Guide to Portable Fire Extinguishers
Want to learn more about how to choose the right fire extinguisher for your facility? Read this PE Fact article for information on fire extinguisher requirements, types, classifications, and labels, as well as proper locations, training, and inspection.
When caught early, most fires can be quickly put out if the proper fire extinguisher is available. In addition, it is extremely important that the person attempting to quench the fire has been trained as to the proper usage of the fire extinguisher at hand.
In order to effectively put out fires, portable fire extinguishers must be:
- Approved by a recognized testing laboratory (Factory Mutual (FM) in the US) and listed by Underwriters' Laboratories, Inc. (UL);
- Of the proper type for the class of fire expected;
- Conveniently located for immediate access, and in sufficient quantity and size to handle the expected fire;
- Regularly inspected and maintained to ensure good operating condition; and
- Operated by trained personnel who can use them effectively.
Classification
Fire extinguishers are classified by the type of fire that they will extinguish.
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Class A fire extinguishers are designed to fight fires caused by common combustibles, such as wood, paper, some plastics and textiles. To extinguish a Class A fire, these extinguishers utilize either the heat-absorbing effects of water or the coating effects of certain dry chemicals. Class A fire extinguishers should be clearly marked with a triangle containing the letter "A." If in color, the triangle should be green. For Class A fire extinguisher options please see 8774, 5467, 1123, 3820. | |
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Class B fire extinguishers are designed to fight fires originating from flammable liquids and gases such as oil, gasoline, etc. These fire extinguishers work by starving the fire of oxygen and interrupting the fire chain by inhibiting the release of combustible vapors. Class B fire extinguishers should be clearly marked with square containing the letter "B." If in color, the square should be red. For Class B fire extinguisher options please see 8774, 5467, 1123, 3820. |
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Class C fire extinguishers are effective on fires that involve live electrical equipment which require the use of electrically nonconductive extinguishing agents. (Once the electrical equipment is deenergized, extinguishers for Class A or B fires may be used.) Class C fire extinguishers should be clearly marked by a circle containing the letter "C." If in color, the circle should be blue. For Class C fire extinguisher options please see 8774, 5467, 1123, 3820. | |
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Class D fire extinguishers are designed for use on fires involving combustible metals such as magnesium, titanium, sodium, etc., which require an extinguishing medium that does not react with the burning metal. Class D fire extinguishers should be clearly marked by a five- point painted star containing the letter "D." If in color, the star should be yellow. For Class D fire extinguisher options please see 9853. | |
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Class K fire extinguishers are effective for fighting fires involving cooking fats, grease, oils, etc., in commercial cooking environments. These fire extinguishers work on the principal of saponification. Saponification takes place when alkaline mixtures such as potassium acetate, potassium citrate or potassium carbonate are applied to burning cooking oil or fat. The alkaline mixture combined with the fatty acid creates a soapy foam on the surface which holds in the vapors and steam and extinguishes the fire. Class K fire extinguishers should be clearly marked with the letter K. For Class K fire extinguisher options please see 138233. | |
Labeling
In order for users to quickly identify a fire extinguisher's classification in the event of an emergency, each unit should be clearly labeled. The approved marking system combines pictographs of both recommended and unacceptable extinguisher types on a single identification label. Here are examples of typical labels.
| Extinguisher for Class A, B and C | ||
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| Extinguisher for Class B and C | ||
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| Extinguisher for Class A and B | ||
|---|---|---|
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| Extinguisher for Class A | ||
|---|---|---|
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In addition, each fire extinguisher is also labeled for its UL rating, which is broken down into Class A and Class B: C ratings. These numerical ratings allow you to compare the relative extinguishing effectiveness of various fire extinguishers. For example, an extinguisher that is rated 4A:20B:C indicates the following:
- The A rating is a water equivalency rating. Each A is equivalent to 1.25 gallons of water. 4A = 5 gallons of water.
- The B:C rating is equivalent to the amount of square footage that related to the degree of training and experience of the operator, the extinguisher can cover. 20 B:C = 20 square feet of coverage.
- The C rating indicates its suitability for use on electrically energized equipment.
