Emerson Electric Company

David J Nelson

Laurence S Slocum

Michael T Clouser

A line leak test probe for use on a liquid conduit. A pressure transducer is mounted in mechanical contact with the liquid in the conduit and a temperature transducer is mounted in thermal contact with the liquid. The transducers provide signals to a microprocessor-based circuit which includes a timer. Software stored in the microprocessor analyzes the time rate of change of the pressure to determine if there is a leak. Normally a sequence of three tests are performed: a catastrophic test, a gross test, and a precision test. The catastrophic test exits to the gross test if the rate of change of the pressure is less than a first rate, and the gross test exits to the precision test if the rate of change is less than a second rate which is less than the first rate. The precision test normally cycles until the pressure drops below 4 psi, and then outputs a leak signal if the pressure drops to below 3 psi in 12 minutes or less. If the temperature change during the test is sufficient to account for the pressure change, or the temperature is out of a range where it can be measured, the test aborts without outputting a leak signal.

Line leak test apparatus measuring rate of pressure change in a liquid

A line leak test probe for use in a liquid storage and dispensing system which includes a pump. The probe is electrically connected to a central monitor. A pressure transducer may be mounted in mechanical contact with the liquid to provide a pressure signal to a microprocessor-based circuit which disables the pump when a leak is detected. An manually operated reset switch is electrically connected to the reset input of the microprocessor through an inverter. Manually pressing the reset switch causes the microprocessor to shut off causing the central monitor to output an error signal. The monitor may be programmed to either enable or disable the pump in response to the error signal. Thus, by programming the monitor to disable the pump, the user may prevent the system from being abused by the placing of a brick or other object on the reset switch to continuously provide a reset when there is a leak. When the reset switch is released, the microprocessor turns back on and resets itself.

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Indianapolis, IN, United States of America

David J Nelson