sized air storage tank reduces frequent cycling and venting.

Compressed air storage also allows you to reduce the pressure at which your air compressor operates. Without a store of compressed air to draw on, the system will have to operate at higher pressures, so it is always ready to meet peak demands. In essence, you are asking your system to operate as if your facility is always running at maximum demand. This leads to increased energy use and wear and tear on the system. On average, for every 2 PSI that you increase the pressure of your system increases the energy demand by 1%. This can lead to hundreds or thousands of dollars added to your energy bills annually. As explained above, adding an air receiver tank to your compressed air system will even out these peaks in demand, allowing you to meet intermittent periods of high demand without increasing the overall pressure of your system.

The heat exchanger function of the air receiver tank helps to improve the efficiency of your air dryer. As air passes slowly through the receiver tank, it cools. Cooler air can’t hold as much moisture as warm air, so excess moisture condenses and falls out of the air as a liquid. The water drains out of a valve at the bottom of the tank. By removing some moisture in advance, the air receiver tank reduces the amount of work the air dryer needs to do. This improved efficiency translates to additional energy savings for your system.

When shopping for an air receiver tank, you may be asked whether you want “wet” or “dry” compressed air storage. The difference is in the location of the air storage tank in your compressed air system; there is no difference in tank construction or design.

“Wet” storage tanks are locatedbeforethe air drying system. Air flows through the tank in this configuration, entering through the bottom port from the compressor and exiting out the top to the dryer.

“Dry” storage tanks are locatedafterthe air dryers to store compressed air that has already been dried and filtered. It is not necessary to flow the compressed air through the tank for dry storage.

With wet air storage, the receiver tank is positioned in between the air compressor and the air dryer. Wet air enters the receiver tank from the air compressor through the lower port in the tank and exits through the upper port to enter the air drying system. A wet air receiver tank has several benefits.

As explained above, wet storage increases the efficiency of your air dryer by allowing excess water and lubricant to condense out of the air before it hits the dryer.

A wet air storage tank also prolongs the life of the pre-filter element, which is located in between the wet storage tank and the dryer. Since the air going through the filter is cleaner and dryer than it would be directly out of the air compressor, slugging of the filter with liquids is minimized, along with resulting pressure drop on the air dryer side of the system.

The compressor does not experience backpressure because the air does not go through filtration before entering the tank. This results in a steadier pressure signal to the compressor controller.

Without a dry air tank, air from the wet tank will have to go through the air dryer before it is used. During periods of high demand, the dryer is at risk of becoming over-capacitated as the system tries to pull air through at higher volumes than the dryer is rated for. If the dryer cannot keep up with the demand, drying efficiency is reduced, potentially leading to unwanted water in the air lines.

The ideal ratio of compressed air storage is1/3 wet to 2/3 dry capacity. For example, if you have a total of 1,200 gallons of compressed air storage, 800 gallons should be dry storage, and 400 gallons should be wet. Dry air is ready to use on-demand. The wet air tank increases the efficiency of the dryer and acts as a secondary reserve when dry air is exhausted. Dry air storage needs to be greater than wet storage to minimize the risk of over-capacitating the air dryer during periods of high demand.

An exception to this rule is for applications that have steady airflow without sharp peaks in demand. In this case, there is no need for a dry storage tank because air will simply flow through it without being stored up. This is often the case in robotic manufacturing facilities where airflow is consistent and predictable.

A good rule of thumb for most applications is to havethree to five gallons of air storage capacity per air compressor CFM output. So if your air compressor is rated for 100 CFM, you would want 300 to 500 gallons of compressed air storage. As explained above, 1/3 of the total storage capacity should be wet storage, and 2/3 should be dry storage.

While the standard rule works well for many applications, you will also want to consider other variables in determining your compressed air storage needs. Flow consistency has a large impact on storage requirements.

