Portable and Mobile Fire Extinguishing Equipment
Portable and mobile equipment
Selection starts with the fire class: A (ordinary combustibles), B (flammable liquids), C (energized electrical), D (combustible metals) and K (cooking oils). Extinguishers carry ratings such as 2A:10B:C: the number before A is the water-equivalent rating, the number before B is the area of a test fire, and C has no numerical rating. Travel distance and area coverage are separate checks. Class A light hazard generally allows a 2A extinguisher per 3000 ft² and a maximum 75 ft travel; Class B distances depend on hazard; Class K is for cooking equipment. Mounting height, signage, visibility and access matter as much as size. Inspection is monthly, maintenance annual, and hydrostatic testing follows the interval for the extinguisher type.
Traps: choosing by physical size rather than rating; using CO2 as a Class A extinguisher; placing a dry-chemical extinguisher where residue will destroy electronics; measuring travel distance in a straight line through walls; and confusing annual maintenance with hydrostatic test.
Worked example: a 100 ft × 60 ft office is 6000 ft². At 3000 ft² per 2A extinguisher, two 2A units are needed, even if one centrally placed unit would meet the 75 ft travel distance to the furthest corner. Check both coverage and travel, then confirm mounting and signage.