Fitting DWV Fittings
To encourage the flow of solid waste through the DWV system, DWV fittings differ significantly from supply fittings. DWV fittings are designed with unobstructed passage in relation to the mating pipe sections and always avoid sharp turns internally. For example, the supply tee branches off at an abrupt angle internally, while the DWV version (called a "sanitary tee") has a more gently curved internal passageway. In addition to sanitary tees, other DWV fittings include the following:
Combo-Tee - A tee with a gradually curving center connecting joint. Used in drain systems to provide a smooth, gradually curving path to reduce the likelihood of clogs and to ease pushing a plumber's snake through a drain system. The "Combo" is a combination of a wye and a 1/8 bend or 45.
Double Sanitary Tee (Sanitary Cross) - Similar to a cross. This fitting differs from a supply cross fitting in that two of the ports have curved inlets. The fitting has been used in the past for connecting the drains of back to back fixtures (such as back to back bathroom sinks). Some current codes (including the 2006 UPC) preclude the use of this fitting for that purpose. Instead a Double Fixture Fitting is required.
Wye - A waste fitting tee which has the side inlet pipe entering at a 45° angle.
Traps - Fittings used to trap water to prevent sewer gases from coming back into a building.
Trap primers - Trap primers regularly inject water into traps so that water seals are maintained. This seal is necessary to keep sewer gases out of buildings.
Clean-outs - Fittings that allow access to drains without removing plumbing fixtures. They are used for allowing an 'auger' or 'plumber's snake' to 'clean out' a plugged drain. Clean-outs should be placed in accessible locations through out a drainage system, and outside the building as these augers have limited length. The minimum is typically at the end of each branch, just ahead of each water closet, at the base of each stack, and both inside and outside the building in the building drain/sewer. Clean-outs normally have screwed-on caps.
Closet flanges - Fittings used to connect toilets to drainage tubes.