If there may be folks trapped in a building they're spraying, they aren't going to worry about the suction pressure so much as the life in the window.
And we sure don't want that debris to end up at the next reducing coupling or blocking a riser nipple/drop/orifice, etc. Worst part is that the flow is all moving toward where the open heads are, so debris is heading right to where it'll interrupt flow, and be swept along to block whatever size it is. Anything that is larger than your system's orifi will block at least one. glc -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Law, Kevin W Sent: Tuesday, March 30, 2010 5:44 PM To: sprinklerforum@firesprinkler.org Subject: RE: Underground flushing velocities We had a problem with our construction group wanting to allow a lower flow than the 10ft/s velocity in the lines saying that it was the maximum the system would flow, but they were only opening a single hydrant. We insisted and finally got them to get more hose monsters and flowed more hydrants to get a proper flush on the underground piping. The wording about the maximum is so that if you have a system that will flow 20ft/s in the line, then that is the rate you flush at to ensure that anything that could break loose and jamb up a sprinkler system has worked its way throught and out of the system and not during a fire when you need it. When the fire department is there and they need more water they are going to get it if it is to be had. Kevin Law, PE Bechtel National, Inc. Waste Treatment Project Fire Protection Engineering Work (509) 371-3280 Cell (509) 531-5715 -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Thom McMahon Sent: Tuesday, March 30, 2010 2:16 PM To: sprinklerforum@firesprinkler.org Subject: RE: Underground flushing velocities I think what #3 is saying is that let's say you have a 6" underground, but reduce at the riser to 3" because that is all of the system demand you have, you can flow a 3" open outlet at the riser to flush the underground, and that is equal to the maximum flow rate available to the system under fire conditions. It will create the maximum velocity in the underground pipe that that pipe will ever see, unless it breaks while it's still 6" or the system is altered and the riser increased in size. Thom McMahon, SET Firetech, Inc. 2560 Copper Ridge Dr P.O. Box 882136 Steamboat Springs, CO 80488 Tel: 970-879-7952 Fax: 970-879-7926 Subject: Underground flushing velocities NFPA 24 says the following: (3) Maximum flow rate available to the system under fire conditions _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: supp...@firesprinkler.org To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: supp...@firesprinkler.org To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: supp...@firesprinkler.org To Unsubscribe, send an email to:sprinklerforum-requ...@firesprinkler.org (Put the word unsubscribe in the subject field)
