I often get too excited and blurt things out and reply to myself several times with corrections and clarifications, like now: 1) I have done a lot of standpipe calcs and I use K=Q/SQRT (P) just like everyone has said here, and I use equivalent length for the valve=31 ft. 2) What I mean by K Value should be more useful than K Factor is, for instance, at 250 GPM eql.=23.65 ft and at 500 GPM it is 26.24 ft. Just another example of the excellence of the NFPA Standards as standards. And if you are pitoting a 2.5" hose valve to estimate the GPM as if it were a hydrant butt, if my concept of K Value is correct, C=.61 should be 'decent'. 3) Coefficient of Discharge = actual measured / ideal, and that is always less than 1.
Brad On Feb 17, 2017 5:19 PM, "Brad Casterline" <[email protected]> wrote: > Shazbot! > 2g=64.4 > (62.4 is the weight in pounds of a cubic foot of water). > On Feb 17, 2017 5:05 PM, "Brad Casterline" <[email protected]> wrote: > >> Vince, >> >> I think you are looking for something with a little more meat on its >> bones than rearranging Q=K*SQRT(P). A few years ago you mentioned K Value. >> Counselor Greenman presented this evidence: >> >> http://www.metropumps.com/ResourcesFrictionLossData.pdf >> >> The first item is Angle Valve, which might be close enough to Hose Valve, >> but the problem is the second item is also Angle Valve with a different >> value and I saw no clarification of what's what with that. But when Steve L >> testified to 3-5 psi loss at 250 gpm I rearanged and I think the second one >> is correct; K Value=2.7- - - >> >> Using the 5 psi loss, hf=11.55 ft. >> I converted 250 gpm to .557 ft^3/sec and 2.5" nominal to .034 ft^2 and >> dividing the first by the second got v= 16.38 ft/sec, squared that, divided >> by 2g (62.4), and then divided 11.55 by that for K Value = 2.77. >> This should be more useful for you because friction head is directly >> proportional to the square of the velocity, and K Value is a counter part >> of Coefficient of Discharge in that C of D = the ideal world based on >> nominal / the reality of the measurement. >> >> still yours after forty years, your first grasshopper, >> >> Brad >> On Feb 17, 2017 8:28 AM, "Vince Sabolik" <[email protected]> wrote: >> >>> Good morning, everyone... >>> >>> Does anybody have a decent K Factor for a 2½" hose valve? >>> >>> Thanks! Vince >>> >>> 11351 Pearl Road / Suite 101 >>> Strongsville, Ohio 44136 >>> Phone 440 238-4800 <(440)%20238-4800> Fax 440 238-4876 >>> <(440)%20238-4876> Cell 440 724-7601 <(440)%20724-7601> >>> >>> >>> * Vince Sabolik * >>> >>> _______________________________________________ >>> Sprinklerforum mailing list >>> [email protected] >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-f >>> iresprinkler.org >>> >>>
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