PVC is a thermoplastic polymer, while CPVC is a thermoplastic produced by the chlorination of PVC resin.

PVC can be used for a wide number of applications, while CPVC is mostly used for hot and cold water pipes, as well as industrial liquid handling.

PVC is less ductile, while CPVC offers greater strength and flexibility.

from: http://www.differencebetween.net/object/difference-between-pvc-and-cpvc/#ixzz4Fbr6sTWc

Text 12

DWV System

Drain-waste-vent (DWV) pipes carry waste and water out of the house without gurgles or fumes. Never install or replace a DWV pipe without consulting a building inspector. These pipes must be installed according to precise specifications.

Drainpipes. The centerpiece of a DWV system is the main stack, usually a pipe 3 or 4 inches in diameter that runs straight up through the roof. A secondary stack, perhaps 2 or 3 inches in diameter, serves a branch of the system.

Branch drainpipes of smaller diameter - typically 1-1/2 or 2 inches - carry water from specific fixtures to a stack.

Drain stacks in older homes are often made of cast iron, which rusts through after 80 years or so. In older homes the branch drains typically are made of galvanized steel, which is much more likely to rust and corrode shut. In newer homes plastic pipe is used for stacks and branch drains. The first plastic pipe to be used was ABS, which is black. Since the 1970s ABS has generally been replaced by white- or cream-color PVC pipe. In rare cases drainpipes are made of copper.

Drainpipes must be sloped, usually about 1/4 inch per foot, so water can run freely through them. Codes require special fittings that make sweeping, rather than abrupt, turns so waste does not get trapped in the pipes.

Drainpipes often have cleanouts - places where a plug can be temporarily removed - so the pipes can be augered to clear a clog.

Main drain line. Water travels downward through the stacks to the main drain line, which leads to the municipal sewage system or to a septic system. In older homes the main drain may be made of clay pipe or other porous material. Tree roots sometimes work their way into the main line, causing wastewater to back up into the house. The solution is to call a company that specializes in augering main lines.

Vent pipes. For water to flow smoothly without gurgling, there must be an air passageway behind the water. Vent pipes extend from the drainpipes up through the roof to provide that passage. Vent pipes also carry odors out of the house.

The drainpipe for each plumping fixture must be connected to a vent that supplies the pipe with air from the outside. In some cases the drainpipe is connected directly to a main or secondary stack pipe, which travels straight up through the roof. Plumbing codes strictly prescribe where vent pipes can connect to the stack and how far they should travel. In most cases a "wet" section of pipe - the part that carries wastewater - cannot be used as a vent, even if it is usually dry.

If your drainpipes gurgle when you run water in a sink or flush a toilet, call a professional plumber for an inspection. A vent may be stopped up and need clearing. Or the plumbing may be incorrect, and you may need a new vent line.

In some cases local codes allow for other venting strategies. For instance a basement sink might be vented with a special wall vent, which simply runs out the wall. Or a cheater vent, a small device that draws air from the room rather than outside, may be allowed.

Branch drainpipes lead from fixture traps to a stack, which carries water out of the house. Vent pipes allow fumes to escape and provide an air passageway behind the drained water.

Why Venting Is Necessary. Try to quickly empty a bottle with a narrow mouth; it will gurgle and glug as it slowly empties. Open the vent cap on a plastic gas container and it flows smoothly. That's because the vent hole allows air to enter behind the flowing liquid, producing a quick, glug-free flow. Vent stacks in a household plumbing system work the same way.

 

Text 13