It appears my question was poorly worded so it put y'all in a difficult position to answer. Travis and David supplied the answer I needed. Thank you all for your help. This has been informative.
On Wednesday, May 18, 2016, Brad Casterline <[email protected]> wrote: > This is Brad not Zach David. > While we are waiting I just wanted to say I have been asking for 4 or 5 > years here if someone will dig up an old certified pump curve and post the > nameplate psi and rpm. I am 99.44% (like Ivory soap) sure > I can tell you what the nameplate impeller diameter says. > Are you game? > > Brad > On May 18, 2016 5:26 PM, "David Bitton" <[email protected]> > wrote: > >> Hello Zach, >> >> >> >> In reviewing the various responses to this thread, I noticed that no one >> actually answered your original question. Here's my attempt: >> >> >> >> The upper limit for the pump pressure rating can be estimated as follows: >> >> >> >> Nominal pressure = (175 psi - Y)/1.2 >> >> Y = Maximum suction pressure (static pressure if the pump is fed by >> municipal mains) >> >> >> >> This formula is based on the following assumptions: >> >> 1. The maximum pressure rating for the piping and system >> accessories is 175 psi. >> >> 2. The pump shut-off pressure is 120% of the pressure at the rated >> flow (this can range from 100% to 140%, depending on the pump model). >> >> >> >> In addition, if the proposed pump will be driven by a diesel engine, the >> nominal pressure derived from the above expression may be divided by 1.21. >> The result would be the maximum pump pressure rating that would not require >> the installation of a relief valve. >> >> >> >> *David Bitton, ing.* >> >> *Les services de prévention des sinistres Quest inc.* >> >> *Quest Loss Control Services Inc.* >> >> 5100, rue de la Savane, bureau 200 >> >> Montréal, QC H4P 1T8 >> >> (514) 341-4545 >> >> *www.questlosscontrol.com <http://www.questlosscontrol.com>* >> >> >> >> >> >> *From:* Sprinklerforum [mailto: >> [email protected]] *On Behalf Of * >> [email protected] >> *Sent:* Wednesday, May 18, 2016 5:15 PM >> *To:* [email protected] >> *Subject:* RE: Equation for sizing fire pump >> >> >> >> In some jurisdictions you have to install an automatic suction control >> valve to assure that you do not pull the municipal system lower than their >> prescribed pressure. >> >> >> >> Typically the 20 psi flow point is provided on hydrant flow tests most of >> the time by extrapolation. If you have that data then determining if the >> pump will draw more than allowed is much simpler. >> >> >> >> >> *Craig L. Prahl* >> Fire Protection Group Lead/SME >> *CH2M* >> 200 Verdae Blvd. >> Greenville, SC 29607 >> Direct - 864.920.7540 >> >> Fax - 864.920.7129 >> >> CH2MHILL Extension 77540 >> [email protected] >> >> >> >> *From:* Sprinklerforum [mailto: >> [email protected]] *On Behalf Of *Zachary >> Siegrist >> *Sent:* Wednesday, May 18, 2016 5:07 PM >> *To:* [email protected] >> *Subject:* Re: Equation for sizing fire pump >> >> >> >> Yes, I was confusing sizing the pump with determining the max capacity >> for the pump. Trying to avoid dropping below 20 psi which has been a >> problem in my jurisdiction. Thank you Brad for your substantive reply. >> On Wednesday, May 18, 2016, Brad Casterline <[email protected]> >> wrote: >> >> Please brush up on NFPA 20. >> >> bc >> >> On May 18, 2016 2:48 PM, "Travis Mack, SET" <[email protected]> wrote: >> >> I think he is trying to get at the max capacity of a pump so that the >> municipal water supply doesn't go below 20 psi. So, if his factor comes to >> a max of 1200 and the system requires a 1500 gpm pump, then a tank is going >> to be required. That is my assumption at least. >> >> Travis Mack, SET >> >> MFP Design, LLC >> >> 2508 E Lodgepole Drive >> >> Gilbert, AZ 85298 >> >> 480-505-9271 >> >> fax: 866-430-6107 >> >> email:[email protected] >> >> >> >> http://www.mfpdesign.com >> >> https://www.facebook.com/pages/MFP-Design-LLC/92218417692 >> >> Send large files to us via: https://www.hightail.com/u/MFPDesign >> >> LinkedIn: https://www.linkedin.com/in/travismack >> >> On 5/18/2016 12:46 PM, [email protected] wrote: >> >> Still not sure what that is supposed to represent or what you’re trying >> to calculate. >> >> >> >> >> *Craig L. Prahl* >> Fire Protection Group Lead/SME >> *CH2M* >> 200 Verdae Blvd. >> Greenville, SC 29607 >> Direct - 864.920.7540 >> >> Fax - 864.920.7129 >> >> CH2MHILL Extension 77540 >> [email protected] >> >> >> >> *From:* Sprinklerforum [ >> mailto:[email protected]] *On Behalf Of *Zachary >> Siegrist >> *Sent:* Wednesday, May 18, 2016 3:42 PM >> *To:* [email protected] >> *Subject:* Re: Equation for sizing fire pump >> >> >> >> Sorry, I am looking at the wrong equation. That equation just ensures I >> have 20 psi available at 159 percent. >> >> On Wednesday, May 18, 2016, <[email protected]> wrote: >> >> What are you supplying with your pump? >> >> >> >> I’m not seeing any correlation between a flow at 20 psi and sizing a >> pump. What flow are you talking about, a municipal flow rate or what? >> >> >> >> If for sprinkler systems, you size the pump based on the characteristics >> of the water supply and the system demands. >> >> >> >> There are ways to get an estimate on pump size but the final selection >> better be verified through hydraulic calculations. >> >> >> >> >> *Craig L. Prahl* >> Fire Protection Group Lead/SME >> *CH2M* >> 200 Verdae Blvd. >> Greenville, SC 29607 >> Direct - 864.920.7540 >> >> Fax - 864.920.7129 >> >> CH2MHILL Extension 77540 >> [email protected] >> >> >> >> *From:* Sprinklerforum [ >> mailto:[email protected]] *On Behalf Of *Zachary >> Siegrist >> *Sent:* Wednesday, May 18, 2016 3:23 PM >> *To:* [email protected] >> *Subject:* Equation for sizing fire pump >> >> >> >> Is there an equation to specify an appropriate pressure when sizing a >> fire pump? For example, when sizing gpm, I've always taken the GPM >> available at 20 psi divided by 1.5 to give me the maximum GPM rating of the >> pump. I'm inquiring to see if such a formula is available to size the >> pressure correctly. Can anyone help? >> >> >> >> Zach Siegrist >> >> >> >> _______________________________________________ >> >> 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 >> >>
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