It doesn't matter in a 13R system. It came into the standard when
antifreeze ESFR systems were being considered, where the delay in full
water delivery for a minute would be a big problem. That's the problem
with the written word, it says what it says, not what the committee meant!
Joe
Fletcher, Ron wrote:
Does it really matter? The antifreeze is only in the pipe, it's not in
the water supply. After the initial fill is gone it's just plain water.
It doesn't seem like a friction loss different from plain water for the
first minute or less is going to make much of difference. If your local
sprinkler scientist (AHJ) wants the antifreeze mixture calc how would
you account for the gradual dilution of the mixer as clean water enters
the system? The viscosity wouldn't be a constant. Sounds like calc with
a computer, measure with a caliper, mark with chalk and cut off with an
axe.
Ron Fletcher
Aero Automatic
Phoenix, AZ
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Roland
Huggins
Sent: Thursday, April 17, 2008 3:28 PM
To: [email protected]
Subject: Re: 13R antifreeze calc
the ability of the chosen equation to reasonable predict friction
lose is not a function of what standard requires the calculation.
The sub-zero antifreeze systems with a high viscosity started this ball
rolling and nothing says at more normal temperatures (like 20 F) the
viscosity issue doesn't matter (so the academic hat is overshadowing the
practicality hat in this debate).
Roland
On Apr 17, 2008, at 2:59 PM, Ed Kramer wrote:
Forum members - your opinions on the following situation, please:
Design standard is 13R 2007 edition. System type will be antifreeze
with a volume exceeding 40 gallon.
Per 13R section 6.8.4, "Piping shall be sized using hydraulic
calculation
procedures in accordance with NFPA 13". NFPA 13 says to use the
Darcy-Weisbach method (section 22.4.4.5.1).
Do you think it's the intent of 13R to require the calcs be done using
Darcy-Weisbach?
Ed Kramer
Littleton, CO
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