I don't want to beat the horse until it is dead, but as an AHJ, I would have to look at the calc area as possibly not being the most demanding area. And, would likely ask for another hydraulic calculation for proof that all areas of the system are hydraulically proven.
Scenario: Say you have 6 branchlines in the calc area, numbered 1 thru 6 (tree system). One being the farthest from the main and six being the closest. And say you input the exact area of coverage of each sprinkler into your hydraulic program. Now suppose branchline 5 had the sprinkler covering the largest floor area. Argument: I would have to argue that the most demanding area has not been hydraulically proven. The more demanding calc would start with branchline 5 at or near the sprinkler covering the largest floor area. Then, add the six branchlines to your calc, numbers 5 thru 11. Although these branchlines are closer to the riser than the given scenario, this calc would be more demanding because of the over discharge that is introduced in all the pipes of the calc area (extra flow in the pipes, thus extra friction loss in the pipes, thus higher pressure demand). The given scenario of branchlines 1 thru 5 would only have over discharge in branchlines 5 and 6. So, the given scenario would not be the most demanding area and therefore all pipe sizes are not hydraulically proven. I'm not stating you can't do what Roland stated, just that it may not be the most demanding scenario...be cautious! You may need additional calcs to prove the entire system works. So, for the sake of time (and profit), it may be easier to use the maximum coverage of all the sprinklers in the calc area. One and done. Duane Johnson, PE Program Manager Division of the Fire Marshal (Support Contractor) Office of Research Services National Institutes of Health 301-496-0487 "Protecting Science - One Sprinkler at a Time" -----Original Message----- From: Roland Huggins [mailto:[email protected]] Sent: Friday, February 25, 2011 10:15 AM To: [email protected] Subject: Re: As = L x S you do not have to assign the maximum coverage to all the sprinklers in the remote area but use the actual coverage for each one. Roland On Feb 25, 2011, at 6:52 AM, <[email protected]> wrote: > Good morning. > Thanks to all of you for your great answers. > I see this in my first training with AFSA in 2004 (great raining) > but once > you are in the field, you have a lot of questions. > I see a lot of times some designers who use in all cases the maximum > coverage per sprinkler to do their hydraulic calculations, and when > I ask > them about the "As", they tell me that us the maximum coverage > (based on the > hazard classification) is a "Best Practice" because you do not need > to find > what is the largest sprinkler coverage in the hole system. With this > forum, > now I know I always need to use the maximum "As" in my most hydraulic > demanding area, and that value will be used for the calcs. > Regards and thanks to all of you. > > Gerzayn Fuentes > CEPI.mx > Mexico > Tel +52 (81) 17660800 > > > _______________________________________________ > 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)
