I'd considered a surge bladder for this, but do't have any field experience with them. May have to wait for the 8-5'ers to get to the office.....I've only used bladderes on AF loops.
Did talk to Clarke, they thought either would work (bladder or PRV). I think the main criteria may be operating speed, in which the bladder would win. Have asked CLA Val and OCV about reaction speed. Ps- TD- are ready to go out or are you coming back in from an early test? glc -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom Duross Sent: Thursday, September 20, 2007 5:38 AM To: [email protected] Subject: RE: PLD and PRV I thought these were out-coded for oversized diesels, constant speed or variable. I'd go back to Clarke. How about a surge/bladder tank? Tom Fire only, manufacturing/warehouse occupancies. :) next to two 2,000 GPM pumps, I thought 2.5" WAS small ! I want to make sure it doesn't get clogged, but DUH, pilot lines aren't 2.5" or ", are they. Will look at 2", smallest without switching styles down to a 3/4". glc Since your only using it to restore the lower operation pressure in the mains why use a 2.5" device? The smaller a device the lower the impact if it fails open. Also if the only usage on this system is for fire, you'll have a small spike at start up, but a very low volume to deal with to return it to 155 / 160 Psi. If the system feeds domestic / industrial uses wouldn't that relieve the excess? Thom McMahon > > We've noticed the PLD's we've installed allow brief surge of > overpressurization while the diesel starts up, builds pressure, and > for the time it takes the PLD to react, there's an inrush of some of > the churn pressure until the governor kicks in and backs it down. Guy > at Clarke confirmed this. > > We have a project with what is possibly fragile UG in many sections of > the facility. We're trying to keep it, and the related interior > systems, from creeping up to high pressure (isn't that why we have the > PLD?). This particular site is getting twin 2,000 @ 150 diesel > vertical turbines, which feed a large looped yard system, in turn > feeding -oh, couple dozen risers scattered around. > > We're thinking a small (2.5"?) Relief valve located past the pump > discharge valve, just before it drops into the yard system, PRV > discharge piped back to the reservoir, set point 5 PSI above the PLD, > set adjustment on reaction time to ASAP setting, so it will bleed off > the excess pressure as soon as possible. We think the size of the yard > loop- complete with sectionals, hydrants, etc.- will absorb the shock > with only a small amount of it getting into the interior systems. If > some does, 1/2" relief valves on the grid will take care of anything > > 175. But we want to be able to have the UG drop back to the 155~160 > range as soon as possible. > > Since the twin pumps go into one yard system, the small PRV only has > to be installed on one of these. Since its relatively small, even if > it failed OPEN the loss wouldn't de-rail the train, we have 150 @ > 4,000 when combined, and demand is about 150 @3,000. Assuming the 2.5" > PRV stuck open wouldn't flow more than 1,000 GPM, it could drop the > water back in the hole to be re-pumped all day long. > > Both pumps will start remotely from elec detection systems on these > large demand systems, and on pressure drop for the conventional wets. > > Yes, the owner has authorized high pressure testing of the UG, still > doesn't mean we can slam the heck out of it or let it sit at 175+ and > not see a main break in a couple yrs. > > Any other thoughts from those with some PLD experience? > > glc _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
