Illustrating The Importance of Proper Compressed Air Supply Lines

“Proper compressed air supply lines” in this context means properly sized air hose, pipe, or tube and properly sized fittings which connect your compressed air supply into an EXAIR product. With under-sized compressed air supply lines and/or fittings a pressure loss through the product will occur. We spend a good amount of time speaking with customers about getting our products plumbed up properly so they may realize the best performance of our products, or any compressed air product.

One of the easiest places to find our recommendations for line sizes is in the Installation and Maintenance Guide included with the product you have purchased. All of the install guides have a chart specific to the EXAIR product which looks like the one below. You may also visit the .pdf library in our website’s Knowledge Base.


(CLICK images to ENLARGE)

Many customers pay close attention to their available pressure and assume if they have enough supply line pressure, then they are OK. And while pressure is necessary it will not make up for a lack of volume of compressed air. You need the right amount of volume of compressed air to maintain a specific pressure level. You cannot feed a fire hose with a garden hose, there is not enough volume of water through the garden hose to support water pressure inside of the fire hose. The water will just trickle out of the larger hose. Air Line sizes which are too small or fittings with small inside diameters will decrease air volume to an extent which lowers air pressure and performance of some products.

Here are a number of images (click on them to enlarge) to illustrate improper sized lines/fittings and a pressure loss.  The large pressure gauge shows the supply pressure and is always set at 80 PSIG. There is also a pressure gauge on the inlet to an EXAIR 12″ Super Air Knife which will fluctuate depending upon the size and type of air line and fitting. The first image shows a very common 1/4″ quick disconnect on a 3/8″ inside diameter hose; you will see the small gage on the knife reading 54 PSIG even though there is 80 PSIG from the inlet compressed air supply. It is the very small inside diameter of the quick disconnect which starves the knife of air.

The second image shows another common hose and fitting setup is to use a push to lock fitting. These fittings again have a small inside diameter which restricts the air flow and results in a pressure loss. And remember the tubing used is called out by referring to its outside diameter. For example a 3/8″ tube refers to the outside diameter of the tube which actually has only a 1/4″ inside diameter in most cases. A 1/4″ inside diameter is not large enough to maintain pressure through this knife and results in a 17 PSIG pressure loss.

And finally, the third image shows what we recommend for this particular setup. It is a 3/8″ inside diameter hose with a hose barb fitting pushed in to the hose and a 1/4 MNPT fitting to screw into the Super Air Knife. You can clearly see that there is no pressure loss through the compressed air supply lines.

If you are experiencing a product which does not seem to be performing very well, or you are getting a trickle of air out of a product which should produce a lot of force, the first thing we will recommend is to place a pipe tee with pressure gauge into the inlet of the product (just as shown in the images) so you may compare your known supply line pressure to the pressure you are getting through the product. This will allow for a good starting point of troubleshooting the application.

Properly sized compressed air lines will maintain peak performance of your EXAIR product by providing enough volume of compressed air  to keep up pressure  to help assure you of a successful application.

If you have any questions about compressed air applications or supply lines, please contact an EXAIR Application Engineer.

Kirk Edwards
EXAIR Corporation

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