Sprinkler Waterflow Alarm
NFPA 13, Standard for Installation of Sprinkler Systems, requires a local waterflow alarm on every sprinkler system with more than 20 sprinklers. The purpose of this waterflow alarm is not to provide occupants notification, but rather to provide outside building notification that the sprinkler system has been operated. Annex A of NFPA 13 recommends approved identification signage near the waterflow alarm device that asks people to call the fire department or police when the bell rings.
(from NFPA 13, A.8.17.1)
The local waterflow alarm requirement may be accomplished by a water-driven bell, commonly called a water-gong, or an electrically operated notification appliances triggered by a waterflow detection device on the sprinkler system. If electrically operated waterflow detection is used, the type of waterflow detection device will vary based on the type of system being indicated. Paddle-type waterflow devices are only permitted on wet sprinkler systems, while dry, preaction, and deluge systems will typically use a pressure type waterflow device.
If an electrically operated waterflow device is used, the device may be connected to a fire alarm system or operate as a standalone device driving an outdoor notification appliance. If the electrically operated waterflow is not part of fire alarm system, it is not required to supervised, but the wiring requirements are governed by NFPA 70 (National Electrical Code), Article 760. If is part of a fire alarm system, the installation must comply with NFPA 72 (National Fire Alarm and Signaling Code). In either case, the outdoor notification appliance used must be listed for outdoor use.
While driving a sprinkler waterflow alarm device from a fire panel does provide advantages (circuit supervision, secondary power), the life safety or building code may also require an interconnection between the systems. The International Building Code (IBC) requires that all sprinkler systems be supervised by the fire alarm system for waterflow and control valve position, and the Life Safety Code (NFPA 101) requires it for some systems. Where interconnection is required in either of these codes, the system requires monitoring by a supervising station as well. The monitoring provides off-premise notification of sprinkler system activation as well as local indication.