Masonry Magazine December 1986 Page. 35
Fire
Extinguishers:
Your First Line
of Defense
Anyone who thinks fighting a small fire is only a matter of grabbing an extinguisher, spraying its contents at the blaze, then waiting around to be acclaimed a hero is all wet-or might wish he was. Proper use of the right extinguisher at the right time often spells the difference between inconvenience and tragedy.
To use portable extinguishers most effectively, the National Fire Protection Association (NFPA) recommends these procedures:
-Place extinguishers in locations that are readily accessible, easily visible, safe from damage or obstruction, and as close as possible to exits and well-traveled areas.
-Choose extinguishers that will put out fires in one or more of the four most common hazard groups. These four groups include:
1. Class A hazards-fires in ordinary materials such as wood, cloth, paper, rubber and many plastics.
2. Class B hazards-fires in liquids and gases such as oils, gasoline, greases, lacquers, oil-base paints, propane, acetylene and natural gas.
3. Class C hazards-fires that involve electrical equipment that is in operation. An extinguisher containing an agent that conducts electricity must not be used with fires of this type. If the electricity is turned off, the fire becomes Class A or Class B, depending on the surrounding material.
4. Class D hazards-fires in metals such as magnesium, titanium, zirconium, sodium, lithium and potassium.
Hazards are also classified as light, ordinary and extra. A light hazard exists in areas where small fires can be expected, including offices, schoolrooms, churches, assembly halls and telephone exchanges.
Ordinary hazard areas include mercantile storage and display areas, auto showrooms, parking garages, light manufacturing plants, industrial arts classrooms and some warehouses.
Extra hazard describes where fires of severe magnitude can be expected-including auto repair, woodworking and aircraft service workshops, warehouses with burnable materials stacked higher than 12 feet, and processes such as flammable liquids handling, painting and dipping.
Because fire extinguishers are typed according to the same classification systems as fires themselves, determining the type of extinguisher to use is simple-it's the same as the fire hazard. As a minimum, at least Class A type protection should be provided.
For all Class A and some Class B hazards, the required rating of the extinguisher and the maximum travel distance (the total feet traveled to get to the extinguisher and back to the fire) may be determined by referring to the accompanying table.
For example, the minimum rating for Class A extinguishers intended as protection from an "extra" hazard would be 2-A, according to Table 1. Table 1 also shows that the maximum travel distance should be 75 feet.
Extinguishers of a higher rating may be used and may be
Table 1 Class A extinguishers-minimum ratings and
maximum travel distances
| | Light hazard | Ordinary hazard | Extra hazard |
| ----------------------- | ------------ | --------------- | ------------ |
| Minimum extinguisher rating | 1A | 2A | 2A |
| Maximum travel distance to extinguisher | 75 feet | 75 feet | 75 feet |
Table 2 Class B extinguishers-minimum ratings and
maximum travel distances
| | Light hazard | Ordinary hazard | Extra hazard |
| ----------------------- | ------------ | --------------- | ------------ |
| Minimum extinguisher rating | 5B, 10в | 10B, 20B | 40B, 80B |
| Maximum travel distance to extinguisher | 30, 50 feet | 30, 50 feet | 30, 50 feet |