:: Air Compressor Parts ::

Reducing air leaks in your plant can save thousands of dollars annually. Compressed air is one of the most costly forms of energy you can use in your plant, of course, it’s one of the most versatile, fast and strong too.

When it’s “quiet time” in the plant, wander around the machinery and listen. You will often hear the gentle (or perhaps not so gentle) hissing of air escaping from the exhaust port of your air valves.

The sound of compressed air “chewing up your dollars” as it wafts to atmosphere can be muted if your air valves have mufflers in the exhaust ports, but nevertheless, it can be heard.

Also, there are commercially available ultra-sonic compressed air leak detectors on the market. If your plant doesn’t have a “quiet time”, which would enable you to actually hear the leaks yourself, investing in an ultrasonic leak detector can bring substantial payback in energy savings.

Usually you’ll have one air valve connected to one air cylinder. Usually that cylinder will be double acting - which means that it will have two air lines running to it, and as the air valve shifts back and forth, air will alternatively flow to the cylinder through one line or the other. When it’s flowing into one line to the cylinder, the other line is allowing the air at the other end of the cylinder to flow through the valve to exhaust.

While an air valve and cylinder are doing work of course there will be air being exhausted continuously from the air valve exhaust ports.

It’s when the machine is down, when it’s doing no useful - and hopefully money generating work for you - that air should not be escaping through the valve exhaust ports. At this point that loss of compressed air is just that; loss - of profits - of money.

Inside, the two ends of the cylinder are separated by a piston. The piston is what drives the rod out and back as the cylinder cycles.

Around that piston will be an air seal that “crunches” between the side of the piston and the inside of the cylinder barrel, effectively stopping air from flowing by (bypassing) the piston.

In time that seal will wear, and air will start bypassing into the other side. This means that this air now has an open path from the supply side down the other air line to the valve, and thence to the exhaust port. And a gentle (or not so gentle) hiss occurs as your compressed air dollars exhaust to atmosphere.

Or….inside your air valve there is, too, a series of seals that normally prevent air from getting from the air supply side into the exhaust side of the valve, and then out the exhaust port. And that air, as it gently (or not so….etc. ) is pouring your compressed air dollars from the plant air supply.

So, which is it that’s leaking; the seal around the piston in the cylinder, or the seal inside the valve that stops the incoming air from getting across to the exhaust port without going up to the cylinder?

Have a look at the cylinder. If the rod is out, air will be entering the air port at the rear of the cylinder. If the cylinder is in - retracted, the air will be coming into the cylinder at the rod end.

Take the air line that is charged, that is, the air line that is supplying air to the cylinder, and crimp it. Many air lines are made of polyethylene or polypropylene, and it’s quite easy to make a bit of a bend in the air line, effectively shutting off air to the cylinder.

Listen at the valve. If the air has stopped escaping the valve’s exhaust port, then it’s the seal in the cylinder that’s at fault.

If, after ensuring that the air to the cylinder is completely stopped, air continues to exhaust from the exhaust port of the valve, then it’s the seal inside the air valve that’s at fault.

Regardless of which is the culprit, the air valve or the cylinder, get it fixed….fast! Compressed air costs a bundle. You don’t want to waste it.

Bill Wade is a former President and Sales Manager of companies that use and
sell compressed air related equipment and supplies. He currently represents a
select group of companies and writes about air at http://www.about-air-compressors.com.

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If you purchase a “do-it-yourself” type air compressor, or if you purchase any type of air compressor for that matter, check to make sure that it comes with an Air Regulator. If not, purchase one. You will be glad you did!

An air regulator is a device that lowers the downstream air pressure. Downstream air is the air that’s moving from the regulator towards your application.

Compressed air will flow from the compressor reservoir into the air regulator (this supply is called upstream air) and through a system of an internal diaphragm and springs, the regulator will maintain a constant downstream air pressure level, despite changes in the upstream supply pressure from the tank.

