Weird. But if the drop in pressure each night is consistent, and you have verified that there are no leaks and there are not people opening valves and using water from the standpipe then I'd be inclined to use the night time pressure as my normal system pressure and re-adjust the pump start set point below THAT value.
Craig L. Prahl, CET Fire Protection Specialist Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [email protected] http://www.ch2m.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of sam b Sent: Tuesday, May 04, 2010 12:21 AM To: [email protected] Subject: Re: Fire Pump Matt, There is some temperature difference of about 6-8 degree celsius only. Pump is in service from only 2-3 weeks. pressure switch? Worth a check.. Craig Supply is from water tanks. There is a check valve provided in the pump discharge. We have water storage in 3 tanks with a common supply to pump. As for yesterday pressure drop was from 20 bar to 15 bar .. On Mon, May 3, 2010 at 11:37 PM, Matt Grise <[email protected]> wrote: > What is the change in temperature from day to night? Is the piping exposed > to outdoor temperatures? Sunlight? > > Is it possible that there are small leaks in the standpipe that could drop > the pressure? > > How long have you had the pump in service? > > If this just started happening, maybe there is a problem with the pressure > switch? > > Matt Grisé PE*, LEED AP > Sales Engineer > Alliance Fire Protection > *Licensed in KS & MO > > 913.888.0647 ph > 913.888.0618 f > 913.927.0222 cell > www. AFPsprink.com > > > -----Original Message----- > From: [email protected] [mailto: > [email protected]] On Behalf Of sam b > Sent: Monday, May 03, 2010 2:30 PM > To: [email protected] > Subject: Re: Fire Pump > > craig > > Surely that can be done.(adjust the differential) > But am worried what is goin wrong? > > > > On Mon, May 3, 2010 at 11:23 PM, <[email protected]> wrote: > > > Tom, look at your conversion factor again. Bar X 14.5 = psi. > > > > Pump rating is 20 bar (290 psi), set point to start is 16 bar (232 psi). > > > > You're saying there is a system pressure differential of 4 bar (58 psi) > > between normal daytime pressure and night time pressures? > > > > Apparently you don't have a jockey pump on the system to maintain the > > pressure? > > > > Any reason not to adjust the differential a bit wider, say drop the start > > point to 14 bar maybe? > > > > Craig L. Prahl, CET > > Fire Protection Specialist > > Mechanical Department > > CH2MHILL > > Lockwood Greene > > 1500 International Drive > > Spartanburg, SC 29304-0491 > > Direct - 864.599.4102 > > Fax - 864.599.8439 > > [email protected] > > http://www.ch2m.com > > > > > > -----Original Message----- > > From: [email protected] [mailto: > > [email protected]] On Behalf Of tom poisal > > Sent: Monday, May 03, 2010 3:18 PM > > To: [email protected] > > Subject: Re: Fire Pump > > > > On Mon, May 3, 2010 at 3:08 PM, sam b <[email protected]> wrote: > > > > > but do you expect this to go down so much ,more than 2 bars even,.? > > > am actually waiting for the status tonight...:) > > > > > > Yeah your talking 2 bars = only .1378 psi, I have seen systems lose 5-6 > > psi > > > overnight and gain it when the sun rises > > > > > > On Mon, May 3, 2010 at 11:02 PM, tom poisal <[email protected]> > wrote: > > > > > > > sam, it is the temp rise/loss; when it gets to night time the water > > > cools > > > > and lowers the temp which lowers the psi/bar same with an overnight > > hydro > > > > test..not much you can do about it that i know. > > > > > > > > > > > > On Mon, May 3, 2010 at 2:57 PM, sam b <[email protected]> wrote: > > > > > > > > > Hii everyone > > > > > > > > > > > > > > > My previos mail in this forum was regarding a temporary fire > > pump(only > > > > > dieselPump) only. > > > > > we have installed this fire pump for temporary fire fighting in > the > > > > site. > > > > > The pump is 500 USGpm @ 20 Bar.(NOn Listed).The risers we have > > > installed > > > > up > > > > > to 7 floors now. > > > > > The pressure switch setting is kept such that when presuure drops > > below > > > > 16 > > > > > Bar the pump automatically starts. > > > > > For the last 2 days we are seeing that the pump starts > automatically > > at > > > > > night time.In the daytime there is no considerable pressure loss > > also. > > > > > our initial assesment was that it may due to air trapped inside ,as > a > > > > > result > > > > > we installed air release valve in both risers .Also the NRV in the > > > > > pumpdiischarge was replaced to ensure there is no leakage. > > > > > > > > > > Any guesses on whtmay b the reason? 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