Information for accurate measurements
49
Information for accurate measurements
This chapter provides information on maintenance aimed at ensuring accuracy, such as
calibration methods.
Zero calibration Cal mode
Zero calibration is an operation adjusting the value of clean water to zero.
The following calibration method is recommended, depending on the degree of turbidity.
If low turbidity water (such as tap water or swimming pool water) is being measured, the
turbidity resulting from air bubbles and matter adhering to the wall surfaces may make it
difficult to accumulate zero water and calibrate it. For that reason, the method of performing
zero calibration while successively running the zero water filtered with an ultra filter is
recommended.
Run zero water continuously, make sure the indications become stable, and then perform zero
calibration when the value of turbidity reaches the lowest level.
When water with a turbidity higher than 10 degrees (such as drain water) is being measured,
any water that is similar in water quality levels to tap water can be used as zero water. Make
sure to see that indications become stable with zero water being accumulated in the turbidity
detector, and then perform zero calibration.
It is necessary to remove all dirt from the inside of the detector with a sponge or the like.
Note
z
If the cell is filled with air, zero calibration cannot be performed.
z
When running zero water, be careful about the formation of air bubbles.
z
Turbidity might rise due to dirt in the piping.
z
For a sample with high salt content, there may be a need to use as zero water the filtered water of
the same salt content.
Q
Zero calibration procedure
Perform the following steps from the Meas. mode.
Zero calibration can be operated in common even for any turbidity standard substances.
1.
Remove the cleaner, and then wash the cell of the detector with a brush.
2.
Close the valve beneath the detector, and pour zero water from above into the line.
Or, switch the lines and run zero water successively.
3.
Wait for indications to become stable. If turbidity fluctuates, cleaning was not
sufficient.
4.
Hold down the CAL key to establish the Zero Calibration mode until the CAL
indicator lights up.
5.
After a measured value has become stable, perform zero calibration. When the ENT
key is pressed, a numerical value blinks. Press the ENT key again at as low a value
as possible to complete zero calibration.
[Hold down]
