make up air shutdown

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nizak

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I have a make up air duct that is located about 40' from a commercial hood exhaust, would this have to be shut down if the fire suppression discharged over the hood? Locally I have spoken to a couple of different fire alarm system technicians and have gotten varying answers. Is there a specific distance that is specified ? Thanks.
 
Makeup air only has to shut down if it is internal to the hood. See NFPA 96:

commercialhoodsnfpa96.jpg
 
Marc, please excuse my ignorance. When it says internal does it actually mean within the "footprint" of the hood itself? So a sheetmetal duct supplying M/U air that is discharging 3' away from the hood could continue to operate? Thanks.
 
The current set up that I have places one hood at the opposite end of the kitchen,( apart from the other two that are supplied with M/U air that is ducted out directly in front of each one).
 
I'm no expert, but it sure seems like makeup air 3' from the hood can continue to run from what I read there. There might be other codes that apply, but I don't know of any other than NFPA 96. There is definately internal discharge makeup air (within the footprint of the hood proper), since I've seen plenty of them. Below is a pictorial example of internal makeup air, with a red arrow pointing to the makeup air diffuser internal to the hood proper:

internalmakeupair.jpg
 
Seems as though every technician, AHJ,and alarm guy have their own interpretation as to what should happen when the system discharges. It's virtually impossible to get a uniform consensus on this, what makes matters worse is that very seldom we ever get drawings that spec what should be done. I appreciate all input from members here.
 
Some (larger) applications will have multiple hoods in one kitchen all utilizing common ductwork.
At the collar connection incorporated to the exhaust hood itself is the last place in the system that a fire rated damper (or some sort) can be installed on the return air system.
 
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