:: Air Compressor Parts ::

FRL is an acronym for Filter, Regulator and Lubricator, devices used to “condition” the compressed air from a compressor before it gets to your application be that through an air valve to air cylinders, powering air tools and so on.

When called in to troubleshoot a complaint from a client that their compressed air filter, regulator or lubricator wasn’t working, the first response is to ask the symptoms. Common complaints are, “the regulator is not working, and it’s leaking oil”, or “my air filter fills up too quickly”. Have you ever had these problems?

The acronym FRL is placed in this order deliberately.

These air treatment units, whether they are an assembly (combination FR + L) or a number of single components - Filter + Regulator + Lubricator - installed in a row, must always be installed with the Filter first, the Regulator next, and the lubricator last.

The filter must ’see’ the air coming from the compressed air supply line first, as it’s the defense against compressed air-borne water and particulates. If you think about it, you would want the filter to remove contaminants and free water from the compressed air before that air gets to more sensitive down-stream components, including the regulator and the lubricator.

The regulator is installed after the filter to ensure that the air getting to the regulator is as clean as that type of compressed air filter will allow, thus increasing the life span and mean-time-between-failures for the regulator.

The regulator’s purpose is to regulate a lower pressure to the downstream application. Some folks are of the opinion that the regulator can be used to “dial-up” the pressure. This is true, as long as it’s understood that the pressure that’s being selected is at a level below the upstream supply pressure. You cannot use a regulator to increase the pressure downstream higher than the supply pressure upstream of that regulator.

Compressors are usually cyclic, meaning that the air pressure in the lines from them varies according to where the pressure is in the compressor receiver. When the air pressure in the compressor receiver falls to the low level set point, the compressor will kick in, and bring the pressure in the receiver up to the high level set point, at which point the compressor will stop. This cycle repeats, sometimes quite quickly, depending on the compressed air demand in the shop. A regulator will dampen the pressure swings from the system as the compressor kicks on and off, ensuring that your application, if the regulator pressure is set at the correct level, will see a constant, steady pressure.

If the regulator is incorrectly installed, upstream from the filter instead of after it, not only is the regulator not protected from air-borne water and particulates, it will negatively affect the flow of air to the filter, decreasing its effectiveness.

The lubricator’s purpose is to provide a steady, metered stream of the appropriate lubricant to the downstream application, be that an air tool, or an air valve / cylinder combination.

The lubricator is installed last in the FRL series to ensure that the lubricant has ready access to the components desired to be lubricated though many modern pneumatic circuits may not need a lubricator at all, what with the high cycle type lubricants that are commonly used by air actuator manufacturer’s.

If the lubricator is incorrectly installed after the filter and before the regulator, the lubricant flow will negatively affect the operation of the regulator. The regulator may be over lubricated to the point where it doesn’t work properly. This may be the cause of the “lubricator’s all gummed up and not working properly” complaint. Most compressed air regulators are relieving type, and if the lubricator is “feeding” lubricant to the regulator, lubricant will wick from the relieving port, hence the “regulator’s leaking oil” complaint.

If the lubricator is installed upstream from the filter and the regulator, the lubricant stream from the lubricator will simply be intercepted by the filter, and not get downstream to the application at all. Thus the filter is “filling up too quickly” complaint.

In the absence of the lubricator, the correct installation if filter first, then regulator.

If the unit you have is a combined filter regulator, it’s internally plumbed to have the air filtered through the filter ‘half’ before the compressed air gets to the regulator.

Remember, it’s FRL on purpose!

Bill Wade is a former sales representative, sales manager, marketing manager and president of companies that use and sell compressed air, along with other equipment and supplies. His sales agency currently represents a select group of companies. Mr. Wade writes about understanding compressed air, how it’s compressed, how it’s treated, and how it’s used 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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