The only issue I can see (and this does not come from experience,
just thinking about it) is that it may create a problem when shutting
down the system and re-activating it. If the system is shut down and
the air is released through the inspector's test connection, would
some of the trapped water make its way into the other part of the
system, and not drain out, creating a potential freeze problem?
At 01:19 AM 1/17/2007, you wrote:
I have a situation almost exactly like this. A well-known FPE firm
advised the client it was necessary to put a connection to the
trapped section through which water could be sucked out. Reasons
were that this slug of water would prevent the DPV from tripping,
and that the section of pipe was on the "dry" side of the DPV. so
had to be dry. Repeated tests proved the first reason
fallacious. The second reason made them believe it mattered, but
did not convince me. The system has no drain connection, and is
still filled with water.
I can visualize a sprinkler opening, the DPV tripping, the, QOD
not working, air continuing to leave through the sprinkler, a slug
of water coming out, another slug of air, followed by constant flow
of water. In this light hazard occupancy, I don't see this as a problem.
Ed Kramer <[EMAIL PROTECTED]> wrote:
I'm working on a project where the engineer is asking for the following:
A dry valve located in the basement (below grade). The pipe leading from
the dry valve will rise up (approx 7') to just below the basement ceiling,
turn horizontally and travel to an exterior wall. At the exterior wall it
turns down (an unknown distance, but I suspect about 2'), turns
horizontally, passes through the foundation wall, travels approx 13'
underground, then turns up into an unheated dock area.
This means there would be approx 17' of trapped 4" supply pipe downstream
of the dry valve (vertical distance = 2'). I can put a drain valve on it
in the basement, but there's no guarantee it'll get used.
Assuming this trapped section of pipe becomes full of water, how will it
affect the tripping of the dry valve? Should I be concerned about it?
(Freezing of the water in the trapped section is not an issue.)
Ed Kramer
Littleton, CO
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Ed Vining
4819 John Muir Rd
Martinez CA 94553
925-228-8792
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Todd G. Williams, PE
Fire Protection Design/Consulting
Stonington, Connecticut
860-535-2080
www.fpdc.com
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