Frans: Your reply is an excellent description of the CO2/clean agent/preaction sprinkler system topic. Great detail!!! The CO2 system and use issue is a hot topic with the Environmental Protection Agency, and their input has been an important part of the current NFPA 12 CO2 standard where all sorts of ramifications and stipulations are required to be in place when CO2 is used. For computer room hazards, other clean agents can be used, i.e. Ecaro-25, FM200, Inergen, etc.
In addition, since the upgrade of the NFPA 12 CO2 standard, my firm has seen an increase in the number of preaction sprinkler systems being installed, both new and renovated. Just my 2 cents. Loren R. Johnson - CFPS, CET Fire Protection Systems Consultant Marquette Heights, IL --- Frans Stoop <[EMAIL PROTECTED]> wrote: > Reza, > > Most subfloors in computer rooms that I know of, are > not only used > for cable runs and some equipment, but also for > cooling the equipment > cabinets on top of the floor by ventilation. For > that purpose the > equipment cabinets in the room are placed over > relatively large > venting holes in the subfloor, thus allowing cool > air from under the > floor to be blown up through the cabinets and leave > through grilles > in the sides or top of the cabinets. The warm air in > the room is > sucked in by air-cool units and discharged > underneath the subfloor, > thus recirculating the air through the room. > > Because of all these holes, the space under the > subfloor and in the > room above have to be considered as one continuum. > If you discharges CO2 under the subfloor, it will > inevitably spread > equally above the subfloor as well and within only a > few minutes the > concentration above the subfloor is the same as > below. For that > reason you have to design your CO2 system for the > whole space, below > + above the subfloor. > > Unless of course, the subfloor is not used for > ventilation and you > are sure that there are no holes in the subfloor, > not even under the > footprint of all the above floor cabinets. > > I agree with al those responders on the forum that > recommend not to > use CO2 for a computer room at all, because of > personnel safety. If > you must use a gaseous protection system, use FM200 > or an inertizing > agent and apply it to the whole room, including > below the subfloor. > The emergency response people will be grateful. > Besides that, many fires start while electricians or > other workers > are making modifications. In other words, when there > are people > present in the room of origin. > > An additional way of protection which might please > your client is by > installing an early warning system with smoke > aspiration detectors. > Client should organize a good emergency response > plan to respond to > such early fire alarm and excersize this regularly. > Provide mobile > CO2 extinguishers which enables the emergency > response people to > manually suppress a starting fire in an early stage > without leaving > any traces. Also, hang one of those special keys to > lift the tiles of > the sub-floor near to each cluster of mobile > extinguishers. The > response people will need it to investigate the > space underneath the subfloor. > > And beyond that, don't forget to install a wet pipe > or pre-action > sprinkler system that will at least reduce the > damage when other > suppression systems fail. Manual suppression might > fail because the > response people do not respond or decide that they > "don't see any > fire". Automatic suppression by extinguishing gas > did sometimes fail > because response people (even fire fighters) opened > the door to the > room too soon, thus allowing fresh air to flow in > and re-ignite the > fire. If the manual response to the early warning is > in due time and > adequate, the temperature in the room will never > rise to a level > where it could trigger a sprinkler. If the response > fails, the > owner/user might be gratefull to you that the > sprinklers confined the fire. > > However, that is how we recommend it. More > experienced owner/users > allow to leave out the gaseous flooding systems: > only early warning > with manual suppression in combination with a wet > pipe or pre-action > sprinkler system. > > Frans Stoop > TOS architecture & fire protection > Netherlands <[EMAIL PROTECTED]> > > At 09:02 2007-08-23 -0700, you wrote: > >Thanks All, > > Ford, if the intent of slow flow rate for deep > seated fires is > > preventing over pressurization, so why NFPA-12 > suggest high flow > > rate for Surface fires involving flammable > liquids, gases, and solids? > > NFpa12 States that "Surface fires are the most > common hazard > > particularly adaptable to extinguishment by total > flooding systems. > > They are subject to prompt extinguishment when > carbon dioxide is > > quickly introduced into the enclosure in > sufficient quantity to > > overcome leakage and provide an extinguishing > concentration for the > > particular materials involved." > > > > NFpa12 also States that "For deep-seated fires, > the required > > extinguishing concentration shall be maintained > for a sufficient > > period of time to allow the smoldering to be > extinguished and the > > material to cool to a point at which reignition > will not occur when > > the inert atmosphere is dissipated." > > > > I think I explained at first in a bad manner. > There are two protected area. > > 1- Computer room: would be protected with FM-200 > system > > 2- Computer room subfloor with electrical > equipment and cable > > runs: would be protected with high pressure carbon > dioxide system. > > My question is about subfloor, while NFPA 12 > states that "For > > deep-seated fires, the design concentration shall > be achieved > > within 7 minutes, but the rate shall be not less > than that required > > to develop a concentration of 30 percent in 2 > minutes." Is it a > > problem if the total discharge time would be only > 1 minute for this case? > > Thanks, > > Reza > > _______________________________________________ > 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) > ____________________________________________________________________________________ Moody friends. Drama queens. Your life? Nope! - their life, your story. Play Sims Stories at Yahoo! Games. http://sims.yahoo.com/ _______________________________________________ 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)
