Compressed Air Regulators: The Design and Function

Regulator

Compressed air regulators are a pressure reducing valve that are used to maintain a proper downstream pressure for pneumatic systems.  There are a variety of styles but the concept is very similar; “maintain a downstream pressure regardless of the variations in flow”.  Regulators are very important in protecting downstream pneumatic systems as well as a useful tool in saving compressed air in blow-off applications.

The basic design of a regulator includes a diaphragm, a stem, a poppet valve, an orifice, compression springs and an adjusting screw.  I will break down the function of each item as follows:

  1. Diaphragm – it separates the internal air pressure from the ambient pressure. They are typically made of a rubber material so that it can stretch and deflect.  They come in two different styles, relieving and non-relieving.  Relieving style has a small hole in the diaphragm to allow the downstream pressure to escape to atmosphere when you need to decrease the output pressure.  The non-relieving style does not allow this, and they are mainly used for gases that are expensive or dangerous.
  2. Stem – It connects the poppet valve to the diaphragm. This is the “linkage” to move the poppet valve to allow compressed air to pass.  As the diaphragm flexes up and down, the stem will close and open the poppet valve.
  3. Poppet valve – it is used to block the orifice inside the regulator. It has a sealing surface to stop the flowing of compressed air during zero-flow conditions.  The poppet valve is assisted by a spring to help “squeeze” the seal against the orifice face.
  4. Orifice – it is an opening that determines the maximum amount of air flow that can be supplied by the regulator. The bigger the orifice, the more air that can pass and be supplied to downstream equipment.
  5. Compression springs – they create the forces to balance between zero pressure to maximum downstream pressure. One spring is below the poppet valve to keep it closed and sealed. The other spring sits on top of the diaphragm and is called the adjusting spring.  This spring is much larger than the poppet valve spring, and it is the main component to determine the downstream pressure ranges.  The higher the spring force, the higher the downstream pressure.
  6. Adjusting screw – it is the mechanism that “squeezes” the adjusting spring. To increase downstream pressure, the adjusting screw decreases the overall length of the adjusting spring.  The compression force increases, allowing for the poppet valve to stay open for a higher pressure.  It works in the opposite direction to decrease the downstream pressure.

With the above items working together, the regulator is designed to keep the downstream pressure at a constant rate.  This constant rate is maintained during zero flow to max flow demands.  But, it does have some inefficiencies.  One of those issues is called “droop”.  Droop is the amount of loss in downstream pressure when air starts flowing through a regulator.  At steady state (the downstream system is not requiring any air flow), the regulator will produce the adjusted pressure (If you have a gage on the regulator, it will show you the downstream pressure).  Once the regulator starts flowing, the downstream pressure will fall.  The amount that it falls is dependent on the size of the orifice inside the regulator and the stem diameter.  Charts are created to show the amount of droop at different set pressures and flow ranges (reference chart below).  This is very important in sizing the correct regulator.  If the regulator is too small, it will affect the performance of the pneumatic system.

The basic ideology on how a regulator works can be explained by the forces created by the springs and the downstream air pressures.  The downstream air pressure is acting against the surface area of the diaphragm creating a force.  (Force is pressure times area).  The adjusting spring force is working against the diaphragm and the spring force under the poppet valve.  A simple balanced force equation can be written as:

Fa  ≡ Fp + (P2 * SA)

Fa – Adjusting Spring Force

Fp – Poppet Valve Spring Force

P2 – Downstream pressure

SA – Surface Area of diaphragm

If we look at the forces as a vector, the left side of the Equation 1 will indicate a positive force vector.  This indicates that the poppet valve is open and compressed air is allowed to pass through the regulator.  The right side of Equation 1 will show a negative vector.  With a negative force vector, the poppet valve is closed, and the compressed air is unable to pass through the regulator (zero flow).

