11-Fire Protection System

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FIRE PROTECTION SYSTEM

Fire sprinkler system is an activefire protection measure, consisting ofa water supply, providing adequate

pressure and flow rate to a waterdistribution piping system, ontowhich fire sprinklers are connected.

Although historically only used in

factories and large commercialbuildings, home and small buildingsystems are now available at arelatively cost-effective price.


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HISTORY: From 1852 to 1885, perforated pipesystems were used in textile millsthroughout New England as a means offire protection. However, they were notautomatic systems; they did not turn on bythemselves.

Inventors first began experimenting withautomatic sprinklers around 1860. The firstautomatic sprinkler system was patentedby Philip W. Pratt of Abington, MA, in1872.


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HISTORY:

Henry S. Parmalee of New Haven,Connecticut is considered the inventor of

the first automatic sprinkler head. Until the 1940s, sprinklers were installedalmost exclusively for the protection ofcommercial buildings. Over the years, fire

sprinklers have become mandatory safetyequipment, and are required by buildingcodes to be placed in hospitals, schools,hotels and other public buildings.


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TYPES:

Wet pipe systems:

An automatic water supply provides water

under pressure to the system piping. All ofthe piping is filled with water. Untilsufficient heat is applied, causing one ormore sprinklers to fuse (open), theautomatic sprinklers prevent the water

from being discharged.


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TYPES:

Dry pipe systems:

Water is not present in the piping until the system

operates. The piping is pressurized with air, at a"maintenance" pressure which is relatively low

compared with the water supply pressure.

To prevent the larger water supply pressure from

forcing water into the piping, the design of the drypipe valve (a specialized type of check valve)intentionally includes a larger valve clapper areaexposed to the maintenance air pressure, as

compared to the water pressure.


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TYPES: Deluge System:"Deluge" systems are systems that have opensprinklers, i.e. the heat sensing operating elementis removed during installation, so that all

sprinklers connected to the water piping systemare open.Water is not present in the piping until the systemoperates. Because the sprinkler orifices are open,the piping is at ambient air pressure. To prevent

the water supply pressure from forcing water intothe piping, a deluge valve is used in the watersupply connection, which is a mechanically latchedvalve. It is a non-resetting valve, and stays openonce tripped.


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SPRINKLER HEADSA sprinkler head will spray waterinto the room if sufficient heatreaches the bulb and causes it toshatter. Sprinkler heads operate

individually. Note the red liquid in theglass bulb.

Each closed-head sprinkler is heldclosed by a heat-sensitive devicecalled a fusible link. The link applies

pressure to a seal which preventswater from flowing until the ambienttemperature around the sprinklerreaches the design temperature ofthe individual sprinkler head.


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TYPICAL DIAGRAM

11-Fire Protection System

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