Providing portable fire extinguishers is a fundamental component of business safety and a requirement for legal compliance. The correct number and type of extinguishers are determined by a calculated approach based on the facility’s size, layout, and the specific risks present. This methodical determination ensures the equipment is appropriate for the hazards and readily available when a fire emergency occurs.
Understanding Fire Classes and Extinguisher Types
The initial step in selecting equipment is understanding the five primary classes of fire, categorized by the fuel source involved. Class A fires involve ordinary combustibles such as wood and paper. Class B fires are fueled by flammable liquids like oil and grease, while Class C fires involve energized electrical equipment. Combustible metals, such as magnesium, produce Class D fires, and Class K fires are specific to cooking oils and fats in commercial kitchens.
Extinguishers are labeled with letters indicating the type of fire they combat. Many general-purpose extinguishers carry multi-class ratings, such as an A-B-C dry chemical unit, making them versatile for common office or retail environments. The effectiveness of a unit is indicated by a numerical rating alongside the letter. For instance, the number preceding the ‘A’ indicates the water equivalency, and the number before the ‘B’ indicates the approximate square footage of a flammable liquid fire the unit can suppress.
Determining the Hazard Level of Your Business
The quantity and placement of fire extinguishers depend directly on classifying the business environment into one of three hazard levels. Light (Low) Hazard occupancies have a low amount of Class A combustible materials and less than one gallon of Class B flammables, such as in professional offices or classrooms.
Ordinary (Moderate) Hazard occupancies contain more Class A combustibles and hold between one and five gallons of Class B flammables. This classification commonly applies to light manufacturing facilities, dry cleaners, and mercantile businesses.
Extra (High) Hazard occupancies are defined by a high quantity and combustibility of materials, or where the total amount of Class B flammables exceeds five gallons. Facilities such as woodworking shops, plastics manufacturing plants, and auto repair garages fall into the Extra Hazard category.
Calculating the Required Number Based on Hazard Level
The core principle for calculating the required number of fire extinguishers is the maximum travel distance an employee must walk to reach an appropriate unit. The travel distance requirement is fixed at 75 feet for Class A (ordinary combustible) hazards across all three occupancy levels. For Class B (flammable liquid) hazards, the maximum distance is shorter due to the rapid spread of these fires, set at 50 feet for Light Hazard and 30 feet for Ordinary and Extra Hazard occupancies.
In addition to travel distance, a Class A extinguisher must not exceed a maximum area coverage, which varies by hazard level. The minimum number of units is calculated by dividing the total floor area by the maximum floor area per unit of A rating. For example, a Light Hazard space requires one 2-A unit for every 6,000 square feet. The same 2-A unit only protects 3,000 square feet in an Ordinary Hazard space, meaning twice as many units are needed for the same floor area. This two-part requirement ensures the equipment is powerful enough for the risk and quickly accessible from any point in the facility.
Specific Placement and Visibility Requirements
Once the correct quantity and type of extinguishers are determined, their physical placement must meet specific installation standards to ensure accessibility. All fire extinguishers must be mounted to be readily available and free from obstructions, typically along normal paths of travel and near exits or designated escape routes. Clear signage is required if the unit is housed within a cabinet or if visual obstructions cannot be avoided.
Mounting height is regulated to prevent physical strain and ensure quick removal in an emergency. Extinguishers weighing 40 pounds or less must have the top of the unit no more than five feet above the floor. Heavier units, weighing more than 40 pounds, must have their top no more than three and a half feet above the floor. Furthermore, all non-wheeled extinguishers must maintain a minimum clearance of four inches between the bottom of the unit and the floor.
Legal Compliance and Maintenance Schedule
Maintaining a regular inspection and maintenance schedule is just as important as the correct selection and placement of the fire extinguishers. Businesses are required to perform a monthly visual inspection of every unit, which can be completed by an employee. This monthly check includes verifying that the unit is in its designated place, is not obstructed, has a visible and operable pressure gauge, and that the safety pin and tamper seal are intact.
Beyond the monthly check, a certified professional must perform comprehensive annual maintenance on all portable fire extinguishers, with the date and signature documented on a tamper-proof tag affixed to the unit. Stored-pressure extinguishers, such as the common dry chemical units, require a more thorough internal examination and recharge every six years to check for internal corrosion or agent compaction.
Additionally, the cylinders of most types of extinguishers must undergo a high-pressure hydrostatic test every twelve years to confirm their structural integrity. Failure to adhere to this mandatory, documented maintenance schedule can result in regulatory penalties and render the business non-compliant.