Ultrasound sensing for industrial maintenance relies on a piezoelectric device measuring vibration in the 20 to 100 kilohertz (khz) range. This is above the range of the human ear. The basic ultrasound instrument takes this frequency and converts it to the 200 to 2000 hertz range which a human can detect with a set of ear phones. All models come with a head set.

The sensing probes are designed for specific applications, to minimize the impact of stray noise. The most frequent application of ultrasound measurement are: 1. bearing noise; 2. gas leaks from pressure lines or vessels; 3. leaks from vacuum lines or vessels; 4. corona discharge from high voltage electric lines. Different adaptors are available to channel the sound wave to the sensor.

1. Bearing noise is usually detected with a sensor held close to the bearing housing. This requires a short, small diameter sensor. 2 & 3, Measuring the sound of gas leaving or entering a container needs a short cone shaped adaptor if the detection is performed close up. If measured at some distance, a long cone is needed. 4. Corona detection is always performed at some distance. Here a long, cone shaped, adaptor is used.

Each manufacturer is offering special designs of the sensors and adaptors for different applications.

For ultrasound measurement, as is for all maintenance measurements, the question is, how is the information going to be used. A scheduled measurement with a handwritten note to be compared later for trends or a benchmark, is one way. Recording a reading by analog or digital signal is another. Sending a signal by wire or transmitter is a third method. For preventive maintenance, any of these methods will be sufficient. To get started with predictive maintenance will require a digital signal of a certain format that can be fed into a software program.

All models displayed are the basic models. Adaptation for specific applications are given by the manufacturers.