Selection and Distribution of Fire Extinguishers

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

Light (low) hazard occupancy

Ordinary (Mod.) Hazard

Extra (High) Hazard

Min. Rated Single Ext. 2-A 2-A 4-A

Maximum floor area per unit of A

3000 sq. ft. 1500 sq. ft. 1000 sq. ft.

Max. floor area for ext.

11250 sq. ft. 11250 sq. ft. 11250 sq. ft.

Max. travel dist. to Ext

75 ft. 75 ft. 75 ft.

Maximum Area Ext. Can Protect

Distribution of Class A Fire Extinguishers

Max. Area to be Protected Per Ext. sq. ft. Max. Travel

Distance

Class A Rating Extra

HazardOrd.

HazardLight

Hazard----- ----- ----- قدم 75 1A

----- 3000 6000 قدم 75 2 A

----- 4500 9000 قدم 75 3 A

4000 6000 11250 قدم 75 4 A

6000 9000 11250 قدم 75 6 A

10000 11250 11250 قدم 75 10 A

11250 11250 11250 قدم 75 20 A

11250 11250 11250 قدم 75 30 A

11250 11250 11250 قدم 75 40 A

Maximum Area Ext. Can Protect

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

CEN System

Application of the Rated Extinguisher

• To determine the number of extinguishers required multiply the floor area of a building in square meters by a factor of 0.065.

• The resulting number is the Class A cover requirement and should be divided by achieved Class A fire extinguishing rating of the extinguisher

Example

• A room has an area of 1000 square meters, so 1000 x 0.065 = 65

• If you assume that 9 litre water extinguishers with a fire rating of 13A will be used.

• By dividing 65 by 13 you will get the number of extinguishers required.

• 65/13 = 5 ext.

Distribution of Class B Fire Extinguishers -

 

 

موقع بين مسافة أقصىالجهاز وموقع الخطر

أداء لمعدل األدنى الحدالجهاز

المخاطر نوع

قدم 30قدم 50

5 B10 B

خفيفة مخاطر

قدم 30قدم 50

10 B20 B

عادية مخاطر

قدم 30قدم 50

40B80B

جسيمة مخاطر

CEN System

Application of the Rated Ext.

• The type of risk should be determined and the following rules should be followed:

1. Each room or enclosure should be considered separately.

2. Risks more than 20 m apart should be considered separately.

3. Where containers are stacked less than 2 m apart they should be considered undivided group.

4. A divided group comprises 2 or more containers more than 2 m but less than 20 m apart.

1. For single open topped containers see table 1, serial 1, the rating must be reached by each extinguisher provided.

2. For undivided groups see table 1, serial 2

3. For divided groups see table 1, serial 3

4. Spillage, see table 1, serial 4

Example 1• Take a single dip-tank with an area of 2 square

meters. The recommended rating of extinguisher is given by:

• Column2: 50x2.0 = 100 i.e. 113B (foam only)

• Column3: 80x2.0 = 160 i.e. 183 (any other type)

• The minimum aggregate rating is recommended as:

• Column4: 150 x 2.0 = 300B (The minimum aggregate rating of 300B is not met by a single ext., therefore: 300 / 183 = 2 183B

Example 2

• Take a bund measuring 2.47 square meters (1.3 x 1.9 m).

• What is the minimum rating extinguisher recommended?

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 RatingsDescription Rating

2.5 gallon water 2A

20 lb Carbon Dioxide 10B:C

5 lb dry chemical (ammonium ph.) 2A:10B:C

10 lb dry chemical (Sod. Bicarb.) 60B:C

10 lb dry chemical (pot. Bicarb.) 80B:C

125 lb dry chemical (amm. Phosph) 40A:240B:C

33 gal. AFFF 20A:160B

5 LB HALON 1211 10B:C

9 LB HALON 1211 1A:10B:C

1.5 LB HALON 1211/1301 1B:C