Roof exhaust fans and ESFR's
Roof exhaust fans and ESFR's
(OP)
Looking for guidance on how to deal with powered exhaust fans located in warehouse roofs, commonly protected by supression mode heads. Can't find anything in NFPA (other than testing is based on them not being present). FM Global used to allow sprinkler heads to be installed in the center of fans up to 4.5-ft. diameters, but that option no longer exists (in FMDS 2-0). Thoughts on shutting down with general fire alarm (water flow, pull station, etc) - similar to what is done for HVLS fans? Anybody ever take airflow measurements near AS heads to see if velocities of 5-ft./sec. exist?
Thanks for your time.
Thanks for your time.





RE: Roof exhaust fans and ESFR's
RE: Roof exhaust fans and ESFR's
RE: Roof exhaust fans and ESFR's
But anything on the sprinkler head data sheet??? Plus code cannot address every issue
RE: Roof exhaust fans and ESFR's
http://www.nfpa.org/aboutthecodes/AboutTheCodes.as...
Nfpa 204m
RE: Roof exhaust fans and ESFR's
RE: Roof exhaust fans and ESFR's
RE: Roof exhaust fans and ESFR's
Regarding the intake/supply fans, the 5-ft./sec. guideline, as I understand it, is measured at the sprinkler heads. If you have a 5-ft. fan and heads spaced 2.5-ft. away on either side, I wonder if the air flow is an issue at those heads. It seems that if you put a false ceiling as descrived in 2.2.1.8(a), then that would push the airflow horizontally towards the heads? The heads are 12 to 18 inches below the roof deck, how far down was the barrier in your case? Does the false ceiling/deflector impact the supply fan performance relative to the overall warehouse air flow.
Thanks again, I apprecaite the expertise. Data Sheet 8-9 sure did simplify things from a design standpoint .... but 2-0 had the opposite effect!
RE: Roof exhaust fans and ESFR's
Yes, the 5ft/sec is at the heads. That is where i took measurements, near the heads, when i was on the lift. I can tell you when i got hit with that 16 ft/sec, 40 ft up, its a bit unverving. Yes, the false ceiling will push it horizontally, out toward the heads. But, keep in mind, before it was going straight down, in one solid column, blasting the heads. By adding the barrier, the air flow is diffused out all four sides, so it decreases. i verified this when i went back up to measusre it after the barriers went in. I can calc water, but dont pls dont ask me about air flows :) so i will leave that to others who know more than me on the air flow subject.
The heads in this case were about 14 in down from the roof deck. The barriers are about 2'6" below the deck. This place gets hot in the summer, and i have not heard any complaints about interrupting the air flow to date.
RE: Roof exhaust fans and ESFR's
Now that you said that did see that set up with detection at the exhaust, many moons ago, been awhile since did a good warehouse job
RE: Roof exhaust fans and ESFR's
RE: Roof exhaust fans and ESFR's
Does IFC address comfort ventilation fans??? That might be running 24 hours a day
RE: Roof exhaust fans and ESFR's
HVAC is different than smoke removal fans. These are two completely different systems.
RE: Roof exhaust fans and ESFR's
So my question is does any standard address these types of fans, if say they run 24 hrs a day and you have a fire ????
Have seen them shut down either on sprinkler flow or some type of detection
But does any standard require it? Or just common since to do it???
RE: Roof exhaust fans and ESFR's
NFPA 13, 2013 Ed coming out in a few weeks will address HVLS High Velocity Low Speed fans such as these
Link
video Link
They need to shut down via water flow or detection regardless if ESFR, area density, etc sprinkler design.
Here VESDA and Big Ass Fans partnered to provide a solution
Link
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Fire Sprinklers Save Firefighters’ Lives Too!
RE: Roof exhaust fans and ESFR's
Regarding the HVLS, testing a few years ago showed these to not be that bif of a deal. Using a water flow switch or simple smoke detector to shut these down is fine. Either way, its best not to place these other high pile storage, but if you interlock as noted, it is ok. I have dealt with these alot, and most plants dont install them over storage anyway. They are normally in processing areas, to keep workers cool in the summer, and these areas normally have low combustible loading.
RE: Roof exhaust fans and ESFR's
RE: Roof exhaust fans and ESFR's