Todd: We've had to deal with this problem a number of times, as well. From a code standpoint, NFPA 20 (2007) 5.6.5 seems to indicate to me that a public water supply must be capable of supplying 150% of the rated capacity of the fire pump. Note that this section does not say, however, that you must use the design-basis water supply curve to justify compliance. Therefore, if the raw flow test results (as opposed to the design-basis water supply data--which accounts for maximum day water system demands, pressure fluctuations, etc.) indicate you can achieve the required flow at 20 psi, then you can make the case that the water supply is, in fact, capable of supplying the required flow, just maybe not all the time (i.e., during periods of peak demands). This has worked in several jurisdictions for us. However, it appears from the data you provided that you'd need a 30 psi increase in overall system pressure just to be able to hit 3,000 gpm at 20 psi--which may not be an option.
Another option is if you can show that a 1,500 gpm pump will work, but you just want to use the 2,000 gpm pump because of the better hydraulics, the AHJ may be willing to approve a variance (or code modification) request using this as your justification. Other points that you can use to support your case include the benefits of the ESFR suppression technology over other (minimum code compliant) control-mode sprinkler options. Good luck!// DCH ___________________ Dale C. Hansen, P.E. Principal/ Senior Fire Protection Engineer (770) 564-3505 x.34 (770) 564-3509 Fax [email protected] www.hgi-fire.com -----Original Message----- From: Ralphy Henderson [mailto:[email protected]] Sent: Friday, August 28, 2009 2:00 PM To: [email protected] Subject: Re: lack of suction volume But can NFPA 25 be invoked since this is a new fire pump going in and not an existing one? --- On Fri, 8/28/09, Michael O'Brian <[email protected]> wrote: From: Michael O'Brian <[email protected]> Subject: Re: lack of suction volume To: "[email protected]" <[email protected]> Date: Friday, August 28, 2009, 5:54 PM Todd One that comes to mind was an old warehouse that the fm found with inadequate sprinkler density for plastic storage The incoming water could not flow 150% so it was tested to 100 % and the insurance was okay, the fm just wanted to make sure he could fall back on code. Case was made on options and why 150 couldn't be achieved Michael O'Brian Code Savvy Consultants www.codesavvyconsultamts.com www.inspector911.com Office: 313-618-6401 Cell: 810-459-0116 On Aug 28, 2009, at 1:27 PM, Todd Williams <[email protected]> wrote: > I am working on a warehouse which presently has very inadequate > protection. One of the improvements needed is a fire pump. I have two > options: a 1500 at 95 or a 2000 at 80. We can't go over the 95 psi or > we end up with a churn pressure over 175 psi. However, the flow drops > to 20 psi at 2400 gpm. The ESFR system I am recommending requires > about 1950 gpm, including hose streams (the fire pump will have to > supply hose streams as well). I want to use the 2000 gpm pump because > it gives me better hydraulics, however, I can't test to 150% flow. > NFPA 25 says "If available suction supplies do not allow flowing of > 150 percent of the rated pump capacity, the fire pump shall be > permitted to operate at maximum allowable discharge." Has anyone > successfully presented this to an insurance company and Fire Marshal > on a new installation and got them to go along? Any hints on how to > present it? > > 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 _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum The mail servers at Harrington Group, Inc. do not accept messages containing unsolicited advertising, or executable attachments. To improve deliverability, large attachments should be converted to zip format. Unencrypted e-mail is not transmitted securely and may not always be authentic. If you have doubts as to the authenticity of this e-mail, or have received it in error, please contact the sender and delete this message. The information in this e-mail is intended solely for the addressee and may contain confidential and/or legally privileged information. Please consider the impact of printing this e-mail on our environment. _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
