39
Safety Manual
00809-0200-5100, Rev GB
Installation and Configuration
February 2017
Installation and Configuration
Step 3 Final adjustment of amplitude thresholds
1. Check if there is any Margin Echo between the SIL Reference Point and the product
surface, i.e. if the SIL Margin Echo Distance is less than the SIL Surface Distance. If this is
the case, you will need to adjust the amplitude thresholds in order to optimize
signal/noise ratio.
To remove Margin Echoes above the product surface do the following:
a. Note the SIL Margin Echo Amplitude.
b. Set the SIL Amplitude Threshold to three times the SIL Margin Echo Amplitude and click
the Apply button.
c. Check if there still is any Margin Echo between the SIL Reference Point and the product
surface.
d. Repeat this procedure until no Margin Echo can be found above the product surface.
e. Check that the SIL Amplitude Threshold is less than 25% of the SIL Surface Amplitude.
f. In case the 25% requirement can not be met you may try to increase the SIL Used Hold
Off Distance instead as described in “How to adjust the SIL Hold Off Distance” on
page 48. Note! The SIL Amplitude Threshold should be set to 25% of the SIL Surface
Amplitude prior to adjusting the SIL Used Hold Off Distance.
If the margin echo can not be filtered out, inspection if the still-pipe may be required,
additionally try to slightly rotate the flange (incl gauge and antenna) one bolt hole at a
time. Monitor the amplitude of margin echoes and select the orientation with the
lowest margin echo amplitude.
2. Click the Apply button to store the configuration.
3. Check that the SIL Write Config Counter is incremented.
4. Click the OK button to close the Change Safety Alarm Parameters window.
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