Fire Extinguisher Safety

Most fires can be put out in their incipient (early stages) with the proper fire extinguisher and properly trained personnel. The requirements for portable fire extinguishers in general industry are governed by OSHA regulation 29 CFR 1910.157. Highlights of the OSHA regulation include:


• Fire extinguishers must be located and marked to be easily seen and the area around the extinguisher must be kept clear.

• Fire extinguishers must be visually inspected monthly and tagging or marking of inspection dates is essential.

• Gauges should be checked for readings to insure the unit is functional. Pressurized units are considered as ‘unfired pressure vessels’ and require periodic hydro-static pressure tests in accordance with NFPA codes.

• Employers shall provide a fire extinguisher use training program. This training program should be completed during the initial hiring and annually thereafter. 

• Water type extinguishers must never be used on electrical or metal fires. Water fire extinguishers without anti-freeze solution should be stored in temperature conditions above 30°F to avoid freezing.

• Operating temperature range for dry chemical extinguishers, –65°F to 125°F and –40°F to 120°F for CO2. 

• Fire extinguishers must be labeled with the class of fire they are effective on.

More questions arise over fire types and how to tell what sorts of fires a given fire extinguisher can handle. There are two steps to answering these questions.

First, you should know what type of fire you are most likely to encounter in a given work area. A system of classifying types of fires has been standardized by the National Fire Protection Association (NFPA). Fires have been grouped as:

• A = Class A Fire (Common Combustibles)

• B = Class B Fire (Flammable Liquids)

• C = Class C Fire (Electrical)

• D = Class D Fire (Flammable Metals)

• K = Class K Fire (Cooking Media)

Once you know what fire risks you run in an area, you’re ready to shop for the right extinguisher for that fire risk. You’ll find a corresponding pictograph chart on the side of each fire extinguisher that includes the Class type of fire that particular extinguisher is designed to fight.

Kitchen fires, for example, tend to be electrical and should be fought with a Class B or Class C extinguisher, or preferably one that fights both B and C fires. 

Once you’ve found the matching portable fire extinguisher for your fire risk, there are a few other questions you should answer before making a final purchase including how large the area is that you may need to cover with your fire extinguisher and how persistent the fire might be. Here is a breakdown to help you choose the right fire extinguisher for the type of fires you might encounter. You may find you need three extinguishers to cover a large work area, or a larger 10lb extinguisher instead of a 2lb. extinguisher. 

TYPE                                                  AGENT                                   RANGE     TIME  

B -Regular Dry Chemical                         Sodium Bicarbonate                   5-20 Ft.      8-25 Sec.

AB or B-Multipurpose Dry Chemical         Ammonium Phosphate               5-20 Ft.      8-25 Sec.

B -Purple K Dry Chemical                       Potassium Bicarbonate              5-20 Ft.      8-25 Sec.

B -KCI Dry Chemical                              Potassium Chloride                    5-20 Ft.      8-25 Sec.

B -Carbon Dioxide Inert                          Carbon Dioxide Gas                    3-8 Ft.        8-30 Sec.

BC-Halogenated Agent                           Halogenated Hydrocarbons         4-8 Ft.        8-10 Sec.

A -Water                                               Tap Water w/Corrosive Inhibitor   30-40 Ft.    1 Min.

A -Water/Anti-Freeze Solution                 Tap Water w/Calcium Chloride   30-40 Ft.    1 Min.

AB-Loaded Stream                                 Alkali-Metal-Salt                       30-40 Ft.    1 Min.

B -Foam and Water                                Foam Water and Detergent        10-15 Ft.    24 Min.

D -Dry Powder                                       Sodium Chloride                        5-20 Ft.      25-30 Sec.  

For further information: 
OSHA Fire Protection for General Industry, 1910.157(Portable fire extinguishers)  

National Fire Protection Association –