I bought a water separation filter for my new compressor. The water separator didn't come with any good documentation. Here's what came in the pack:

A diagram on the packaging:

package diagram

The device:

the unit

The device as seen from the top (note the markings):

the top of the unit

The side with the square marking:

enter image description here

The side with the triangle marking:

enter image description here

Which end should be connected to the compressor and which end should be connected to the hose?

1 Answer 1


the arrow (triangle) always points in the direction of air flow (from the compressor to the tool). In this case you would attach the filter (arrow side) to the air line usually after a valve (but not always) and on the opposite side a hose (or whatever accessories there may be). Use Teflon tape on all threads And don't use paste which may clog tool ports. And a good habit is to drain the tank of condensation regularly.

  • So, just to be sure, I will have the following setup. Compressor -> quick release valve -> quick coupling -> filter (triangle) -> filter (square) -> quick release valve -> hose. Does that sound ok? Commented Sep 27, 2015 at 14:55
  • 1
    you may want to reconsider installing the quick release coupling valve and install a full port 1/4" threaded ball valve. This is how I would set up my compressor starting with the (1/4"?) air line out from the tank: ball valve (shut off valve), air filter (triangle side), female quick coupling (square side), and male coupling (attached to hose). Quick release couplings are best attached to hoses and tools. You want the filter and shut off valves to remain rigid and secure.
    – ojait
    Commented Sep 27, 2015 at 15:17
  • This is true for all gas/liquid fittings. If flow direction matters, there will be an arrow pointing out the proper direction of flow.
    – Tester101
    Commented Sep 27, 2015 at 15:40
  • Thanks for all the feedback. I will take your advice, ojait, and head out to the hardware store. Commented Sep 27, 2015 at 15:42

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