How many Fire Extinguishers do I need?

Kitchen Fire

Step 1:

First calculate the floor size in square meters. Measure the length and width of the area you’re calculating using meters and centimeters. Multiply the length and width together to get the area in square meters.

Step 2

Now check SANS 10400 part A and verify the occupancy class of the building you’re evaluating. The occupancy class refers to the use of the building. Keep in mind there may be more than 1 type of occupancy in one building. (Offices and Warehouse in the same building)

Class of occupancy Occupancy
A1 Entertainment and public assembly Occupancy where persons gather to eat, drink, dance or participate in other recreation.
A2   Theatrical and indoor sport Occupancy where persons gather for the viewing of theatrical, operatic, orchestral, choral, cinematographical or sport performances.  
A3 Places of instruction Occupancy where school children, students or other persons assemble for the purpose of tuition or learning
A4 Worship Occupancy where persons assemble for the purpose of worshipping
A5 Outdoor sport Occupancy where persons view outdoor sports events
B1   High risk commercial service Occupancy where a non-industrial process is carried out and where either the material handled in the process carried out is liable, in the event of fire, to cause combustion with extreme rapidity or give rise to poisonous fumes, or cause explosions.
B2 Moderate risk commercial service Occupancy where a non-industrial process is carried out and where either the material handled or the process carried out is liable, in the event of fire, to cause combustion with moderate rapidity but is not likely to give rise to poisonous fumes, or cause explosions.
B3 Low risk commercial service Occupancy where a non-industrial process is carried out and where neither the material handled, nor the process carried out falls into the high or moderate risk category.
C1   Exhibition hall Occupancy where goods are displayed primarily for viewing by the public.
C2 Museum Occupancy comprising a museum, art gallery or library.
D1         High risk industrial Occupancy where an industrial process is carried out and where either the material handled or the process carried out is liable, in the event of fire, to cause combustion with extreme rapidity or give rise to poisonous fumes, or cause explosions.
D2   Moderate risk industrial Occupancy where an industrial process is carried out and where either the material handled or the process carried out is liable, in the event of fire, to cause combustion with moderate rapidity but is not likely to give rise to poisonous fumes, or cause explosions
D3       Low risk industrial Occupancy where an industrial process is carried out and where neither the material handled nor the process carried out falls into the high or moderate risk category.
D4     Plant room Occupancy comprising usually unattended mechanical or electrical services necessary for the running of a building.
E1     Place of detention Occupancy where people are detained for punitive or corrective reasons or because of their mental condition.
E2 Hospital Occupancy where people are cared for or treated because of physical or mental disabilities and where they are generally bed-ridden.
E3   Other institutional (residential) Occupancy where groups of people who either are fully fit, or who are restricted in their movements or their ability to make decisions, reside and are cared for.
E4 Medical facilities Occupancy which is a common place of long term or transient living for a number of unrelated persons consisting of a single unit on its own site who, due to varying degrees of incapacity, are provided with personal care services or are undergoing medical treatment
F1   Large shop Occupancy where merchandise is displayed and offered for sale to the public and the floor area exceeds 250m².
F2   Small shop Occupancy where merchandise is displayed and offered for sale to the public and the floor area does not exceed 250m².
F3 Wholesalers’ store Occupancy where goods are displayed and stored and where only a limited selected group of persons is present at any one time.
G1 Offices Occupancy comprising offices, banks, consulting rooms and other similar usage.
H1 Hotel Occupancy where persons rent furnished rooms, not being dwelling units.
H2   Dormitory Occupancy where groups of people are accommodated in one room
H3   Domestic Residence Occupancy consisting of two or more dwelling units on a single site.  
H4   Dwelling house Occupancy consisting of a dwelling unit on its own site including a garage and other domestic buildings if any.
H5 Hospitality Occupancy where unrelated persons rent furnished rooms on a transient basis within a dwelling house or domestic residence with sleeping accommodation for not more than 16 persons within a dwelling unit.
J1       High risk storage Occupancy where material is stored and where the stored material is liable, in the event of fire, to cause combustion with extreme rapidity or give rise to poisonous fumes, or cause explosions.
J2 Moderate risk storage Occupancy where material is stored and where the stored material is liable, in the event of fire, to cause combustion with moderate rapidity but is not likely to give rise to poisonous fumes, or cause explosions.
J3   Low risk storage Occupancy where the material stored does not fall into the high or moderate risk category.
J4 Parking garage Occupancy used for storing or parking of more than 10 motor vehicles.

Step 3

The next step is to check table 11 of SANS 10400 part T for the guidance on the number of fire extinguishers you will need for the specified occupancy class.

