>From legal AHJ perspective you must approve. What did your spec's say? If nothing you have to approve. Otherwise enforce the specs.
If your density is 0.15 it might be industrial but not real scary at least in that area. And remember for not scary things there is some appropriate over design in what we normally do. QR heads even some more over design as compared to SR. For the most part (but not all) there is some appropriate over design in H-W. Want to see the effects, do a D-W with the equivalent of a 95 c-factor and about 1000 sq.ft. On the other side is it a straight line approval drawing or did they have extras for field conditions? Might be negative with a few elbows added in the field. Are you sure they have the right elevation? Don't know how many times I saw cheating when they needed a pound or two (to get over the mystical 5). Right pipe type in the field as calc'ed? Another area for mistakes, saw lotsa sched 7 for calc and sched 10 or 40 for the spec compliance. Oh and if he's that on the mark make sure you are in the RA. Move over a bit with 5.6 heads and it might be a different story with overflow in the lines. If every thing is correct I'd approve. Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax Email: [email protected] Mail: P.O. Box 69 Waverly, MN 55390 Location: 4439 Hwy 12 SW Waverly, MN 55390 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Monday, November 30, 2009 2:11 PM To: [email protected] Subject: Calcs-How much margin I've got a calc I'm reviewing, after all said and done, 3.63 psi margin between demand and available. Designer used 4.2K heads to get the flow exactly to the decimal of the required flow. This is an industrial type project. With a .15 gpm/sf density at 92 sf per head, the flow would be 13.8 gpm and he's dead on the money. The concern would be that over the years if there was any change in the water supply or decay of the piping, that the operation of half the design area would be questionable. Would you approve or reject this design? Is this cutting it just a bit close? Craig L. Prahl, CET Fire Protection Specialist Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [email protected] http://www.ch2m.com _______________________________________________ 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)
