Chris, I see your point about "OMG..."! I was not trying to do anything elaborate, and the conclusions for the post had been arrived at-- still I wondered about worst case activation time difference (only). I suppose I should have kept it to myself. I found the HRR that would be just enough to activate a 286 SR at 9" below a 27' ceiling in about 180 seconds (my benchmark). This was about 1 Megawatt, very low, and it produces the greatest activation time difference (using my benchmark, in my model). If I used a 2 MW fire, not only would the activation times be less, but so would the activation time differences (I am going to put numbers to it tonight after work). Duane, nice bit about the condensation- it makes sense- the water returns the heat it soaked up in being vaporized! Another complication for 'sprinkler skipping'. I will get off this thread now.
-----Original Message----- From: Johnson, Duane (NIH/OD/ORS) [C] [mailto:johnson...@mail.nih.gov] Sent: Monday, October 01, 2012 8:28 AM To: sprinklerforum@firesprinkler.org Subject: RE: Sprinkler head Temperature requirement Yes, keep the overall picture in mind. RTI is only one aspect. As others have said, as more sprinklers operate, the discharge density decreases. Why activate additional sprinklers and decrease the density if it is not necessary? One more piece of info for high heat release rate fires and the use of high temp sprinklers. The water discharged from the sprinklers can be returned to the ceiling as steam. The steam can condense on sprinklers outside the fire area and activate the sprinklers (see commentary for 8.3.2.4). Once again, it can be detrimental to the system design to activate sprinklers outside the fire area. This is one reason why intermediate and high temp sprinklers are used in storage apps. 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: Cahill, Christopher [mailto:ccah...@burnsmcd.com] Sent: Monday, October 01, 2012 8:13 AM To: sprinklerforum@firesprinkler.org Subject: RE: Sprinkler head Temperature requirement And so???? Response time difference is only one factor to consider. Many would draw the conclusion 'OMG 100 seconds difference but what about the children'. Just because the first sprinkler operates later has NO direct singular correlation to the outcome. This is WHY we use higher temperature heads in high heat release heat fires - in order to keep the wet stuff on the red stuff (or at least real close factoring in plume dynamics). So the potential here is possibly BETTER fire protection performance because although delayed fewer heads operate thus more water where it's needed. Be careful in drawing any conclusions when only doing part of an analysis. I realize you are not intending your FDS model to be the conclusion of this discussion but you, Ron and I are not the only ones reading this forum. (PS anyone know how many subscribers these days?) Chris Cahill, PE* Senior Fire Protection Engineer, Aviation & Facilities Group Burns & McDonnell 8201 Norman Center Drive Bloomington, MN 55437 Phone: 952.656.3652 Fax: 952.229.2923 ccah...@burnsmcd.com www.burnsmcd.com Proud to be one of FORTUNE's 100 Best Companies to Work For *Registered in: MN -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of bcasterl...@fsc-inc.com Sent: Sunday, September 30, 2012 11:07 AM To: sprinklerforum@firesprinkler.org Subject: Re: Sprinkler head Temperature requirement all i got is some numbers: 27' ceiling height, 9" deflector distance, couch on fire in the middle of a large, open furniture showroom--- 286F, standard response- activation time = 188 seconds 286F, quick response- activation time = 172 seconds 212F, standard response- activation time = 97 seconds 212F, quick response- activation time = 80 seconds (details available upon request) regards, Anyone...? :) _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
