YOKOGAWA TB820D, User Manual, Page: 52 / 87

< 7. Calibration >
7-3
IM 12E01B30-02EN 2nd Edition : June 09 , 2021-00
l
Calibration others
Zero shift correction (7.7)
Update the Zero correction factor (B in Equation 7.2) using Zero water.
Sensitivity correction (7.8)
Update the basic Sensitivity correction factor (K in Equation 7.2) by correcting to an arbitrary
sample value. Be sure to do this after Zero shift correction.
2 Points correction (7.9)
Update the Zero correction factor (B in Equation7.2) and Sensitivity correction factor (K in
Equation 7.2) all together, by using samples of two different concentration except for zero.
Reference sensitivity calibration (7.10)
Update the Reference sensitivity (S0 in Equation 7.1) which is an important parameter for
concentration calculation. Slope is initialized to 100 %. Usually this calibration is performed
only prior to factory shipment.
[Calibration status and calibration recovery status]
If you enter calibration’s screen from calibration menu without turning on the maintenance mode,
the turbidity meter enters calibration status and enters the maintenance contact and auto hold
target status. When calibration is finished or interrupted and the unit returns to the main screen,
contact status and mA hold status remain unchanged, and the flashes.
After confirming that the reading is normal, press the flashing to cancel calibration recovery
and return to measurement mode. When 1 hour has elapsed with calibration recovery state, the
measuring mode is automatically returned.
7.2 Turbidity standards
The turbidity standards are used as reference for adjusting a zero or span point of a turbidity
detector.
n
Zero Standard
l
Zero Turbidity Standard Solution
Filtered tap water is used as a zero turbidity standard solution for TB820D turbidity detector.
For zero calibration, tap water should be filtered in two steps: first through a 1 µm filter and then
through a 0.2 µm filter. If the measuring range exceeds 2.0 NTU, tap water filtered only through a
1 µm filter, can be used.
Note: The instrument has been pre-calibrated for zero point using tap water filtered through a
0.2 µm filter as a zero turbidity standard solution at the factory before shipment.
l
Zero Turbidity Filter
The specifications of the zero turbidity filter that can be purchased from Yokogawa is as follows.
Item 1 µm Zero Turbidity Filter 0.2 µm Zero Turbidity Filter
Part number K9411UA K9726EF
Piping connection Rc1/2 Rc1/2
Maximum pressure 500 kPa 500 kPa
Cartridge material Polypropylene Polypropylene
Filter size 1 µm 0.2 µm
Accessory Air vent plug Air vent plug