OK, I understand that P traps is OK and S trap should be avoided, codes, etc.

I understand how an S trap can be siphoned and it will be empty. why that does not happen with a P trap as well? if there is enough pressure difference, can't a P-trap be siphoned?

second question: I did some work recently and I noticed that the connection between P trap and trap arm does not have a seal. Why? they give you a washer to put between drain and P trap, but no washer between P trap and arm.

Thanks

EDIT: example here, they show slip washers between tail pipe and P trap and between Arm and wall, but not between P trap and Arm

[www.youtube.com]



Edited 1 time(s). Last edit at 08/16/2020 10:04PM by space-time.

.....don't forget....love.....is the tender trap....

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There are plenty of answers to S trap vs P trap with a little googling.

The connection between the P trap and the arm generally has a beveled edge that is effectively compressed when tightened. The other connections use a straight pipe connection, hence the need for a compression gasket.

Quote
MikeF
There are plenty of answers to S trap vs P trap with a little googling.

The connection between the P trap and the arm generally has a beveled edge that is effectively compressed when tightened. The other connections use a straight pipe connection, hence the need for a compression gasket.

This. It has a built in “gasket”

As for the P-trap not being siphoned, the simplest answer is that the water levels out in a p-trap to keep the water from going all out, even with a light pressure.



Edited 1 time(s). Last edit at 08/16/2020 11:59PM by Carm.