I'd agree, but sometimes it isn't much. We had a 572 HP diesel for a 3,000 @ 170 PLD that dropped like 400 RPM from churn to 150% (4,500 GPM!!!) Limited selection in the big variable speed diesel drivers. Had to increase pumproom 2' in width to fit the testosterone in.
George L. Church, Jr., CET Rowe Sprinkler Systems, Inc. PO Box 407, Middleburg, PA 17842 877-324-ROWE 570-837-6335 fax g...@rowesprinkler.com -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of djj8...@aol.com Sent: Wednesday, October 03, 2012 2:09 PM To: sprinklerforum@firesprinkler.org Subject: Re: Fire pump annual test When testing a fire pump, pump speed ALWAYS drops with increased flow. In a message dated 10/3/2012 8:43:56 A.M. Eastern Daylight Time, bcasterl...@fsc-inc.com writes: Tom, let me back-up and try to benefit from your experience. The speed is not suppose to change, but it does, right? Years ago I helped a fitter with some annual tests-- no matter what the rating, we took all the readings at several (increasing) flow rates. I think I remember the speed dropping, if only slightly, otherwise why measure it more than once! It seems 'illegal' to not drop. BTW- good advice on not using the individual 2.5" valves to calibrate the flow- it is hard to forget having to use both hands, elbows and forearms to keep them from vibrating out of whack while being screamed at by an old.edu fitter, ankle deep in water, hung-over, no rubber boots or coffee, early morning, mid- November in Kansas :) -----Original Message----- From: bcasterl...@fsc-inc.com [mailto:bcasterl...@fsc-inc.com] Sent: Wednesday, October 03, 2012 5:30 AM To: sprinklerforum@firesprinkler.org Subject: RE: Fire pump annual test Tom, I guess once we equate what goes out of the tachometer with what goes into the thermometer, the speed does not change-- the magic of the second law of thermodynamics! (or, as you put it-- 'Pump affinity'). Quoting Tom Duross <tduro...@comcast.net>: > Brad, we measure rpm as a means of adjusting pressures to rated > speed. These pumps are magic and speed is not supposed to change. > Pump affinity. Also, when you have more than one pipe size > difference between discharge and suction, you should adjust for > velocity pressure (or read discharge after the increaser). _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attachments/20121003/ff9da196/attachment.html> _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
