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NFPA-33-18 exhaust fan operation during fire condition

Question asked by gnmager on Feb 27, 2020
Latest reply on Feb 27, 2020 by cdafd

Hello,

I have been selling and installing Industrial Spray  booths for quite sometime. it has always been that in the event of a fire condition either in  the booth or elsewhere in the building and the fire  alarm is actuated the booth is expected to shut down to prevent the fire from being either spread or fed with air. I believe the concept here is to also starve the fire of oxygen and reduce its ability to spread. this along with the requirement that the booth shall contain the fire for a minimum of 1 hour aids in the ability for the Fire department to arrive before the fire turns into a worse situation.

Yet NFPA 33-18 chapter 9 section 9.2 states that  " Air Make-up systems and spray area exhaust systems shall remain functioning during and fire condition" this seem counterintuitive and dangerous. what is going to keep the fire from being drawn up the exhaust stack to the roof potentially setting the roof or any thing within the general are from catching fire? 

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