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 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
