A plenum duct liner shall have a maximum smoke index of

A plenum duct liner shall have a maximum smoke index of

• A. 50
• B. 40
• C. 60
• D. 70

Answer: (A)

Smoke index indicates how much smoke a material releases when it burns. For duct liners inside plenums, keeping smoke production low is crucial because the liner is in the air-path that distributes smoke through the building during a fire, which can hinder evacuation and firefighting. Codes set a maximum smoke index of 50 for plenum duct liners, so the material must not exceed that value. Values higher than 50 would mean more smoke and greater danger, while 50 is the allowable upper limit. This is why the maximum allowed is 50.

Smoke index indicates how much smoke a material releases when it burns. For duct liners inside plenums, keeping smoke production low is crucial because the liner is in the air-path that distributes smoke through the building during a fire, which can hinder evacuation and firefighting. Codes set a maximum smoke index of 50 for plenum duct liners, so the material must not exceed that value. Values higher than 50 would mean more smoke and greater danger, while 50 is the allowable upper limit. This is why the maximum allowed is 50.