It sounds like I'm the only one out there not designing systems with
Mach 3 velocities. There has to physically be some upper limit to
what a pipe can carry. You're not going to get 800 gpm through a
piece of 1", even though you can calculate the friction loss with HW.
Where is the practical limit? (Joe may be able to shed some insight.
hint, hint....)
At 11:27 AM 6/2/2008, you wrote:
The formula that I was taught some time back is, Pu = $s (pressure unused
equals dollars spent).
BK
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Fletcher, Ron
Sent: Monday, June 02, 2008 9:12 AM
To: [email protected]
Subject: RE: High velocities
Burn it up!
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Chris
Cahill
Sent: Monday, June 02, 2008 7:47 AM
To: [email protected]
Subject: High velocities
A question for where there is healthy pressures. Around here 60 is
considered high. I know places with 28 static.
Got a OHII system that needs to be changed to EXII.
That's not negotiable. It's a 40 yo pipe schedule system. That
appears to be in good shape. The BL need to be replaced for 100 sq.ft.
but the main even the last 12'
of 2.5", 25' of 3" and 36' of 3.5" can fly without being replaced. The
openings are where I need them. There is a FP with about 140 psi at the
900gpm demand. The "problem"
is the velocities in one segment of pipe are just about 40 (last piece
of 3") and about 30 in the 3.5". I quote problem because I know 13 has
no limit, this is not FM.
There is still better than 15 psi safety.
So the question is where you have pressure do you typically burn it up
with small pipe size at the cost of velocities getting high or do you
leave a lot of safety?
Again not FM and OK per 13.
Any thoughts on why this is a bad idea? It's easy to say just pull the
offending pipe. In reality though you all know the competitive market
and spending owners money.
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
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Todd G. Williams, PE
Fire Protection Design/Consulting
Stonington, Connecticut
www.fpdc.com
860.535.2080
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