My wye strainer is clearly marked with a direction of flow, so how to orientate it with retaliation to that is not in question.

However, the directions are unclear if I can mount so that the 'Y' points upward or sticks out horizontally. All pictures I've found on line seem to have it installed so that the 'Y' points downward as shown below.

enter image description here

2 Answers 2


I think it is understood the because of the force of gravity settling debris to the lowest point, the best orientation would be down. The screen assembly is located in the 'Y' branch.

  • That makes sense if there's a basket but for ones where you just have a cylinder should it really matter?
    – virtualxtc
    Apr 2, 2018 at 9:47

After much research, it appears that manufacturers differ in their recommendations.

For instance, Valvida specifically says “ Y “ – strainers should never be installed in vertical pipelines in the upward flow condition:

Valveda Installation Diagram

While Wilkins seems to claim that their valves function correctly while installed in an upward flow condition:

Wilkins upward flow installation

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