Extech Instruments TB400 User Manual page 4

Calibration
A complete calibration will require testing with both 0 NTU and 100 NTU test solutions.
Ensure that the sides of the bottle are clean and dry to prevent measurement errors.
Calibration Procedure (0 NTU and 100 NTU)
Note: Make sure you complete the calibration steps with as little time as possible between
the 0 NTU and the 100 NTU test bottles.
1. Insert the Zero NTU solution bottle into the testing chamber, line up the white marks, and
close and latch the cover. Turn on the meter and Press and hold the "CAL" button until the
LCD displays "CAL" then release the "CAL" button.
2. Wait one second and then the LCD will display:
Note: If the LCD does not display zero when using "0 NTU" liquid, press the "ZERO" button
continuously until the LCD displays a zero value.
3. The meter is now ready for "0 NTU" calibration.
4. Momentarily press "CAL" button. The LCD will flash CAL for about 10 seconds and then show
the following display:
5. The LCD will then display:
6. Lift the lid on the test chamber and remove the 0 NTU test solution bottle.
800.561.8187
CAL
0.00
CAL
CAL
0.00
100
CAL
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