Mario,
The 20 fps limit was never in NFPA 13. FM introduced it into their
standards in the late 70's to limit foolish designs in the then new grid
systems that eliminated any tolerance for operating additional
sprinklers on a branch line.. It only applied to branch lines in grids.
It was proposed to NFPA 13 and rejected because it was deemed not needed
in addition to the 1.2 shape factor used in hydraulic designs. It
ultimately caused more confusion than it was worth to FM customers, so
FM eliminated it several years ago.
There is nothing inherently incorrect or unfair about designing a system
with high velocities. So long as the design is (and remains) correct for
the occupancy, there is no problem. It's just another example of the
existing process that cuts the end-user out of the decision process and
takes the decision of whether cheaper installation is actually cost
effective away from him.
Joe
[EMAIL PROTECTED] wrote:
Mark,
Several years ago I wrote several e-mails to the Forum on this subject; they
may be in the Archives. In the past 20 fps was indicated in NFPA 13; slowly
thru the years that 20 fps was taken out; if a limit is not given then
anarchy , chaos will happen. I have reviewed plans with 56 fps and the
contractor is right ,nfpa 13 says no limits in velocity. The statement about
good design , conservative design, prudent design is not read.
For the same job if a contractor calculates the pipe with 20 fps , other
contractor calculates with 30 fps and another with 50 fps; the contractor with
50 fps will win the bid. Is that correct? is that fair?
Mario Berrios,P.E.
-----Original Message-----
From: [EMAIL PROTECTED]
To: [email protected]
Sent: Wed, 10 Jan 2007 1:16 PM
Subject: RE: max velocity
Brilliant!
It will take several Guinesses to get through this I'm sure.
LMAO,
Steve Leyton
Protection Design & Consulting
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Wednesday, January 10, 2007 10:04 AM
To: [email protected]
Subject: RE: max velocity
Because water faster than 20fps can quickly get out of control and drown
people in nursing homes. Slower water is less threatening.
But seriously, why place a limit of 20? There are times that through a
particular section of pipe where the velocity may exceed that. It makes
little sense to have to increase a 5ft piece of pipe because the
velocity in it may have hit 30fps. You've got to use some common sense
and good engineering judgment, balancing a practical design AND
installation.
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 Mark
Sornsin
Sent: Wednesday, January 10, 2007 12:50 PM
To: [email protected]
Subject: RE: max velocity
Mario:
Given all that has been said on this forum, in addition to Roland's
dissertation, I have to ask why the 20 fps limitation?
If we engineers are going to require such a limitation, I believe we
have to be ready to defend it. (this holds true to anything we write in
our specifcations
Mark A. Sornsin, PE
Fire Protection Engineer
Ulteig Engineers, Inc.
Fargo, ND
701.280.8591
[EMAIL PROTECTED]
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
[EMAIL PROTECTED]
Sent: Wednesday, January 10, 2007 11:35 AM
To: [email protected]
Subject: Re: max velocity
I recommend maximum 20 feet per second water velocity in fire sprinklers
systems .
Mario Berrios, P.E.
-----Original Message-----
From: [EMAIL PROTECTED]
To: [email protected]
Sent: Wed, 10 Jan 2007 11:44 AM
Subject: RE: max velocity
NFPA 13 does not stipulate a maximum limit on velocities; some
insurances companies modify NFPA 13, such as FM, to restrict 20fps on
gridded sprinkler systems. I believe NFPA 15 does require velocities
pressures. Anyway, I was always taught that good engineering practices
restrict velocities pressures to a maximum of 32 fps in branchline
piping.
Hope this helps.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Ivan
Cabrera
Sent: Tuesday, January 09, 2007 4:58 PM
To: [email protected]
Subject: max velocity
Would anyone be able to give me any info on the max velocity for
sprinkler piping? If so, can you give me a code section it would be
under?
Thank you,
Ivan Cabrera
Fire Plans Examiner
Town of Gilbert
90 E. Civic Center Drive
Gilbert, AZ 85296
ph 480-503-6957
fax 480-497-4923
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