Good point- especially in the low tolerance Potter QRS, so ya don't lunch it !
glc -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom Duross Sent: Wednesday, October 24, 2007 3:56 AM To: [email protected] Subject: RE: Supervisory Alarm - Low Air And a bleeder valve for testing/setting, like you would with any pressure switch monitoring (high-low not null, like PS-10's). I've had pretty good luck with the standard Ashcroft 1005 series 3-2-3 gauges, 0-80 w/retard. 5 year life cycle per #25. We've cut them into the main rather than at the dry pipe valve. Must the gauge be listed? I always thought so. Tom Just a word of caution regarding low differential DPV supervisory air or any critical low air alarm. Always use a calibrated test gauge to set the pressure switch. Trying to find 7 PSI on a the best gauge that $5.00 can buy will always be a challenge. At one time some of the valves came with gauges with 0-300 lb scales . . . a standard trim gauge. . . in my view not suitable for the application. A good gauge with a scale of 0-50 lb would be a worthwhile investment when dealing with such low pressures. Mike Cabral ---- George Church <[EMAIL PROTECTED]> wrote: > What if its one of those new-fangled low differentials that runs on 13 PSI. > Won't the customer complain of the constant trouble signal? I know, reset > it. > > However, if it sits at 13 PSI and trips at 7, where do the wiring guys get > off telling us the proper drop in pressure and making it code? A low air > that goes off 4 PSi below the trip point is of little value. Guess it makes > a nice high air alarm, if that's what we were concerned with. > > Guess that's why our buildings here in PA don't get any alarms, eh? > > glc > > > Hello Dave, > > If the "little red box" is a Potter PS40-2A is has 2 sets of contacts > in it. One for "Low Air" and the other for "High Air". It is factory > set to operate on Increase at 50 PSI and on Decrease at 30 PSI. The > set pressure can be adjusted from 10-175 PSI. The 2 switches can be > adjusted independently of each other to anywhere in that range. > > If the "little red box" is a Potter PS40-1A it only has 1 set of > contacts that operates on decrease. If is factory set to operate on > decrease at 30 PSI. > > I would think the newer System Sensor brand can do the about the same. > > I have found that most of the time the alarm company does not tie into > the high pressure switch. > > > > > Tuesday, October 23, 2007, 5:52:35 PM, you wrote: > > > Something new to me popped up today as we are now using the 2002 editions > of > > 13 & 72 here. > > > On a dry pipe sprinkler the National Fire Alarm Code - NFPA 72 states that > > the air supervisory sensor shall signal on loss of 10 PSI but also on 10 > PSI > > greater than the system set pressure. Check out 5.13 for yourself but I'm > > thinking Ive never seen or tested for air greater than 10 PSI of the set > > pressure before. > > > How is this being handled in the field during installs and maintenance ? > > Does the typical air pressure switch in the little red cover actually > cover > > both loss and increase pressures? > > > Thanks. > > > Dave - a NJ AHJ > > > -- > Best regards, _______________________________________________ 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)