Facilities with very steady airflow, such as robotic facilities, typically don’t need as much stored air. That’s because they don’t have frequent high bursts of demand that rely on stored air. In this case, air storage can be reduced to 2 gallons per CFM of air compressor capacity. All storage should be wet storage in this case, as explained above.

Facilities with high variability in airflow and large peaks in demand may require larger volumes of stored air. This extra capacity will ensure that the system will be able to keep up with periods of high demand. Testing to determine CFM at peak demand will be needed to calculate air storage requirements.

The final consideration in determining compressed air storage requirements is the size of the pipework in the system. The pipes also store air for your compressed air system, and the larger the pipes, the more storage they provide. For systems with pipework of 2” or greater diameter, it may be worthwhile to consider that volume into the calculation.

Compressed air receiver tanks can be bulky, so many compressed air system owners would prefer to store them outside. Outdoor storage saves precious floor space in the facility.

It also helps to reduce strain on your HVAC system in warm weather. The compressed air storage tank radiates heat as hot air from the compressor cools within the tank, raising temperatures in the compressor room. Storing your tank outside avoids excess heat buildup in the compressor room and also helps the storage tank perform its secondary job as a heat exchanger more efficiently.

However, outdoor storage only works in milder, non-freezing climates. Make sure your climate is suitable for outdoor placement of your compressed air tank.

Outdoor storage of the air receiver tank is only appropriate for environments that stay above freezing year-round. In freezing temperatures, outdoor tanks can ice up and even rupture—a costly and potentially dangerous outcome. If your area experiences freezing temperatures during part of the year, it is safest to keep your tank indoors.

If you are storing your air receiver tank outdoors, be sure to conduct frequent inspections to monitor for corrosion. Any signs of corrosion should be addressed immediately to maintain the integrity of the tank.

If your area is subject to cooler temperatures with occasional risk of icing, take special care of your tank in cooler weather. The tank will generate some heat on its own. However, if temperatures drop too far, the tank is still at risk of freezing. Insulating your tank and providing auxiliary heating during cold weather may be necessary to prevent damage.

The majority of air receiver tanks are bare steel on the inside with a primer coating on the outside to reduce corrosion. The exterior paint is commonly matched to the compressor equipment. A basic steel tank works well for most applications and is the least expensive option. However, they may be prone to corrosion if too much liquid is allowed to build up inside the tank.

Epoxy coatings are sprayed onto the interior as a liquid and then cured into a tough, anti-corrosive coating. Epoxies work by creating a moisture-proof barrier between the air and the base metal of the tank.

Galvanized tanks are treated with a protective zinc coating that halts the formation of rust. Zinc protects the base metal by reacting chemically with corrosive agents before they can reach the base.

Both methods provide long-lasting protection for the interior of the tank, but they do add to the cost and lead time. Coated or galvanized tanks are better at maintaining air purity because they reduce the risk of particulates caused by corrosion entering the airstream. Applications needing higher purity air, or users concerned about the longevity of their air tanks, may want to consider one of these options.

Stainless steel air receiver tanks are primarily used for specialty applications where very high-purity air is required. They are the most expensive option, but they are highly durable and corrosion-resistant and maintain exceptional air purity. Hospitals, labs, electronics manufacturers, and other applications requiring high-purity air should consider a stainless steel tank.

Air receiver tank accessories are essential for tank safety and operation. While the tank itself is just a large sealed metal tube, all tanks must have at a minimum:

Automatic drain valves eliminate the need for daily manual draining of liquid inside the air receiver tank. Anelectric automatic drain valveis programmed to open at set intervals to let accumulated liquid drain out.

Zero air-loss condensate drainsalso provide automatic drainage of the tank. Instead of draining at set intervals, they use a float mechanism to control drainage. The drain will only open when needed, saving energy and reducing air loss from the tank.

The pressure gauge provides a visual indicator for the interior pressure of the air in the tank. You need the gauge to monitor pressures and ensure that the tank is not under stress from over-pressurization.

