So, I picked up an oil/water filter for painting with my compressor. Unfortunately, the thing had zilch for instructions, and I'm not sure which way the air should flow. Which side (male threaded side or female threaded side) should be connected to the compressor, and which should be connected to the tool?enter image description here

  • 1
    I think that's a version of a "coalescing filter" and in the incoming air should go through the filter element (which appears to the be via the male fitting, but that could be misleading appearance.) Here's some detailed info on the type of filter: teamtechnical.com/html/Parker%20Basics%20of%20Coalescing.pdf
    – Ecnerwal
    Feb 4, 2016 at 1:41

1 Answer 1


tool --> female-filter-male <-- compressor

By putting the male end toward the compressor, the water drain valve will be on the "low end" when you drain it.

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