The airgun pump I have breathes air through a little hole under the handle. There is no provision for keeping out dust or critters. Here are the guts to my solution for this problem.

     And here's how it looks assembled. It adds 3/8" to the height of the pump.I am using a portion of a purpose made air compressor filter which looks like felt. I did not use foam because it deteriorates over time and might contaminate the insides before I realized it was getting old. I expected the felt to add to the pumping effort because it doesn't look very porous but I don't notice any change from having no filter.

Last fiddled with 18 Aug. 01.   Click here to go back one page.