Types of fire sprinkler heads

While all types of fire sprinklers bear a close resemblance to one another, different fire sprinkler heads are designed for different environments and different applications, and require careful consideration. All fire sprinklers are one of four types: pendent, upright, sidewall, or concealed.

Sprinkler systems are broken down into two system designs: pipe schedule system and hydraulic designed system. Both designs include four types of systems: wet pipe, dry pipe, pre-action and deluge.

Wet pipe systems are the most common type of fire sprinkler systems. These systems are filled with water from an automatic source, and when a sprinkler head is exposed to enough heat, the heat-sensitive element will release and water will be allowed to flow from that sprinkler.

With the wet-pipe system (Figure 13-4), water is in the pipes at all times and is released when heat ruptures the seal in the sprinkler head. This is the most common system and is applicable where freezing is no threat to its operation.

on fire, electrical and related hazards

►Sprinklers operated effectively in 88% of the fires large enough to activate them. Reported sprinkler failures (660 per year) were twice as common as reported fires in which sprinklers were ineffective and did not control the fire.

Inadequate performance by the sprinkler system itself.

Although considered reliable, sprinkler system components can fail and adversely affect the operation of the entire system. Data has shown that these types of failures are a very small fraction of the overall reasons for failure.

How many fire sprinklers will activate when there is a fire? Only the sprinklers in the room or area of the fire will activate. Based on residential fire sprinkler designs, most rooms will have two sprinkler heads activate.

At different pressures, the sprinkler head and nozzle will consume different amounts of water. For example, at 35 pounds per square inch (PSI) the 5000 Series Rotor using the 3.0 nozzle will use 3.11 gallons per minute (GPM). If your home’s water capacity was 10 GPM, you could place 3 heads per zone.

main. necessary, lines shall be permitted to be increased to nine sprinklers by making the two end lengths 1 in.

Most residential sprinkler heads are designed to flow between 10 and Page 3 13 gallons per minute. Generally, a fire hose will flow an average of 100 gallons per minute.

Residential Sprinklers

The Sprinkler-Driven minimum flow becomes Q = k√P = 5.8 x √7.6 = 16.0 gpm. Assuming an NFPA 13 design, the Density-Area minimum flow becomes Q = 0.10 gpm/sqft x (12 ft x 12 ft) = 14.4 gpm.

The k–factor for a fire sprinkler is the discharge coefficient, or in normal human terms just relates to the amount of water that is permitted through the sprinkler. The k–factor is dependent upon the orifice diameter of the sprinkler – a low k–factor (such as K2.

Fire flow = length X width ÷ 3

This formula is most easily applied if the estimated square footage of the entire structure is used to determine an approximate fire flow for the total structure and is then reduced accordingly for various percentages of fire involvement.

: the quantity of water available (as in a city) for fire-protection purposes in excess of that required for other purposes.

Needed fire flow (NFF) is the amount of water that should be available for providing fire protection at selected locations throughout a community. ISO has prepared a guide for estimating NFF. The publication requires knowledge and experience in fire protection engineering for its effective application.