Recognize that you can only use a compressed air regulator to increase the downstream air pressure up to the level of the upstream supply air pressure. An air regulator will not enable you to “dial up” the downstream air pressure higher than the upstream level.

However, if you can figure out how to do that, do let me know, and we’ll both get rich! ;-}

You will want to set the downstream air pressure from your regulator at a pressure level that is below the lowest air pressure that will be incoming from your air compressor. Here’s why.

The compressor maximum pressure set point is the pressure level inside the compressor receiver at which the compressor shuts itself off. This is also known as the “cut out” pressure.

When the cut out pressure is reached, the compressor stops compressing air. When you start to use compressed air from the compressor tank, the pressure inside starts to drop, and eventually the compressor will start again. This is the “cut in” pressure point.

As a result, your application, be it an air tool or an air brush, will “see” varying pressures from the tank as the compressor cycles on and off between the two set points.

For most applications, a varying air pressure supply isn’t satisfactory and it is particularly problematical for folks that use compressed air to spray paint. Despite your best efforts with the air brush, if the supply air pressure is constantly changing, so too will the quality of your work.

This brings us back to the why you will always want to have an air regulator installed in the line between the compressor and your application.

If you set the downstream air pressure at a pressure level BELOW the cut in pressure level of the air compressor, in theory, the air pressure to your application should never change. As the air compressor goes through its normal cut-in and cut-out cycle your air regulator ensures that your downstream device will see a steady, non-fluctuating, supply of compressed air.

This is theoretical only, unfortunately. If your application consumes more compressed air than your compressor can generate, even though you have set your air regulator at a “safe” level, eventually the air pressure from the tank will fall below the level your regulator is set for, and the downstream device will see a steadily diminishing air pressure supply too; this even though your compressor may have cut-in, and is trying desperately to build up a supply of compressed air inside the tank.

This is why you really want to know how much air you need for your application to ensure that your air compressor has enough capacity to oversupply your needs. Check out details of this at ABOUT-air-compressors. com!

Know that air pressure regulators come with different levels of accuracy with the least accurate being, as you might guess, the least expensive.

Most general purpose compressed air regulators will have an accuracy of 3-5 PSI, meaning that the actual air pressure that your device is being supplied through the regulator will vary within that range, despite what it says on the gauge.

If you need more accuracy, opt for a precision regulator, and depending on the manufacturer, you may be able to get a downstream air pressure within a .5 PSI accuracy of the pressure reading on the gauge.

General purpose air pressure regulators normally have an operating range in the area of of 0 - 120 PSI. Others will be rated for pressures of 0-100 or 0-150 PSI.

You can also get air regulators with a narrower and more specialty oriented range of pressures such as: 0-10 PSI, 0-20, 20-60 PSI and so on. At the other end of the scale, you can purchase regulators that can safely handle many thousands of PSI.

For most do-it-yourself types, a general compressed air regulator with a range of 0-100 PSI will do just fine.

Bill Wade’s experience in compressed air and other industries spans decades; from field sales positions through to the corporate presidential office. His sales agency represents a select group of industrial firms. Mr. Wade writes about all facets of compressed air at http://www.about-air-compressors.com

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Recently, I published an article on this site titled: What’s a 2/2 compressed air valve? Here, in the next installment in this series, is information on a slightly more complex air valve; the 3/2 style.

The first number in the 3/2 air valve, the three, refers to the number of “working” air ports that are found in the valve body. That is, the number of ports that supply air to the valve, and channel the compressed air to whatever it is that the valve is supposed to do.

Most 3/2 valves will have numbers or letters etched, cast or painted near each of their three “working” air ports. If there are numbers near the ports, the number 1 would be the supply port to bring the compressed air to that valve.

Port number 2 would be the working port from which air would flow to accomplish whatever task that you wanted that valve to do.

The third port in a 3/2 air valve is an “exhaust” port and if numbered, it could be a 3 or a 5. If the port designations in a 3/2 valve are letters, then port ‘A’ would be the supply port and port ‘B’ the working port, with the third port normally being an ‘E’.

