Types of Sprinklers: Commercial
Industrial/commercial sprinklers can be divided into three basic categories. They are Control-mode density area (CMDA), control-mode specific application (CMSA), and suppression-mode. Within these categories, sprinklers can be made in three orientations: upright, pendent, and sidewall.
Control-mode density area sprinklers are the oldest form of fire protection sprinklers. Their evolution over the years has changed their size and shape, but their function has remained basically the same since the nineteenth century. They control a fire though a combination of pre-wetting combustible material on the periphery of the fire and cooling hot gas from a fire at the roof or ceiling. Very little, if any, of the water from the sprinklers actually penetrates the flames. If the sprinkler design is adequate for the occupancy being protected, the pre-wetting limits the fire spread while the cooling effect maintains structural stability until the fire is extinguished by firefighters. This type of protection, while less expensive than others, is limited to the hazards it can protect against and results in larger areas of fire, smoke, and water damage that newer sprinkler technology. Designs for this sprinkler are specified in terms of a discharge density over a sprinkler operation area.
Control-mode specific application sprinklers are a newer technology that also control fire in the same manner as control-mode density area sprinklers. These sprinklers were originally developed to provide control for high-hazard type occupancies, such as storage. Sprinkler system designed for this sprinkler type is specified in terms of the number of sprinklers expected to operate during a fire at a given minimum required pressure.
Suppression-mode sprinkles represent the newest technology, and were specifically developed to protect storage without the need for in-rack sprinklers. Through a combination of increased sensitivity and a highly engineered, high-momentum water discharge, they respond while a fire is small, and suppress its growth, reducing fire and non-thermal damage. While offering obvious advantages, this type of sprinkler requires careful design and installation; otherwise, the sprinkler performance could be crippled. Sprinkler system designs for this sprinkler type are also classified by a number of sprinklers expected to operate during a fire at a given minimum required pressure.
Upright Sprinklers-are designed for installation on the top of sprinkler piping, with the deflector positioned above the orifice. This is the most common orientation for control-mode sprinklers.
Pendent Sprinklers are installed on the underside of piping, with the deflector located below the orifice. This orientation is most common for suppression-mode sprinklers. This type of sprinkler is not commonly used in either dry or preaction-type systems because of the inability to completely drain the water that would accumulate directly above the sprinkler. This would expose the sprinkler potential freeze damage or the internal piping of the sprinkler to iron oxidation. In addition, this type of sprinkler is not commonly used when the water source for fire protection is from an open body of water, wherein sediment and other foreign material can enter the sprinkler system and potentially settle on top of the sprinkler.