Class of occupancy Number of portable fire extinguishers requiredᵃ per m²   Water   Foam   Carbon Dioxide   Dry Chemical Powder
A1 1/200 9 L 9 L 5 kg 4,5 kg
A2 1/200 9 L 9 L 5 kg 4,5 kg
A3 1/200 9 L 9 L 5 kg 4,5 kg
A4 1/400 9 L 9 L 5 kg 4,5 kg
A5 1/400 9 L 9 L 5 kg 4,5 kg
B1 1/100 9 L 9 L 10 kg 9 kg
B2 1/200 9 L 9 L 10 kg 9 kg
B3 1/400 9 L 9 L 10 kg 9 kg
C1 1/200 9 L 9 L 10 kg 9 kg
C2 1/200 9 L 9 L 10 kg 9 kg
D1 1/100 9 L 9 L 10 kg 9 kg
D2 1/100 9 L 9 L 10 kg 9 kg
D3 1/200 9 L 9 L 10 kg 9 kg
D4 1/400 9 L 9 L 10 kg 9 kg
E1 1/200 9 L 9 L 5 kg 4,5 kg
E2 1/200 9 L 9 L 5 kg 4,5 kg
E3 1/200 9 L 9 L 5 kg 4,5 kg
E4 1/200 9 L 9 L 5 kg 4,5 kg
F1 1/200 9 L 9 L 5 kg 4,5 kg
F2 1/200 9 L 9 L 5 kg 4,5 kg
F3 1/200 9 L 9 L 5 kg 4,5 kg
G1 1/200 9 L 9 L 5 kg 4,5 kg
H1 1/200 9 L 9 L 5 kg 4,5 kg
H2 1/200 9 L 9 L 5 kg 4,5 kg
H3 1/400 9 L 9 L 5 kg 4,5 kg
H5 1/100 9 L 9 L 5 kg 4,5 kg
J1 1/100 9 L 9 L 10 kg 9 kg
J2 1/100 9 L 9 L 10 kg 9 kg
J3 1/400 9 L 9 L 10 kg 9 kg
J4 1/400 9 L 9 L 10 kg 9 kg

Remember:

If the size of extinguisher required is 1 x 9 kg powder extinguisher per 200m² as with a C1 occupancy, the owner of the building may install 2 x 4,5 kg extinguishers of the same type per 200m².

Example:

If you are working in an office 30 meters long and 20 meters wide. 30 x 20 = 600m2.

An office is classified as a G1 occupancy and Table 11 indicates that a G1 occupancy needs 1 fire extinguisher for every 200m2. Based on table 11 you will need 3 fire extinguishers for the floor area of 600m2. Table 11 gives you a choice of 4 different types fire extinguishers, you can either install a 9-liter water type extinguisher, or a 9 liter Foam type extinguisher, or a 5kg CO2 extinguisher, or a 4.5 kg Dry Powder fire extinguisher. 

Which Type of Fire Extinguisher to buy

Every type is good in dealing with one class but no single type of extinguisher is fully effective on every class of fire. Before buying a fire extinguisher, it is vital to look carefully at what type of fire you could possibly have to deal with.  Choosing the wrong type of fire extinguisher for the job can be very dangerous, make the fire worse and risk injuring those attempting to fight the fire.

Classification of Fire

The fire classification system categorizes fires into groups based on the type of fuel involved.

Classification Fuel Type
Class A Solids such as wood, paper, plastic.
Class B Flammable liquids such as paraffin, petrol and oil.
Class C Live electrical
Class D Metals such as aluminium, magnesium and titanium

Note: Class F – Cooking fats and oils are classified in most countries as Class F fires. This classification has not been adopted by SABS under SANS 1475 in South Africa.

Fire extinguishers are available in different types. Each one having specific fire classes that they are suitable for use on.

Type Colour Classification  Use
Water Red Class A Water extinguishers are used on Class A fires involving solid combustibles.
They are not suitable for fires involving flammable liquids, or where live electricity is involved.
Foam Cream Class A and B Foam is ideal for class B fires, but also effective on class A
CO2 Black Class B and C CO2 fire extinguishers are effective on class C fires, as it is not a conductor and does not leave behind any harmful residue. 
Dry Powder Blue Class A, B and C Dry powder extinguishers can be used on Class A, B and C. Dry powder is messy and can cause damage to goods and machinery.

When in doubt, a fire risk assessment will help you to identify the fire risks and exactly which extinguisher is needed.

Service and maintenance of fire extinguishers will be discussed in a future post!

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