As in the 2/2 valve there may be one or two additional ports in the ends of the 3/2 valve to allow an air signal line or lines to be connected. If this is the case, this 3/2 valve will either be single, or double air piloted.

The 2 in a 3/2 air valve indicates the number of positions that the internal valve mechanism has. In this case, two. When this valve is operated or actuated, it will either open or close and air will either flow to the application upon actuation, or it will be prevented from flowing.

Most 3/2 compressed air valves will be NC, or normally closed. When the valve is not actuated, it’s normal state is closed, and compressed air cannot pass through it.

If your application calls for air to flow through the valve when it’s not actuated, that the circuit needs air to be flowing through this valve when it is at rest, then a NO or normally open configured valve would be selected.

All 3/2 valves have actuators that will operate or ’shift’ the air valve. An external button, or toggle, or perhaps a solenoid actuator would be the visible actuator. Inside, there will likely be an internal actuator - a spring - which will shift the valve to the off position when the external actuator is not being used.

If the external actuator is ‘detented’, then when the valve is operated, it will stay in it’s last selected position until an operator changes it. Detented means it will stay where it’s put! This is useful when an operator needs to actuate the valve, and then manually perform another operation while the air valve feeds air to the application.

Unlike it’s less complex 2/2 valve cousin, the 3/2 valve is used when a compressed air supply is needed to an application or device that uses compressed air to power it, yet in itself has no integral air pathway to atmosphere. Therefore, when the device has performed it’s function, and it’s time to ‘deflate’ it or to let the compressed air back out, the third port in the 3/2 valve comes into play.

When the compressed air supply through the valve is shut off internally, a pathway back through the valve to atmosphere will be opened, to allow the compressed air to escape. The air supply is shut, so the compressed air flowing to the valve cannot flow through it, and the compressed air that was formerly in the device or application can now bleed back down the air line through the valve to exhaust.

So, what type of devices are these?

Usually they are single acting type actuators. One comes to mind immediately; “Air springs”.

Both Firestone and Goodyear (among others) manufacture “air springs”. These are devices that look like tires, but rather than have an opening in the middle of the doughnut where the rim goes, they are closed on both sides with steel plates. In one side there will be an air port to which an air line from a 3/2 valve can be connected. These “air springs” are mounted on their sides, picture a tire lying flat after you’ve taken it off your car, and can generate huge actuation forces. Force equals pressure times area, and the “piston” size inside an air spring can be huge. The application of air springs mirrors that of typical air cylinders, yet offer large capacity at a fraction of the cost of an air cylinder of a necessary size to generate the same force as the air spring.

Another application for 3/2 valves is single acting air cylinders. Whether they are spring extend or spring retract, an air supply is required to operate the SA cylinder. A 3/2 valve is designed to do just that.

A couple of more points; the 3/2 valve can have the exhaust port plugged, and voila, you have a 2/2 valve.

If the cost of the valve is the same, you can use a 3/2 air valve anywhere you might use a 2/2 valve. Since 2/2 valves always have to have the “working port” ultimately plumbed to atmosphere, that there is an exhaust port in a 3/2 valve offers no obstacle to it’s use.

If you have a double acting air cylinder, and you don’t have a 4/2 or 5/2 (more on these valves next article) available, you can use two 3/2 valves to operate any cylinder that requires two supply lines in order for it to extend and retract.

At ABOUT-air-compressors.com my e-book entitled All About Air Valves - Volume One is now available. If you are interested in more information about air valves, do visit the site and download a copy. This first e-book is an introduction to air valves, and focuses on the 2/2 iteration. Future volumes will focus on 3/2 valves, and then the 4/2 & 5/2 configurations.

And as always, if you have any questions, please send me a message from the contact screen at my web site.

Bill Wade’s experience in compressed air and other industries spans decades; from field sales positions through to the corporate presidential office. His sales agency represents a select group of industrial firms. Mr. Wade writes about all facets of compressed air at http://www.about-air-compressors.com

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