Selecting Extinguishers
The size and type of portable fire extinguisher is based on the total amount of Class A combustible materials, the total amount of Class B flammables, or, for some occupancies, a combination of both.
For many areas, the extinguishing agent also must be compatible with energized electrical equipment.
Classification of Hazards
Light (Low) Hazard:
Are locations in which the total amount of Class A combustible materials, including furnishings, decorations, and contents, is minor.
These occupancies may include buildings or rooms occupied as offices, classrooms, assembly halls.
Small amount of Class B flammables used in duplicating machines, art departments, and the like are included.
Ordinary (Moderate) Hazard:
Are locations in which the total amount of Class A and Class B are present in greater amounts than may be expected in light hazard occupancies.
Dining areas, mercantile shops and their allied storage, light manufacturing facilities, auto show rooms, parking garages, and warehouses containing Class I or Class II commodities.
Extra (High) Hazards:
Are locations in which the total amount of Class A and Class B present in storage, in production, or as finished products is over that expected in ordinary hazard occupancies.
Woodworking shops, vehicle repair areas, aircraft and boat servicing facilities, cooking areas, painting, dipping and coating areas, also included is warehousing or in-process storage of commodities other than Class I and II commodities.
Distributing Extinguishers
Extinguishers should be placed in locations provide easy access and are readily free from temporary blockage.
Near normal paths of travel, near exits and entrances.
Mounted on walls, the operating instructions must face outwards, and can be removed easily.
Continue
Ext. with gross weight of no more than 40 pounds (18 kgs) should be installed so that the top of the extinguisher is not more than 5 feet above the floor.
Ext. more than 40 pounds (except wheeled types) should be installed so that the top of the extinguisher is not more than 3.5 feet from the floor.
In no case should the clearance between the bottom of the extinguisher and the floor be less than 4 inches.
Minimum number and rating for Class A fires
Maximum Area Ext. Can Protect
Distribution of Class A Fire Extinguishers
Example
Area = 450X150 = 67500 Ft²
From the table:
67500 / 11250 = 6 fire ext.
6 x 4A light hazard
6 x 10A ordinary hazard
6 x 20A extra hazard
The travel distance rule (75ft) has been violated.
Example
Area 67500 Ft²
67500 / 6000 = 12 fire extinguishers
12 x 2A light hazard
12 x 4A ordinary hazard
12 x 6A extra hazard
In this case both distribution and travel distance rules are fulfilled.
Example
Distribution of Class B Fire Extinguishers
Distribution for CLASS C
Installed where there is live electrical equipment.
Carbon Dioxide, Dry Chemical, and Halons
Power has cut off the fire becomes Class A or Class B.
Distribution for Class D
The amount of agent needed normally is figured according to the surface area of the metal plus the shape and form of the metal which can contribute to the severity of the fire.
Travel distance 75 ft.
Classification and Ratings
