Hach-Lange ORBISPHERE Model 51x User Manual - Manual (Page 63)

61
Calibration menu
7.1 Definitions
7.2 EC gas sensor calibration
Definitions
We define 2 types of calibration:
•
the calibration of the gas to measure (e.g. O
2
for an O
2
sensor)
• the calibration of interferences (e.g. H
2
O for a CO
2
sensor)
To calibrate the gas to measure (main gas), the user usually puts the sensor in the main gas without any
interfering gas.
To calibrate the interferences, the user usually puts the sensor in the interfering gas without any of the
main gas.
Calibrations can only be performed once the instrument has been installed, configured and each channel
has been set up. You must also ensure that you have the correct access rights to access the calibration
menu (minimum of level 2 for sensor calibrations and level 3 for barometric pressure calibration).
Select sensor calibration from the calibration menu, then select the channel to calibrate.
There are two types of gas sensor calibration available, depending on the gas being measured and the
type of sensor being used:
1.
In Air: For Oxygen and Ozone with an EC sensor.
2. Direct value: Any gas with either an EC or TC sensor. This calibration exposes the sensor to a gas
with a known partial pressure, or a liquid sample with a known gas concentration.
Note: All the calibration information for a smart EC Sensor is stored in the sensor’s memory. When a
smart sensor is connected to the instrument for the first time, a calibration report (see example in
Calibration reports on page 66 ) is automatically generated giving the details of the last calibration.
If the sensor being calibrated is an EC sensor, follow the instructions in the next section entitled EC gas
sensor calibration . For TC sensors, refer to TC gas sensor calibration on page 63 .
Calibration of the measured gas
Start Before initiating a calibration process, the calibration parameters must be
set by pressing on the Modify button. The last calibration parameters are
memorized, so this step can be ignored if the correct parameters are
already set.
Note:
When calibration is started, a calibration event is set, and the analog
output and relay are put on hold (if selected below) to avoid unwanted alarms
or potential process problems. This resumes when calibration is finished.
Modify calibration
parameters • Calibration mode : 2 types available, depending on the gas being
measured:
•
Direct value : Any gas
• In Air (default): For O
2
or O
3
• Medium : Select liquid or gas (direct calibration only)
• Concentration unit type : Partial, fraction or dissolved (dissolved is
for calibration in a liquid only)
• Concentration unit : The list of available units depends on unit type
selected above.
• Liquid : Select as appropriate, available when liquid has been selected
in medium (above).
• Enter the gas concentration according to the value in the calibration
media, when direct value is used
• Hold during calibration : On by default, this stops any output from the
instrument during the calibration process to avoid sending invalid
information to any connected device.
• Interference enabled : If selected, this takes into account the influence
of interferences (see settings below) during calibration. By default the
same interference as during measurement is selected.
Press OK to start calibration