Tel: +44 (0) 1543 264 034 Fax: +44 (0) 1543 414 367

Automatic Fire Suppression Systems

Generally used for the protection of high risk or sensitive equipment, such as computer rooms, server rooms, IT facilities, telephone exchanges, or sub stations, electrical switch rooms, food processing environments or anywhere where flammable goods are either stored or produced.

Selecting the correctly engineered system and fire suppressant for a given risk is paramount. At the front end of any AFS system is the fire detection. Based on smoke detection, heat detection, flame detection, or an air aspirating system. Connected to which would be one of the following:

A correctly designed system is protecting the property 24 hours a day, 365 days a year. In the event that it needs to operate, fires are normally detected and extinguished in the shortest possible time with the minimum amount of damage, enabling the user to be back up and running in the shortest possible time frame.

The choice :-

Co2  (Carbon Dioxide) A naturally occurring gas at atmospheric pressure, stored as a liquid in high pressure cylinders, and conveyed to the risk location via pipe work and discharge nozzles. Co2 systems are suitable for unmanned areas. If installed in a manned situation then they need to be “locked off” when people are present. It is very effective on, both deep seated and surface fires. The amount of Co2 required needs to be calculated from the volume of the room or surface area of the risk (local application systems only). Co2 extinguishes the fire by smothering the fire in a blanket of Co2 preventing Oxygen from combining with the heat and fuel within the fire, and also by cooling.

HFC’s such as FM200

Sometime called “Halon replacements”. Such systems are very quick to discharge (normally less than 10 seconds) meaning that any fire is extinguished very quickly and efficiently with the minimum of damage to equipment and down time. These systems are suitable for normally occupied areas. Such systems utilise a fire suppressant that is stored as a liquid in the cylinder, on release it is conveyed to the discharge nozzle via pipe work, where it vaporises and permeates into all spaces within the risk area. These systems extinguish the fire chemically and also provide rapid cooling. The amount of agent required is calculated from the volume of the risk being protected.

Fire suppression systems utilising inert gas or gases, utilise a mix of inert gas that is naturally occurring in the atmosphere. This is stored in a cylinder or cylinders and on release, conveyed via pipe work to discharge nozzles. Inert systems are suitable for occupied areas. Oxygen is present in the atmosphere at 21%. Most carbonaceous fires will extinguish if the available Oxygen falls to 15%. Inert gas systems are designed to lower the available oxygen to below this level. The fire then is extinguished because it becomes starved of oxygen.

Water mist systems utilise water under pressure.

The most important component in the system is the nozzle that creates a fine droplet mist on discharge. This has the effect of absorbing much of the heat given off by a fire and also smothers the fire reducing the amount of oxygen able to recombine with the fuel and heat within the fireball.

These systems are very effective where flammable liquids are in use such as kitchen hoods, engine compartments and cooking ranges.

Pre-action valve set systems are used in such areas as computer rooms and IT areas where it is not possible to use a system as described above. It is normal to utilise smoke detection, via an AFS system control panel at the front end, which in turn is “holding” a pre action valve set shut. Connected to this valve is a dry sprinkler system what is installed above the risk. In the event that a fire is detected by one or more smoke detectors, the control panel signals the pre-action valve to open, allowing water to flood the pipe work up to the sprinkler head position. In the event that sufficient heat is generated under the sprinkler head, the sprinkler bulb fractures, and water is dispersed to extinguish the fire.

Sprinkler systems. There are many types of sprinkler systems in use, and they are all job specific, meaning that a considerable amount of information is required about the size \ shape of building, and what is to be stored in the building that could burn or pose a risk. Systems can be designed to suit residential premises through to heavy industrial risks. The total cost depends on the availability of a suitable water supply either derived from the “town main” if deemed adequate, or if not, via a storage tank and pump set / controls. A sprinkler system combines automatic fire detection with fire extinguishing and is very effective at controlling and extinguishing a fire, with the minimum of cost impact and down time.
 
Sprinkler Systems are widely used to protect buildings and the products stored from fire. They operate as both “fire detection” and “fire extinguishing” systems. The sprinkler head consists of a form of alcohol enclosed in a quartz bulb, which is in turn holding a seal in place stopping the water in the pipe that is under a small amount of pressure, from escaping. The alcohol expands at a predetermined temperature, shattering the quartz bulb. The seal falls away and water is discharged onto the seat of the fire. Should the fire spread, then further sprinkler heads will rupture, thereby bringing the fire under control with generally the minimum of fire damage to the building or goods stored within. Sprinkler systems can be specifically designed to cover a multitude of risks including

*          Commercial buildings, including shops, hospitals and hotels.
*          Warehouses.
*          Residential risks.
*          Industrial complexes including Petro Chem.
*          Sensitive areas such as IT \ Computer Rooms (via “pre action” valve sets operated by smoke detection systems as described above).

Sprinkler systems can be fed from the “Town Main” assuming the system pressure and water flow is sufficient. Or, if not sufficient, then via an on site storage tank, pump set and control gear. Systems are “Automatic” meaning that as soon as the sprinkler head has ruptured, water is released under pressure from the town main supply, or via the system pumps, if fitted.

 Fire fighting foam is sometimes added to a sprinkler system to improve the fire fighting characteristics. This is most beneficial in areas where flammable products are stored, one main benefit being that generally, owing to the “wetting effect” of foam, less water is required.