I would add to George's response that to do the test in accordance with
NFPA 291 you should also have a static to residual drop of 25 % and your
flow should exceed the expected sprinkler demand plus hose streams in
gpm. In other words your static should drop from 60 psi to at least 45
psi (you may have to open more than one hydrant or more than one butt)
and your flow should exceed gpm (if you anticipate 0.20 over 3,000
square feet you will need at lease 600 gpm plus 500 gpm hose so a
minimum flow of 1,100 gpm).
Also, if you use the pumper connection there is an additional
coefficient to include in addition to the 0.7. 0.8, or 0.9. Again, see
NFPA 291.
Scott
(763) 425-1001 Office
(612) 759-5556 Cell
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of George
Church
Sent: Friday, August 03, 2007 12:45 PM
To: [email protected]
Subject: RE: Proper Flow Test Recording
There's actually quite a bit to know, and I hope to remember them since
I
plan to run one this afternoon, too- if they fix the main break. Since
it's
2 miles south of my house, what a great thing to do on a Fri in August.
If the flow is from one direction, you read static from the hydrant
before
where your tap is, or will be, and flow a hydrant past it. If direction
of
flow in a grid isn't obvious, you could reverse it, but if it is a big
main
and flows aren't taxing it, I wouldn't sweat it.
Measure the ID of the hydrant butt(s) you're flowing, confirming 2.5" or
adjust in the formula. Check if it is a .7,.8, or .9 hydrant, so you can
enter the appropriate coefficient (and not have to drive back and
explain to
the police why you've got your finger in a hydrant butt on Friday
night).
If it's a .9, and FM is your job's underwriter, you'll have to use a .8
coefficient and degrade supply. Fortunately, if it's a .7 you get a
bonus
from FM, it's still a .8 if you wish, but I'd still use the .7- just a
jab
at standardization of variables.
Make sure your gauges are new or calibrated, liquid-filled to minimize
bouncing. Might be too late to go buy a couple Hose Monsters, we swear
by
them for all sorts of things- we know, for instance, what gpm we flushed
an
UG lead-in at.
Get elevation difference between your static/residual hydrant and FF of
your
building.
Ask the water co what their tank elevation was during the test, what
lowest
tank gradient is, and subtract the elevation pressure from both static
and
residual points on your curve- that's the worst your supply should get
(except the zillion other things like a new bottling plant that can
affect
it in the future).
The pitot tube I assume you're using should be held half the diameter
away
from the opening when taking readings, and you need to bleed the air out
of
the zone between the tip and the gauge- that's what that little bleeder
valve is for.
Wear rubbers or boots. Let the water co guy open and close the hydrant.
Don't rip up crops. Don't attach a hose monster directly to a hydrant,
it
needs some hose for accuracy and sometimes they start spinning on the
hydrant - leading to a large amount of water on your head -repeatedly.
We
found this can cause severe abdominal distress to young design managers
witnessing this, plus its cold when you walk in a store to get coffee
cause
you're soaked on the way home. Watch where the puddles form so you don't
get
drenched by passing traffic. Be prepared to laugh if a convertible
drives
thru it. Obviously, 30+ years of water test war stories could add a lot
to
this, but I need to get some stuff dome before going to mine.
Finally- enjoy being out of the office and playing with static and
dynamic
energy.
glc
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Richard
Lindner
Sent: Friday, August 03, 2007 12:46 PM
To: [email protected]
Subject: Proper Flow Test Recording
In order to get a flow test done for a project, the local water utility
will
perform the flow test but we need to be present to "record the numbers".
Being that I have never had to do this, I wanted to ask the group for
their
thoughts and recommendations of what is considered "standard operating
procedure".
I have already printed out a copy of AFSA's "Flow Test Information
Sheet".
I can pretty much figure out where to put most of the "info" but would
appreciate any pointers, methods, etc that others use. What should I be
looking for, what should I be asking for, etc.
One item that I was told a while back when requesting a flow test was to
ask
for the system to be tested both directions, ie, read static on hydrant
1,
residual on hyd 2 and then switch everything around to then be able to
static hyd 2, residual hyd 1. Guess my question is.. is that necessary
or
just overkill and a waste of time?
Appreciate any pointers.
Richard
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