WATER BASED FIRE EXTINGUISHING SYSTEMS

Sprinkler systems are used for automatic fire fighting, to protect life and property. The operating principle is straightforward and reliable. These systems utilize the inexpensive and readily available medium of water to discharge onto flames through a normally fixed piping system. There are 4 main types of water based protection systems. The hazard / risk to be protected will determine the most suitable type of system you need.

In the case of sprinkler systems, the pipe networks are equipped with sealed nozzles that open individually when heated and the fire water spray is targeted to the fire source. You can fight or extinguish the fire directly at the source as a result of the resulting cooling effect of water evaporation and the subsequent exclusion of air due to the mist. An extinguishing operation is triggered in case of a temperature rise directly at the sprinkler head. This is achieved by the expansion of a liquid or by the separation of a solder joint. The response sensitivity can be influenced by the design of the sprinkler. An extensive pipeline network with a closed extinguisher nozzle protects the relevant areas. An adequate water supply is provided from compressed air containers, elevated tanks, mains water, master or intermediate containers with pump systems or various combinations of the systems stated above.

In case of fire, one or more sprinklers in the fire area open automatically as a result of the heat. The extinguishing water escapes under pressure and is sprayed on a sprinkler plate; it is then distributed as parabolic drizzle on the fire. In parallel to the opening of the sprinkler an alarm bell and an alarm message will be triggered. Depending on the version of the system, the extinguishing water is first supplied via a compressed air water tank. If the pressure drops, the sprinkler pump is switched on, which pumps the extinguishing water from a water tank.

Wet systems are installed area not at risk from frost or overheating. Compared with dry plants they have a shorter delay up to the beginning of the extinguishing process. However, it must be ensured that the ambient temperature does not drop below 5°C. In standby mode the entire pipe network is filled with water under high pressure (10 bar). When a sprinkler is opened, water comes out immediately.

Dry systems are installed in frost-prone areas (such as garages or canopies) and high-temperature rooms (e.g. dryers). In standby mode the pipe network is filled by the sprinklers with compressed air up to the alarm valve. A sprinkler opens due to the heat, the pressure drops in the pipe system, the alarm valve opens and floods the pipe network. This frost resistance is at the price of a prolonged reaction time of sprinkler systems in the event of fire.

Deluge fire protection systems are engineered with water spray nozzles connected to a fire water piping system as open-ended sprinklers. The mechanical heat sensing element common to sprinkler systems is removed, and replaced by a fire detection system, engineered to be fit-for-purpose to specific areas. Common applications include power generation equipment (e.g. transformers), belt conveyors, flammable liquid storage, oil and diesel tanks and process plants. Fire suppression is achieved by the use of medium or high velocity water spray nozzles, which can be activated manually or automatically by means of hydraulic, pneumatic or electrical fire detection systems.

These systems require independent detection systems to be used in conjuction with closed pipe sprnkler systems. The detection system may be hydraulic, pneumatic or electric, and may be actuated by smoke, heat, optical detectors, or be manual actuation. Detection systems typically operate before the sprinklers fuse and give an alarm. Preaction systems are usually supervised with air pressure. The purpose of the supervision is to monitor the integrity of the system. If the sprinkler head is broken or fused, or the piping is network is broken, the pressure will be reduced in the piping and an alarm will sound. There will also be an alarm due to low air supply pressure. There are several types of Preaction Sprinkler Systems.

            1. Non-Interlock
An automatic sprinkler control valve (typically a deluge valve) is activated, by either a sprinkler head opening or the detection system activating. Water is discharged into the piping and is discharged out of the now open sprinkler (if it has opened).

            2. Single-Interlock
The detection system activates the automatic sprinkler control valve (deluge valve), allowing water to flow into the piping system. However, if no sprinklers have activated the water remains in the piping without discharging. If sufficient heat is created by the fire, on or more sprinkler heads will activate. This wil allow the water to flow our of the sprinkler and begin to control or extinguish the fire. In addition to a sprinkler opening, a supervisory signal is provided to the control panel indicating a loss of air pressure.

            3. Double-Interlock
Water is only discharged after two operations have occurred. Both a sprinkler head must open (loss of air pressure) AND a detection device must activate. When both of these things have occurred, then and only then with the automatic sprinkler control valve (deluge valve) open and begin discharging water into the piping system.