Let’s start at an initial condition where the force of the adjusting spring is at zero (the adjusting screw is not compressing the spring), the downstream pressure will be zero.  Then the equation above will show a value of only Fp.  This is a negative force vector and the poppet valve is closed. To increase the downstream pressure, the adjusting screw is turned to compress the adjusting spring.  The additional spring force pushes down on the diaphragm.  The diaphragm will deflect to push the stem and open the poppet valve.  This will allow the compressed air to flow through the regulator.  The equation will show a positive force vector: Fa > Fp + (P2 * SA).  As the pressure downstream builds, the force under the diaphragm will build, counteracting the force of the adjusting spring.  The diaphragm will start to close the poppet valve.  When a pneumatic system calls for compressed air, the downstream pressure will begin to drop.  The adjusting spring force will become dominant, and it will push the diaphragm again into a positive force vector.  The poppet valve will open, allowing the air to flow to the pneumatic device.  If we want to decrease the downstream air pressure, the adjusting screw is turned to reduce the adjusting spring force.  This now becomes a negative force vector; Fa < Fp + (P2 * SA).  The diaphragm will deflect in the opposite direction.  This is important for relieving style diaphragms.  This deflection will open a small hole in the diaphragm to allow the downstream air pressure to escape until it reaches an equal force vector, Fa = Fp + (P2 * SA).  As the pneumatic system operates, the components of the regulator work together to open and close the poppet valve to supply pressurized air downstream.

Compressed air is expensive to make; and for a system that is unregulated, the inefficiencies are much greater, wasting money in your company.  For blow-off applications, you can over-use the amount of compressed air required to “do the job”.  EXAIR offers a line of regulators to control the amount of compressed air to our products.  EXAIR is a leader in manufacturing very efficient products for compressed air use, but in conjunction with a regulator, you will be able to save even more money.  Also, to make it easy for you to purchase, EXAIR offer kits with our products which will include a regulator.  The regulators are already properly sized to provide the correct amount of compressed air with very little droop.   If you need help in finding the correct kit for your blow-off application, an Application Engineer at EXAIR will be able to help you.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

EXAIR Safety Air Gun Accessories Improve Effectiveness and Safety

Safety Air Gun with accessories

EXAIR offers 5 different styles of Safety Air Guns; Precision, VariBlast, Soft Grip, Heavy Duty and Super Blast.   You can read more about the different styles of Safety Air Guns from a previous EXAIR blog “Not All Compressed Air Guns Are The Same” written by Justin Nichol. I will be targeting the accessories that can enhance the features of the EXAIR Safety Air Guns. These additions will make the Safety Air Guns more dynamic without sacrificing safety, efficiency, or durability.

Precision Safety Air Gun with Chip Shield
eg. 1408SS-CS

Chip Shields:

OSHA 1910.242(b) requires chip guarding when compressed air is used for cleaning. EXAIR offers Chip Shields with our Safety Air Guns to meet this requirement. They are made from a polycarbonate disc which is practically unbreakable and protects the operator from any blow back of metal shavings or coolant. They come with a durable rubber grommet that squeezes onto the extensions and can be adjusted to maximize protection. We offer Chip Shields for the Precision, VariBlast, Soft Grip, and Heavy Duty Safety Air Guns with or without aluminum extensions.

Heavy Duty Safety Air Gun with extension.
eg. 1350-72

Extension Pipes:

For those far away targets and hard-to-reach areas, EXAIR offers aluminum extension pipes to attach to the Safety Air Guns. They can range from 6” (15 cm) to 72” (183 cm) in length. This light-weight and durable material allows for easy handling to reach high above your head or to span across unsafe areas. With the EXAIR air nozzles at the end, the blowing force is not sacrificed as the back pressure will generate a high velocity air stream. The aluminum extensions are offered with the Variblast, Soft Grip, and Heavy Duty Safety Air Guns. The Super Blast Safety Air Guns has the option for two different lengths of extensions, 3 feet (91cm) and 6 feet (183 cm).

Soft Grip Safety Air Gun with Stay Set Hose.
eg. 1210-6SSH

Stay Set Hose:

In certain situations, you may need a way to blow air around a corner or in a tight space. The Stay Set Hose gives you that possibility of manually adjusting or re-adjusting the nozzles to target the correct areas. The hose has a “memory” function, and it will not creep or droop until you physically move it again. They come in lengths from 6” (15cm) to 36” (91cm), and they are offered with the Soft Grip and the Heavy Duty Safety Air Guns.

Coiled Hose

Coiled Hoses:

To get the proper amount of compressed air from the piping system to the Safety Air Guns, EXAIR offers a series of Coiled Hoses. They are made of a durable abrasion-resistant nylon material that is 12 feet long (3.6 meters). They have swivel fittings to allow for easy uncoiling, and a spring strain relief to keep the hose from kinking at the ends. The coiled design makes it easy to reach around the work area and retract back to the substation. This will help to keep the hose off the ground where potential dangers could occur. We offer 3 different connection sizes of 1/8” NPT, ¼” NPT, and 3/8” NPT. They can be used with our Precision, VariBlast, Soft Grip, and Heavy Duty Safety Air Guns. With the proper size, the Coiled Hoses can connect easily to the Safety Air Guns and supply the required amount of air with a minimal amount of pressure drop.

