Chris, Did you ask the contractor about the elevations of the hydrants?
The only way I see the gaged and flowed PSI both 20 is if the flowed is about 8 feet lower than the gaged and the margin of error in synchronization of the gages is a pound or 2. I got the 7'-11" elevation difference using my secret recipe of definite proportions of feet and seconds with a dash of pure gravity on top ;) thanks, Brad -----Original Message----- From: Cahill, Christopher [mailto:[email protected]] Sent: Thursday, December 19, 2013 11:30 AM To: [email protected] Subject: RE: Flow Test Residual and Pitot The Same? Well done Mark - Exactly. And what I'm hearing thus far is yes it's possible. If I were standing there I wouldn't ask the question. I'd see what was going on and trust the results. When I'm not there, and no one I trust, I get skeptical. I guess the good news is the test is such crap they will have a pump. If it's a bad test and they really have more water no harm except to the owners pocket book. If it were showing we didn't need a pump but was really less than reported that would potentially make the sprinklers ineffective. I realize even with the pump in this case the test could be worse and still short on water. But as bad as it is, odds are it can't be much worse. Much more harm if there is a fire and short on water. The report is issued correct, the contractor described a correct process so I guess I have to reluctantly accept. About the only unknown is calibration of the gauges. I suppose I can ask and will get a certificate showing they are. But just like the flow report and description of the procedure it's all trusting the other end is honest. I just found painted heads in a building where they haven't started painting anything....hmm, trying to reuse heads? I know most folks are honest but a few mistakes do occur. Chris Cahill, PE* Senior Fire Protection Engineer Burns & McDonnell 8201 Norman Center Drive Bloomington, MN 55437 Phone: 952.656.3652 Fax: 952.229.2923 [email protected] www.burnsmcd.com Proud to be one of FORTUNE's 100 Best Companies to Work For *Registered in: MN -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mark A. Sornsin, P.E. Sent: Thursday, December 19, 2013 10:33 AM To: [email protected] Subject: RE: Flow Test Residual and Pitot The Same? Tim - If I may speak for Chris - he is not confusing the residual with the Pitot. He's simply noting that a contractor has told him their test shows a Pitot pressure that is the same value as the Residual pressure. So the question is "Is this possible?" Mark A. Sornsin, P.E. | Karges-Faulconbridge, Inc. | Fire Protection Engineer | Fargo, ND | direct: 701.552.9905 | mobile: 701.371.5759 | http://www.kfiengineers.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of G. Tim Stone Sent: Thursday, December 19, 2013 5:58 AM To: [email protected] Subject: RE: Flow Test Residual and Pitot The Same? Chris, My understanding is that you are asking about 2 different pressures. The Static and Residual pressure readings we acquire are acting in all directions inside a pressurized pipe. Static or dynamic represents pressure of at rest or non moving/flowing condition while the residual lower change in pressure we expect to see when water is allowed to flow from an open valve. >From the next hydrant that is allowed to flow we are measuring for GPM by use of the Pitot which is measuring the pressure at the center of that water flow stream and that pressure is created by the force of that moving water past the end of the Pitot. These are two different pressures and should not be confused. Regards, G. Tim Stone G. Tim Stone Consulting, LLC NICET Level III Engineering Technician Fire Protection Sprinkler Design and Consulting Services 117 Old Stage Rd. - Essex Jct., VT. 05452 CELL: (802) 373-0638 TEL: (802) 434-2968 Fax: (802) 434-4343 [email protected] > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > Cahill, Christopher > Sent: Wednesday, December 18, 2013 5:44 PM > To: [email protected] > Subject: Flow Test Residual and Pitot The Same? > > I have a flow test report showing the residual and pitot pressure > being the > same. 60 static, 20 residual with a 20 pitot on a 2.5" opening for > 750 gpm. I talked to the contractor and they described doing it > correctly, two hydrants one static/residual, one flowing. I don't > believe it's possible to have the residual and pitot the same pressure > but I'm having a hard time > articulating why not. I know I've never seen this before and probably have > done almost 1,000 tests in my life. Any input? Is it possible? > Either way why or why not? > > Chris Cahill, PE* > Senior Fire Protection Engineer > Burns & McDonnell > 8201 Norman Center Drive > Bloomington, MN 55437 > Phone: 952.656.3652 > Fax: 952.229.2923 > [email protected]<mailto:[email protected]> > www.burnsmcd.com<http://www.burnsmcd.com/> > > Proud to be one of FORTUNE's 100 Best Companies to Work For > *Registered in: > MN > > > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum- > firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. 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