APPENDIX 1

TYPES OF FIRES AND FIRE EXTINGUISHERS

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.