Fire suppression is a blanket term used to describe the systems in place to suppress and extinguish a fire. Methods will vary depending on the property and any pre-identified fire risks.
How Fires Begin
In order to understand how fire suppressions work, it is helpful to know how fires occur in the first place. The fire triangle - which consists of three elements: Fuel, oxygen and heat - is a useful model used to demonstrate the chemical reaction and elements required for a fire to begin.
Fuel can be any type of combustible material, for example grease within a restaurant's kitchen or fabrics within a retail clothing store. When designing a new system for a premises, the moisture content, size and shape of any potential fuel must be taken into consideration. For example, flammable liquids may require foam suppression to suffocate flammable vapours and prevent re-ignition, whereas an electrical source may require C02, which replaces oxygen to suffocate the fire without damaging equipment.
Fire ignition occurs when combustible materials reach a certain temperature. Highly flammable materials such as petrol and industrial solvents will ignite at lower temperatures than less flammable materials such as wood and paper. Once a fire has taken hold, the increased presence of heat removes moisture from nearby fuel, which becomes more flammable, helping the fire to grow.
Oxygen is the final element required for a fire to take place and acts as the oxidizing agent.
Since each of the elements within the fire triangle are required for a fire to begin and continue, removing one of these elements will result in fire extinguishment while weakening one of these elements will result in fire suppression.
Method of fire suppression
Fire suppression systems are carefully designed to weaken and remove the elements needed for a fire to continue. The method of suppression will vary depending on a combination of factors which should be taken into consideration during the initial fire risk assessment.
Automatic fire suppression, such as a water sprinkler or gas system, greatly improve a properties level of fire protection as the need for human intervention is replaced with detection devices that can instantly identify a fire and respond immediately.
If smoke or heat are detected within a room, the system will be activated and begin suppressing the fire. Sprinkler systems can utilise either water, gas or a chemical agent to control the fire.
Water systems
Water systems can be used for most classes of fire to reduce heat, displace oxygen and control the fuel source. Water droplets are used to absorb and evaporate heat in the form of steam. Water droplets also saturate the air, helping to displace oxygen and also add moisture to nearby fuel which has not yet combusted, reducing its flammability.
Water mist systems create smaller droplets that have more surface area than systems that produce droplets, resulting in more evaporation and further heat reduction. Mist systems also use less water which means reduced damage to any valuable assets within the property. Mist systems require higher pressure than traditional systems and the correct nozzle design and pressure are essential to create the correct sized droplets.
Chemical Systems
In some instances, water from a sprinkler system may cause more damage to the property and its assets than the fire, even then a water mist system has been installed. In cases such as these, a chemical system may be more appropriate in order to protect valuable assets, such as works of art or electronics.
Extinguishers & Fire Blankets
In addition to automatic sprinkler systems, fire extinguishers and fire blankets can be used to manually suppress a fire. Similar to sprinkler systems, fire extinguishers use a range of substances to suppress the fire depending on the environment as fire risk. Fire blankets are used to remove oxygen and suffocate the fire.
Installing the right system
At Sygma Fire Services, we have specialist knowledge in the design and implementation of water mist suppression systems and gas suppression systems to protect your building, assets and people against the risk of fire.
We can assist with the implementation of the suppression system during the construction of the building, or more commonly, assist with the retro-fit solution to enable a building to be protected by suppression post construction.
