Mario,
I don't know where you got your information, but the Hazen-Williams
formula was not developed for channel flow nor is it limited to 3 fps.
Hazen-williams has always been used for flow in pipe. The Manning
formula was developed for flow in channels.
Joe
[EMAIL PROTECTED] wrote:
Mr. Rahe Loftin,P.E.:
I agree with you. Usually the customer changes the occupancy or the use of the
building or certain areas of the building or increase the size of the building.
If the piping is at the beginning small then the customer is penalized because
he has to revamp the system. There are some agencies that specify 20 fps to
allow them to expand the building; to have a margin of safety if the city drops
the pressure;to be sure to have 7 psi at the last sprinklers; to be sure that
the highest branch has 15 psi.
The water pressure will compensate if high velocities are used if the city
would provide more pressure.
The Hazen Williams formula was developed at 3 fps for open channels.
Keep up the good work.
Thank you.
Mario Berrios, P.E.
-----Original Message-----
From: [EMAIL PROTECTED]
To: [email protected]
Sent: Mon, 15 Jan 2007 4:03 PM
Subject: RE: max velocity
I suggest that Schedules 10 and 40 domestic pipe and (with a few quality
imports excepted) domestic fittings as well, are the best way to assure
the proverbial 50-year building. But the rest of it is just a waste
of taxpayer money, as far as I'm concerned - especially velocity limits
or any other unsubstantiated provision that only adds cost to the
construction without tangible benefit. Our firm does a measurable
percentage of work in the Federal jurisdiction (NAVFAC and ACOE,
primarily) as well as State of California projects for schools and
licensed healthcare. Although this work contributes to our bottom line
and puts food on the table, I always marvel at how public money seems to
be "cheaper" than private money - at least to the folks who spend it.
Steve Leyton
Protection Design & Consulting
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Monday, January 15, 2007 10:55 AM
To: [email protected]
Subject: RE: max velocity
Folks,
Here is some more food for thought. I provide the sprinkler
specification for all of my federal projects. I use 20 fps velocity as
a limit and a maximum C of 100 to insure that I have a system that has a
chance to last for the life of the building (approximately 50+ years).
Our buildings are always being changed with the sprinkler system being
drained and modified many many times by all sorts of contractors, from
the best to the worst.
Once the building is constructed and occupied, the local GSA service
center does all of the work in the building, usually with the lowest
bidder.
Therefore, we need some sort of hedge against all of this. Once the
building is built, it is out of my control. I see no problem specifying
these limits as long as everyone is bidding the same job.
Any suggestions?
Thank You
Rahe Loftin, P.E.
Region 7 - GSA
Office - 817-978-7299
Fax - 817-978-8644
Cell - 817-371-3102
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