Mike, Many years ago(1970's) we had a problem with pressure switch tripping where the water supply was from a city main and there was a well pump close to the tee off from the street. Problem in the end was a faulty check valve on the well pump which allowed the water to back flow into the well when the pumped stopped, then the check valve slammed shut and sent a water hammer surge up the pipe into the nearby sprinkler takeoff. The Sprinkler Alarm Valves were about 50m away and the pressure wave would lift the alarm valve and pass into the installation. The pressure wave then bounced in the closed installation pipework and produce rapid rises and drops of pressure in the installation at the Alarm Valve. This is all without water actually flowing and is the effect of pressure waves. We observed this on a number of cycles. One evening, and were able to convince the City Council to pull the pump and repair the check valve. What was more amazing is that the sprinkler system was kept pressurized at least 300kPa above normal supply pressure(700kPa)as we use drop in pressure Fire Brigade signalling in NZ with a manually controlled jockey pump to super pressure the system.
Regards, Russell Russell Gregory Ph 03 338 4853 e-mail [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mike Hairfield Sent: Wednesday, 7 November 2012 9:27 AM To: AFSA SprinklerFORUM Subject: RE: Water Hammer Problem We used restricted unions with 3/32" holes. Mike > Subject: Re: Water Hammer Problem > From: [email protected] > Date: Tue, 6 Nov 2012 15:24:36 -0500 > To: [email protected] > > Are the two checks with with small holes present in the sensing lines, > might solve your problem. See NFPA 20 for suggested arrangement > > Regards, > Jamey > > On 2012-11-06, at 2:52 PM, Mike Hairfield <[email protected]> wrote: > > > > > > > I have a dry system fed by a booster pump that takes suction off of > > a pumped well system feeding a plant. > > > > The darn dry pipe valve keeps tripping and my thoughts are that when > > the plant well pumps shut off it's sending a water hammer into the fire pump suction line. > > > > I believe the water hammer is causing the pump sensing line to act > > erratic causing the pump to run thus tripping the dry pipe valve. > > > > Anyone have any suggestions about how to fix my problem, a expansion > > tank or water hammer arrestor comes to mind. > > > > Thanks, > > > > Mike Hairfield > > > > > > -------------- next part -------------- An HTML attachment was > > scrubbed... > > URL: > > <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/at > > tachments/20121106/3f3e2708/attachment.html> > > _______________________________________________ > > Sprinklerforum mailing list > > [email protected] > > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attachment s/20121106/eb61a0c1/attachment.html> _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