Regulator and Filter

Filter Separators/Regulators:

To improve the use of the Safety Air Guns, EXAIR offers a series of filters and regulators. The filters will remove dirty particles and liquid water from the compressed air that can affect the performance of the Safety Air Gun as well as contaminate the surface that you are cleaning. The regulators can control the amount of air pressure used for the Safety Air Gun; making them even more efficient. The idea for compressed air savings is to use the least amount of compressed air to do the job. If you only need 40 PSIG (2.8 Bar) to blow off an area, then you can save almost 40% of your compressed air as compared to doing that same job at 80 PSIG (5.5 Bar). The combination of a filter and regulator will allow you to control the proper amount of clean dry air to be used.

 

All of our Safety Air Guns are fitted with our engineered Air Nozzles  which make them OSHA compliant for noise and dead-end pressure. With the accessories, you can optimize the use of the Safety Air Guns to better fit your application. If you need help in determine the correct Safety Air Guns and accessory items, you can contact an Application Engineer for help. If you are within the U.S. or Canada, you can take advantage of our 30-day unconditional guarantee to trial any of our stocked Safety Air Guns.

John Ball
Application Engineer
Email: mailto:johnball@exair.com
Twitter: @EXAIR_jb

Super Air Amplifiers – Adjustability for Blowoff, Drying, Cooling, Circulation and Ventilation

The Super Air Amplifier is a powerful, efficient, and quiet air mover. Applications currently in place include blowoff, drying, cooling, circulation and ventilation. Sizes from 3/4″ to 8″ are available to best match the air volume that is necessary to achieve the process goals. There are a couple of ways to change the performance of the Super Air Amplifier if either a small or large change to the output flow is required.AirAmplifiers

The chart below shows the Total Output Flow for each of the 6 models. As an example, the Model 120021 or 121021, when operated at 60 PSIG of compressed air supply, will have a total output flow of 120 SCFM. These same devices when operated at 80 PSIG will have a total flow of 146 SCFM. By simply using a pressure regulation device on the compressed air supply, the output performance can be tuned to match the desired outcome.

Capture

For those applications where much greater flow and/or force is needed, the option of installing a thicker shim is available.  The Super Air Amplifiers are supplied with a 0.003″ shim installed (the 8″ model 120028, has a 0.009″ shim as standard) and can be fitted with shims of thicknesses of 0.006″ or 0.009″ (the 8″ model has an optional 0.015″ shim.) Installation of a thicker shim increases the slotted air gap, allowing for a greater amount of controlled air flow.  As a general rule, doubling the shim thickness will double the air flow rates.

Super Air Amplifier Shims
Patented* Shim Design for Super Air Amplifiers

The Super Air Amplifier design provides for a constant, high velocity outlet flow across the entire cross sectional area,.  The balanced outlet flow minimizes wind shear to produce sound levels that are typically three times quieter than other air movers. By regulating the compressed air supply pressure and use of the optional shims, adjustability and flexibility of the unit is wide ranging and sure to meet your process needs.

If you have questions regarding the Super Air Amplifier, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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*Patent #5402938

EXAIR Accessories – We’ve Got you Covered

When you work with us here at EXAIR, we strive to have all the ancillary items that you might need to make your installation a success, without having to find components at the last minute or perhaps using the wrong sized components. Each specific product line such as Super Air Knives or Line Vac air operated conveyors have specific accessories such as mounting brackets or plumbing kits which EXAIR has made to simplify the installation of those particular products. We also carry generalized accessories which work across all of the product lines so you do not have to use multiple vendors or purchase orders.

Silencing Mufflers – Per OSHA Standard 1910.95(a), a worker must not be exposed to sounds levels above 90 dBA for any eight hour shift of a 40 hour work week.  EXAIR offers several types of mufflers including – Reclassifying, Sintered Bronze, Straight-Through and Heavy Duty.  For reducing the noise associated with an EXAIR E-Vac Generator, Vortex Tube, Cabinet Cooler System, or the exhaust air from cylinders, valves and other air powered equipment, we’ve got a muffler that will help to keep the noise level at an acceptable level.

