An automatic fire sprinkler system head is a valve, in broad terms there are two types of sprinkler heads. All valve type sprinkler heads contain a heat-sensitive element and plug to control the flow of water;
There is a third type of sprinkler head that strictly speaking is not a valve. These fire sprinkler heads are the open type. An open type sprinkler head does not contain a temperature sensitive element or plug. This type of sprinkler head is associated with deluge fire sprinkler systems. The purpose of these sprinkler head is to distribute water according to the water spray pattern of the head.
The glass bulb for an automatic fire sprinkler head is the active component that breaks when it reaches its nominal operating temperature. There are generally two sizes of the glass bulb;
Due to thermal conductivity, the thinner (3mm) quick response will respond more quickly to a rise in temperature and operate more quickly than the 5mm standard response.
The glass bulb or fusible link in an automatic fire sprinkler system is calibrated to operate at a designated temperature. Sprinkler heads are selected and installed taking into consideration the use, location and typical ambient operating temperatures.
The Australian Standard AS 2118.1 states that the temperature rating chosen shall be not less than 30ºC above the highest anticipated temperature conditions except under specific conditions;