Basic about Fire sprinkler head

 Basic about Fire sprinkler head

A fire sprinkler or sprinkler head is the component of a fire sprinkler system that discharges water when the effects of a fire have been detected, such as when a predetermined temperature has been exceeded. Fire sprinklers are extensively used worldwide, with over 40 million sprinkler heads fitted each year.

Sprinkler heads feature a glass bulb filled with a glycerin-based liquid. This liquid expands when it comes in contact with air heated to between 135 and 165 degrees. When the liquid expands, it shatters its glass confines and the sprinkler head activates.

Sprinkler heads must be a maximum of 12-15 feet apart, depending on the hazard rating of the space (it ranges from Light Hazard to Extra Hazard 1&2), and at least half that distance from the nearest walls (typically 7.5 feet away).

Orifice (Opening)

The orifice varies in size, but has a major impact on the sprinkler's k-factor which ultimately governs the sprinkler's relationship between flow and pressure. Opening sizes vary fairly dramatically but in general are not a major driver for sprinkler selection.

Threading

The nominal threading sizes range in quarter-inch increments from 1/2-inch to 1-1/4-inch (although some dry pendent shafts do have 1-1/2-inch threads). Thread size of sprinklers can be gathered in the field simply by measuring the diameter of the thread shaft. Sprinklers with a k-factor greater than 5.6 are no longer allowed to have thread sizes of 1/2-inch (NFPA 13 2002-2016 Section 8.3.5).

Plug

The plug retains the water (and pressure) within the sprinkler and pipe network. Breakage of the liquid-filled glass bulb results in the release of the plug, and thereafter the water.

Sealed Liquid-Filled Glass Bulb

Modern commercial sprinklers mostly rely on the colored glass bulb as the thermal sensor in the fire sprinkler, but other types are still frequent as well. Color of the liquid within the bulb indicate the listed activation temperature of the sprinkler (and can be found in NFPA 13 2002-2016 Table 6.2.5.1).

Frame & Deflector

The frame can have many finishes, of which some of the more common are listed above. The deflector offers the basic premise of the fire sprinkler - which is to distribute water in a specific pattern to best combat a fire hazard within an enclosure. Deflectors vary depending upon the style of the sprinkler and work to achieve different objectives. A residential pendent, for example, throws water with greater emphasis to the walls and ceiling where hazards are more commonly present in residential occupancies.