And the building code may say something to the effect that if you change a sprinkler system, you have to do it in accordance with NFPA #13.
If you look at #13, and you see all the rules for hydraulic calcs, you may come to understand that there is a requirement to Quantify the effect of your changes. Now many systems can be "eyeballed" that, for ex, a shell calc'd to OH 2 as Brian would have done, with a 20' deck and SSU's and a 10 PSI cushion, now being converted with straight drops to LH and 10' ceilings with QR SPs, well likely even a few more heads in the MRA won't hurt when you know that the flow is cut in half, the MRA reduced by up to 40%. This is a "no-brainer". Alas, if you search #13 for "No-brainer" you'll come up as empty as if you were looking for "head". That's because while many of us can look at and analyze these "no-brainers", there's no QC check or certification that states "This enables the bearer to make judgment calls and seat of pants decisions on sprinkler systems without having to go thru al the requirements of the normally required code process." Since there are at least a few people in this industry who SHOULD NOT be making these judgment calls, but because of insufficient self-examination of their won abilities, or perhaps because they have "PE after their names, they ARE making judgment calls they shouldn't. Sometimes when I point out how obvious something is, Ken asks how to prepare a submittal of the obvious without going thru the steps of drawing it up, calc'g it, and submitting what we should have done to Quantify the obvious so the AHJ can agree with us-before I wasted our time discussing how obvious the answer was and we shouldn't have to waste time making a submittal. The answer is simple- if you don't quantify the impact, you can't show how obvious it is that you wouldn't have to do it. glc -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Todd Williams - FPDC Sent: Thursday, February 07, 2008 12:46 PM To: [email protected] Subject: Re: Arm over Calculations It depends on the original hydraulics. Was there an allowance included for future arm overs/drops? If so, then how does that compare? Was the system originally calculated based on 1500 sqft and you could now use 900? What was the original spacing. It comes down to being a judgement. At what point should it be done? If you think that your work will negatively impact the hydraulics, then you should do it. Also, the AHJ/Insurance company may have a say in this? >My question is regarding an existing light hazard system. We are >currently using the 2002 NFPA 13. > >The system was calculated last year when this was a shell space as >light hazard. They are now fitting this space out, and have >submitted plans showing a number of arm overs and some additional >heads to accommodate the layout of the space. > >The question has now come up as to if we should require calculations. > >At what point would you say the calculations were needed for this >type of work? >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > >To Unsubscribe, send an email to:[EMAIL PROTECTED] >(Put the word unsubscribe in the subject field) > > >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > >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://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
