About Leak Amount Display - JFE Advantech MK-750ST-E Instruction Manual

8. About leak amount display

The displayed leak amount is calculated value from the correlation between sound pressure
(loudness) and leak amount we confirmed at our facility. The error may become large since
measured sound pressure differs depending on inner pressure, measurement distance, leak section
area size, leak area shape, measurement angle, surrounding environment temperature, humidity,
and others.
8.1 Preconditions for leak amount calculation
Gas leak hole diameter Φ0.6mm
Surrounding temperature 20℃, relative humidity 65%, atmospheric pressure 1
8.2 Factors of leak amount error
(1) Hole diameter
The estimated leak amount displayed on the instrument is based on the hole diameter size 0.6mm.
The leak amount may change depending on the hole diameter causing the leak sound to be different
leading to an error between the estimated and actual leak amount large.
For example, even assuming the actual leak sound is same compared to the one from 0.6mm hole,
the actual leak amount may be one severalth with 0.2mm diameter hole. On the other hand, actual
leak amount may become two times more with 1.0 mm diameter hole.
Even larger error can be created depending on the shape where the leak is from.
(2) Measurement angle
Distribution of generated sound may not be the same in case the leak is from a through hole on a
pipe. It has been confirmed that sound pressure is higher when you measure from an angle toward
to the target hole than when you measure from the front. Please measure in various angles to find
the direction with the maximum leak amount.
It is useful to confirm maximum sound pressure if you turn "Peak Value Window" ON to let the
display show you the peak value. (Refer to p.14)
(3) Attenuation of sound
① Measurement distance
Leak sound diffuse around sound source. Therefore, as the distance to the measurement target gets
larger, the lower the sound pressure attenuation gets. For example, with measurement distance
being 3 meter, sound pressure gets larger if you get 1 meter closer which increases the displayed
leak amount by about 20%. On the other hand, if you step away by 1 meter, the displayed leak
amount decreases by about 20%.
The change rate differs depending on the base distance. The displayed leak amount increases about
28