3. The Procedure for Gas Leak Diagnosis
072-65284M-02 (SonicMan SN1) 24 Feb 2005
10
3
SonicMan
’s Principle of Detection
3.1
Leak locations generate a warning sound by their very nature
There are many cases in the field where large amounts
of fluid are leaking from the screwed or flanged areas of
piping joints or from gaskets.
An ultrasonic signal is generated at these types of leak
locations. (“Ultrasonic” is used here to refer to sounds
in high frequency bands that cannot be heard by the
human ear.)
This ultrasonic signal is generated even in the case of
very small leaks, and offers a much higher chance of leak location detection than does
relying on the spectrum of sound that is audible to the human ear.
3.2
Detecting ultrasonic signals and converting them to audible sound
SonicMan
employs an ultrasonic microphone and an electrical
band path filter to isolate and detect ultrasonic signals.
Furthermore, the ultrasonic signals that have been detected and
converted to audible sound can then be
heard through the earphones.
Additionally, concentrating the directional
ability of the ultrasonic microphone
facilitates the identification of leak
locations, and the added use of the laser
pointer effects a great increase in the
efficiency of leak detection and location identification.
3.3
Automatic Calculation of Estimated Leakage Level
When the reading’s distance and relevant information about the object being tested have
been input,
SonicMan
displays an automatic calculation of the estimated leakage level
(within 4 levels), based on the reading gained during detection. This can be used as a
rough measure of the total quantity of losses.
The calculation of leakage level is made possible by using information, stored in
SonicMan
, that has been gained from previous laboratory experiments.
The relation between leak level and the leakage
amount is approximately as shown below.
Leakage Rate
Leak
Level
Gas (N·m
3
/h) Steam
(kg/h)
1
0.3 or less
1.0 or less
2
From 0.3 to 1.0
From 1.0 to 2.0
3
From 1.0 to 2.5
From 2.0 to 5.0
4
Over 2.5
Over 5.0
Note: The estimation of leak level includes a variety of factors such as the condition of
the generated ultrasonic signal, fluid type and error due to measuring distance.
Therefore these values are only estimates for reference.
Ultrasonic
waves
? ?
?
! !
123 x 45 – 67 = 5468
