Maintenance Of The Hydrogen Sensor; Hydrogen Sensor Handling; Calibration - Swann AMI Hydrogen QED Operator's Manual

AMI Hydrogen QED
Maintenance
6.3.
6.3.1
6.3.2
34

Maintenance of the Hydrogen Sensor

Hydrogen Sensor Handling

 Never attempt to open the hydrogen sensor.
 Always store the sensor in water or in the wet flow cell.
 Always keep the sensor connected to the AMI transmitter.
 Always keep the sensor polarized. Without polarization the
sensor suffers a loss of sensitivity.
The AMI Hydrogen QED has a buffered polarization source
which will keep the hydrogen sensor polarized for some days,
even if the AMI Hydrogen QED is switched off.
However, it is a good idea to keep the AMI running all the
time. The AMI Hydrogen QED should be connected to the
power supply and switched on even if it is not in use.
 During calibration, do not expose the sensor to 100% hydro-
gen for more than 6 minutes. Otherwise the extremely dry gas
might dry out the capillary layer of electrolyte between plati-
num anode and plastic membrane, which makes the sensor
response unstable.
 The hydrogen molecule is very small and migrates into al-
most any material including electrolyte, plastics and even
metals and will remain there for some time. After a calibration
it may take a few hours until the residual current of the sensor
has dropped enough to measure very low levels of hydrogen
again.
 The hydrogen sensor usually shows a small positive offset,
which means there is a small positive value in air (without hy-
drogen, normally below one ppb). This value can be set to
zero: <Installation > Sensors > Miscellaneous > Offset. Use
with care!

Calibration

The hydrogen sensor of the AMI Hydrogen QED is calibrated with
pure hydrogen. To perform a calibration proceed as follows:
NOTICE: Do not expose the sensor to 100% hydrogen for more
than 6 minutes.
1 Stop the sample flow at the main tap.
2 Navigate to menu <Maintenance> /<Calibration>.
A-96.250.791 / 040219