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b)
Calibration point selection:
The instrument has been calibrated at full range before leaving the
factory. Users can select 2 or more points as needed to calibrate, as long as the target measurement
range is in between of the two calibration points. In calibration setup mode, press or
to
select the calibration point.
c)
Low turbidity calibration requirement
•
For low turbidity measurements (measurement less than 2 NTU), please test 0.0 NTU calibration
solution. If the accuracy is not meeting your requirements, calibrate the instrument at 0.0 NTU
and 20.0 NTU before test; then use 1
#
or 2
#
vial for measurement.
•
Using the same sample vial to calibrate and measure can eliminate the error caused by different
vials, thus achieving higher accuracy. For example, add distilled water to 1
#
vial for zero point
calibration and then add sample solution to 1
#
vial for measurement. Note that the test vial
should be rinsed thoroughly when changing solutions.
d)
High turbidity calibration requirement:
For turbidity measurement greater than 2 NTU, it is
recommended to calibrate once a week, or to test a calibration solution close to the sample solution.
If the error is large, the instrument needs to be recalibrated.
e) The instrument does not automatically recognize the calibration solution. If the wrong solution is
selected for calibration, the measurement will be completely wrong. To fix this problem, simply re-
calibrate the meter selecting the correct calibration solutions.
f)
Place the instrument on a flat and level surface. Do not hold the instrument in hand while operating.
g) If using Formazin standards for calibration, please note that the diluted Formazin standard is
unstable. Please make sure to use freshly made Formazin standard to ensure calibration accuracy.
5
TURBIDITY MEASUREMENT
5.1
Sample Vial Handling
1) There are 6 sample vials contained in the case, marked 1#~6# on the cap and bottom of the vial.
Please note the number of sample vial should be same as that of vial cap, and do not mix up. Please
always use 1
#
~2
#
sample vial to measure samples with turbidity less than 2 NTU. 3#~6# sample vials
are used for measurement of other solutions.
2) Sample vials have been meticulously cleaned and disinfected before they leave factories. They can
be used directly for the first time. Before subsequent uses, sample vials should be thoroughly cleaned:
wash the interior and exterior of the vial in a detergent solution. Repeatedly rinse with clean distilled
water or deionized water. Rinse sample vial with sample solution twice. Fill sample vial with sample
solution then screw the vial cap tightly.
5.2
Measurement Preparation
1) Collect sample solution in a clean container, fill sample solution to the 4/5 position of the sample vial