DWV v PVC

[mrcaptainbob]

Was picking up some supplies for the next phase of this project, the plumbing. Wanted to get some 2" DWV, but the largest available was 1 1/2. So the guy says it's okay to use the PVC. Also, while rummaging around the fittings isle, I find there's special fittings for DWV and special for PVC. Okay...what's the diff? Why can't a 90 with the 'collars' be as good as a 90 that has no collars? Their both glued the same. Both are schedule 40. Need some educamation.....

[LazyPup]

Although PVC & DWV are both made of the same material and the pipe and fittings are both the same size there is a major difference.

PVC pipe is commonly made in sizes from 1/2" to 24" and wall thicknesses from Schedule 20 thru Schedule 200. All PVC pipe will have an ASTM (American Society of Testing Materials) pressure and temperature rating printed on the pipe and is intended for use on pressurized supply systems. (PVC pipe is listed as approved and may be used for sanitary waste lines.)

DWV (Drain, Waste & Vent) pipe is not pressure rated and may only be used for sanitary drain, waste and vent applications.

When examining fittings you will not that PVC pressure fittings will be listed by Schedule (Wall thickness) and all pressure fittings are rated by the degree of bend. I.E. 45 deg, 60deg, 90deg. etc.

In physical appearance PVC pressure fittings have sharp bends on the corners. PVC pressure fittings MAY NOT be used for drain, waste or vent applications because the sharp bends will restrict the flow of gravity pressure waste systems which would cause clogs, and they will not permit a snake to pass through the joint for rodding the line.

DWV fittings are listed by the fraction of a circle (called BENDS) thus a 90 deg angle DWV fitting would be listed as a 1/4 BEND (90 degress is 1/4 of a full circle).

In physical appearance DWV fittings will have a radious curve at all changes of direction to reduce internal friction of flow and permit rodding a line.

You will also find Black ABS pipe and fittings listed for DWV purposes. ABS is made in exactly the same sizes and shapes as PVC DWV pipe and fittings, and either material may be used for the drain, waste and Vent system in a structure, however..

PVC and ABS pipe or fittings may not be intermixed. The code prohibits gluing dissimilar plastics together therefore, when making repairs, whichever material is present in your home must be used to make the repairs.

In cases where availability is a problem the code will permit ONE JOINT to transition from PVC to ABS or vice versa if that transition is made by means of and approved rubber collar coupling (FERNCO). Some local codes will allow ONE direct glue joint to make the transition providing the joint is in an exposed position.

Once the transition from one material to the other is made all additional pipe and fittings must be the new material (ABS or PVC).

The codes also require that you must use solvent cleaner prior to gluing when making all joints. You will note that the cleaner comes in two varieties, clear and purple dye. Either one will work just as well, but we are required to use the purple dye type in new construction so the inspector can insure that cleaner was used on the joint prior to gluing. If you must have your project inspected I would strongly recommend using the purple dye type, but if you are making home repairs or un-inspected maintenance you may prefer the clear type because if you happen to drip some of the purple dye type on a wood, vinyl or carpeted floor it will instantly make a permanent stain.

When selecting glue read the label carefully. Some glues are rated for either PVC or ABS and you may not use the wrong glue. There is also a universal glue that is rated for both PVC and ABS. (Note-read the label as most of the ppl in the big box stores dont know the difference.)

Also, when laying the pipe, it must be installed in such a manner so that the writing on the pipe is readily available for inspection. When a pipe is laid in a trench it MUST BE laid with the writing on the top side of the pipe. When running the pipe indoors it must be installed so the writing is clearly visible when looking directly at the pipe. (Many inspectors will red tag a job if the writing is not clearly visible for inspection).

[mrcaptainbob]

You're good. I'd've never thought of the snaking out of the DWV as one of the reasons. Was kinda leaning toward the reason for the generous sweeps of the fittings as enabling a better flow, but .... What an education I get from this forum..and from you, Hazy, KactusKid and the rest...Thanks...