Fire extinguishers

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Author Message David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 313 Registered: 03-2002 Posted on Friday, July 30, 2004 - 05:28 pm:    An architect told me that I don't have to specify the weight of the fire extinguisher just the designation (2A-10BC). Is this true? I know that what the letter designations (A, B, C, D &K) mean, but what does the numerals (2, 10, etc.) mean? Yes I did look in NFPA 10 but could not find it. Dave Metzger Senior Member Username: davemetzger Post Number: 85 Registered: 07-2001 Posted on Friday, July 30, 2004 - 05:46 pm:    The number is a rating that indicates the relative extinguishing effectiveness. This is applicable only for Class A and B fires; Class C, Class D, and Class K fires are not required to have a numeral precede the classification letter. While this number is related to the capacity of the extinguisher, it is not necessarily a unique one-to-one relationship. For example, for multi-purpose dry chemical extinguishers, 3-A:40-B:C is available in both 5 lb and 6 lb capacities, and there are 5 lb units with 2-A:10-B:C capacity. So I recommend that both the capacity of the extinguisher and the number-letter designations be specified. David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 314 Registered: 03-2002 Posted on Friday, July 30, 2004 - 06:00 pm:    Thanks Dave! What do you mean by "relative effectiveness"? Relative to what? David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 315 Registered: 03-2002 Posted on Friday, July 30, 2004 - 06:03 pm:    BTW, we used to never specify extinguishers, only cabinets. The Owner typically had a service contract with a company that supplied and maintained extinguishers. That said, the trend is towards the Owner wanting the GC to provide extinguishers as part of the construction. Also, the new IBC has eliminated portable fire extinquishers if the building is sprinklered. The exceptions are hazardous areas such as kitchens, laboratories, etc. Dave Metzger Senior Member Username: davemetzger Post Number: 86 Registered: 07-2001 Posted on Saturday, July 31, 2004 - 06:03 pm:    Relative to other extinguishers, for size/capacity and for extinguishing agent (multi-purpose dry chemical, pressurized water, etc) Richard Howard, AIA CSI CCS Senior Member Username: rick_howard Post Number: 27 Registered: 07-2003 Posted on Saturday, July 31, 2004 - 10:02 pm:    I got the following explanation from my local fire chief: Class A Extinguishers will put out fires in ordinary combustibles, such as wood and paper. The numerical rating for this class of fire extinguisher equates to an amount of water and the amount of fire it will extinguish. Class B Extinguishers should be used on fires involving flammable liquids, such as grease, gasoline, oil, etc. The numerical rating for this class of fire extinguisher relates to the approximate number of square feet of a flammable liquid fire that a non-expert person can expect to extinguish. Class C Extinguishers are suitable for use on electrically energized fires. This class of fire extinguishers does not have a numerical rating. The presence of the letter “C” indicates that the extinguishing agent is non-conductive. Class D Extinguishers are designed for use on flammable metals and are often specific for the type of metal in question. These extinguishers generally have no rating nor are they given a multi-purpose rating for use on other types of fires. Anne Whitacre, CCS CSI Senior Member Username: awhitacre Post Number: 106 Registered: 07-2002 Posted on Monday, August 02, 2004 - 01:23 pm:    David: I thought I had already posted this, but the explanation for the numbers is the square footage (or hundreds of square feet) covered by the extinguisher. If its a type A extinguisher, the number is the 1000 square feet covered for that type of fire: a 2:A is 2000 square feet of normal combustible material. For B and C fires, its the square footage: a 10:B:C is 10 square feet of type B or type C fire. These are not CO2 or water energized extinguishers, but usually a smothering type. The various extinguisher catalogs have this information. Its how you size the thing for the space. David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 317 Registered: 03-2002 Posted on Monday, August 02, 2004 - 02:03 pm:    Anne: I think Richard's explanation is correct. For Type A extinguishers the numeral stands for how comperable the extinguishing capacity is to many gallons of water. For example a 2A extinguisher can put out that same amount as 2 gallons of water.