Thanks Burton, I completely agree with you. For Surface fires which grow fast, we should reach extinguishment concentration in 1 minute, but for deep seated fires which don't grow fast, we can reach extinguishment concentration in 2 minutes and can control over pressurization to some extent. But as a designer of a carbon dioxide system for a deep seated fire, in a situation where over pressurization is not a matter of importance, which one do you prefer? 1 Minute or 2 minutes to reach extinguishment concentration? Many thanks for your kind attention, Reza
"Ford, Charles" <[EMAIL PROTECTED]> wrote: Surface fires involving flammable liquids, gases, and solids protected by total flooding do not have a "high" flow rate, [ 1 minute to reach extinguishment concentration] it just a higher rate than deep seated ( 2 Min to reach 30%). My theory is that Surface fires involving flammable liquids, gases, and solids will continue to grow in size or become more difficult to extinguish as time goes on. Re-flash also becomes more likely. Deep seated fires are by definition "not going anywhere soon" and 7 minutes are allowed to reach design concentration. Subfloors don't have the venting problem because they are connected by many holes and vents to the main room. But frankly, I'm uncomfortable with your design concept. I know of NO computer room application where the above floor was protected with a clean agent and the subfloor protected with a different clean agent. I am neither an AHJ nor a PE, but I am a certifier of systems. I wouldn't certify such a system if I ran into it installed somewhere. I would order it tagged "Non-compliant". Burton Ford SET, CFPS Member AFAA [EMAIL PROTECTED] 267-487-1000 Fax 267-487-1010 This e-mail transmission contains information that is intended to be confidential and privileged. If you receive this e-mail and you are not a named addressee you are hereby notified that you are not authorized to read, print, retain, copy or disseminate this communication without the consent of the sender and that doing so is prohibited and may be unlawful. Please reply to the message immediately by informing the sender that the message was misdirected. After replying, please delete and otherwise erase it and any attachments from your computer system. Your assistance in correcting this error is appreciated. Thank you. Cintas Corporation -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Reza Esmaeili Sent: Thursday, August 23, 2007 12:03 PM To: [email protected] Subject: RE: Carbon Dioxide System Discharge Time 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 [EMAIL PROTECTED] wrote: I don't disagree just haven't had any of the sparky/computer types have any warm fuzzies when you speak of wet pipe sprinklers. Usually with reluctance they will accept the pre-action scheme but would rather have nothing with water in the room at all. Then you explain the fact that if there's a fire, the responders will most likely be bringing hoses in and that sometimes gets their attention. In any case these types of situation are always a point of contention mostly due to a lot of misinformation and fables. But can you blame them with all those leaking, false tripping, deluge systems they see on TV? Craig L. Prahl, CET Fire Protection Group Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [EMAIL PROTECTED] http://www.lg.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, August 23, 2007 11:29 AM To: [email protected] Subject: RE: Carbon Dioxide System Discharge Time Craig: I wasn't saying a pre-action sprinkler system instead of a wet pipe system. My preference is a wet system with independent smoke sensors tied to the fire alarm system. The only time I use pre-action is when the owner is the nervous type. Otherwise, the water damage can be greater due to potential operation of more heads due to the operational delay. Regards, James L.(Jim) Roberts, PE, SET Fluor Corporation 100 Fluor Daniel Drive - C104F Greenville, SC 29607 864.281.5149 864.281.4916(Fax) Sent by: [EMAIL PROTECTED] To prinkler.org 08/23/2007 11:07 AM cc Please respond to sprinklerforum Subject RE: Carbon Dioxide System Discharge Time Can the room be occupied at any time either by service personnel or other occasional operators? Typically the answer would be yes as all equipment needs human intervention at some time. What Jim is saying is that a Pre-action sprinkler system would actually be the best choice and the most cost effective with something like FM-200 as the next choice instead of CO2. There are some serious life safety issues you must consider when using CO2 in potentially occupied spaces. Craig L. Prahl, CET Fire Protection Group Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [EMAIL PROTECTED] http://www.lg.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Reza Esmaeili Sent: Thursday, August 23, 2007 10:59 AM To: [email protected] Subject: Re: Carbon Dioxide System Discharge Time Jim, I forgot to explain, the room doesn't have any operators at all, and carbon dioxide is the best choice. Thanks, Reza [EMAIL PROTECTED] wrote: Reza: I would not recommend a CO2 system as it is potentially too dangerous. I would consider a clean agent sytem per NFPA 2001. Hopefully, this is only a back-up to a wet pipe system, which is still my favorite. Regards, James L.(Jim) Roberts, PE, SET Fluor Corporation 100 Fluor Daniel Drive - C104F Greenville, SC 29607 864.281.5149 864.281.4916(Fax) Reza Esmaeili Sent by: To [EMAIL PROTECTED] [email protected] prinkler.org cc 08/23/2007 10:18 AM Please respond to Subject sprinklerforum Carbon Dioxide System Discharge Time Hi all, For designing a total flooding high pressure carbon dioxide system in a 3,500 cubic feet computer room with electrical equipment and cable runs, I have specified my room as "Dry electrical hazard" with flooding factor of 0.083 lb/cubic.feet and 50% design concentration according to NFPA-12. My questions are as below: 1)- Is a computer room fire a deep seated fire? 2)- 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? Many thanks for your help in advance. Reza --------------------------------- Pinpoint customers who are looking for what you sell. _______________________________________________ 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) ------------------------------------------------------------ The information transmitted is intended only for the person or entity to which it is addressed and may contain proprietary, business-confidential and/or privileged material. If you are not the intended recipient of this message you are hereby notified that any use, review, retransmission, dissemination, distribution, reproduction or any action taken in reliance upon this message is prohibited. If you received this in error, please contact the sender and delete the material from any computer. 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