Fire Ratings
Fire ratings provide a means of measuring the effectiveness of an extinguisher in terms of the maximum size of the fire that can be extinguished.
Class A rating is related to a wooden crib fire 0.5m wide x 0.56m high x length. The rating figure is ten times the length in metres, e.g. 13A uses a crib 1.3 metres long.
Class B is related to fire surface area and the rating figure is the quantity of flammable liquid in a ratio of one third water and two third fuel that can be extinguished in a circular tray.
Class F relates to cooking oil and cooking fat fires. There are four benchmark tests using 5, 15, 25 and 75 litres of sunflower oil. The oil is heated to auto-ignition and allowed to pre burn for two minutes. The fire is extinguished and no pre-ignition shall occur within ten minutes of extinguishing the fire.
