Adapt removable P trap to Schedule 40

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Kevin121

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Hi all - I am working through my water softener drain installation. I have the sanitary tee and couplings tied into the stack and now am working on the vent, P-trap, and air-gap connections (excuse the messy primer job :( ). As you can see in the picture (everything still just dry-fit currently), the P-trap I have is 1-1/2" Schedule 40 so I won't be able to remove it after it's glued up. I want to swap that out for the threaded removable type that is typically found underneath kitchen/bath sinks that is a thinner plastic, but I'm not sure what I need to be able to adapt my Schedule 40 tail-piece/stand pipe (below the Air-gap) to the trap on the inlet side, and the Schedule 40 90 degree elbow to the trap out on outlet side.

I see there is an adapter called a Marvel Adapter, but I'm not sure if that is all I need to connect both ends of the trap to a threaded trap. I see some trap kits at Lowe's that already have the threaded nuts and compression gaskets, so can I buy one of those with the Marvel adapters to connect to my Schedule 40?

I also was looking for a clear/see-through trap so that I can easily periodically check that the trap is full, and the fact that the water softener only discharges once every 4-5 weeks. These don't seem to be as readily available from what I'm seeing though, any thoughts on doing this?


2022-06-26 11_03_36-Plumbing2.png
 

Reach4

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The adapter piece is called a "trap adapter". "Spigot" trap adapters glue into a hub, and "hub" trap adapters glue onto a pipe.

The slip joint trap would not be as strong, so you would want to provide a clamp for the standpipe to resist forces.

If you glued your trap just as you show, you could convert later by sawing off the trap arm, and gluing on a trap adapter.
 
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Kevin121

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The thing you pointed to would glue onto a pipe. It would not thread onto anything. It does have threads for its own nut to compress the washer around the slip joint tube of the p-trap.

The standpipe would be maybe two of these in series. https://www.lowes.com/pd/Keeney-1-1-2-in-Plastic-Straight-Coupling/1071501
Thanks! Just debating in this situation whether to just use the glued Schedule 40 trap, or the removable polypropylene that could be removed if necessary. I suppose the Schedule 40 could always be cut if it had to be and is a little stronger/rigid.
 

wwhitney

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For an exposed standpipe, you could use the solvent weld trap type that has a union in the middle. That would let you disconnect the u-bend and the standpipe (which are glued together) from the trap outlet elbow and the trap arm. If you desire the ability to remove and access the u-bend, for whatever reason.

Cheers, Wayne
 

Kevin121

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For an exposed standpipe, you could use the solvent weld trap type that has a union in the middle. That would let you disconnect the u-bend and the standpipe (which are glued together) from the trap outlet elbow and the trap arm. If you desire the ability to remove and access the u-bend, for whatever reason.

Cheers, Wayne
I like the idea Wayne however with the standpipe being glued in the inlet side and the 90 degree elbow glued on the trap arm how does this allow the trap to be removed if needed? It seems that the glued ends would not allow for any movement of the trap. I must be overlooking something obvious...
 

Tuttles Revenge

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I've never dealt with water softeners before so I'm not familiar with what is in the discharge or the flow rate.

There are clear p-traps available, tho I'm not sure if they're approved for sanitary use..

A trap primer could be installed, which is what we typically install to ensure a trap has water in it no matter how often the trap gets used..

A sight glass might be fun to build out of clear tubing with ports on each side of the trap. Probably not legal either.

Here is a fancy Pyrex trap.

1656428602531.png
 

Kevin121

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wwhitney

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Or you're say the entire section, including the stand-pipe could be removed as one piece?
Yes, that's what I said in post #6, the standpipe and u-bend can come off as one piece.

If you wanted to be able to separate the standpipe from the u-bend, you'd need to use tubular fittings. Which you could do with the union solvent weld trap, just on the standpipe side, by gluing a trap adapter into the u-bend inlet. But at that point I think you'd better off just using a tubular trap and standpipe and putting the trap adapter on the san-tee.

Cheers, Wayne
 

Kevin121

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Thanks! Do you recommend pipe thread sealant or teflon tape on the threads of the union? The person at my local hardware store said this wasn't required.
 

wwhitney

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Thanks! Do you recommend pipe thread sealant or teflon tape on the threads of the union? The person at my local hardware store said this wasn't required.
You only use thread sealant/teflon tape on threads where the threads are the sealing mechanism.

I don't have one of those traps in front of me to confirm, but generally on unions there are mating smooth bevels or flat surfaces, and the threads just provide the clamping pressure for the mating surfaces to seal against each other. In which case you don't use any thread sealant.

It's occasionally useful to use something to lubricate the union threads to be able to more easily tighten them, but I don't believe that would be necessary for plastic/plastic threads, given the natural lubricity of most plastics. If you did want to use something it would be a tiny tiny amount of plastic safe pipe dope. Too much could inhibit tightening the threads sufficiently to get the mating surfaces to seal.

Cheers, Wayne
 

Reach4

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I've never dealt with water softeners before so I'm not familiar with what is in the discharge or the flow rate.

There are clear p-traps available, tho I'm not sure if they're approved for sanitary use..

A trap primer could be installed, which is what we typically install to ensure a trap has water in it no matter how often the trap gets used..

A sight glass might be fun to build out of clear tubing with ports on each side of the trap. Probably not legal either.

Here is a fancy Pyrex trap.
A clear trap would be useful for somebody who suspected a vent problem.

Pyrex would be very pricy. https://www.homedepot.com/p/Everbilt-1-1-2-in-Clear-Plastic-Sink-Drain-P-Trap-C9705/205153971 would be cheaper for temporary troubleshooting, but reviews would suggest it is not so durable. Maybe discontinued. https://www.homedepot.com/p/1-1-2-in-ABS-Slip-Joint-P-Trap-PT5022/317741203 could be used by somebody who wanted a clear trap for diagnosis.

Here is a new thing I had not see before. Clear bowl. I don't see how this is going to fulfill vent requirements.
n-a-abs-fittings-pt5001-2-4f_100.jpg

Looking at http://www.sink-genie.com/Video3.mp4 time 2:50 says to me that this works similarly to a drum trap, in that the diameter is too big to allow siphoning.. I could see that the unscrewable sump could overcome the main objection to drum traps. Website http://www.sink-genie.com/ says "MEETS ASME A112.18.2-2015/CSA B125.2-15, UNIFORM PLUMBING CODE (UPC®)".

One thing about slip joint: you can mix materials, so an ABS or brass or polypropylene trap could be put into a PVC trap adapter.
 
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