Hach Pocket Colorimeter II Instruction Manuals page 45

Chlorine, Free and Total, HR,
continued
A user calibration or a user-prepared chlorine standard may be required by a regulatory
official or agency. Two options are available on the Pocket Colorimeter II to meet this
requirement.
A chlorine standard may be prepared and used to validate the calibration curve using
the Standard Calibration Adjust feature (see page 2—13 for more information). The
concentration of the prepared standard must be determined with an alternate
instrument such as a spectrophotometer, colorimeter, or by using an alternate method
such as amperometric titration. The concentration of the chlorine standard for the HR
procedure must be between 4.5 and 7.0 mg/L chlorine.
In addition, a user-generated calibration curve can be programmed into the
Pocket Colorimeter II. See User-Entered Calibration on page 2—15 for more
information.
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