I don't know what you mean...PE's are the coolest! Matt Grisé PE*, LEED AP Sales Engineer Alliance Fire Protection *Licensed in KS & MO
913.888.0647 ph 913.888.0618 f 913.927.0222 cell www. AFPsprink.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of George Church Sent: Monday, November 30, 2009 4:04 PM To: [email protected] Subject: RE: Calcs-How much margin Some day maybe I'll see if I can cut and paste what a PE around here required. I haven't been able to figure it out, it was easier to not bid their work. I do know it had nice things like: No field-installed offsets without revised calcs submitted and approved. (Know how well that works with virtually any schedule?) Adjust C factors to like 85 for dry black steel, 100 for wet steel- cause evidently the rest of us don't know jack. A description of how to knock 10, 15, 20% from the flowtest that leaves me (and others here) scratching our heads on how to actually do what they ask (as in 15% of what- flow? Pressure? Static? Residual? Everything?) Plus after adjusting the C factors, you can no longer discuss the cushion with anyone else (insur AHJ, local AHJ) intelligently since the c-factors are set more appropriately to a more conservative setting (we'd call it FULL ANAL RETENTIVE) in case the pipe ages quicker than we expect. glc -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Matt Grise Sent: Monday, November 30, 2009 4:04 PM To: '[email protected]' Subject: RE: Calcs-How much margin I have to agree that all questions of water supply aside, 8.3.4.1 seems pretty clear that k4.2 sprinks cannot be used in anything except light hazard occupancy. Supposing they had used the proper heads...I would reject on the basis that they tested a water main that does not feed the building. It seems like they may have just fudged the placement a little in order to suggest that they probably might have water similar to what was tested. Supposing they had the right heads and had tested the right line...I would approve. Especially if they have knocked 10% off already. The reason that there is a cut-off is because you have to be able to say yes or no at some point. Obviously more safety is more better, but we can't all drive around in tanks wearing football helmets. My understanding is that the 10% number is just one that was picked out of thin air as something that people are generally ok with. I see specs call for 10% psi, or 10psi, or 20 (both ways). There are some jurisdictions around here that tried to push 30% for a while. Matt Grisé PE*, LEED AP Sales Engineer Alliance Fire Protection *Licensed in KS & MO 913.888.0647 ph 913.888.0618 f 913.927.0222 cell www. AFPsprink.com -----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) _______________________________________________ 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)
