BA 4000 Inj.
5.1.1 Test gases for calibration
-Zero gas
Zero gas is used to calibrate the zero point. It must not contain oxygen and should not be susceptible to magnetism. Depending
on the application, nitrogen N
2
or carbon dioxide CO
2
can be used as zero gas. The selector switch at the back of the unit must be
set accordingly.
-Span gas
Span gas is used to calibrate the sensitivity (in the measuring range). It is a mixture of oxygen and the respective zero gas or am-
bient air. The oxygen content of the span gas should be as close to the O
2
ratio of the sample gas. However, it should not be less
than 15 Vol.%.
NOTICE
The span gas should preferably be added under the same conditions as the sample gas.
When using sample gas conditioning, the span gas should therefore be added upstream
from this system.
Span gas supply:
For units with built-in sample gas pump:
– Add the span gas via T-fitting with the sample gas pump on.
– Set the output pressure on the span gas cylinder so an excess of span gas is dispersed at the T-fitting.
For units without built-in sample gas pump:
– The span gas should be added to the unit with the same pressure and the same flow rate as the sample gas.
5.1.2 Calibration for BA 4000 Inj. GV
The unit should be on for approx. 30 min. before calibrating it so all components are at operating temperature. The puncture
device should be removed from the gas inlet during calibration.
Adjusting the zero point
– Switch on the pump using the pump/valve switch.
– Connect a hose to the gas inlet. Connect the test gas cylinder and set the pressure regulator on the cylinder to max. 0.1 bar
overpressure.
Use the same anaerobic gas (N
2
or CO
2
) as the zero gas used to gas the packaging to be tested. Set the toggle switch at the
back of the unit to the corresponding setting.
– Slowly open the valve on the pressure regulator. If the reading on the analyser’s gauge fluctuates, reduce the pressure with
the pressure regulator.
– If the reading is steady, switch off the pump, shut off the zero gas and disconnect the hose (calibration with stagnant gas).
– Use the zero potentiometer to set to 0.0 %.
Adjusting the range (sensitivity)
– Connect a hose to the gas inlet. Switch on the pump using the pump/valve switch, add span gas or ambient air and wait for
the reading to stabilise.
– Switch off the pump/valve switch and disconnect the hose.
– If necessary, set the "Span" potentiometer via the front panel on the unit so the value matches the span gas (e.g. 20.9 Vol.%
for air).
In the event of significant deviations from setpoint during calibration, it’s advisable to repeat calibration to verify.
9
Bühler Technologies GmbH
BE550004 ◦ 07/2016-2
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