Art,
If you don't make that adjustment for the elevation change you've just
cheated yourself out of a couple of pounds, at least,
in source pressure. If the main is 5'-0" below grade, and the outlet is
18" above, that's 6'-6" roughly, or about 2.8 psi less
than the pressure at the point where the hydrant is fed from the main.
And my program, and my own expectations, are to use the pressure
available at the point where the main I'm going to
design and install actually connects to the municipal main, not at a
test point which is more or less 6'-6" higher.
Just my thoughts.
PARSLEY CONSULTING
Ken Wagoner, SET
760.745.6181 voice
760.745.0537 fax
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> e-mail
www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website
art wrote:
What good is pressure 5' below grade. Don't you expect pressures to be at
grade or at finished floor? Adjust from gage to finished floor elevation.
Does your program expect to see pressures 5' below grade?
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis
Sent: Friday, December 14, 2007 12:16 PM
To: sprinklerforum@firesprinkler.org
Subject: RE: Flow test effective point.
Yes, you must correct for elevation.
Paul J. Pinigis, P.E.
Chief Life Safety Engineer
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Todd
Williams - FPDC
Sent: Thursday, December 13, 2007 5:52 PM
To: sprinklerforum@firesprinkler.org
Subject: Flow test effective point.
I thought I understood this, but maybe not. When determining the
effective point for a hydrant flow test, I was told that it is at the
junction of the flowing and non-flowing water. (for the purposes of
this discussion, let's assume that we are talking about a single
main, fed from both directions, with hydrants on branches off the
main. Pressures are read at one hydrant and another single hydrant is
flowed) If this is the case, then the effective point of of the flow
test would be at the junction of the main and the branch to the
hydrant where the pressures are read. However, this junction occurs
underground. If we assume that the gauge on the hydrant is 1'-6" off
the ground and the main is 5 ft underground, this would mean that the
pressures are read 6.5 ft above the effective point. The pressures at
the effective point would be 2.8 psi greater than those read at the
hydrant. Is or should a correction be included?
This makes a difference on programs such as Autosprink where you draw
a 3D model of the underground system and insert a supply at the
effective point.
Todd G. Williams, PE
Fire Protection Design/Consulting
Stonington, Connecticut
www.fpdc.com
860.535.2080
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