Having spent 12 years installing sprinklers, 5 years in management, and the
last 21 years designing them, I can tell you that the type of system (in
field personell terminology) is called "waterlogged". Any time that you
have trapped water in the system the trip time GREATLY increases. I've seen
it happen many times. In fact, everytime after correcting the trapped
section of pipe, the trip time decreased to at least half of the previous
trip time. I can't explain exactly why, but it WILL happen.
-Bill
----- Original Message -----
From: "Ed Kramer" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, January 16, 2007 8:40 PM
Subject: Dry pipe systems & trapped water
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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