An automatic sprinkler system is intended to detect, control and extinguish a fire, and warn the occupants of the occurrence of fire.
The installation comprises fire pumps, water storage tanks, control valve sets, sprinkler heads, flow switches, pressure switches, pipework and valves. The system operates automatically without human intervention. The sprinkler head has a liquid filled glass bulb that breaks due to the heat of the fire and releases water that sprays over the fire. The various types of sprinkler systems are as follows:
- Wet pipe installation where the pipework is filled with water and ready to discharge once the sprinkler bulb breaks.
- Dry pipe installation where the pipe is always filled with air under pressure. Air is released when the sprinkler bulb breaks and water fill the pipe and is discharged at the sprinkler head.
- Pre-action installation where the pipework is normally charged with air under pressure and a valve is opened to fill the system with water when fire is detected by smoke or heat detectors. Water is discharged only when the sprinkler bulb breaks.
- Deluge installation where the sprinkler head has no bulb and water is discharged simultaneously from all heads when fire is detected and the deluge valve is opened.
The wet pipe installation is the most common type. Sprinklers installed at 17 meters and above the floor to be protected are no longer effective and alternative solutions such as early response sprinkler heads, large droplet sprinkler heads or deluge systems have to be considered.
Fig 1 – up right sprinkler head with operating temperature range of quartz bulb
Difference between sprinkled and non-sprinkled building