Using 11.2.3.4.3 is the answer for calculating the grease duct sprinklers. Spacings and locations per Chapter 7 using K-factors of 1.4 - 5.6 and minimum end head pressure of 7psi. Keep the amount of water in the duct to a reasonable amount. A 5.6K head in a 12" dia duct is overkill.
Remember drainage of the duct is up to the mechanical engineer/contractor. The sprinkler designer needs to inform them of the potential amount but how it's drained is their issue. NFPA 13, 2007, Figure A.7.10.2 gives a good illustration of heads within the duct system. 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 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Parsley Consulting Sent: Monday, January 26, 2009 11:48 AM To: [email protected] Subject: Re: Calculating sprinklers in horizontal grease ducts Ron, How about this, from the 2007 edition of NFPA-13? 11.2.3.4 Special Design Areas. 11.2.3.4.1 Where the design area consists of a building service chute supplied by a separate riser, the maximum number of sprinklers that needs to be calculated is three each with a minimum discharge of 15 gpm (57 L/min). 11.2.3.4.2* Where an area is to be protected by a single line of sprinklers, the design area shall include all sprinklers on the line up to a maximum of seven. 11.2.3.4.3 Sprinklers in ducts as described in Section 7.10 and 8.15.12 shall be hydraulically designed to provide a discharge pressure of not less than 7 psi (0.5 bar) at each sprinkler with all sprinklers within the duct flowing. I'm not sure, but I think at least some of that applies to what you're describing. PARSLEY CONSULTING Ken Wagoner, SET 760.745.6181 voice 760.745.0537 fax [email protected] <mailto:[email protected]> e-mail www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website _______________________________________________ Sprinklerforum mailing list http://lists.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 http://lists.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)
