To answer your question: *P1 *V1* = P2 * V2 when tested at close to the same temperature. V2 = (P1*V1)/P2 where P1 = 200 psi/14.7 psi = 13.6 atm, V1 = volumen of your pipe system, P2 is 1 atm. V2 = 13.6 * V1 If we have a 4 gpm pump, replace V2 with (4 gpm * x min), rearrange to solve for minutes. If we have 2 pumps operating in parallel, we use the flow rate of the pump with the lower developed-pressure. V1 is in gallons.
X minutes to fill = (13.6 * V1 ) / 4 gpm * FF FF is a fudge factor. It accounts for leaks, the fact that your pump may not be exactly 4 gpm, the fact your pump flow rate will decrease as the pressure it pushes against increases, and FF accounts for plain and simple entropy. My hunch is FF is about 1.3. But don't take my word for it, record the results yourself and show how bad this hunch is. "The inspector came back after the requisite 2 hours and signed it off. It's all about relationships." Life is not fair. But strangely, virtually all mammals[3] (with the exception of some individual humans), some birds[2], some fish and a couple of reptiles demonstrate they understand and expect fair behavior. It is sad, but it being ' all about the relationships' is equivalent to working on the premise of ' we only accept information from reliable sources.' Even if sources were ethically reliable, which no resources are all the time, sources make honest mistakes too. It being '...about the relationships' is equivalent to one AHJ jurisdiction I know, saying we only trust one source of information as accurate (e.g. the NFPA). Judging life safety decisions should not be this way. Basing one's judgment upon whom presents the evidence is a fallacy known as Argumentum ad Auctoridad. While a court of law puts great importance on eye-witness statements, the truth is ---our ability to judge who and when someone is lying is not much better than ... 50% or blind chance[1]. In science, basing one's judgment on the reputation of the presenter is the undisputed lowest level of evidential quality. (Scientists are not immune to making wrong judgments based on this Authority fallacy themselves... as witnessed by the widespread belief in a male presented view that a single meteor-event wiped out the dinosaurs... rather than a female presented view with better evidence which indicates long-term volcanic action is responsible for the die offs). AHJs should treat taxpayers in their jurisdiction fairly and evenly. Yes, of course we must make hunches on whose work is accurate, but that should not condone rubber stamping, favoritism, or denying equal opportunity to examine all numerical, falsifiable evidence on behalf of property and life safety. AHJ are paid by taxpayers, and the pupose of government is to serve its people, not play favorites. Scot Deal - Excelsior Risk and Fire -- gms: +420 606 872 129 La semplicità è la sofisticatezza finale - da vince [1]. https://knowablemagazine.org/article/mind/2021/the-truth-about-lying?tm_source=join1440&utm_medium=email&; One out of nine black men on death row are there for crimes they did not commit. These men may have had a previous record, but our society's record of wrongly judging guilty 1-out-of-9 stands as a testimony to how poorly the accuracy of our lie detection systems has worked in the past. [2]. corvids <https://www.popsci.com/science/article/2013-02/no-fair-crows-say/#:~:text=A%20new%20experiment%20found%20crows,just%20like%20people%20and%20dogs.&text=People%2C%20primates%20and%20dogs%20all,for%20doing%20the%20same%20work.&text=The%20researchers%20then%20created%20same,for%20a%20series%20of%20experiments.> [3]. monkeys demonstrate understanding of fairness <https://www.youtube.com/watch?v=meiU6TxysCg> > Cc: Tom Duross <tduro...@comcast.net> > Subject: [EXTERNAL] Standpipe Testing > > I'm wondering if anyone here on the list can help me with some estimates. > > I have 3 elevated roadway standpipes to pressure test and flow test. All > set with the flow testing part. > > My question is pressure testing. Never did this part before. I can use > the public hydrants to fill to street pressure. No problem. Static on > grade is about 75# as I have a couple of pumps in the area I test annually. > Standpipes are about 50' above. I need to figure out if I need to rent a > pump capable of reaching 200+ psi or how long will these 2 little ½ and ¾ > hp hydro pumps I have will take. This is all witnessed and the plan is > hydro for 2 hours, walk and check everything, drain completely, hook up the > pumper and pull the trigger. Can't make the fire guy stand there for 2 > hours while the little pump hits 200 plus 50 feet. > > > > If I took each of the standpipes, calculated their volume (close to a mile > in total), figured in all the expansion joints, pipe to the double wye's, > air vents, low point drains, dual FDC's, etc., and came up volume. Use fire > hose to reach static. I take my little pumps at 4 or 6 gpm, decreases as > pressure grows obviously, I need to figure how long these will take to > reach 200-225#. Thinking hours. So maybe I need to look into rentals but > I need to know what size I need. > > > > Ideas? > > > > TD > > _______________________________________________ > Sprinklerforum mailing list > Sprinklerforum@lists.firesprinkler.org > > https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.firesprinkler.org_listinfo.cgi_sprinklerforum-2Dfiresprinkler.org&d=DwIFAw&c=wn3mZQLIuInh2ClcJ0_DIA&r=dLwiR71i_XhSFqam3ZLeaFLiQJ3cDTUB0ReB4-yDDcg&m=cicIkTxPTDGmY6Z2ABtrc37sNC4Fz5auvLmpPxfRXWM&s=WufeO6alS7HhoyKVAjj7QIHxIFzsw-grgIKY_ERsmY4&e= > _______________________________________________ > Sprinklerforum mailing list > Sprinklerforum@lists.firesprinkler.org > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > _______________________________________________ Sprinklerforum mailing list Sprinklerforum@lists.firesprinkler.org http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
