FM put into Data Sheet 2-8N the maximum in sprinkler piping of 16, 20 and 22 ft/sec in the early 1970's. This restriction was put into place when the use of wet grid system started. The maximum velocities were used to assure that the sprinkler heads on the small pipes would operate as design. Standard heads can mist if the pressure was too great. One way to keep the pressures down when the first few heads operate is to restrict the velocities by requiring the use of larger piping systems. By the late 1970's, FM added a requirement that the first number of operating heads on a system could only see a pressure of noted pressure for 1/2 inch and large orifice heads. This requirement was issued as a Technical Advisory Bulletin. This requirement never made it into FM Data Sheet 2-8N. The restriction related to velocities has been removed from Data Sheet 2-8N.
Dale Eggen, PE Bechtel National INC Richland, WA 509-371-3240 (Former Chief District Engineer) -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brown, Mike Sent: Wednesday, October 28, 2009 3:19 AM To: [email protected] Subject: RE: Fw: Re: FM's Max. Velocity I talked with a FM rep yesterday and he said "we no longer have the maximum 20 fps like we used to have for grids. Now, it is whatever NFPA codes advise." Thanks for everyone's help. Mike Brown Project Designer Sunland Fire Protection 1218 Elon Place High Point, NC 27263 Ph. 336.886.7027 Ext. 140 Fax: 336.886.7024 WWW.SUNLANDFIRE.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)
