Fire Dampers vs UL Rated Installations

[nuuvox000]

In IBC 714.3.1.2 (with IMC 607.1.2 in mind), it says (paraphrasing) that you can use an ASTM E814 tested penetration firestop system in lieu of fire dampers. I am looking at the UL listings on the 3M website and some of the duct penetrations are listed as large as 30"x24" with just some fire wrap and fire caulk.

I'm just thinking about what happens when there is a fire in the room; won't the fire spread through the 30"x24" opening quite easily? (assuming the duct stops inside the room right after penetration, think of a transfer air duct between rooms). It just seems strange that they're so worried about the annular space around the penetration and not the size of the penetration itself. Any thoughts and comments are appreciated as I am still an engineer in training.

Thanks!

 

[GT-EGR]

The UL listed penetration has been Performance tested to prove out that it meets the equivalent of closing a damper.

I’d check the assembly listing details - and expect it should include some kind of sleeve expectation - and/or the code exception that allows you to use it may restrict having an open grill right at the penetration. 3M also has good support and will provide engineering judgements for their assemblies if you have a certain variation or question.

Fires don’t behave like smoke to where they push and travel and jump through different areas. So for a fire to get from one side of a room to the other may not be as easy as it sounds. But an old/dirty/dusty duct is another issue.

Code compliance aside, you also have to apply your own judgement, so if installing it in your scenario seems wrong, don’t do it.

 

[nuuvox000]

Thank you for your response GT-EGR