Hach ORBISPHERE 3658 Manuel D'utilisation Simplifié page 20

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 that used for the
calibration. For accurate results it is recommended to use a model 32311 Flow Meter set at 50% for the
optimum flow rate of 150mL/min. at room temperature (25°C).
6.2.4 Calibration in CO
The sensor can be calibrated in pure CO
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
calibration.
1. Set the gas measurement phase to Gaseous (see
the calibration medium to In measured pure gas at atmospheric pressure (see
medium on page 17).
2. Connect a source of pure CO
on page 19, 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
4. 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.
6.2.5 Calibration in CO
The sensor can be calibrated in pure CO
accurate pressure gauge connected to the exit of the flow chamber.
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 (see
the calibration medium to In a liquid or a gaseous sample at known concentration (see
Calibration medium
2. Connect a source of pure CO
on page 19, and 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 (see 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.
20 English
at atmospheric pressure
2
gas at atmospheric pressure.
2
Barometric pressure sensor calibration
gas to the inlet of the flow chamber, as illustrated in
2
at elevated pressure
2
gas at an elevated pressure. This method requires an
2
on page 17).
gas to the inlet of the flow chamber, as illustrated in
2
on page 17 before attempting this
Gas measurement phase
on page 17).
Gas measurement phase
on page 17).
on page 16) and set
Calibration
Figure 3
on page 16) and set
Figure 3