Scot - I don't think your base equation is quite right. You may be trying to use the ideal gas law here, on a liquid, which doesn't work. Also, I think technically you would be changing "n" in the equation, not V (the volume of the system is constant at P1 and P2), but I don't think this really matters. I think your equation is essentially correct, but only if we were talking about a system being filled and tested with a gas, not water.
Tom - I have considered this problem in the past, when I had to test a run of underground piping in the middle of nowhere, and I wanted to know how big of a tank I would need to bring to get to 200 psi after the piping was full of water. Because water does not compress very much (see link below for a graph; less than .5% at 1000 PSI), the answer was extremely small (less than 10 gallons). I don't want to run through the math again (it doesn't really matter because we are talking about only needing to add a very small volume of water to increase the pressure substantially). The huge key is having no air in the system. Air is very much compressible, as shown in Scot's equation. I say all of this because my advice is that you should vent out as much air as possible. If you can do this, it shouldn't take much time to pressure up the system up to 200 psi, even with a small pump. Getting all the air out is usually easier said than done (theory can be much different than real life), but with what I just told you, it is worth making an attempt. https://www.quora.com/How-much-force-would-be-needed-to-compress-water-within-an-indestructible-vessel-And-what-would-happen Thanks, Skyler Bilbo 1700 S. Raney Street Effingham, IL 62401 217-819-6404 Cell [email protected] www.wenteplumbing.com On Fri, Apr 16, 2021 at 3:27 AM å... .... via Sprinklerforum < [email protected]> wrote: > 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 <[email protected]> > > 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 > > [email protected] > > > > > 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 > > [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 > _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
