Types of PVC Pipes

Polyvinyl chloride (PVC) pipe fills plumbing needs all over the world. Cheap, stable and easy to work with, it has become the material of choice for most plumbing needs. PVC pipe is sized according to the nominal inside diameter of the pipe. A 2-inch pipe will therefore be referring to the interior dimension of the pipe, since the exterior diameter will be greater. As the walls of pipes get thicker, the outside dimensions stay the same and the inside diameter shrinks to accommodate the thicker walls.

Schedule 40

The most commonly used type of PVC pipe is Schedule 40. These pipes are white in color and have the largest inside dimension of the three schedules. The main drawback to Schedule 40 is that it is only rated to handle temperatures up to 140 degrees Fahrenheit, meaning that it cannot be used for hot water systems. Schedule 40 is used for drains, vents and cold water supply.

Schedule 80

Schedule 80 pipe is sometimes found in houses, but more often it is used in commercial applications. The inner diameter of this pipe is a little bit smaller than the comparable Schedule 40 pipe due to the thicker side walls. Like Schedule 40, it is used for drains, vents and cold water supply. To differentiate it from Schedule 40, this pipe is gray in color.

Schedule 120

This pipe has the thickest walls of the three, and therefore the smallest inside diameter in comparably sized pipes. Schedule 120 is usually only found in commercial applications due to its higher costs. While it also comes in white, it is hard to confuse it with Schedule 40 as it is much thicker and heavier. It is also only available at commercial plumbing houses.

CPVC

Chlorinated polyvinyl chloride pipe (CPVC) is the newest version of PVC pipe. It can withstand heat up to 180 degrees Fahrenheit, so it is suitable for domestic hot water systems and is available in the same schedules and uses the same color schemes.

Variations.

PVC pipe used for nonpotable water--water that can't be used for drinking--is green in color so that it isn't accidentally installed with standard PVC pipe in a water supply system.

Gray Schedule 40 does exist, but only for use as electrical conduit, and this is stamped all over the outside of the pipe. It also does not exactly match the outside diameters of pipe used for water systems.