Hach ORBISPHERE 3654 Basic User Manual page 23

When calibrating in gas phase, the flow chamber and sensor head must be dry. To ensure that the
flow chamber and sensor components are dry, remove and dry them with a clean soft tissue.
1. Set the gas measurement phase to Gaseous. Refer to
the calibration medium to In a liquid or a gaseous sample at known concentration. Refer to
Calibration medium
2. Connect a source of pure gas to the inlet of the flow chamber. Refer to
on page 21. Adjust the gas flow exiting from the flow chamber to be in the range of 1 to 5 bar (it is
best to use a pressure close to the application conditions).
3. Press the CAL button. Remember, this button may have been locked out to prevent an accidental
reset. Refer to Locking out the instrument's CAL button
4. A brief clearing message [---] appears.
5. Press CAL again within a 3 second period. The instrument then displays the absolute pressure of
calibration gas (i.e. gauge pressure plus atmospheric pressure).
6. Modify this reading using the Up/Down Arrow keys until the displayed pressure agrees with that
of the gauge plus atmospheric pressure.
7. Press CAL again.
If the instrument makes three 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.
7.2.4 Calibration in a liquid solution
The sensor can be calibrated in a standard liquid solution that has a known concentration of H
N . You can create a solution with a known concentration by dissolving H
2
measured temperature and pressure.
1. Set the gas measurement phase to Dissolved. Refer to
Set the calibration medium to In a liquid or a gaseous sample at known concentration. Refer
to Calibration medium
2. Press the CAL button. Remember, this button may have been locked out to prevent an accidental
reset. Refer to Locking out the instrument's CAL button
3. A brief clearing message [---] appears.
4. Press CAL again within a 3 second period. The instrument then displays the concentration of H
or N , based on the last value of the calibration coefficient.
2
5. Modify this reading using the Up/Down Arrow keys until the displayed concentration agrees with
that of the calibration solution.
6. Press CAL again.
7. Start the flow of the standard (calibration) solution through the flow chamber. Adjust the flow until
the liquid is foam-free. The flow rate should be a minimum of 150 ml/min and be stable.
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.
Note: A flow rate lower that 150 ml/min can be used for the calibration, but you must ensure that all
measurements made after the calibration are made at exactly the same flow rate as is used for the calibration.
To ensure accurate results it is recommended to use a model 32311 Flow Meter.
on page 20.
on page 20.
Gas measurement phase
Calibration setup
on page 20.
or N
2 2
Gas measurement phase
on page 20.
on page 19. Set
or
2
in water at a
on page 19.
2
English 23