Design & Installation

Combustibility of CPVC

Ignition Temperature

CPVC has a flash ignition temperature of 900°F which is the lowest temperature at which sufficient combustion gas is evolved that can be ignited by a small external flame. Many other ordinary combustibles, such as wood, ignite at 500°F or less.

Burning Resistance

CPVC will not sustain burning. It must be forced to burn due to its very high Limiting Oxygen Index (LOI) of 60. LOI is the percentage of oxygen needed in an atmosphere to support combustion. Since the Earth's atmosphere is only 21% oxygen, CPVC will not burn unless a flame is constantly applied, and stops burning when the ignition source is removed.

Smoke Toxicity

United States Testing company, using the University of Pittsburgh Test Protocol, found that CPVC was "not considered more toxic than Douglas fir." CPVC emitted smoke levels are also exceptionally low. Testing at Underwriters Laboratories of Canada has shown that CPVC produces only one-third of the smoke of kiln-dried wood.

Flame/Smoke Spread Development Rating

In many commercial buildings, the area above the suspended ceiling is used as a return air plenum. The building codes restrict the kinds of materials that can be installed in air plenums. Various tests are used to evaluate surface burning characteristics of construction materials. The most common reference is to restrict materials allowed within plenums to those meeting a 25/50 flame spread/smoke developed criteria when tested in accordance with UL 723/ASTM E84, "Standard Test Method for Surface Burning characteristics of Building Materials" (NFPA 255 and UBC 8-1). As a comparison to the 25/50 requirement, asbestos cement has a 0/0, and red oak wood has a 100/100 flame spread/smoke developed rating. Southwest Research Institute (SwRI) has tested water filled 1/2" and 2" FlowGuard Gold^® pipe, 1/2" and 3/4" empty FlowGuard Gold^® pipe, and water filled 1/2" and 6" SCH 80 Corzan^® pipe in general accordance with UL 723/ASTM E84. Test results indicate that all materials gave a flame and smoke rating less than 25/50.

SwRI FlowGuard Gold® Pipe Test Report
SwRI Corzan® Pipe Test Report

Penetrating Fire Rated Walls, Floors and Ceilings

Building codes require penetrations through fire rated walls, floors and ceilings to be protected with approved penetration firestop systems. A number of firestop manufacturers have systems that are listed for use with CPVC pipe. Consult the UL Fire Resistive Directory, Warnock Hersey Certification Listing, or the PPFA Plastic Pipe in Fire Resistive Construction Manual for a listing of products. Some firestop sealants or wrap strips contain solvents or plasticizers that may be damaging to CPVC. Always consult the manufacturer of the firestop material to confirm chemical compatibility with CPVC pipe and fittings.