Fire suppression

[edit] Introduction

Buildings need to be designed to offer an acceptable level of fire safety and minimise the risks from heat and smoke. One fire safety objective is to protect the occupants and others who may become involved, such as the fire and rescue service. Also crucial are protecting contents and ensuring that as much as possible of a building can continue to function after a fire - and that it can be repaired. The risk to adjoining properties also needs to be considered, as well as possible environmental pollution.

[edit] Different aspects of fire safety

There are several terms used to describe different fire safety measures. While there may be some overlap, they are primarily categorised as prevention, protection and suppression.

[edit] Prevention

Fire prevention is defined as proactive measures that are designed to minimise hazards. Part 3 of Schedule 1 of The Regulatory Reform (Fire Safety) Order 2005 specifies some of the principles of prevention, including:

• Avoiding risks.
• Evaluating the risks which cannot be avoided.
• Combating the risks at source.
• Adapting to technical progress.
• Replacing the dangerous with the non-dangerous or less dangerous.
• Developing a coherent overall prevention policy which covers technology, organisation of work and the influence of factors relating to the working environment.
• Giving collective protective measures priority over individual protective measures.
• Giving appropriate instructions to employees.

[edit] Protection

Fire protection reduces damage and helps to safely evacuate a building. This means identifying risks and designing safeguards that help prevent and control the effects of fire.

The Building Regulations Part B: Fire Safety, addresses precautionary protection measures necessary to provide safety from fires for building occupants, persons in the vicinity of buildings, and firefighters. Requirements cover; means of escape, fire detection and warning systems, the fire resistance of structural elements, fire separation, protection, compartmentation and isolation to prevent fire spread, control of flammable materials, and access and facilities for firefighting.

[edit] Suppression

Finally, fire suppression systems are those measures that are used to contain and extinguish fires. These systems are primarily designed to control flames and prevent their ability to spread.

[edit] Fire suppression systems

Fire suppression is an active containment measure that operates - either manually or automatically - only when fire is present.

There are many different types of fire suppression systems, including fixed components (such as sprinklers) or portable equipment (such as extinguishers):

• Water. By deploying large quantities of water, a fire suppression system can lower ignition temperatures and suppress combustion.
• Chemical agents. Fire extinguishers use different types of active chemical compounds to suppress fires. See Fire extinguishers
• Inert gases. These substances remove the flow of oxygen to flames. One inert gas used in fire suppression is the clean agent known as Inergen, which uses components such as nitrogen, argon and carbon dioxide. Clean agents used in engineered fire suppression systems engulf the entire space and suppress flames without harming the people or equipment in the environment. Pre-engineered systems are designed to accomplish the same purpose, but they work in smaller spaces or in targeted areas that contain specific hazards. Carbon dioxide is also used on its own in fire suppression.

The suitability of different fire suppression systems tends to depend on the type of fire exposure or risk that is to be expected within a structure. For instance, certain fire extinguishers may be designed to protect against specific hazards or materials. These extinguishers are colour coded to indicate what type of fire they should be used to extinguish.

See Extinguishment.

[edit] Fire suppression operations

Fire suppression operations are classified as either offensive or defensive:

• Offensive measures occur when a fire suppression system is activated or when fire and rescue services advance with hoses into a building. This direct approach is used when there is a chance that people may be alive inside the building, and the structure is still considered safe enough to enter.
• Defensive suppression operations occur when fire services operate away from the fire at a safe distance - either by directing water streams from the ground or deploying suppression agents by air. This approach is meant to isolate the fire to prevent it from getting worse, although it may mean the the building itself - cannot be saved. Its purpose is to protect fire and rescue services as well as people and other buildings that may be nearby.

[edit] Related articles on Designing Buildings Wiki

• BS 9999: Code of practice for fire safety in the design, management and use of buildings.
• CIBSE updates Fire Safety Engineering guidance.
• Extinguishment.
• Fire protection engineering.
• Fire retardant.
• Fire safety design.
• Flame retardant.
• Managing fire risk in commercial buildings: A guide for facilities managers
• Sprinkler.
• Sprinkler systems explained: A guide to sprinkler installation standards and rules.
• The role of codes, standards and approvals in delivering fire safety.