Typical Sprinkler Water Supply
Here’s what you’ll have with a typical stand-alone fire sprinklers. The water supply for the sprinklers comes from the household water main. There will be a “T” connection between the main and the water meter, feeding the sprinklers. This is called the “riser.”
The riser is really the brains of the layout. It includes the pressure gauge, a flow switch and a backflow valve (where required) and the test and drain assembly. NFPA 13D doesn’t require a flow alarm, but your local codes might.
The flow switch monitors any water flow through the fire sprinklers and is wired to an inside bell. The flow switch can be wired to an outside horn or strobe to alert neighbors to sprinkler activation in case fire strikes when no one is at home. The switch can also be tied in to a monitored security system.
Backflow prevention devices are installed to isolate the water used for sprinklers from the water used for domestic purposes, to prevent any cross-contamination of potable water. Many local jurisdictions require these.
Backflow prevention devices and water meters reduce the available pressure for the sprinklers, however, so when they are used it is necessary to use larger water taps and meters of at least one inch or more. Your sprinkler contractor will ensure you have the information you need to know about taps and meters before you install the system.
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