PVC and CPVC pipe are both made of polyvinyl chloride, but CPVC is chlorinated in order to withstand a wider range of temperatures. PVC pipes can only be used at temperatures below 140 degrees, but CPVC pipes can handle up to 200 degrees. CPVC is also more expensive than PVC and requires different primers and solvents.
PVC pipes are white plastic pipes commonly used for plumbing and drainage. To make CPVC, the chlorine content of PVC is increased to 67 percent through a process called chlorination.
Many building codes require the use of CPVC over PVC in hot water applications such as hot water heaters. Aside from its greater resistance to heat, CPVC also has significantly higher crush resistance and overall mechanical strength, which is why it is often used as a replacement for metal pipes. PVC and CPVC are both highly resistant to fire, but the chlorine content of CPVC means that, when incinerated, it releases chlorinated dioxins, an environmental pollutant.
PVC pipe has its own North American pipe sizing standard called Nominal Pipe Size. Unlike PVC pipes, CPVC pipes are available in Nominal Pipe Size standards or Copper Tube Size standards, the system used for sizing copper pipes.