Mufflers

Solenoid and Manual Valves – The easiest way to reduce compressed air usage and save on operating expense is to turn off the compressed air to a device when it isn’t needed. EXAIR carries a wide assortment of solenoid valves, with offerings in the NEMA 4/4X classification, and supply voltages of 24VDC, 120VAC, and 240VAC.  We also have manual ball valves from 1/4 NPT to 1-1/4 NPT and a foot operated valve, with 1/4 NPT connections.

Valves

Swivel Fittings, Stay Set Hoses and Magnetic Bases – To provide a great degree of flexibility for positioning an EXAIR Super Air Nozzle, Air Jets or Air Amplifiers, EXAIR offers several items.  The Swivel Fittings have 25 degree of movement from the center axis, providing a total of 50 degree of adjustability.  The position is locked in place and holds until adjustment is needed. For applications where frequent re-positioning of the air device is required, the Stay Set Hoses are ideal.  Simply mount the hose close to the application, bend it to the shape preferred, and because the hose has “memory”, it will not creep or bend.  Lastly, the Magnetic Bases are another option for flexible, movable installations.  The base has a on/off valve, and a powerful magnet to hold in any vertical or horizontal mounting arrangement.

Swivels, StaySets,MagBases2

 

Hoses – EXAIR can provide hoses for your application.  For the Line Vac air operated conveyor applications, we offer conveyance hose – a durable, clear reinforced PVC hose, in diameters of 3/8″ to 3″ ID, and lengths up to 50′. On the compressed air side, we can provide 12′ Coiled Hoses with 1/8, 1/4, and 3/8 NPT connections, and also 3/8″ and 1/2″ ID hose in lengths to 50′.

Hoses

Filter Separators, Oil Removal Filters and Pressure Regulators – Perhaps the most important accessories for use on a compressed air device are filters and regulators. Filtering the compressed air of dirt, debris, moisture and oil will help to prevent build up inside the EXAIR products, leading to longer service life, and less time spent cleaning, while providing optimum performance. Regulating the air pressure allows for tuning of the performance, using the proper amount of compressed air to obtain satisfactory results.

Filter and Regualtors

If you have questions regarding accessories for use with any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Video Blog: How To Rebuild Pressure Regulators

Today’s video blog is a how-to on rebuilding EXAIR pressure regulators.   Regulators can wear out over time and extensive adjustment as well as if they are not used on a clean compressed air supply.  If you have any questions on an EXAIR product, please contact an Application Engineer.

Thanks for watching!

 

 

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

Oil And Water Don’t Mix, But Oil And Air Sure Do

Do you have oil in your compressed air system? It may be there on purpose…air operated tools require it, and there are a number of devices on the market that provide a precise amount of oil to keep the moving parts in these tools well lubricated and properly operating.

If it’s not there on purpose, it’s not necessarily a problem, though, and it’s hardly uncommon. Many air compressors are oil lubricated, which means there’s oil being pumped at a constant rate, directly towards the piston rings, and a little bit is always going to end up in the air. As the rings wear, even more makes it past…this is impossible to prevent, but, with proper maintenance, it’s kept to a very minimal amount. There are, of course, oil-less compressor designs, which can eliminate this entirely, but they’ve been known to carry a little heavier price tag. Some situations, though, make them worth every penny.

Trace amounts of oil like this don’t affect a lot of compressed air applications, including the performance of most of our products. There are times, however, when oil needs to be addressed…for instance:

*Blow off prior to painting or coating. Even trace amounts of oil on a surface to be painted can cause big problems.
*Electrical enclosure cooling. Oil won’t affect the heat removal performance of an EXAIR Cabinet Cooler System, but it can indeed cause serious issues with electrical/electronic components and devices if it’s present in the cold air that’s blowing on them.
*Air operated conveyors. Likewise, oil won’t hurt the performance of a Line Vac, but keep in mind that anything in the air supply will get on the material or product you’re conveying.
*Static Eliminators. Here’s a situation where oil in the air WILL have an effect on product performance…the emitter points of your EXAIR Static Eliminator need to be kept clean (including oil free) for proper operation. And, again, anything in your air is going to get onto your product.

