Sounds like you're in pretty good shape from an information standpoint. So if you've already gotten the foam mfgr. to help determine densities, (not straight NFPA 30 densities hopefully) then how about just giving him a call and ask about the P.G.? I'm sure the PG system is cheaper as long as it's maintained and setup properly. That's where the gamble lies.
Now the point to consider is that once a sprinkler fuses, the PG will be released at that point followed by water, but what is not known is how PG from the system will migrate to the discharge point and eventually mix with the discharging foam. Since there's no foam in the system until you have a discharge, you may dilute what is present in the system enough to where it's not an issue at all. But remember, there have been discussions here about glycol based systems discharging onto heaters and other instances where the glycol has become a fuel to the fire upon initial discharge. All my design guides point to preaction for areas subject to freezing and for wet systems say initial fill to be water. Couldn't find any support anywhere for Glycol in foam systems. Craig L. Prahl, CET Fire Protection Specialist 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.ch2m.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mark Sornsin Sent: Monday, July 06, 2009 12:12 PM To: '[email protected]' Subject: RE: NFPA 30 - and Propylene Glycol We've got all the MSDS; all of the liquids classifications and we know the densities required. This issue is limited to the use of Prop glycol antifreeze on a 'wet' AFFF sprinkler system for flammable liquids storage. (FYI - The liquids range in classification from IB to IIIB, many miscibles, and both poly and metal drums - all 55 gal. drums on end, up to two high). PG doesn't seem wise unless someone (manufacturer) can prove to me it is compatible with the AFFF in the pipes; AND that there isn't an adverse affect from dumping PG on the flammable liquids fire prior to the foam. It's use over preaction is based on cost, according to the contractor. Don't yet know if they have the means included to fully drain the PG every year for testing and refill. Mark -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Monday, July 06, 2009 7:40 AM To: [email protected] Subject: RE: NFPA 30 - and Propylene Glycol Uh, no. If there is a problem with freezing they can use a single interlock preaction foam-water system. You don't mix P.G. in it, that won't work. The preaction conforms to NFPA 30, dry systems are not permitted. Now before anyone starts anything, there needs to be an analysis of the chemicals being stored to determine the appropriate design criteria for protection of the area. Just because he's storing flammables doesn't mean you automatically go to AFFF, you may need AR-AFFF or some other means of suppression may be acceptable. I've found that most people don't know the difference between flammable and combustibles and there is a difference when determining protection schemes. Plus the density depends on the chemicals being stored. There's no magic number you can just plug in. Get ALL the MSDS info on everything in the storage area. Don't just ask for or get the "flammables". Get everything. There are code issues at hand concerning how much of certain chemicals can be stored inside Once you've determined what the chemicals are, their classifications, quantities, etc. then you can check codes to determine whether he can actually store them inside or not, if anything needs to be done to the building or if they can store without any changes. Then contact your favorite foam vendor and have their chemist look at the chemicals you're dealing with and give you a recommendation on protection. MSDS info is invaluable but don't rely on just one mfgr. Get a copy of the chemicals from a couple of different suppliers since information on MSDS can vary in it's completeness. These things will also give you recommendations for fire fighting measures and warn if something is reactive or if something special is needed. Someone has a lot of homework to do. Craig L. Prahl, CET Fire Protection Specialist 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.ch2m.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mark Sornsin Sent: Thursday, July 02, 2009 4:11 PM To: '[email protected]' Subject: NFPA 30 - and Propylene Glycol Forum: I have a client who wants to store flammable liquids in a cold-storage warehouse. They would like to use an AFFF sprinkler system with propylene glycol to prevent freezing. I am not a fan of this idea and won't support it for a number of reasons. Do any of you have any views you'd like to share on this matter? Mark A. Sornsin, PE Fire Protection Engineer Ulteig Engineers, Inc. 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