Good Valve
Time Series View
The advantage of ultrasound spectral analysis is that the inspector can hear and see the sound sample as it plays.
Here is a typical good compressor valve. Note the distinct “open” “close” of the valve.
Bad Valve
Time Series View
This is an example if a leaking reciprocating compressor valve. It does not close as sharply as in the sample of the “Good” reciprocating valve.
You will also note the longer “open” segment in the time series.