Dave,
This is a known problem, although there is some controversy swirling
around. There are two potential problems: delayed operation of ESFRs
due to the air movement and obstruction presented by fan blades.
Proposals have been made for 13, but final decisions are awaiting
testing. The limited testing done so far is not encouraging. At this
point, the prudent designer would not consider ESFRs a viable option for
use with "Big Ass (tm)" fans or similar large diameter fans.
Joe
Dave Phelan wrote:
Good evening all,
I ran into something today on a warehouse inspection that made me wonder
..... This is an ESFR protected warehouse of +- 200,000 sq. feet and 30 foot
roof height. They had installed ceiling fans for interior enviroment
purposes that were about 25 feet in diameter, several throughout the space.
These fans run at relatively low blade speed but are rated for upwards of
300,000 CFM. They do produce a very noticeable breeze without being
overpowering or noisy. No swoosh-swoosh sounds like in the 'old days'. So
why do I care .....
What impact would these operating fans and their downward push have on the
rising heat plume of a fire, particularly in an ESFR system?? I called the
manufacturer and posed just that question. It seems that the practical
implications have not yet been tested but are under consideration. I was
informed that the fans were 'NFPA 13 compliant'. I asked the gentleman if
he knew what that meant and he agreed not really. I'm willing to bet that
was relating to obstruction rules and not element response or head skipping.
He also mentioned using shut-offs and fire alarm relays but thats not going
to help when the initial waterflow signal is delayed. I also dont know of
any code-leg to stand on if I wanted to push something. I'm really looking
for just some background knowledge.
So I'm wondering if anyone else has run across this issue. I know that Tyco
did testing on residential fan operation and sprinkler response that did
indicate downward air movement could delay sprinkler operation. This is far
from a residential fan or system so I'm thinking its magnified that much
more.
Thanks.
Dave P.
An AHJ in NJ
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