Owen,
Let me offer a couple of thoughts here.
First, please be aware that that figure of 26 gpm for two sprinklers
flowing makes a couple of dubious assumptions. If the layout used
horizontal sidewall sprinklers and covered an area 14' wide with a throw
of 26', the required flow is 42 gpm each. If two such sprinklers were
in a compartment the flow is at least 84 gpm which is more than three
times the value of 26 gpm. And, should those HSW's be placed in a
compartment with a sloped and beamed ceiling with the sprinklers in each
pocket formed by the beams, and that compartment exceeded 600 ft² the
AHJ may have a mandate that in such situations a three sprinkler flowing
calculation is required, or perhaps a greater flow. The calculations
could easily require more than 120 gpm.
I agree that these demands are likely to be quite low on the supply
curve available from the water purveyor.
My suggestion would be that you follow the guidance of Steve Leyton with
the following additional thoughts. Contact the AHJ and bring this
matter to their attention. Remind them of the provision of §10.1.2 of
NFPA 13D which notes that if the water supply is from a public or
private main of 4" or greater diameter that the static pressure shall be
permitted to be used in preparing the hydraulic calculations. Make the
AHJ aware of the decision of the water purveyor to ignore this section,
which by the way is the law in California.
Such an arbitrary decision by a water purveyor does indeed place a
greater cost impact on the owner/builder and the AHJ should be made
aware of that.
sincerely.
*Ken Wagoner, SET
*Parsley Consulting***
*350 West 9th Avenue, Suite 206
*Escondido, California 92025
*****Phone 760-745-6181*
Visit the website <http://www.parsleyconsulting.com/> ***
On 11/19/2019 4:45 AM, firstin--- via Sprinklerforum wrote:
Bruce,
13D allows calculations to be developed from static pressure only when the
system is being supplied from a reliable water supply like a municipal system.
Because the demand of a 13D system is so minimal (26 gpm, two heads flowing) a
water supply curve developed from a flow test (static, residual, and flow) is
not required. The water company charges $600 to perform a flow test. Our
forefathers developed the 13D standard to be a minimal system to keep the cost
down to reduce the resistance from developers and municipalities. A flow test
for a 13D system is monumental waist of time and money. But try and explain
that to the new inspector (who has all the power yet very little knowledge and
training) who is just passing through on the promotional track. Very
frustrating.
Sent from my iPhone
On Nov 18, 2019, at 11:28 PM, Bruce Verhei via Sprinklerforum
<[email protected]> wrote:
I don’t get it. It’s not off a home well.
On Nov 18, 2019, at 20:24, firstin--- via Sprinklerforum
<[email protected]> wrote:
The water purveyor does the test at a cost of $600 plus the delay waiting for
it to get done.
We all know how things can evolve over time as people in different positions
come and go. Since 1991, up until now, the procedure was the water purveyor
provided the static pressure at the proposed job site. This was the third party
verification for the development of the calculations by the installing
contractor.
Sent from my iPhone
On Nov 18, 2019, at 8:02 PM, Mark.Phelps via Sprinklerforum
<[email protected]> wrote:
Do you have to perform the test or do they do it?
Mark at Aero
602 820-7894
Sent from my iPhone
On Nov 18, 2019, at 8:57 PM, firstin--- via Sprinklerforum
<[email protected]> wrote:
Need advice on the best way to fight a non required requirement.
Someone at the local water purveyor came up the the great idea to require a
full blown flow test for ALL proposed SFR fire sprinkler systems at a cost of
$600 each. The vast majority of water mains that run down residential streets
are 6”. There are a few 4” and that’s the smallest. Who on Gods green earth
thinks that two residential heads flowing could over-run the municipal water
supply, therefore, a flow test is required to develop supply curve, really?
Am I missing something or is this requirement BS and nothing but a money grab?
Owen Evans
Sent from my iPhone
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