Ultrasonic leak detecting apparatus

Abstract

An ultrasonic leak detector with a wide dynamic bandwidth and repeatable fixed attenuation reference points includes a transducer which receives ultrasonic energy and converts it into an electrical output signal related in intensity and frequency to the received ultrasonic energy. A high gain charge preamplifier is connected to the transducer and generates an amplified version of the transducer's electrical output signal. The amplified signal is then passed through a multi-level logarithmic attenuator having at least one fixed attenuation reference point to create an attenuated version of the detected and amplified ultrasonic signal. The output of the logarithmic attenuator is connected to a frequency shift circuit which converts the ultrasonic frequency signal into an audio frequency signal related in magnitude and frequency to the attenuated signal. The audio frequency signal is then amplified by an audio amplifier and used to drive a signal level indicator which provides an indication of the magnitude of the amplified output signal. The detector may be used with a lubrication tool to determine the amount of lubrication applied to a sealed mechanical device, such as a bearing, by detecting the decrease in received ultrasonic energy as the lubrication reaches the device. The detector may also be used to detect the increase in ultrasonic energy associated with pending mechanical failure.