Operating Instructions

25Operating Instructions VisiFerm
™
mA Sensors
MAINTENANCEMAINTENANCE
7. 3 . 2 Calibration in Air (Calibration Point Air)
1) Make sure temperature, humidity and pressure values are
constant (Figure 13)
2) Power the VisiFerm and connect to ArcAir via the Arc Wireless
Converter BT
3) Select the sensor in the sensor list
4) Open the Calibration tab
5) Select Calibration Point Air
6) Click Start to start the calibration wizard
7) Follow the instructions on the screen
O
2
O
2
O
2
Air: Pressure and humidity
compensation required
Figure 13: Calibration setup in air
NOTE: The value of the saturated oxygen concentration
at different temperatures, different pressures and air
humidity play an important role for the calibration of
dissolved oxygen. For an accurate calibration Hamilton
strongly recommend to to enter the atmospheric pressure
and humidity values in the ArcAir calibration, product
calibration and verification wizards.
7.3.3 Zero Point Calibration
(Point Zero Oxygen)
1) Install the sensor into the calibration station and connected
the Nitrogen calibration gas (Figure 14)
2) Power the VisiFerm mA and connect to ArcAir via the Arc
Wireless Converter BT
3) Select the sensor in the sensor list
4) Open the Calibration tab
5) Select Zero Point calibration
6) Immerse the sensor into an oxygen-free environment (Figure
13) for e.g. nitrogen. Verify that the flow rate does not exceed
0.5 L/min and avoid overpressure
7) Click Start to start the calibration wizard
8) Follow the instructions on the screen
N
2
Sensor for calibration
in zero oxygen
Tube: on the top open
(no overpressure)
Valve for setting the
flow of 0.5 L/min
Nitrogen bottle
with purity of 5.0
Figure 14: Zero point calibration setup
7.4 Product calibration
The product calibration is an in-process calibration procedure in
order to adjust the measurement to specific process conditions.
Product calibration is an additional calibration procedure to a
standard calibration.
If product calibration is activated, the VisiFerm mA calibration
curve is calculated from the data of last calibration at point 1
and from the data of the product calibration (Figure 15). In order
to restore the original standard calibration curve, the product
calibration can be at any time by selecting on the Product calibra-
tion command «cancel». A new standard calibration cancels a
product calibration as well.