Never mind - I finally go tin the office to read the table - they would have had to go .15 / 4,000 sq ft to use the chart....I dont know how they came up with this one. I am putting back in the AHJS hands
On Mon, Jul 1, 2013 at 6:58 AM, Greg McGahan <[email protected]> wrote: > Let me start OVER..... > > We have been asked to correct an overspacing problem in an existing > building by the local AHJ.... > > The existing calc plate indicates the original system - which was > installed for Retail Store 16 years ago - was calculated with 14.5 k heads > at .15 / 1,500 sq ft......We can re-create the calcs using this info and > duplicate the results on the plate almost exactly. HOWEVER, if we try to > calc it using .20 / 2,000 the system does not work AS IS CURRENTLY > INSTALLED WITH NO MODIFICATIONS.... > > If we add a row of sprinklers across the system - one head on each line , > or feeding the additional heads from adjacent branchlines, the calcs will > work @ .15/2,000. Since they did not work at .20 on the original system, > adding heads gets us even further away if we try the .20........ > > > The question is - Is there any precedence, NFPA #13 reference, or sound > judgement in using the current sprinklers we can buy - which have > specifically listed flows by OCCUPANCY - in conjunction with density, at > the lower density to avoid a MAJOR revamping of the existing system in > order to add these heads? Please understand my logic....If the answer is a > flat NO, and the owner moves or removes the new wall he installed so that > there is not an overspacing issue - the system is STILL only calcs at the > .15 / 2,000. So I do not see how we could possibly be harming the > effectiveness of the system by adding additional sprinklers using the > current design criteria. I DO understand that we would be stepping outside > of the the NEW or CURRENT head listings. To m y knowledge there is not a > 14k head available that is listed with the lower density but larger remote > area..... > > What other options are there but to reduce the spacing by adding several > branchlines and heads between existing heads throughout the entire space? > > > Greg > > > On Mon, Jul 1, 2013 at 5:58 AM, Johnson, Duane (NIH/OD/ORS) [C] < > [email protected]> wrote: > >> Try reconfiguring to 18x18 to start with a lower end head pressure. Then >> you can take the QR reduction if necessary too. Look at the friction loss >> per ft to identify troublesome segments of pipe that could be upsized. >> >> Duane Johnson, PE >> Program Manager >> Division of the Fire Marshal (Contractor) >> Office of Research Services >> National Institutes of Health >> 301-496-0487 >> >> "Protecting Science - One Sprinkler at a Time" >> >> -----Original Message----- >> From: Greg McGahan [mailto:[email protected]] >> Sent: Saturday, June 29, 2013 11:17 PM >> To: [email protected] >> Cc: Bobby Gillett >> Subject: Modifications to system with existing ECOH sprinklers >> >> Hello, >> >> We have an existing system installed 20 x 20 with 14.5K ECOH sprinklers. >> They have now installed a new wall separating the space into 2 spaces and >> left the sprinklers overspaced off the wall. The Calc plate indicates that >> the design was originally .15 fpm over 2,000 soft and when we re-calc the >> system we are nearly identical to the results recorded on the data plate. >> If we calculate it at .20/1,500 it does not work. >> >> Question is how to we even begin to sort this out in order to add a row >> of new heads to correct the overspacing? The new sprinklers all seem to be >> specifically listed for .20 (OH2) and i do not see a loophole to utilize a >> lower density and a larger Remote Area as in the original design. I also do >> not see an allowance in 13 for such a scenario (similar to the allowance >> for modifications to existing systems with residential heads that were >> originally designed for less than 7 psi end head pressure) >> >> I do not think there will be any salvaging this system if we cannot >> reduce the density... >> >> Thanks for any help, >> Greg >> >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org >> > > > > -- > Greg McGahan > Living Water Fire Protection, LLC <http://www.livingwaterfp.com> > 1160 McKenzie Road > Cantonment, FL 32533 > 850-937-1850 > fax 850-937-1852 > -- Greg McGahan Living Water Fire Protection, LLC <http://www.livingwaterfp.com> 1160 McKenzie Road Cantonment, FL 32533 850-937-1850 fax 850-937-1852 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
