schedule 40 dwv fittings and pressure fittings

Ed from chicago · Sep 2, 2005

Hi all, can you tell me what the difference is between the two types of fittings, and why one has to be used for dwv, and the other for pressure? Someone at the store told me I can't use pressure fittings for drain pipes (1.25 and 1.5 inch fittings). I'm confused.

Thanks...this is a great forum.

hj · Sep 2, 2005

fittings

There are other reasons also, but the major one it that pressure fittings all have right angle designs, whereas, DWV fittings have the turns "relieved" to provide a smooth transition to the new direction. It is like the difference between entering the freeway from an on ramp, or having a stop sign and right turn interchange.

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Ed from chicago · Sep 2, 2005

HJ,

Thanks for your response...so DWV fittings, such as a 90, is not as sharp a turn internally as a presure fitting would be, and the same for a 45 too? I got the impression it had something to do with the stop on the inside of the fitting. Does the fatter hub, or whatever it is on the DWV fittings serve a purpose?

Thanks again

Finnegan · Sep 2, 2005

While I expect they probably make pvc pressure fittings in 1.5" or larger sizes for industrial applications, I doubt you would find these at most home centers. When you get into the smaller sizes you will come across cpvc pressure fittings.

hj · Sep 2, 2005

fitting

That is one of the other differences that I referred to. The hub is the same size, but the interior of the fitting is smaller so it is the same size as the pipe to present a "smooth" surface to the water flow. A pressure fitting will create a "snag" at every joint. Even 45's, (1/8 bends in DWV), have a smoother change in direction than a pressure fitting.

hj · Sep 2, 2005

finnegan said:
While I expect they probably make pvc pressure fittings in 1.5" or larger sizes for industrial applications, I doubt you would find these at most home centers. When you get into the smaller sizes you will come across cpvc pressure fittings.

The make pressure fittings in bery large sizes, but they also make DWV in larger sizes. PVC and CPVC are entirely different materials and are sized differently also, so you cannot use the fittings in one material with the pipe of the other one. PVC is made in the same small sizes as CPVC, the CPVC pipe and fittings are just smaller for any given size.

Finnegan · Sep 2, 2005

Sure, but have you ever seen a home center that carries 1.5" or larger pvc pressure fittings rather than dwv fittings? I have never.

hj · Sep 2, 2005

fittings

I would never buy them there so I have never checked, but I would assume they have up to 2" fittings which is the largest a homeowner might ever use.

Jimbo · Sep 2, 2005

Here, all the usual suspects ( Depot, Lowes, Marshalls, etc.) carry PVC sch. 40 up to 2"

schedule 40 dwv fittings and pressure fittings

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