Class               Materials burning,                 Preferred                    Never use

            of fire                or conditions                         extinguisher                ──────────


            A                     Wood, paper, cloth                  Water, CO2                  CCl4**

                                                                                    Dry NaHCO3‑type*


            B                      Flammable liquids                     Dry NaHCO3‑type*,    CCl4**

                                    and gases,                                CO2

                                    hydrocarbon solids,                 

                                    rubber, plastics


            C                     The above, whenever                Dry NaHCO3‑type*,    Water, 

                                    electrical contacts                     CO2                             Soda‑acid,

                                    must be taken into                                                         Foam,

                                    consideration                                                                CCl4**


            D                     Alkali metals (also                     Dry NaHCO3‑type*,    Water,

                                    alkaline earths, Al)***              Dry graphite*,              Soda‑acid,

                                                                                    sand                             Foam,

                                                                                    Dry NaCl*                   CO2,

                                                                                    (for Na or K)               CCl4**


            * Dry solids in cylinder pressurised with N2, a CO2 cartridge, or a propellant such as freon.  Dry solid extinguishers are the most common type stocked in the Chemistry Department and are the best type of extinguisher to use on Class A, Class B and Class C fires, hence the ABC designation on the sides of these extinguishers. Some extinguishers in the Department are the CO2 type which are also excellent extinguishers for Class A, B and C type fires. The CO2 extinguishers are recognizable by their long tapered black nozzles whereas the dry chemical extinguishers have a flexible 3/4" diameter hose.


            ** Not recommended in general; however CCl4 extinguishers may be used on small fires with adequate ventilation, if it is the only type of extinguisher available. CCl4 extinguishers are not stocked in the Chemistry Department.


            *** For procedures to use in the destruction of these materials see Appendix 3.