Craig
There's plenty of data and experience out there
if you look beyond the US. Not all mist systems
need pumps - I have been responsible for a number
where all that was needed was two cylinders of
water and one of nitrogen.
There is a draft EN (European Standard) 14972 for
mist systems. We are developing our own in the UK
draft BS (British Standards) for both residential
(BS 8458) and industrial/commercial (BS 8459)
being well advanced. Don't overlook the work and
publications produced by FM. Sadly, I find NFPA
750 of little use in writing specifications.
While mist will never be a replacement for
sprinklers in wide area applications we cannot
ignore the fact that in some occupancies they do
offer significant advantages providing you can
live with the fact that each system has to be
specifically engineered for the risk and that it
is not just a matter of applying NFPA 13 or EN
12845 and following well established principles.
It's worth noting that US conglomerate UTC (which
owns many fire protection names) recently
purchased Marioff OY of Finland who are the
world's largest specialist mist company.
Happy New Year to all
Stewart
I dealt with some water mist on a couple of
European projects last year. After doing some
research into the system it appears that for LH
and OH it beat standard spray type sprinklers in
the time to extinguish a fire hands down. The
systems had not been tested for anything above
OH.
No one wants to be the guinea pig and these
systems have not been with any great regularity
or acceptance in the States. The other issue is
we always seem to be chasing water supply issues
and a water mist delivers it's discharge at a
much higher pressure than most LH and OH systems
would require. So, you would end up needing a
pump on systems that may normally not require
one otherwise. Added cost. Other issue is
limited experience with the systems on the part
of designers and contractor's alike.
There's virtually nothing in the building codes
referencing water mist systems, not that they
couldn't be submitted as a substitute system but
someone would have to have a really good reason
to go that route instead of standard NFPA 13
sprinkler systems.
Craig L. Prahl, CET
Fire Protection Group
Mechanical Department
CH2MHILL
Lockwood Greene
1500 International Drive
PO Box 491, Spartanburg, SC 29304-0491
Direct - 864.599.4102
Fax - 864.599.8439
[EMAIL PROTECTED]
http://www.lg.com
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
On Behalf Of å... ....
Sent: Thursday, January 03, 2008 5:11 AM
To: [email protected]
Subject: high pressure water mist vs NFPA 13: 175:psig systems
Why does it seem I don´t hear what seems like a
lot about water mist installation questions in
the US?
Is water mist too expensive versus NFPA 13?
Is it that water mist is not as familiar to contractors (likely)?
Is it that water mist is not as widely endorsed by the Building Codes?
My perception is that water mist will take
longer to control a fire than a NFPA 13 system
would, for fire hazards in the LH to OH-1
sprinkler classification. I have been corrected
on this perception by several people.
I am wondering about peoples perceptions and
experiences with installing water mist systems
in OH-1 fire occupancies:
successes, drawbacks, comparisons...
scot deal
excelsior fire engineering
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