Why have a compressed air pre-filter?

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compressed air pre-filter
(Last Updated On: October 5, 2020)

There are many applications that demand more protection than the typical 30-40 micron compressed air filter can provide. At one time, when air logic was the norm, the compressed air used in the control circuit had to be very clean indeed, as much of the logic had to do with the speed that compressed air passed through small orifices, and air cleaned even at the 40 micron level wasn’t clean enough.

compressed air filter

In these types of applications a 5 micron or even finer filter would be installed.

In the event that the compressed air stream to that 5 micron filter was dirty, which is often the case, the element would plug solid in a very short time, as it was stopping small debris, but also the “bricks and 2 x 4’s” that accompany the compressed air from most compressors, necessitating an element change.

The finer sized element may not cost any  more than the 40 micron element used in a general purpose compressed air filter. The real cost to the user is in the interruption of production due to air starvation, as the small holes in the micro filter quickly filled and blocked passage of the compressed air requiring a machine shut down to replace the plugged element.

To extend the life of the finer-element filter, consider adding a 30-40 micron pre-filter just upstream from the finer element filter. This “coarser” filter element will remove all the  “bricks and 2 x 4’s” (yes, this is an exaggeration) before they can get to, and quickly plug up, the finer element holes, thus extending the mean-time-between failures of the finer filter element, and improving machine up-time.

Hello, I am Bill, the Compressed-Air-Man. I have years of experience in industrial and residential compressed air applications, air compressors and general pneumatics. I created this site to help professionals, students, and DIYers understand and properly implement and maintain compress3ed air systems.

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