VEGA VEGAFLEX series 60 Recurring function test - Manual (Page 11)

3 .4 Verification of echo data
For this test point, you require the sensor documentation of the setup
or a sensor documentation created at least 6 months ago.
If none of these sensor documentations is available, the described
recurring function test (λ
du
92 %) cannot be carried out.
Only the test at a detection rate of 88 % of all dangerous undetected
failures is possible. In this case, just skip this test point.
In this case, continue with the test point "Sensor reaction on level
change".
Use the two pdf files of the sensor documentation again for
assessment of the level echo.
Under chapter "Echo curve" you will find a short chart containing the
"E
cho data". The data of this chart are relevant for the assessment.
Compare the values of the two echo data charts. The echo curve itself
cannot be compared.
The following criteria must correspond when comparing the echo data:
l
The level echo (highest useful echo probability) is at the top of the
echo data chart.
l
The amplitude [dB] of the actual level echo (highest useful echo
probability) corresponds to the respective value of the level echo
from the setup (tolerance max. -6 dB). This means that the actual
level echo can be higher, but only max. 6 dB lower than the level
echo during setup.
With cable probes > 10 m proceed as follows:
1 Compare the distance [m] of the two level echoes (actual/setup).
2 Calculate the difference of the distance [m] of the two level echoes
(actual/setup).
Round off this value to the metre (m).
3 Multiply the difference by the factor 0.5.
4 If the distance of the actual level is smaller than the distance
during setup, subtract this value from the amplitude of the actual
level value.
If the distance of the actual level is larger than the distance during
setup,
add this value to the amplitude of the actual level value.
5 This corrected value of the amplitude [dB] of the actual level echo
can be higher, but only max. 6 dB lower than the level echo during
setup.
Exception: Cable probes
> 10
m
Recurring function test • for VEGAFLEX series 60 11
3 Sequence of the recurring function test
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