A pressure relief valve is required for all air receiver tanks per OSHA and ASME guidelines. The pressure relief valve opens automatically to release some air if pressures in the tank are too high. This safety mechanism is essential to minimize the risk of a dangerous rupture due to over-pressurization. The relief valve is typically set to 10% higher than the working pressure of the compressed air system but never more than the rated pressure of the tank’s ASME certification.

Vibration pads are not required for all applications, but they are recommended if the air compressor is mounted on top of the tank. Vibration pads absorb vibrations from the compressor motor and reduce fatigue on the tank.

Many buyers wonder if ASME certification is important for air receiver tanks—and the answer is yes. All air receiver tanks used in industrial applications must be certified by ASME for safety and performance.

The American Society of Mechanical Engineers, or ASME, is an organization that sets engineering codes and manufacturing standards for a variety of machines, parts, and system components. ASME acts as an independent quality assurance organization to ensure the safety and quality of manufactured items. An ASME certification stamp means that the manufacturer has met all safety and engineering standards for their product.

ASME has developed a set of codes and standards for pressure vessels, including air receiver tanks. The ASMEBoiler and Pressure Vessel Certification Programsets rules governing the design, fabrication, assembly, and inspection of pressure vessel components during construction. These rules include engineering standards for the thickness of the tank body, welds and joints, connections, and other components of the tank. Tank manufacturers must conform to all of the rules to obtain ASME certification.

Some big box stores carry non-code air receiver tanks. While these may be cheaper, they have not undergone the rigorous manufacturing processes and quality testing needed to ensure that they are safe and reliable. Using a non-code air receiver tank could put your life and the lives of your coworkers at risk.

If you are not sure whether or not your air receiver tank meets code requirements, you should have it inspected. Your local Fire Marshall may provide this service. They will stop in and test your tank with ultrasonic metalthickness testing technology. If your air receiver tank does not pass the inspection, it should be decommissioned and replaced immediately.

All air receiver tanks must also be inspected periodically once they are installed. OSHA does not mandate a specific testing interval, but it is recommended that all air receiver tanks be inspected at least annually. Your insurance company or local governing board may have different requirements. OSHA requires that formal inspections be performed by an inspector holding a validNational Board Commissionand in accordance with the applicable chapters of the National Board Inspection Code. Manufacturers are required to keep records of formal inspections and make them available to OSHA representatives upon request.

In between formal board inspections, manufacturers should conduct frequent visual inspections of the air receiver tank to look for signs of corrosion, damage or weld failure. Check drains daily and pressure relief valves quarterly to make sure they are operating correctly. Contact your manufacturer or compressed air system installer immediately if you see any signs of problems with your air receiver tank.

Pressure vessels must be built to withstand high internal pressures over a long period of time. Over time, corrosion, stress, and fatigue can make tank failure more likely. The most common causes of air receiver failure are:

The high internal pressures within an air receiver tank make failure extremely hazardous. Cracking or weld failure can cause the tank to burst with explosive force, projecting large pieces of metal or fragments of shrapnel at high speed. Air receiver tank failure may result in extensive damage to the facility and nearby equipment and severe injury or death for nearby workers.

An appropriately-sized air receiver tank will improve the efficiency of your system—and can even reduce your operating costs for your compressed air system. Your air receiver tank reduces energy consumption and saves wear and tear on your system.

Your compressed air receiver tank is like a battery for your facility, providing an extra reservoir of compressed air you can draw on during periods of high demand. This lets you reduce the overall operating pressures for your system, resulting in lower energy costs. You may also be able to purchase a smaller air compressor with lower CFM capacity by relying on your air receiver tank for high-demand events.

As explained above, the air receiver tank reduces cycles counts for your air compressor by evening out peaks in compressed air demands. Lower cycle counts add up to lower energy use and less wear and tear on other system components, extending the life of your air compressor.

The air receiver tank functions as a pulsation dampening device, absorbing vibrations from the air compressor motor and pulsations in the air stream