In most commercial buildings, the areas above the suspended ceiling used for air circulation are identified as air plenums. These cavities are particularly challenging during a fire, explains Sewell Direct: They contain a lot of fresh oxygen that can make a fire grow quickly and because the air is forced, smoke and fumes can spread throughout the building.
As a result, model codes restrict the surface burning characteristics of the materials that can be installed in air plenums.
Various tests are used to evaluate the surface-burning characteristics of constructions materials. The most common requirement is to restrict materials permitted within plenums to those meeting a 25/50 flame spread/smoke developed when tested in accordance with ASTM E84. As a reference, asbestos cement has a 0/0 flame spread/smoke developed rating and red oak has a 100/100 flame spread/smoke developed rating.
Corzan® and FlowGuard Gold® pipe and fittings have been listed by ICC-ES under PMG 1264. The following models have been tested water filled or dry in general accordance with UL 723/ASTM E84 test methods for surface burning characteristics and have been found to meet the 25/50 flame spread/smoke developed requirements of the International Mechanical Code® (IMC) and the Uniform Mechanical Code® (UMC) for installation in ducts and plenums:
For more information, visit our plenum rating page or download the full ICC-ES report.