Q1 2021

Compressed Air Piping

By Bruce Grossman, EZtimers Manufacturing

Last issue, I addressed the harmful effects of moisture and water as well as devices used in removing these contaminants from a compressed air system. This time we’ll cover the piping practices and components that route dehumidified air to your machinery and eliminate any residual water, providing your machinery with clean dry air.

Two physical forces are used to remove any remaining water and debris from the compressed air stream. Gravity, we all know what that is; and inertia, which is the tendency of objects to keep moving in a straight line at constant velocity. Follow along using the accompanying illustration.

  1. GRAVITY- Notice first that the large pipe called a header is tapped from at each machine by branches called drops used to supply compressed air to individual machines. When designed properly the drops are taken off the top of the headers. Since water is much heavier than air it flows along the bottom of the header pushed along by the flow of the air while the air flows along the top. Thus, gravity provides a very effective additional stage of separation. I’ve seen many installations where the drops were taken off at the bottom of the headers literally capturing and forcing water down into the machinery; a very unhappy situation causing machine performance nightmares. At the end of the airline it is beneficial to have what is known as a “drip leg.” A drip leg in its simplest form is nothing but a vertical piece of pipe used to collect and retain water and debris entrained in the compressed air system.


  1. INERTIA- Any remaining water and debris entrained in the compressed air are moving rapidly along through the headers and drops. Because of inertia they want to keep moving in a straight line. An abrupt change of direction in the drop is created by inserting a tee and piping the air flow to the machine from the side of the tee. Lighter compressed air makes the 90 degree turn out of the tee while the heavier water and debris continue moving in a straight line and are captured in the drip leg.


A combination of components after the tee provide the remaining pathway conducting the compressed air to the machinery. A ball valve is used to shut off the compressed air flow from the drop to the machine for maintenance and a combined filter/regulator provides another stage of water and debris removal along with filtration and air pressure regulation. Draining the drip legs can be done manually with a simple ball valve or automatically using a device known as a “drip leg drain.” I use an inexpensive air filter purchased from Harbor Freight, Item #68279 plugged at the outlet side as a drip leg drain.


I’m aware that in almost all cases the piping for the machinery already exists and you’re not going to get into replacing it because of this article. However, look at the diagram in the lower right of the illustration. It is very easy to just re-pipe the section at the end of the drop to the machine. Use soft copper tubing and compression fittings from the drop to the machine. Just having this section done properly will eliminate a great many problems. That’s it for now, I’m looking for suggestions for a topic for our next issue. Call me at 702-376-6693 if you have any suggestions, I’m always delighted to hear from a reader.


Bruce Grossman is the Chief of R&D for EZtimers Manufacturing. EZtimers offers several proven products for testing and protecting your plants boiler and steam system; SENTINEL, EZ-LEVEL and TATTLER steam trap tester. In addition also a line of separator water processing and disposal equipment for drycleaning machines using any type of solvent; the time tested SAHARA and DROP IN THE BUCKET misters. See our Ad in this issue and for further information on EZtimers products visit   www.eztimers.com   Please address any questions or comments for Bruce to   bruce@eztimers.com  or call 702-376-6693. © 2015 by BRUCE GROSSMAN all rights reserved under International and Pan American copyright conventions.



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