Hach-Lange POLYMETRON 9240 Operator Manual - Manual (Page 95)

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Section 8 Calibration
8.1 General
Before attempting to calibrate the analyzer, ensure that you have read and understood how to
enter and update data fields as described in the section entitled
Function keys on page 59 .
Note: The instrument cannot be calibrated until at least one complete measurement cycle has been
successfully performed. An attempt to calibrate the instrument before this will result in a “Not authorized”
message being displayed.
In order to obtain accurate measurement results, the analyzer should be calibrated on a regular
basis. Two basic methods of calibration are available:
• Manual calibration - The user can manually perform a calibration on an ad-hoc basis.
• Automatic calibration - Parameters can be set up so that the analyzer will perform a
calibration automatically on pre-defined days at a pre-defined time (see Automatic calibration
setup on page 99 ). This type of calibration is always done using known calibration solution
concentrations.
Note: Before starting a calibration It is very important to ensure that the Reactivation Frequency
parameter (see Reactivation frequency on page 82 ) is greater than zero. If set to zero, the electrode
reactivation process will not take place during calibration and as such the measurement results may well be
out of limits.
To access the calibration menu, select CALIBRATION from the main menu and press the Enter
function key.
8.2 Calibration solution concentrations
Important Note: The maximum concentration value for any calibration solution cannot be
greater than 2000 ppm . Any value superior to this is outside the analyzer specifications and
cannot be processed.
Manual calibration
For a manual calibration, the calibration solutions must be between 100 ppb and 2000 ppm
and must respect the following rules:
• LOW CAL SOL must be ≥ sample concentration of Na + and a minimum of 100 ppb
• HIGH CAL SOL = (LOW CAL SOL x 10)
Example 1 : sample concentration of Na + = 20 ppb
→ LOW CAL SOL = minimum value = 100 ppb Na +
→ HIGH CAL SOL = (100 ppb x 10) = 1000 ppb Na +
Example 2 : sample concentration of Na + = 450 ppb
→ LOW CAL SOL = ≥ sample concentration of Na + = 500 ppb Na +
→ HIGH CAL SOL = (500 ppb x 10) = 5000 ppb Na +
Note: The values LOW CAL SOL and HIGH CAL SOL must be entered into the system (see One point
calibration on page 97 or Two point calibration on page 98 ).
Automatic calibration
For an automatic calibration, the calibration solution must be between 10 ppm and 2000 ppm
and must respect the following rules:
• CAL SOL minimum = 10 ppm
• CAL SOL = (sample concentration of Na + x 1000)
Example 1 : sample concentration of Na + = 0.1 ppb
→ CAL SOL = minimum value = 10 ppm Na +
Example 2 : sample concentration of Na + = 1 ppm
→ CAL SOL = (1 ppm x 1000) = 1000 ppm Na +
Note: The value CAL SOL must be entered into the system (see Automatic calibration setup on page 99 ).