The ends of this filter are slightly different and before I replace the old one I was wondering if the right side should go up or down? The last time it was replaced I didn't check to see how it was positioned and I just guessed. This time I wanted to do it the "right" way. I believe this is an inline pre-filter that feeds a Nanopure resin filtration system that supplies liquid chromotagrahpy machines. My guess is that the right side should go up because the housing unit looks smaller near the top. Thanks for your help.

When you install it, one side should feel tighter than the other if it has a slight taper to it. From the appearance, it looks as though water should come into the right side and it should be pointed to the supply, the water should pass through the screen and into the body of the black plastic dohickey (technical I know). The right side of the filter looks like it would sit at the 11 o'clock position roughly if the filtered water is coming out at the 5 o'clock. I could be bassackwards but the filter itself should trap and contain any particulates inside of it, and not on the outside in the filter housing (the dohickey)

Actually the 5 o'clock position you refer to is not the outlet it's just a flush valve. The horizontal pipe on the top feeds a nanopure filtration system which is located further to the right (not in the picture)

That is a simple "Y" strainer and the filter media is NOT directional, so it can be inserted in either direction.

DITTO

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638