This section of the building was built in the 1950s and was all pipe
schedule. At some point, some one allegedly did hydraulics (due to
the rack storage) and this is where the placard came from. There have
been at least 5 owners that I am aware of. When and how this was done
is beyond me. As far a due diligence, the last time I saw an FM
Global guy on a job, he was training someone new in hydraulics. His
line was "Ignore the riser nipples, they don't have any impact. Just
include the elevation." I doubt if many insurance companies actually
do hydraulics before they write a risk; they just look at the placards.
At 11:25 AM 10/15/2008, you wrote:
I wonder what the inspectors were doing when they reviewed the info on
the hydraulic placard simple math and some common sense would have
indicated that something was wrong. The density 0.45 gpm per sq. ft.
times the area of operation 2,500 sq. ft. times 1.3 (30% increase for
hydraulic inefficiency of tree system) indicates a flow requirement of
1,462.5 rounded up to 1,465 gpm for the system. It appears that the
hydraulic placard was based on the design density multiplied by area of
operation plus 100 gpm.
What happened to the HPR carriers plan review of the shop drawings and
hydraulic calculation or due diligence when taking over the account from
another carrier.
I hope that the sprinkler contractor doing the annual inspection is
following NFPA 25 to the letter and not using any "modified" version of
the NFPA 25 inspection form.
Just goes to show that you must verify all info given to you.
Jim Davidson
Davidson Associates
302-994-9500
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Todd
Williams - FPDC
Sent: Wednesday, October 15, 2008 10:15 AM
To: [email protected]
Subject: Placard fact check
This weeks crisis, so far.......
I am working on a plant in MA where they need to add in rack
sprinklers. The existing ceiling system is a pipe schedule and the
placard at the riser says it can deliver .45/2500 at a flow of 1220
gpm at 52 psi. It seemed light, but I don't jump 'til I crunch the
numbers. In actuality, it requires 1558 gpm at 286 psi at the supply.
Everybody, including the HPR carrier, has bought into the numbers on
the riser. Now the excrement is about to impact the vortex generator.
Moral of the story; don't believe everything you read.
Todd G. Williams, PE
Fire Protection Design/Consulting
Stonington, Connecticut
www.fpdc.com
860.535.2080
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Todd G. Williams, PE
Fire Protection Design/Consulting
Stonington, Connecticut
www.fpdc.com
860.535.2080
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