This, from the catalog cut sheet on the new Firetrol FTA 1930. It would appear that the manufacturer is touting both electrical AND hydraulic benefits with regard to the soft starting and stopping functions:
Firetrol(r) FTA1930 Digital Solid State Starting Fire Pump Controllers feature soft start, soft stop and system sensing capabilities that not only provide for reduced current starting, but also offer an improved level of hydro-mechanical performance. The controller monitors, displays and records fire pump system information. When called to run, the motor will accelerate beginning at 100% of motor FLA up to a maximum of 300% FLA while rated torque is reduced to 15%. When stopping, the motor will decelerate to a preset level and pause, allowing for a restart if required, limiting stress in the piping system. If no additional starting causes are present, the motor will continue to decelerate to a full stop. This controller helps to reduce water hammer in the system. Steve Leyton Protection Design & Consulting San Diego, CA -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom Duross Sent: Monday, February 02, 2009 6:20 AM To: [email protected] Subject: RE: - prescriptions against soft-start pumps in NFPA watersupplies.. I would think that a properly set jockey and fire pump shouldn't introduce that much hammer to an underground. For a 175 PSI main, the jockey would be set for about 165-175 and the fire pump 160-170. So the UG would only really drop 15 PSI before the big pump kicked in. I've found soft starts to create more hammer due to the time to speed as pressures continue to drop. I don't think there's a time limit to speed (like with transfers) right now as all these software based controllers are all over the place for boot-up. I might try a main regulator to absorb the surge or multiple pumps in a primary-secondary pressure setup. There's a newer high-rise in Boston I tested with primary-secondary jockeys, cool setup with 5 PSI lag on the secondary (5 HP JP1, 15 HP JP2 and then 100 HP FP). Tom Duross FGOL I was under the impression that the soft start was more to reduce hammer on the electrical supply. Bruce is correct that a jockey pump(s) maintaining churn pressure on the systems would reduce the hammer; in a large volume system, we wouldn't expect as much hammer as in a short section of piping not up to churn pressure. A small surge suppressor of the bladder style might be a less costly answer if you are concerned about old underground whose integrity might be questionable, but if this is the case, additional testing of it might be prudent since without UG, you can't get water out of remote systems.\ glc _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) __________ Information from ESET NOD32 Antivirus, version of virus signature database 3818 (20090202) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 3819 (20090202) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
