Nov 01 2011

Smoke Dampers in HVAC Ductwork

Category: Fire & Smoke Dampers,Questions and AnswersBKeyes @ 9:14 pm
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Q: During a recent survey, we were cited by the surveyor for a 6 inch round duct that did not have a smoke damper installed where it penetrated a smoke compartment barrier, in an area of our hospital that is not protected with automatic sprinklers. I informed the surveyor that our local building code allows HVAC duct up to 6 inches diameter to penetrate a smoke compartment barrier and not be required to have a smoke damper. He did not accept that explanation and cited us anyway. I thought if one AHJ had an exception for a code requirement, then all AHJs had to accept that. What gives?

A: No, there is nothing that says one AHJ has to accept the decision of another AHJ, although they often do on a case-by-case basis. Besides, you are comparing apples to oranges here. The local building code probably does not recognize the NFPA LSC while the surveyor (if they were Joint Commission or CMS surveyors) only surveys you according to the LSC. You are required to comply with all local and state regulations, but when these regulations differ with the LSC, you have to comply with the most restrictive. In this case, section 19.5.2.1 of the 2000 edition of the LSC requires compliance with section 9.2 which requires compliance with NFPA 90A Standard for the Installation of Air-Conditioning and Ventilation Systems (1999 edition). NFPA 90A does not have any exceptions for HVAC duct 6 inches or less in regards to requiring smoke dampers. You may be able to negotiate an agreement with the AHJ who cited you that you are in compliance with the local building codes, and see if they would accept that, but you would have to do this with every AHJ. The most practical thing to do is install smoke dampers in the 6 inch round ducts, or install sprinklers in the smoke compartments bordering this smoke barrier. According to section 19.3.7.3 of the LSC, you are not required to have smoke dampers, but if you go this route, make sure your local building codes have the same exceptions.