Can insulated plastic piping meet the 25/50 requirement?
Plastic Piping in Return Air Plenums by R. C. Wilging – PE Summary:Because plastic materials do not qualify as non-combustibles their use in air handling plenums has been an issue for years. The code provisions that cover this subject clearly refer to “exposed” materials. Questions about whether insulated plastic piping would meet the 25/50 limits have now been answered in the affirmative by ASTM E 84 tests of 4″ and 6″ PVC and ABS pipe with solid wall and with cellular core wall. Introduction: Over the 26 years that I worked in the plastic piping industry, I received many calls pertaining to this subject. Usually the conversation started with a question that included the terms plastic piping and 25 / 50. From these references I could rather quickly bring the issue into focus by asking the following questions – Are you dealing with plastic piping in plenums ? Are you dealing with PVC sanitary waste / vent piping and roof drains ? Most often the responses were in the affirmative. I had
