Try putting a recording type gauge on the water supply, one that will measure and keep the high point (or there are electronic systems that will give you a timeline profile of the pressure). Years ago, we had a three-building warehouse parcel at the terminus of a long dead-end main, that was supplied by a water system that also fed agricultural users. We found out after the fact that float valves on drop tanks that were used to flood strawberry and tomato fields would shut off with such force that it caused a hammer down the line. These hammers were going right through the RPDA's and hitting the building systems. We found all of this out after the fact, when an 8" riser blew out of the floor.
The water district denied it was their system or their fault. The building owner was livid - already handing off to his lawyer to sue us into the Great Beyond. We got the idea to put a recording gauge on the last fire hydrant on site, as well as a public one just outside the RPDA. 3 days later, we noted a 285psi peak onsite and 245 outside. We watched for a week and got on-site pressure in excess of 300 psi. Which implies a peak hammer of 1,500psi or higher. So we called out the water dept. GM again, and the owner (and his attorney) and showed them the conditions, which led to actual due diligence by the water co., which led to the drop tank finding. The point is that there could be a dozen or more different explanations for why the pressure was so high at your subject; the first step is to establish whether it's chronic or seasonal or a one-time phenomenon. Then, with substantiating evidence in hand, you go the water purveyor and ask them to diagnose and manage the pressure issue. It could be as simple as work being done upstream on that zone just once or twice ... Steve Leyton -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Douglas Hicks Sent: Thursday, March 21, 2013 1:11 AM To: [email protected] Subject: Low Air Switch On March 11, I got a call to investigate a low air signal. I arrived on scene and found the water pressure at 225 pounds, air at 52 pounds. The FACP showed normal. I shut the main control valves off. I opened the main drain to relieve the water pressure, leaving the valve open 2 or 3 turns. I opened the priming water drain and got only air. I opened the condensation drain and let the air bleed to 30 PSI. I let the riser mount compressor build to 47 PSI, where the compressor shut off. I opened the butterfly valves, the water pressure was at 80 PSI. The compressor kicked on and shut off twice, in rapid sequence. The system is at the end of the city water line and at a low point. In September, the water pressure was 70 PSI, the air was 45 PSI. The gauges were replaced or compared with certified gauges in September. There is no backflow or pressure reducing valve on the system. I have not contacted the water department to ask if there have been any pressure bumps. But, another account a few blocks away did not show the 225 water PSI on their wet system. We service 100% (all 3 ) of the sprinkler systems in the community. Any suggestions? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attach ments/20130321/cac9a629/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
