Hach-Lange 2100 AN Laboratory Turbidimeter Basic User Manual - Manual (Page 21)

Table 4 Diagnostic codes (continued)
Code Display Description
23 Test results are shown. Keyboard test
24 Test results are shown. Memory test
Delete calibration data
To delete any calibration data entered by the user:
1. Turn off the instrument.
2. Push and hold CAL/Zero.
3. Turn on the instrument.
The CAL? light flashes. The instrument starts in Calibration mode.
4. Calibrate the instrument before use.
Flashing 9s
When manual ranging is selected, the display will flash all 9s when the
sample being measured is greater than the selected range.
When automatic ranging is selected, the display will flash 9s when the
sample is greater than the maximum range of the instrument. The
display will also flash 9s if Ratio is off and the measurement is greater
than 40 NTUs (268 nephelos or 9.8 EBCs). Turn Ratio on.
Flashing 0s
When manual ranging is selected, the display will flash all 0s when the
sample measured is less than the selected range.
When automatic ranging is selected, the display will flash all 0s when the
measurement is less than the range of the instrument or a negative
value. Calibrate the instrument.
• When measuring color, absorbance or transmittance, set the zero
reference point again.
• When measuring absorbance, make sure that the reading is positive.
To measure samples with negative absorbance, set the analytical
zero using the sample with the greatest absorbance and read the
sample with the least absorbance. Record the reading as negative
absorbance.
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