Sprinkler heads are the last line of defense in many commercial and residential structures with regards to fire protection and over the years, have developed suitable actuating mechanisms to accomplish this task. There are many different types of sprinkler heads that are specifically designed to provide spray coverage of fire suppressing water or foam, utilizing different methods and under differing circumstances. In this article you will see the types and intended uses of common sprinkler heads.
General sprinkler head information
- Automatic sprinkler heads for wet and dry systems are sealed with temperature sensitive materials; such as: a bursting tube or fusible link.
- They are purchased according to the desired temperature range they would be expected to function at. See the temperature chart below.
- Sprinkler heads come in various designs, coverage patterns, materials and finishes.
- Appropriate sprinkler head types are usually an engineered aspect of commercial/industrial buildings.
Sprinkler head temperature chart
|Operating Temperature||Glass Bulb Color||Fusible link color|
|135-170F / 57-77C||Orange(135)
|None / Black|
|175-225F / 79-107C||Yellow(175) Green(200)||White|
|250-300F / 121-149C||Blue||Blue|
|300F / 149C||Purple||Red|
|375F / 191C||Black||Green|
|475F / 246C||Black||Orange|
|625F / 329C||Black||Orange|
*Source – NFPA 2007
Sprinkler heads types
Glass bulb sprinkler heads
Glass bulb actuated sprinkler heads are filled with a liquid that will expand and burst when a certain temperature is reached. The color of the liquid inside the glass tube is indicative of the temperature range in which it will function and release water onto the heat source.
Fusible link sprinkler heads
Sprinkler heads using a fusible link operate using metals with relatively low melting points. Typically two independent pieces of metal are fused together with a metal such as Wood’s metal that has a melting point of 71C. When the fusible alloy reaches its melting point the the two pieces of metal will separate and the sprinkler head will function.
Pendant type sprinkler heads
Pendant sprinkler heads drop down from the pipe and provide fire suppression to an area below. The deflector of a pendant sprinkler head will typically be slightly convex or flat.
Upright sprinkler heads
Upright sprinkler heads, as the name implies; are connected to the top side of the pipe and have a concave deflector that directs the flow of water below.
Side wall sprinkler heads
Sidewall sprinkler heads are designed to be placed along a wall and have a defector that creates a semi-circular spray pattern.
Open orifice sprinkler heads
Open orifice sprinkler heads are only used in Deluge sprinkler systems. Their design is nearly identical to other sprinkler heads minus the bursting tube and plug.