No, Larry, actually I didn't miss it at all. I read it quite carefully, and believed that it was a fairly simple statement informing any designer or contractor seeking guidance from the FM data sheets that for fire sprinkler systems the use of velocity pressure calculations wasn't mandated, even though it provided a very well written explanation for how they were to be performed.
I suppose what I missed was how velocity pressure hydraulic calculations had anything to do with limiting velocities in overhead fire sprinkler system piping design, because I, apparently mistakenly, had the belief that the two were unrelated. Since Mike's question dealt with limits on velocities for water in pipes it was my impression that velocity pressure calculations had no bearing on those limits. Now that I know otherwise, I'll be more careful in the responses I make to forum requests and inquiries. I do know that under certain conditions in a fixed waterspray system designed to NFPA-15 standards that velocity pressure calculations are indeed required, or at least they were in the 2007 edition which was applicable on a system I designed last month. I'm reminded every day of how much I still have to learn about our industry, and this is a good example of it. Maybe I need to go back to school instead of teaching. -- 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 Larry Shulman wrote: > -----Forwarded Message----- > >> From: Larry Shulman <[email protected]> >> Sent: Oct 27, 2009 3:42 PM >> To: ParsleyConsulting <[email protected]> >> Subject: Re: FM's Max. Velocity >> >> Ken; FM Global dropped velocity requirements for sprinkler systems a quarter >> century ago. That would explain why DS 2-8N is silent on the topic. >> Remember that DS 2-8N (really FM's footnoted NFPA Standard 13) is just an >> installation standard, and not a design standard. It is weak on explaining >> the concepts on system design. FM's answer to that weakness was the >> development of DS 3-0, which was already in place when I joined FM in 1977 >> and spent 32 years there. >> >> We'll have to await the release of new DS 2-0 soon to see what commentary is >> provided on this subject, but I wouldn't expect any real change. >> >> You might have overlooked the statement "There is no need to use velocity >> pressure in sprinkler system calculations" in the last paragraph of page 39. >> >> -----Original Message----- >> >>> From: ParsleyConsulting <[email protected]> >>> Sent: Oct 27, 2009 3:12 PM >>> To: [email protected], Larry Shulman >>> <[email protected]> >>> Subject: Re: FM's Max. Velocity >>> >>> Larry, >>> >>> I'm not sure everybody has it wrong. I think several people have noted >>> that there are no longer the limits on velocities in risers, overhead >>> mains, and branch lines as there were previously. In looking at the >>> last copy of 2-8N that I have there is no mention of it as well. >>> >>> The information you referred to in 3-0 on page 39 and subsequently in 40 >>> is not by any stretch a rule for velocity in a sprinkler system, but is >>> more appropriately described as a means of performing hydraulic >>> calculations where velocity pressures are taken into account, which is >>> quite a different matter altogether. >>> >>> Those are just my thoughts. >>> -- >>> 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 >>> >>> >>> Larry Shulman wrote: >>> >>>> Well, everybody here has got it wrong so far. The FM Global rules for >>>> velocity in sprinkler systems (there really are none) can be found in Data >>>> Sheet 3-0, near the bottom of page 39. Velocity for fire pumps is 15 >>>> ft/sec and is found in DS 3-7, page 9, and the velocity for underground >>>> mains is 20 ft/sec and is found in DS 3-10, page 8. >>>> >>>> >>>> -----Original Message----- >>>> >>>>> From: Todd Williams <[email protected]> >>>>> Sent: Oct 27, 2009 2:19 PM >>>>> To: [email protected] >>>>> Subject: Re: FM's Max. Velocity >>>>> >>>>> If there is any (and I don't believe so), it is probably 2-8N >>>>> >>>>> >>>>> At 04:00 PM 10/27/2009, you wrote: >>>>> >>>>> >>>>>> Can someone tell which FM Data sheet talks about the max velocity in a >>>>>> wet system? >>>>>> >>>>>> >>>>>> >>>>>> 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 <http://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) >>>>>> >>>>>> >>>>> Todd G. Williams, PE >>>>> Fire Protection Design/Consulting >>>>> Stonington, Connecticut >>>>> www.fpdc.com >>>>> 860.535.2080 >>>>> _______________________________________________ >>>>> 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)
