George, True, it can be done without assumptions, although one needs an integral to solve it. The integral is of a type that cannot be calculated, but has to be discovered. It is a lengthy formula and it works for tree type systems only. With the integral it is possible to calculate directly the normal pressure on nozzles, sprinklers and branch lines without "looking" forward at the upstream flow. In 1983 I could prove mathematically that the integral exists. In 1984 I finally discovered the integral. The reason that I was looking for it, was that computers were still very slow at that time, so iteration required a lot of patience.
Incorporating normal pressures in a grid or looped system can still be done by iteration only (= with assumptions), although the assumptions can be estimated automatically. That same year (1984) I used the formula for the first time in hydraulic calculations for a Du Pont de Nemours plant in Holland. Du Pont invited me for engineering purposes to Wilmington, where I also met Mr. Howard W. Packer, member of the NFPA TC for water based systems. At one of those trips I brought my self-built portable computer case, containing a Sinclair ZX81 with a Memorex spreadsheet module (a.o. peripherals). Du Pont had organized a television set to act as computer screen and I had changed the Sinclair from the European PAL output format to NTSC. This configuration allowed us to perform computerized hydraulic calculation of the deluge-systems, incorporating normal pressures in the calculation. The output was printed by a Sinclair printer on an aluminium colored 4 inch wide paper strip. In those days Du Pont also had their first Intergraph computer to make digital process piping layouts. The Intergraph computer was so expensive that they had 3 shifts operating it 24 hours a day. Around 1995 we shared the formula with Kevin Kimmel and Mark Lentocha of FPE Software, who where our business partners at that time. As far as I know FPE never used it. In our office we still use the formula almost every day. It is embedded in a spreadsheet program. We think it is too tricky to embed it in a commercial program, because the user must be very well trained to distinguish in which cases the formula can be used and when not. Actually it works for standard tree type deluge, waterspray and sprinkler systems only. When sold as a program it will probably generate a lot of helpdesk requests. That's why we didn't market it. Today's computers are so fast that it makes hardly any difference if you calculate with iteration (= with assumptions) or single run only using the normal pressure integral. Frans Stoop TOS architecture & fire protection Netherlands <[email protected]> Tel. +31-24-324 0112 At 13:24 23-11-2009 -0500, you wrote: >Actually, I believe a newbie to the industry with a really smart father has >developed a method to NOT make assumptions, but use his formula to simply >plug in your values and go. I believe it will be released soon, once >marketing determines how to make a buck on it. > >Glc > >-----Original Message----- >From: [email protected] >[mailto:[email protected]] On Behalf Of Roland >Huggins >Sent: Monday, November 23, 2009 12:30 PM >To: [email protected] >Subject: Re: Sprinklerforum Digest, Vol 4, Issue 16 > >I did an article on it a long time ago (around the time that NFPA 15 >started requiring it). I'll see if I can put my hands on an >electronic copy and email it to you. > >If memory serves me correctly, the challenging part is noting that you >have to make an initial ASSUMPTION on how much is flowing out of the >sprinkler since the velocity and flow is calculated for the pipe >section upstream from the sprinkler, you then modify your initial >assumption for the final result (like when using the Hardy-Cross >method for calculating multiple loops by hand though it's a bit more >work). > >Roland > >On Nov 22, 2009, at 5:04 PM, Miguel A. Lopez wrote: > > > I am trying to learn how to manually calculate a sprinkler system > > using the > > velocity pressure method for the NICET exam, I took a webminar on the > > subject, but it did not workout for me, I still confuse with the > > method. > > Will someone recommends me a book that will help me? > > Please respond to my E-Mail address [email protected] > > I want to thank you in advance for your time and consideration > > Miguel A. Lopez > > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]] On Behalf Of > > [email protected] > > Sent: Thursday, November 12, 2009 10:20 PM > > To: [email protected] > > Subject: Sprinklerforum Digest, Vol 4, Issue 16 > > > > Send Sprinklerforum mailing list submissions to > > [email protected] > > > > To subscribe or unsubscribe via the World Wide Web, visit > > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > or, via email, send a message with subject or body 'help' to > > [email protected] > > > > You can reach the person managing the list at > > [email protected] > > > > When replying, please edit your Subject line so it is more specific > > than "Re: Contents of Sprinklerforum digest..." > > > > _______________________________________________ > > Sprinklerforum mailing list > > [email protected] > > http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > > > > For Technical Assistance, send an email to: [email protected] > > > > To Unsubscribe, send an email to:[email protected] > > (Put the word unsubscribe in the subject field) > > > >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > >For Technical Assistance, send an email to: [email protected] > >To Unsubscribe, send an email to:[email protected] >(Put the word unsubscribe in the subject field) > >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum > >For Technical Assistance, send an email to: [email protected] > >To Unsubscribe, send an email to:[email protected] >(Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
