Class Materials burning, Preferred Never use
of fire or conditions extinguisher ──────────
A Wood, paper, cloth Water, CO2 CCl4**
B Flammable liquids Dry NaHCO3‑type*, CCl4**
and gases, CO2
C The above, whenever Dry NaHCO3‑type*, Water,
electrical contacts CO2 Soda‑acid,
must be taken into Foam,
D Alkali metals (also Dry NaHCO3‑type*, Water,
alkaline earths, Al)*** Dry graphite*, Soda‑acid,
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.