HACH LANGE ORBISPHERE 3654, Руководство пользователя, Страница: 37 / 58

35
Calibrations
6.2.2 Calibration in H
2
or N
2
at atmospheric pressure
The sensor can be calibrated in pure H
2
or N
2
gas at atmospheric pressure.
WARNING
Handle H
2
gas with great care. It is extremely flammable and explosive.
To ensure that the flow chamber and sensor components are dry, remove and blow dry the flow
chamber. Dry the sensor head surface with a clean soft tissue.
The analyzer uses an internal barometric pressure sensor during this calibration. First check
that the pressure sensor is correct and does not need recalibrating. If it does need to be
recalibrated then follow the instructions in
Barometric pressure sensor calibration on page 33
before attempting this calibration.
1.
Set the gas measurement phase to
Gaseous
and set the calibration medium to
In
measured pure gas at atmospheric pressure
(as detailed in Calibration medium on
page 31 ).
2.
Connect a source of pure H
2
or N
2
gas to the inlet of the flow chamber, as illustrated in
Figure 10 on page 34 , and adjust the gas flow to one bubble per second when the exit tube
is immersed in water.
3.
Press the
CAL
button. Remember, this button
may have been locked out to prevent an
accidental reset (see
Locking out the
instrument’s CAL button on page 32 for details).
4.
A brief clearing message
[---]
appears.
5.
Press
CAL
again within a 3 second period.
If the instrument makes two consecutive
measurements with less than 1% difference, it
calibrates against this stabilized value. The LCD
then displays the message
[CAL]
to indicate
calibration has been successfully completed
If the calibration does not complete, the LCD
displays the message
[Err]
. The reason for
this calibration error is either that the measured
gas partial pressure is under 5 mbar, or that a
wrong instrument key was pressed during the
calibration steps.