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Author:
sum (FL)
I need to install two 2" PVC unions, one before and one after a pump for swimming pool mechanical.
I am pretty sure these unions are not directional, right? But I have seen some brass ball valves where it seems that it wouldn't matter which way you install them, but there is an arrow showing the direction of flow. Does it matter which way you install a PVC union? Put the female nut part upstream of the flow or downstream of the flow?
In addition, if you have a choice to install the union on a vertical section of the pipe or the horizontal section of the pipe, is one better than the other?
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Author:
bernabeu (SC)
pvc unions have a non directional 'o' ring seal
metallic unions have a nozzle to seat mating seal - male -> female (but not 'required')
when installing on vertical pipe (as in in a wall cavity) place the side with the ring on top so the ring can not slide down and be lost in wall
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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Author:
hj (AZ)
Completely non directional. The arrow on the ball valve may just be there for the convenience of someone trying to decide which way the water is flowing. Direction DOES make a difference with globe valves and stops.
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Author:
bernabeu (SC)
direction DOES make a difference with SOME unions
[static.grainger.com]
preferred flow would be from top of pic (male side) -> bottom (female)
there is a ground bronze 'seat' integral to the union
this issue is particularly important with steam
however
for general homeowner applications: makes no difference, merely a matter of good/best practice
(if done 'right' it will last forever)
==============================================
"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Author:
LI Guy (IN)
PVC Unions are non-directional in terms of flow, and position is usually determined to allow for easy access and disassembly.
Before assembly, remove the O Ring and lube generously with teflon lube so the O ring is coated in lube on all sides. Also put a smear on the face of the male end that the O ring seals against. This keeps the O ring pliable and from sticking to the PVC over extended assembly times and ensures easy disassembly.
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Not a plumber by trade but a fierce DIYer
Edited 3 times.
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