UL Standard for Safety Waterflow Indicators for Fire Protective Signaling Systems (Fifth Edition; Reprint with Revisions Through and Including October 30@ 2014)
These requirements cover vane type waterflow indicators intended for use in fire protective signaling systems to be employed in ordinary indoor locations@ in accordance with the National Fire Alarm Code@ NFPA 72. Waterflow indicators covered by these requirements include sizes 3/4 inch and larger. The indicator sizes refer to the nominal inside diameter of the main sprinkler pipe or tubing on which they are installed. A vane type waterflow indicator is an assembly of a mechanism having electrical contacts arranged to transmit a coded or noncoded signal when the vane@ located in the supply pipe (riser) of a sprinkler system@ is moved by the flow of water in the pipe. This flow is normally caused by the opening of one or more sprinkler heads resulting from a fire condition. The signaling contacts are intended to be connected to circuits of private fire protective signaling systems. These requirements do not cover pressure-operated waterflow indicators.