Inventors:
George L. Britton - Yellow Springs OH
David A. Ratino - Mesa AZ
Alfred W. Peterman - Dayton OH
International Classification:
G01M 308
Abstract:
A pipe flow detector for activating a solenoid to automatically close a pipe shutoff valve in the event of a leak. The detector comprises a piezoelectric film transducer attached to the pipe, the transducer producing a fluctuating electrical signal in response to pipe vibration. An amplifier amplifies the signal, which is then passed to a tunable low-pass filter. The output from the filter is passed to an averaging circuit to produce an electrical signal representative of the total voltage changes of the fluctuating electrical signals. An LED is connected to the output of the averaging circuit to provide a means to tune the filter. The filter may be tuned by: (a) providing a pipe flow substantially equal to the pipe flow that would occur in the presence of a leak and tuning the filter to provide the brightest output of the LED; (b) starting and stopping pipe flow and tuning the filter to a point where an output of the LED is generally present only in the presence of a flow; or, (c) externally causing a starting and stopping pipe vibration and tuning the filter to a point where the LED generally does not become brighter in response to the externally caused pipe vibration. During unattended operation, the averaging circuit output is passed through an RC timing circuit that passes the averaging circuit output after a preselected period of time. A latchable level detector receives the timing means output and, when a high enough signal level is received, sends a signal to a solenoid driver which drives the solenoid.