So if the max. velocity is only 2fps there's no issue? Then why the talk of 10fps in the appendix with mention of high velocity and Table relating to 10fps?
If any velocity was acceptable then why not just say it doesn't matter or say nothing at all? 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 Roland Huggins Sent: Wednesday, March 31, 2010 12:51 PM To: [email protected] Subject: Re: Underground flushing velocities The 10 fps applies only to option 2, not all the options. As long as you meet any ONE of the options, where's the beef? The objective is to keep loose objects in the main from potentially blocking the sprinkler system. Option 2 assures us that we will remove the loose objects. The other options assure us that the objects will not reach the system since the maximum possible velocity (being less than 10 ft/s) has removed the objects that will move at system demand (which would be the likely lowest velocity). Option 3 allows us to simply open multiple outlets and let it flow whatever flows without having to prove anything. Roland On Mar 30, 2010, at 1:47 PM, <[email protected]> <[email protected] > wrote: > NFPA 24 says the following: > > NFPA 24: 10.10.2.1.3 The minimum rate of flow shall be not less than > one of the following: > (1) Hydraulically calculated water demand flow rate of the system, > including any hose requirements > (2) Flow necessary to provide a velocity of 10 ft/sec (3.1 m/sec) in > accordance with Table 10.10.2.1.3 > (3) Maximum flow rate available to the system under fire conditions > > > > > > Debate is whether that means that the flow rate dictates the velocity > and it has no absolute requirement or the minimum is 10fps. > > Based on wording in the Appendix it would appear that 10fps is the > desired minimum. > > So for example I have a flow rate of 8000 gpm (fire flow per local > AHJ) and the line size ends up being 24" Vel= 6.74 fps. Is that > acceptable per NFPA 24, 10.10.2.1.3? There are issues with the > distance between source and pump suction and larger pipe equal less > friction loss but also lowers velocities. > > I read it that it can be less than any one of the following with > 10fps being the minimum. Sometimes simpler wording for non-FP > types would make life easier. <sigh> > > Thought, comments, etc????????? > > 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)
