The fire safety of buildings comprises many measures that should always be considered as inter-related. A major component of these measures are extinguishers. In the early stages of a fire, fire extinguishers are highly valuable. Immediate availability and fast mobility contribute to a fast extinguishing attempt (ISO 7165:2009).
A competent person should make a risk assessment (RIE) of the location, taking into consideration the layout and use of the location and the normal and special risks that are present. This should result in a ground plan whereby the current number and types of fire extinguishers are indicated.
The ground plan should at least be contain:
- Fire risk per project zone (high, normal, low);
- Description of the location, layout of the location and the project zones;
- Description of special and normal fire risks;
- Description of the type of fire extinguisher and the location per type (fire class);
- Description of the requirements through safety signs;
- Possible ignition sources.
Note 1: fire hose are included in the ground plan as fire extinguishing unit, provided the fire class indication of the fire extinguishers present allows this.
Note 2: For special risks it is recommended to indicate the projection zones, the fire extinguishers and fire hose reels to be used on floor plans.
SELECTING THE FIRE EXTINGUISHING MEDIUM
The most important extinguishing media are:
- Water with additives;
- Extinguishing powder;
- Carbon dioxide (CO2);
- Chemical extinguishing gases.
The selected extinguishing medium should be suitable for the most probable type of fire in the area for which the extinguisher is intended.
All extinguishers installed near live electric equipment should be suitable for extinguishing this equipment, with no risk to the user. Extinguishers with chemical extinguishing gases or CO2, as extinguishing medium, can be used for this.
The use of powder extinguishers in a confined space will strongly hinder observation. This will make rescuing and evacuating people, as well as other emergency measures, very difficult. In such cases, foam or water extinguishers are preferred.
The ambient temperature has an effect on the function of extinguishers. Extinguishers have a label stating the range of temperatures within which the extinguisher can be used. Extinguishers may not be exposed to temperatures outside the indicated use temperatures.
Using a CO2 extinguisher in a confined space will lead to a decrease of the oxygen concentration. This could lead to suffocation or reduced consciousness. For each CO2 extinguisher there should be at least 12.5 Mᵌ of available space.
Materials that are not directly involved with a fire can be damaged by the extinguishing media. This is referred to as collateral damage. Although the selection of extinguishers is primarily based on safety and effectiveness, when selecting the extinguishing medium you should take into account the risk of collateral damage.
The number of extinguishers required depends on:
- The projection zone;
- The basic safety unit;
- The maximum walking distance to the nearest extinguisher;
- The possible presence of fire hose reels.
Firstly, the building is subdivided into projection zones in order to determine the correct number of extinguishers.
A projection zone is an area in which similar types of activities are performed (office, factory, storage), in which primarily one major fire class can be distinguished (fire class A, B, C, D or F) and of which all individual rooms are interconnected.
Usually, a projection zone will correspond with the fire compartmentalisation of a building. The required number of extinguishers is determined per projection zone in the building/shipyard. On locations with an above average fire hazard, additional extinguishing equipment might be necessary.
The rooms in a building are designated as an individual projection zone:
Situation A > If they are not adjacent;
Situation B > If they are adjacent, but separated by obstacles that reduce the reachability of an extinguisher in case of fire.
In the normal operational situation, closed doors hinder the reachability of extinguishing equipment and make it necessary to define the rooms at both sides of the door as separate projection zones. Areas at both sides of a fire resistant partition, with or without openings, are regarded as areas that are not connected with one another. These will always form two separate projection zones.
Basic safety unit
The type, number and location of extinguishers depends on the use of the projection zone, the content of those extinguishers, the maximum walking distance and the presence of fire hose reels. The different uses are included in the following table. A projection zone will always only have one use.
Maximum walking distance
The fire extinguishers must be placed in such a way that the walking distance from any point within the projection zone to the nearest extinguisher is never more than 20 m.
Fire hose reels
Fire hose reels are counted as basic safety units, if there are fire hose reels present in the projection zone that can be used effectively and safely to fight the expected risk of fire.
Based on the risk assessment, additional extinguishers for the benefit of special fire risks should be placed, in addition to the basic equipment.
It is not allowed to combine additional safety for different special risks within one projection zone. Irrespective of the layout of the area, an additional extinguisher should always be reachable within 5 m of the specific risk. The extinguishers should be placed in such a way that reachability is not hindered by the expected source of fire.
OUTDOOR STORAGE OF FLAMMABLE SUBSTANCES OR MATERIALS
Parts of sites or sites where storage of materials or flammable substances occurs, must be provided with additional safety measures. Per 150 M² or part thereof, consisting of:
- One 6 kg extinguisher with ABC or BC powder as extinguishing medium, or
- One 6 litre extinguisher with water, water plus additives or foam as extinguishing medium.
Instead of portable extinguishers, it is possible to use mobile extinguishers. One mobile extinguisher with a content of 50 kg of powder, or 45 of 50 litres of foam will replace eight portable extinguishers with a content of 6 kg of powder, or 6 litres of foam, or five portable extinguishers with a content of 9 kg or 12 kg of powder, or 9 litres of foam.
FIRE HAZARDOUS WORK
There should be at least one extinguisher with a content of at least 6 kg/ 4 litres present within 5m of temporary activities with open fire (NEN4001+C1, 2008).
Note: Based on the risk assessment, earlier fire extinguishers can be prescribed.
LOCATING THE FIRE EXTINGUISHERS
Fire extinguishers should be placed in clearly visible places on stands or suspension brackets. Persons using the escape routes should be able to see the fire extinguisher easily. Suitable locations are central entry halls, stairwells, corridors and near room exits. Fire extinguishers should be placed in such a way that the access to the extinguishers is not hindered by the expected risk of fire.
The locations of the fire extinguishers must be marked in accordance with the symbol below. The location of the fire extinguisher can be indicated with additional signs. The organisation should maintain an overview (evacuation floor plan) containing the numbers, locations and types of extinguishers. Fire extinguishers that are placed outdoors, must be provided with a fitting protection against degradation as a result of weather influences. Fire extinguishers that are placed in rooms with high volume of dust (carpentry shops) should be protected against this dust which might hinder the working of the extinguisher in case of an emergency.
Fire extinguishers that are intended for rooms in which the temperatures occur that are not in line with the usage temperature of the extinguisher, may be placed outside the rooms near each access.
Suspension height for a fire extinguisher
- For a portable extinguisher with a content of 4 kg or 3 litres or less, a maximum height will apply of 1.5 metres (X);
- For a portable extinguisher with a content of 5 kg or 6 litres or more, a maximum height will apply of 1.0 metres (X).
Using mobile fire extinguishers as a basic safety for large rooms
In storage locations and factory halls with a floor surface area greater than 2500 M² that have an open arrangement and have wide walking paths between racks, machines or such half of the required extinguishers may be replaced by mobile fire extinguishers.
The projection must be tested after installation:
- At final delivery;
- After intermediate changes.
The reports and the design of the conformity inspections must be stored in a logbook. This logbook should be available at all times to the users and be present in the building.