An adjustment for lowest tank gradient is not only prudent, sound "engineering", it may stop the N word (negligence) from coming up at trial.
We ask the water purveyor for the tank level during the flow test and the lowest level they reasonably anticipate where the tank low point is, and we adjust the basis of our calculations to that. Naturally a pump fed by this would have the demand satisfying calc be lowered by tank gradient, and if you're up near or above 175 PSI churn, your calc on that would be adjusted UP to the highest tank gradient to reflect reality. Nice double-edged sword for those of us that "split hairs like nobody I've ever seen", to quote an independent designer who know longer works for us. If you're not adjusting for lowest tank gradient on a gravity system, and are aware the level in water company tanks varies, you might want to start doing that adjustment so you don't have the "Aha!" experience in front of the jury. glc -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bobby McCullough Sent: Wednesday, September 23, 2009 3:44 PM To: [email protected] Subject: RE: Safety factor Another consideration is 13 (2007) 23.2.1.2 which says an adjustment to the public water supply shall be made for several conditions. More than one AHJ in the Atlanta area requires the water test be adjusted and the system demand a pound or three below the supply (adjusted). Bobby -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Matthew J. Willis Sent: Wednesday, September 23, 2009 3:03 PM To: [email protected] Subject: RE: Safety factor Not that I have seen. As far as 13 goes, you can design right to the available supply. The different state and jurisdictions most times have a limit in place. R/ Matt Matthew J. Willis, CET Automatic Fire Sprinklers Norred Fire Systems L.L.C. 318-387-1134 Voice 318-387-1163 Facsimile [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Karen Purvis Sent: Wednesday, September 23, 2009 1:47 PM To: [email protected] Subject: Safety factor Can anyone tell me, does NFPA 13 or 14 say anything about a particular safety factor to be used in the hydraulic calculations? Karen Purvis Senior Designer Facility Systems Consultants 713 South Central Street, Suite 101 Knoxville, TN 37902 ph.865-246-0164 fax 865-246-1084 _______________________________________________ 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)