This is where proper filtration comes in: properly installed downstream of a Filter Separator, EXAIR’s coalescing Oil Removal Filters take out even trace amounts of oil from the air flow, ensuring your process doesn’t see anything but clean, dry air.

EXAIR Model 9027 Oil Removal Filter, installed between Model 9004 Filter Separator and 9008 Pressure Regulator, using our Modular Coupling Kits
EXAIR Model 9027 Oil Removal Filter, installed between Model 9004 Automatic Drain Filter Separator and 9008 Pressure Regulator, using our Modular Coupling Kits.

Again, oil in your air isn’t always a problem. If you have questions about your application, though, give us a call…if it IS a problem, we’ve got a solution.

Russ Bowman
Application Engineer
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Compressed Air Accessories – Filters and Regulators – The Rest of the Solution

IMG_5696
EXAIR Regulator with gauge and Filter/Separator

Many times in the stories that are written in our daily blogs, we espouse the many benefits of installing and using EXAIR made products into our many customers’ compressed air-based applications. From the guy who has a small shop in his home garage using our Atto Super Air Nozzle to much larger applications where customers use our 84” Long Super Air Knives to do such things as drying cast Acrylic Sheets used in tub and shower surrounds, the message is a very consistent one. Customers benefit by saving money, increasing the safety level of an application, reducing sound levels and improving productivity.  There’s no doubt that our customers will excel in these areas.

Knowing there is much more to a compressed air system than just point of use products, lets shed a little light on the other “parts” of a typical system set-up. Those would be the compressed air filter / separators and the pressure regulators that are a highly recommended part of a good installation. But why are they so highly recommended? What exactly is their role and why would anyone want or need to install them?

First, the blunt realities of compressed air and its relative “un-clean” condition once it arrives at the point of use. Since compressed air a utility that is produced in-house, the quality and quantity available will vary widely from facility to facility. And since it is not a regulated utility such as gas or electricity are, there are no universal minimums of quality that compressed air must meet before sent out to the distribution system. Yes, of course, companies are all the time getting better at this part, but many still operate with older, iron pipe systems that produce rust and scale which wreak havoc on the components within mechanical products that use compressed air as their power source. The point is that you are never sure of the quality of the air you will get at the point of use, so install a compressed air filter near that point to keep the debris out of your Air Knife, Nozzle, Line Vac or even other components like solenoid valves, air motors and the like. Believe me when I say it is much easier to un-screw a bowl from a filter housing and change an element than it is to disassemble an air motor or an 84” long Super Air Knife because rust migrated in from the pipes. So it is quite safe to say that an ounce of prevention in this case is worth a pound of cure!

Second, the discussion turns to the Regulator part of the equation. As many know, our products and those of other pneumatic product manufacturers have a certain set of specifications regarding performance at stated input pressures. But what if your application doesn’t require that “full, rated performance”? Maybe instead of needing two pounds of force, you only need one pound? In fact, if you provided two pounds of blowing force, you would end up “over-blowing” your target. By that, I mean you cause damage to the target or other surrounding items in the application. Or, perhaps blowing to hard (or sucking too hard in the case of a Line Vac or E-vac) might cause the vessel or the material you are picking up to collapse or deform (due to too much power).  There is also the concern about using more energy than one really needs to in order to achieve the desired effect in an application. In other words, if you can achieve your goals with only 40 PSIG, then why would you ever use 80 PSIG to accomplish the goal? By reducing your compressed air from 80 down to 40 PSIG, you can easily reduce the air consumption of the “engineered” solution by another 40% + …………that’s the cherry on top of the cake when you compare the benefits of simply “bolting on” the solution of an engineered air nozzle vs. an open pipe in the first place. Then there is the issue of taking advantage of the pressure differential (from 80 down to 40 PSIG) that creates a little bit more air volume capacity. At 80 PSIG, your compressed air to free air volume ratio is 6.4:1. At 40 PSIG, it is only 3.7:1. The net effect is you effectively have an overall larger volume of air at the disposal of the application which is always a good thing.

Regulating pressure is definitely warranted given the benefits that compliment the operation of the core EXAIR products.

If you need a deeper understanding about how EXAIR’s products can help your application, feel free to contact us and we will do our best to give you a clear understanding of all the benefits that can be had by our products’ use as well as proper implementation of accessory items such as compressed air filters and regulators.

Neal Raker, International Sales Manager
nealraker@exair.com
@EXAIR_NR
www.EXAIR.com