Judging the lack of response to your question I don’t think anyone else wants to tackle it. I’m modifying my response and responding back through the forum in hopes of stimulating interest.
On the surface it doesn't feel good. I am confused about the airflow described. It seems that the supply air is ducted from an HVAC unit in the room to the underfloor area, passing through the floor openings into the room, through openings in the ceiling, with return air ducted from the ceiling back to the HVAC unit. There are area-type smoke detectors on the ceiling. I am not sure about the detectors under the floor. By your words “duct-type smoke detectors” these may be only in the supply duct or ducts in the underfloor. Both the space above the ceiling and the underfloor space will have high air velocities. Smoke from a fire in the overhead will be diluted by the airflow. It may be deleted further by makeup air at the HVAC unit. The diluted smoke will pass one or more of the underfloor duct detectors. Also, if a fire were to occur when the air system is down, there would be no detector protection of the overhead or underfloor. This means the preaction system would not discharge water until smoke migrated to a detector. It is unlikely that the performance of the smoke detectors would meet the expectations of the owner. I am somewhat notorious for saying, “The damn system won’t work”. In this case it depends on the expectations. If the ONLY task of the smoke detection is to provide the “trigger” to permit the preaction valve to open when a sprinkler operates (and the HVAC system is operating), the system should do its job. If the system is to provide early warning to limit fire and smoke damage, it will not accomplish that. There are holes in the floor to bring air into the room through equipment. If there is a detector by each of these holes, smoke in the underfloor should be detected appropriately. If smoke detectors in the underfloor are space as they are for normal room protection, it is likely that smoke can travel from the underfloor without passing a detector. Ceiling area-type detectors will be looking at diluted smoke. Hopefully these detectors are present at each return grille. This seems to be an area which would best be served by an air aspirating system. Hopefully too, the air handling system is shut down when smoke causes an alarm. This so the sprinklers will have a chance to operate sooner. I’m not sure what your “Certification” is supposed to represent, but if it is to include some assurance the system will do its job, I think this one would not. Even adding area-type smoke detectors would not be much of an improvement. So what is the goal? Without a goal there can’t be valid tests. On Mon, Apr 6, 2015 at 6:18 AM, Charles G Key <[email protected]> wrote: > Greetings, I have a project with an It room that has sprinklers below the > raised floor, in the ceiling and above the ceiling. This is a double > interlock system and they have installed detectors below the floor and in > the ceiling. They are stating that the detection for the area above the > ceiling is in the duct detectors below the floor.(supply). Since I am asked > to certify the system, does anyone have an idea on the proper method to > test > the detectors for the above ceiling area? I could set off a smoke bomb > above > the ceiling, but how much smoke should it take? Ideas? > > > > C.Gregg Key SET > Key Fire Protection Enterprises,LLC > 3200 Mike Padgett Hwy. > Augusta, GA. 30906 > 706-790-3473 Office > 706-738-2119 Facsimile > 706-220-8821 Mobile > [email protected] > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > -- Ed Vining 4819 John Muir Rd Martinez CA 94553 925-228-8792 Cell 925-787-0465 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
