Endress+Hauser Turbimax CUS51D - Page 36

Operation Turbimax CUS51D
36 Endress+Hauser
• Make sure the medium is always well mixed (homogeneity).
• Avoid temperature changes during the calibration.
Ensure that the temperatures of the dilution water and the medium are as identical as
possible.
• Do not alter the position of the sensor during calibration.
• It is also possible to edit the calibration set points in the CM44x at a later stage (e.g. if
the reference value of the laboratory measurement is not yet known at the time of
calibration).
Performing a calibration:
Using the example of a two-point calibration in the expected measuring range 2 to 6 g/l.
1. At the CM44x transmitter, select a free data record and the suitable application.
2. Wait at least 1 minute (to stabilize).
3.
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Start the calibration for measuring point 1 (e.g. 2 l (0.5 gal). Sample with a
concentration of 6 g/l (0.05 lb/gal)).
4. Enter the value of the sample determined in the laboratory as the set point (e.g.
6 g/l (0.05 lb/gal)) or edit the value later.
5.
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2
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Perform a 1:3 dilution of the sample. Add water (4 l (1.1 gal)); in the example this
results in 2 g/l (0.02 lb/gal).
6. Avoid air bubbles beneath the sensor.
7. Calibrate measuring point 2. Enter a third of the laboratory value as the set point.
The calibration can also be performed in increasing concentrations (less advisable).
Stability criterion
During calibration, the measured values provided by the sensor are checked to ensure they
are constant. The maximum deviations that may occur in measured values during a
calibration are defined in the stability criterion.
The specifications comprise the following:
• The maximum permitted deviation in temperature measurement
• The maximum permitted deviation in measured value as a %
• The minimum time frame in which these values must be maintained
The calibration resumes as soon as the stability criteria for signal values and temperature
have been reached. If these criteria are not met in the maximum time frame of 5 minutes,
no calibration is performed - a warning is issued.