Tubular P-Trap vs Non Tubular

[diyron]

I have a P-trap in one bathroom that is labeled 1 and 1/2" ABS tubular and two more in another bathroom that are labeled 1 and 1/2" ABS and they are obviously larger in diameter than the tubular.

Why is tubular used on some bathroom faucet traps and not on others? Both say 1 and 1/2 but are different sizes. A little confusing. Thanks

 

[frodo]

tubular p traps such as an 1 1/2 is 1 1/2'' outside dimension

be it brass,plastic or chromed brass the OD is the same. the ID is different due to pipe gauge/thickness

the DWV pipe in the wall that the trap slides into, is also 1 1/2'' Inside dimension


the 1 1/2'' tubular traps in your house are the same OD
what you are seeing MAY be 1 1/4 traps under the lavatory sink and 1 /2'' rap under the kitchen sink

the tail piece on a lav sink is 1 1/4'' tail piece on kitchen sink is 1 1 /2''

 

[diyron]

Appreciate the very thorough reply with diagram and pic, Frodo.



The 1 1/2 replacement trap I purchased (pictured, right) for the bathroom trap is smaller than the 1 1/2 trap previously installed (left). Both traps are marked 1 and 1/2 inch. Don't want to belabor the point, just seems confusing.

Any thoughts?

 

[phishfood]

1 1/2" tubular is 1 5/8 outside diameter. The thickness of the walls of the tubing will vary, but it will be somewhere around 1 1/2" inside diameter.

1 !/2" Schedule 40 IPS, which is what your original P trap is, is slightly more than 1 1/2" inside diameter, and somewhere around 1 7/8" outside diameter.

Others disagree, but I prefer to use a tubular trap and use one of those 1 1/2" DWV/IPS tubular adapters shown in Frodo's post to transition on the drain stubout that comes out of the wall. That makes it very convenient to access the drain arm to clean the drain in the future.

 

[frodo]

where are you seeing 1 5/8'' od on brass traps ?

 

[phishfood]

I will admit that I have never measured the OD of 1 1/2" tubular.

I do know from much experience that 1/2" tube is 5/8" OD, 3/4" tube is 7/8" OD, 1" tube is 1 1/8".

So it would seem to follow that 1 1/4" tube is 1 3/8" OD, and 1 1/2" tube is 1 5/8" OD.

Dang it, now I have to measure it tomorrow!

 

[diyron]

Thank you both for your help. Makes sense. Appreciate you clearing that up for me. Couldnt make sense of it before!