Australian Standard AS/NZS 1850:2009 covers the classification, rating and performance testing of fire extinguishers.
The Standard was originally developed to define a system of classification and rating of fire extinguishers. This classification system also defines a method of test in order to determine if an extinguisher can be given a rating appropriate to the class of fire.
The ultimate classification and rating of an extinguisher or its recommended use is based on its fire extinguishing potential, as determined by the appropriate tests.
Fires may be categorised in one of six classes;
A Class A fire is one that involves carbonaceous solids. A carbonaceous solid is one where the primary chemical element is carbon that serves as the base fuel. Carbonaceous solids commonly found around the home, workshop or workplace include cardboard, timber, cloth, dry garden clippings, etc.
Almost every type of fire extinguisher can be used with a Class A fire however Carbon Dioxide fire extinguishers are less effective than the other types.
A Class B fire is one that involves flammable liquids. The globally harmonised system ("GHS") for the classification and labelling of chemicals GHS defines a flammable liquid as a liquid having a flash point of not more than 93°C.
A flammable liquid is classified in one of four categories for this class according to the following table:
|1||Flash point <23°C and initial boiling point < 35oC|
|2||Flash point <23°C and initial boiling point > 35°C|
|3||Flash point >23°C and < 60°C|
|4||Flash point >60°C and < 93°C|
A service station, workshop, garden shed or paint store are some of the most common locations that a member of the public might come into contact with flammable and combustible liquids on a regular basis.
A Class C fire is one that involves flammable gasses. There are 9 classes of dangerous goods, and Division 2.1 - defines a Flammable Gas as material that is a gas at 20ºC or below and 101.3 kPa of pressure (ambient temperature and pressure), i.e. the material has a boiling point of 20ºC at sea level and:
A Class D fire is one that involves combustible metals. A combustible metal is defined as any metal composed of distinct particles or pieces, regardless of shape, size or chemical composition that will burn.
The following is a list of combustible metals that require a Class D fire extinguisher:
A Class E fire is one that involves electrical equipment. Electrical equipment includes any machine powered by electricity. It usually consists of an enclosure, a variety of electrical components, and often a power switch.
More specifically, electrical equipment refers to the individual components of an electrical distribution system. These components may involve:
The National Construction Code ("NCC") requires a Class A(E) or Class (E) fire extinguisher adjacent to an emergency services switchboard is one which sustains emergency equipment operating in the emergency mode.
A Class F fire is one that involves cooking oils and fats. Technically a fire fires involving cooking oils and fats are actually a type of fire caused by flammable liquids or gases at high temperatures. These type of fires differ from conventional fires because they burn at incredibly high temperatures.
Cooking oil and fat fires are a major cause of fires and loss in the home. Kitchen fires triggered by cooking oil or fats cause the fastest-spreading destruction of any kind of fire.
The ideal type of fire extinguisher for burning oils and fat fires is a "wet chemical" fire extinguisher. A wet chemical fire extinguisher is red in colour with a beige band around the extinguisher cylinder.