Uggggg!, Jim I mean this in no way a disrespect to you. Clearly I'm having
a bad day with other so called "engineers" and needed to further vent. I'm
sorry to the rest of the forum for making my problem your email but this
matter (arbitrary values or rules of thumb are not to be confused with good
engineering) needs some more discussion.
Any velocity limit (or insert most issues, like outside wall post, pipe wall
thickness and fabrication method, safety factor, deflector distance, etc.)
of an arbitrary number be it 20 or 32 is NOT a good engineering practice.
At best it's a rule of thumb at worst it's one's opinion and is wrong. A
good engineering practice would be determine what the concern or issues is
and determine/calculate a solution. So for velocities what are the concerns
with higher values? To be honest I don't know. Is it forces generated by
the weight of the moving water? That can be calculated and designed for, by
either slowing it down and/or correctly designed hangers/bracing. As a side
note has high velocity ever left a failure of any kind related to forces in
overhead sprinkler pipe besides some knucklehead slamming closed the valve
on a 6" main at full flow? I've seen pictures of wrecked underground from
1. quick stops usually firefighter induced and 2. vacuum over peaks.
Resiliency of the system if more heads go off on a line than planned? That
can be calc'ed even easier just tell us the shape of the remote area, still
see 1.4 once in a while.
Rrrrrrrr! Engineers that can't even spell spirknerls. Not that I really
want to start that monthly discussion.
Chris Cahill, P.E.
Fire Protection Engineer
Sentry Fire Protection, Inc.
763-658-4483
763-658-4921 fax
Email: [EMAIL PROTECTED]
Mail: P.O. Box 69
Waverly, MN 55390
Location: 4439 Hwy 12 SW
Waverly, MN 55390
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jim Niehoff
Sent: Wednesday, January 10, 2007 10:45 AM
To: [email protected]
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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