For a new install there is nothing to find, the designer controls where the most demanding area occurs.
Ron Fletcher Aero Automatic Phoenix, AZ -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Roland Huggins Sent: Friday, February 25, 2011 11:31 AM To: [email protected] Subject: Re: As = L x S the trick is picking the most demanding hydraulically remote area (with each sprinkler assigned their actual area of coverage). When the system is not nice and symmetrical, one may need to look at more than one possible remote area. Bottom line is if the location of the hydraulically most remote area is not apparent, you need to be able to show the AHJ why your selection is right. Roland On Feb 25, 2011, at 9:45 AM, Johnson, Duane (NIH/OD/ORS) [C] wrote: > 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 _______________________________________________ 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)
