code requirement of pvc duct

[sfxf]

Can anyone help me with the code (united mechanical code and international code) limitation on the use of PVC duct? The PVC duct is used to supply conditioned air (not exhaut) and it is to be routed inside of the return plenum. The plenum is sprinkler protected.

 

[walkes]

You would probably have to verify the flame-spread rating of the PVC with the manufacturer. There are types of PVC piping with a coating to improve the flame-spread rating to allow use in a return air plenum.

 

[cme]

This is what my spec reads:

A. General requirements - Non-combustible materials, Class 1 (25 flame spread, 50 smoke developed), conforming to NFPA 90A, NFPA 90B, NFPA 91 and UL 181.

 

[sfxf]

Thanks, walkes and cme. Per my understanding, International Mechanical Code restricts the use of PVC ductwork/piping to be underground only. Similar to Uniform Mechanical Code, it requires plastic duct/piping in the return plenum to meet 25/50 requirement and there is no exception (it does not matter if the return plenum has srpinkler or not).

Please advise if anything above not accurate.

 

[KenRad]

sfxf,

Harvel makes a CPVC that meets the 25/50 requirement of the IMC, (

http://www.harvel.com/).

But 603.7.4 of the 2000 IMC does say that "Plastic duct and fittings shall be utilized in underground installations only," so I believe that you need to look at other materials.

What is your application that you would need to use PVC for supply air?

---KenRad