There is no numerical rating for Class C or Class D fires. Class C fires are fundamentally either Class A or Class B fires involving energized electrical equipment where the fire extinguishing media must be non-conductive. A Class C fire extinguisher should be based on the amount of the Class A or Class B component. For extinguisher use on a Class D fire, the relative effectiveness is detailed on the extinguisher nameplate for the specific combustible metal fire for which it is recommended.
Location
According to OSHA's standards, employers must select and distribute fire extinguishers based on the classes of anticipated workplace fires and also on the size and degree of the hazard which would affect their use. The following chart contains OSHA requirements for classes of fires and travel distance to an extinguisher. NOTE: There is no distance requirement for Class K extinguishers. Ideally, they should be located at the point of possible cooking fire ignition. Some local requirements may be stricter, so you should always check with your local fire marshal and insurance agent.
| Fire Class | Travel Distance |
|---|---|
| Class A* | 75 ft. (22.9m) or less |
| Class B | 50 ft. (15.2m) |
| Class C | Based on appropriate A or B Hazard |
| Class D | 75 ft. |
*In place of Class A fire extinguishers, employers have the option of using uniformly spaced standpipe systems or hose stations connected to a sprinkler system installed for emergency use by employee. Such systems must meet the respective requirements of 29 CFR 1910.158 or 1910.159—that they provide total coverage of the area to be protected, and that employees are trained at least annually in their use.
Training
In addition to providing the proper fire extinguishers, employers must also establish an educational program to train employees on the principles and use of the extinguishers. Each new employee should complete his or her fire extinguisher training program upon being hired, and should subsequently attend an annual training program.
Inspections
It is imperative that portable fire extinguishers be visually inspected monthly to ensure that:
- Fire extinguishers are in their assigned place;
- Fire extinguishers are not blocked or hidden;
- Pressure gauges show adequate pressure (CO2 extinguisher must be weighted to determine if leakage has occurred);
- Pin and seals are in place;
- Fire extinguishers show no visual sign of damage or abuse;
- Nozzles are free of blockage.
Fire extinguisher maintenance should be done at least annually and consists of complete examination of the unit, and involves disassembly and inspection of each part and replacement where necessary. Hydrostatic testing of portable fire extinguishers is done to protect against unexpected in-service failure. This can be caused by internal corrosion, external corrosion, and damage from abuse, etc. Hydrostatic testing must be performed by trained personnel with proper test equipment and facilities. OSHA requires hydrostatic testing according to the following schedule:
Table 1 from 29 CFR 1910.157
| Type of Extinguisher | Test Interval (Years) |
| Soda acid (soldered brass shells) (until 1/1/82) | (*) |
| Soda acid (stainless steel shell) | 5 |
| Cartridge operated water and/or antifreeze | 5 |
| Stored pressure water and/or antifreeze | 5 |
| Wetting agent | 5 |
| Foam (soldered brass shells) (until 1/1/82) | (*) |
| Foam (stainless steel shell) | 5 |
| Aqueous Film Forming Foam (AFFF) | 5 |
| Loaded stream | 5 |
| Dry chemical with stainless steel | 5 |
| Carbon dioxide | 5 |
| Dry chemical, stored pressure, with mild steel, brazed brass or aluminum shells | 12 |
| Dry chemical, cartridge or cylinder operated, with mild steel shells | 12 |
| Halon 1211 | 12 |
| Halon 1301 | 12 |
| Dry powder, cartridge or cylinder operated with mild steel shells | 12 |
| * Extinguishers having shells constructed of copper or brass joined by solf solder or rivets shall not be hydrostatically tested and shall be removed from service by January 1, 1982. (Not permitted.) | |
Employers are responsible for fire extinguisher maintenance, inspection and testing. A record of annual maintenance dates should be kept for the life of the shell of the extinguisher. Hydrostatic testing must be performed by trained personnel with proper test equipment and facilities.
When used correctly, fire extinguishers can be very effective in preventing major fire damage and monetary loss. For further information on the proper placement and use of portable fire extinguishers, contact your local fire department.
Commonly Asked Questions
Q. Are signs required to identify fire extinguisher locations?
A. Locations must be identified, but signs are not required. 29 CFR 1910.157(c)(1)
Q. Can Halon still be purchased in a portable fire extinguisher?
A. Recycled Halon can still be used in portable fire extinguishers, although it is very expensive and alternatives such as CO2 should be used when possible.
Please Note: The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.
