Have several water supply/flow test/ambient condition discrepancy stories, but I'll save them for another time. The closest situation I had to this was where a sporadic condition was occurring on a water main system that fed "drop tanks" that served an agricultural user whose land abutted the industrial park in which we were working. In that case, an adjustment was made in the fill system that served the tanks, which sounds like it might apply here. Are you saying that a large user consumes water in the public tank(s), that cause the water level and thus the static elevation head pressure to drop, or is it that the municipal system drops radically in resid' when it starts to fill the user's private tank(s)? If that's the case, then the private system can be modified to come on sooner and fill for longer periods at lower flow rate and pressure and/or put on a timer so that the auto-fill would run at off-peak hours.
Steve Leyton Protection Design & Consulting -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Todd Williams - FPDC Sent: Monday, October 01, 2007 1:30 PM To: [email protected] Subject: water supply fluctuation I just ran into a situation that makes me a little nervous about water department flow tests. I have been asked to straighten out a mess on a system in a 7 story condo (multiple issues). A designer who was asked to verify some hydraulics got a flow test from the municipality which was about 23 pounds higher than the design test, which was done several years ago. At that time, she was told this was due to improvements in the public system. They had been doing a lot of work on the system, so it was believable. System pressure gauges were with a reasonable number of the static pressure. When I got on board, I also checked with the water department and was told the same thing. Recently, a contractor working on the system noticed the the pressures reading lower. Upon further investigation, including pressure recorders on hydrants, it was found that the pressures varied 30 psi over a 3 day period. The water department was not aware of the range of fluctuation until they did this test. Their explanation was various pumps kicking in to fill tanks, including for the town's largest water user. Now we are going back and re-calculating the systems with a much lower static pressure. Has anybody run into this type of thing? Is there a good way to detect it? I consider myself fairly savvy and sniffing out problems, but this caught me off guard. How can a water department not know this type of thing is going on. This is a small city in CT. Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut www.fpdc.com 860.535.2080 _______________________________________________ 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)
