Just a side story. A designer I know was told the existing fire pump had a head of 180 feet. He designed the sprinkler system thinking he had a 415 psi (instead of 78 psi) fire pump boosting the 60 psi city supply. He thought he had this huge supply, but didn't think he needed any PRV's. The contractor as usual used a "rubber stamping" PE. The AHJ, underwriter and EOR didn't have a clue. So it slipped through the cracks and the ESFR system for the warehouse was installed with mostly 1" branch lines. Ten years after it was installed there was an addition and the insurance began asking questions as the piping for the addition was considerably larger. Then, as they say, the @#$% hit the fan.
Tony -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Fletcher, Ron Sent: April 8, 2008 9:47 AM To: [email protected] Subject: RE: Failed Bucket Test 25 psi equals 57.7 feet of elevation and partially closed valves can account for a reduced static pressure when dealing with city water mains. Ron Fletcher Aero Automatic Phoenix, AZ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ron Greenman Sent: Tuesday, April 08, 2008 8:32 AM To: [email protected] Subject: Re: Failed Bucket Test Brian, Static doesn't change, even with a blockage (recovery time is slower but eventually reaches the pre-recorded pressure--hence the value of a main drain test), unless the original test was done during off-peak and your bucket test was done during peak, there is a pump involved that is not coming on or has been removed from service (your bucket test may not have enough demand to fire it up but a hydrant test would--this begs the differences in static), the grid has been changed and the source, if gravity, is lower, relative to the site, than before, the level of the tank was lower during your test (25 psi equals a little less than 11 feet) or the guy that produced the original numbers didn't know what he was doing (I got a report once that showed the residual pressure and velocity pressure to be the same--the water guy wouldn't budge). If you're in a residential area I'd look at the time of day and time of year the test was done as well as the area, read grid, growth since the time the test was done. Mid day and mid night are off peak times as is winter in general during peak. The tanks may be low and your test may have been done during or at the end of morning peak or the beginning of evening peak. The original test may have been done during summer at midnight when usage was down and the tanks freshly replenished for tomorrow's lawn watering. Lots of possibilities. I think our reliable, automatic water supplies are less than reliable but the alternative seems to be stored water and pumps--extra equipment to fail. On Tue, Apr 8, 2008 at 7:22 AM, Brian Harris <[EMAIL PROTECTED]> wrote: > -- Ron Greenman at home.... _______________________________________________ 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) _______________________________________________ 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)
