Xylem CL500 ONLINE CHLORINE ANALYZERS - Manual (Page 17)

6.0 Instrument Calibration
The instrument was tested prior to leaving the factory. Since it operates from a pre-
determined calibration curve, no calibration is required.
Calibration can easily be performed if required. The method is by comparison against
another instrument, such as a laboratory or hand held photometer.
There are two points of calibration. The slope or gain and the zero (offset). To perform the
zero the instrument must be plumbed to a sample of known chlorine free water such as de-
ionized water for a zero adjustment.
6.1 Slope (gain) Calibration Procedure
It is important that the chlorine level be quite stable to use this method. The comparison
will be made against a trusted measurement such as a chlorine photometer,
spectrophotometer, or an amperometric titration.
1. Obtain a grab sample of the flow.
2. Measure the value of the sample with one of the methods shown above.
3. On the CL500, press the MODE/EXIT button once. The screen is shown below.
4. Press to enter the calibration adjustment.
5. The screen will show the current reading on the CL500. Using the S & T buttons
adjust the reading to agree with the laboratory method or portable photometer.
6. Press to accept the calibration adjustment and return to AUTO measurement
mode.
There is a limit to the size of the change that can be made to a current
reading. The upper limit is the current reading times 1.5. The lower limit is
the current reading divided by 1.5.
Ensure a reading is posted to the display before calibrating to avoid a nOnE
error.
CL500 (2/08) Page 13
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