6.3 Keeping a stable Zeroing of the Detector
6.3.1 The OptoBAS™ function
The OptoBAS™ function of PG11 is keeping the Maintenance requirements of the detector to a
minimum by taking away the need to do manual zeroing of the detector. This will make sure
the detector will show zero gas value when there is no gas present. The OptoBAS™ function
will make minor adjustments to the zero level over a long period of time to keep the Detector
stable. If there is any gas present the OptoBAS™ will not perform any adjustments.
6.3.2 Manual zero adjustment
Warning! This procedure should only be performed by trained Operators. If this is not done
in a proper way, the performance of the detector can be jeopardized.
Normally this is not needed, but for some special applications this might be useful. For
example if the detector is used in an application requiring the OptoBAS be deactivated due to
a low background level of gas present at all times. Also the OptoBAS™ has a limited range it
will handle and a Manual zeroing of the Detector might in some cases be needed.
Requirements:
● Gas Sampling kit
● Nitrogen or clean air
● The Detector shall prior to starting the procedure below be powered up for at least 20
minutes in a stable environment between 15 - 30°C.
Procedure:
1. Clean the Detector optics, both mirror and lens.
2. Connect to the detector through HART® or Modbus RTU as described in those chapters
3. Connect the tube from the Gas cylinder to one of the nozzles on the Gas Sampling kit
4. Fit the Gas Sampling kit as illustrated in “Performing a Calibration check”.
5. Apply the nitrogen or clean air at a flow rate above 0.3 liters/min
6. Wait for 1-2 minutes until the reading stabilizes
7. Start Zeroing from the HART interface.
8. Wait for confirmation.
Document 022-80036-OM Revision R03 Page 30 of 48
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