Hach 410M Manual Básico Del Usuario página 22

Option
Value
Hold during calibration On by default, this stops any output from the instrument during the
2. Press OK to start calibration
• A calibration screen will be displayed showing current measurement data which is continually
refreshed.
• The value "% ideal current" is a percentage of the current against the ideal current for the
membrane type selected. If this percentage is not within the accepted range, an error message
is displayed and the calibration process fails. A warning message can be displayed when this
value is close to the boundaries, but when calibration can be accepted.
• The message is first displayed in the result box. The dialog box with the error message or the
warning is displayed when the finish button is pressed.
• The value "% last calibration" shows the ratio between the current measurement and the
previous sensor calibration.
• The value "% variation" indicates the variation during the last 3 measurements, which is the
stability of the measurements. A variation as low as possible is needed for a precise
calibration.
• The display shows the actual calibration parameters, and the actual readings (temperature,
barometer, current).
7.4.2.2 O sensor calibration
2
The O sensor needs to be calibrated after each sensor service. Wait at least 30 minutes after
2
mounting a new membrane before re-calibrating. The sensor is in contact with either:
• Air at atmospheric pressure (In Air)
• O at known concentration (Direct value). The gas can be dissolved or not.
2
In air calibration
This calibration procedure places the O
reference against which to calibrate.
Dry the sensor thoroughly, before placing the sensor storage cap under tap water. Shake off any
excess water, but leave a few drops inside the cap. Verify that the screw-on protection cap is in place
on the sensor head. If you use a Dacron mesh inside the protection cap, make sure it is dry before
attempting to calibrate. Then, loosely place the storage cap back on the sensor, holding it in place
with a few turns of its collar.
Set the calibration parameters accordingly and press calibrate.
Direct calibration
This procedure calibrates the oxygen sensor against a liquid sample containing a known level of
dissolved O flowing through the sample line.
2
The instrument displays the sensitivity of the sensor as a percentage of the sensitivity determined
when calibration was last performed.
Set the calibration parameters accordingly and press calibrate.
7.4.2.3 O sensor calibration
3
The sensor is either in contact with:
• Air at atmospheric pressure (In Air)
• O at known concentration (Direct Value). The gas can be dissolved or not.
3
The procedure is the same as for the O
measures O during calibration. The O
2
22 English
Description
Enter the gas concentration according to the value in the calibration
media, when direct value is used.
calibration process to avoid sending invalid information to any
connected device.
sensor in water-saturated air, to provide a known oxygen
2
sensor. In the case of the "In air" calibration, the sensor
2
coefficient is deduced taking into account how the sensor
3