So I'll jump in before Roland pops a vein...... Logical consistency would suggest that a simpler process that provided built in safety and additional protection would be the process of choice. Calculations using Pn are more complex and less conservative. There is no such thing as pure calculations regarding fire sprinkler systems. One may choose to apply as many variables as one wishes, but with fluctuating values for those variables, there can be no pure calculation. Therefore, consistency requires our use of the simpler and more conservative approach. I'd call it elegant.
It should be recognized that the above is my opinion as a member of the NFPA, and has not been processed as a formal interpretation in accordance with the NFPA Regulations Governing Committee Projects and should therefore not be considered, nor relied upon, as the official position of the the NFPA, nor any of their technical committees. Sincerely, Cecil Bilbo Academy of Fire Sprinkler Technology Champaign, IL 217.607.0325 www.sprinkleracademy.com [email protected] OUR STUDENTS SAVE LIVES!! > From: [email protected] > To: [email protected] > Subject: RE: Suggestion for new definition in NFPA #13- Operating Pressure. > Date: Fri, 24 Apr 2015 11:16:54 -0500 > > Thanks Roland, but instead of additional complexity I would call it logical > consistency, along the lines of: > > "Where Minimum Operating Pressure is used in this standard, it shall mean > the calculated normal pressure, Pn, at the sprinkler". > > just a suggestion that might appeal to the "Calculation Procedures purists" > in a lot of us!!! > > Brad > > -----Original Message----- > From: Sprinklerforum [mailto:[email protected]] > On Behalf Of Roland Huggins > Sent: Friday, April 24, 2015 11:00 AM > To: [email protected] > Subject: Re: Suggestion for new definition in NFPA #13- Operating Pressure. > > Since other than NFPA 15 systems, virtually NO ONE applies Pv so why add the > additional complexity. This is especially true with Pt being a MORE > conservative approach. > > > Roland Huggins, PE - VP Engineering > American Fire Sprinkler Assn. --- Fire Sprinklers Saves Lives > Dallas, TX > http://www.firesprinkler.org <http://www.firesprinkler.org/> > > > > > > > On Apr 24, 2015, at 8:11 AM, Brad Casterline <[email protected]> > wrote: > > > > Working pressure is defined, and used in a few places in the text. > Operating > > Pressure is not defined but is used extensively and is obviously meant to > be > > used to calculate the discharge rate of sprinkler heads. According to > > Webster's, Working and Operating are synonymous, but this results in a > > problem where ~minimum operating pressure (for sprinklers) shall be 7 > psi~, > > due to the "2nd head phenomena", where the Pv between the end and 2nd > heads > > exceeds the Pf, making Pn at the 2nd head less than 7 psi. Since only the > Pn > > produces flow at the 2nd head we are "allowed" to subtract Pv. > > > > > > > > So the suggestion for the definition of Operating Pressure regarding > > sprinkler discharge is to specify minimum Pn shall be 7 psi. > > > > > > > > Just wanted to get that off my chest. > > > > > > > > thanks, > > > > > > > > > > > > Brad Casterline, NICET IV > > > > Fire Protection Division > > > > > > > > FSC, Inc. > > > > P: 913-722-3473 > > > > [email protected] > > > > www.fsc-inc.com > > > > > > > > Engineering Solutions for the Built Environment > > > > > > > > _______________________________________________ > > 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 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
