Sprinklers are the most effective way of fighting the spread of a fire in its early stages. And fighting a fire when it's small is the best way to prevent injury to people and damage to property.
According to the National Fire Protection Association (NFPA), when sprinklers are present, the chances of dying in a fire are reduced by one-half to three-fourths and the average property loss per fire is cut by one-half to two-thirds, compared to fires where sprinklers aren't present.
This quick course will:
- Give you an overview of the kinds of sprinklers and how they work
- Show you some conditions that can prevent sprinklers from working properly
- Debunk some common myths about sprinklers
Automatic sprinkler temperature ratings
The National Fire Protection Association's Standard 13 (NFPA 13) contains a temperature rating system for sprinklers. The appropriate temperature rating for the sprinklers at a particular location depends on the maximum expected ceiling temperatures. Selection of the proper temperature rating will reduce the possibility of premature opening of sprinklers.
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Frangible bulb sprinklers
A frangible bulb sprinkler has a liquid-filled glass bulb that holds the cap on the sprinkler orifice, preventing water flow. In case of a fire, as the temperature begins to rise, the liquid in the bulb expands. When the air temperature gets hot enough, the liquid expands to the point of breaking the bulb.
That lets the water pressure push off the cap. Water flows out of the orifice and hits the deflector. The deflector creates a spray that covers the specified area.
Automatic sprinkler guards
If a sprinkler is installed in a place where moving objects could strike and damage it, a sprinkler guard should protect it. For example, in a warehouse with rack storage, sprinkler guards can minimize damage from moving pallet loads.
Sprinkler guards can also protect people from injury in places with low clearance:
Photo courtesy of Schmidt Structural Products
Sprinkler guards minimize damage from moving pallet loads:
Impairments: Painted sprinklers
Painting a sprinkler can slow down the response to heat, interfere with free movement of the parts, and make the sprinkler inoperative.
Dried paint can seal the cap to the orifice, preventing the flow of water. Paint on a fusible link can prevent the solder from melting at the specified temperature. The only way to fix a painted sprinkler is to replace it with a new sprinkler with the same characteristics.
Painted sprinkler head:
Automatic sprinklers obstructions
When a sprinkler head activates, it's critical that the water reaches the burning material quickly. An obstruction not only impedes rapid water delivery—allowing a fire to grow—but also causes splashing and cooling that can prevent or delay additional sprinkler heads from opening.
A well-designed sprinkler system minimizes obstructions, such as:
- Building structures
- Bar joists
- Bridge strapping
- Electrical conduits
- Lighting fixtures
- Ventilation ductwork
- Cable trays
An obstructed sprinkler:
Defractor is above styrofoam ceiling:
Automatic sprinklers summary
Simply installing a sprinkler system doesn't guarantee adequate fire protection. To be effective, a sprinkler system must be properly designed, installed, tested, and maintained.
- Personnel must immediately replace any damaged sprinkler or any sprinkler that has discharged.
- The system's designers must choose the appropriate type and temperature rating.
- The system's installers must position the sprinklers properly.
- No one should ever paint a sprinkler.
- Nothing should block a sprinkler.
- Nothing should hang from sprinkler pipes.
We have trained field staff to evaluate the design, installation, and condition of sprinkler systems anywhere in the country. Water supply should adequately supply all sprinklers that operate during a fire, and provide enough water for fire department operations.
Report: Sprinkler Assessment Report