Flow sensor and fire detection system utilizing same
First Claim
1. In a fire sprinkler system having a water pipe and a sprinkler head connected to said water pipe, a water flow sensor unit mounted on said pipe upstream of said sprinkler head for detecting water flow to said sprinkler head, said sensor unit comprising a sensor support, said sensor support being adapted to experience movement during water flow in said pipe, a sensor mounted on said sensor support and adapted to sense movement of said sensor support, a detector circuit connected to said sensor and responsive to sensing by said sensor of movement of said sensor support caused by water flow in said pipe to produce a detector signal, and a processing circuit for processing said detector signal to produce an alarm signal when said detector signal meets selected criteria.
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Accused Products
Abstract
In a fire sprinkler system, flow sensors are used having strain gauges mounted on supports which project into the sprinkler pipes. When water flow occurs, the supports bend, changing the strain gauge resistance and producing a signal which can be analyzed to indicate which sprinkler heads are open. Since there are no mechanical switches, the sensor units are much smaller and cheaper than previously, and provide more information. A strain gauge can also or alternatively be located outside the pipe to detect vibration caused by flowing water. As an alternative to strain gauges, piezo film can be used, with a vibration analyzer to analyze the signal from the film to determine whether water flow is occurring and which sprinkler heads are open. A piezo film can also be placed on the pipe exterior and the signals from the two piezo films can be applied to differential inputs of a differential amplifier, to cancel signals caused by external influences such as pipe vibration. A thermistor can also be used to sense water flow, using temperature changes when the water begins to flow.
32 Citations
23 Claims
- 1. In a fire sprinkler system having a water pipe and a sprinkler head connected to said water pipe, a water flow sensor unit mounted on said pipe upstream of said sprinkler head for detecting water flow to said sprinkler head, said sensor unit comprising a sensor support, said sensor support being adapted to experience movement during water flow in said pipe, a sensor mounted on said sensor support and adapted to sense movement of said sensor support, a detector circuit connected to said sensor and responsive to sensing by said sensor of movement of said sensor support caused by water flow in said pipe to produce a detector signal, and a processing circuit for processing said detector signal to produce an alarm signal when said detector signal meets selected criteria.
- 13. In a fire sprinkler system having a water pipe and a sprinkler head connected to said water pipe, a water flow sensor unit mounted on said pipe upstream of said sprinkler head for detecting water flow to said sprinkler head, said sensor unit comprising a sensor support, a thermistor mounted on said sensor support and projecting into said pipe, a detector circuit connected to said thermistor and responsive to variations in water temperature sensed by said thermistor resulting from water flow in said pipe to produce a detector signal, and a processing circuit for processing said detector signal to produce an alarm signal when said detector signal meets selected criteria.
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15. A sensor for sensing a fluid flow in a conduit, the sensor comprising:
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a) a sensor base adapted for connection to said conduit;
b) a flexible stem connected to said sensor base, said stem being adapted to experience movement during said fluid flow in said conduit, said stem comprising a piezo film adapted to produce a voltage upon movement of said stem; and
c) a floater connected to a distal end of said stem, said floater comprising a counterweight located at a tip of said floater. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification