Maintenance
61
2.
Check the amount of light for zero calibration.
3.
Check the number of days elapsed from the last zero calibration.
Note
The fluctuations in the amount of light from a light source over time are about 5
to 10
per year.
If the amount of transmitted light has decreased to a level of 40
or less of the initial amount of
light, an error announcement will be issued to indicate the decrease in the amount of light. It is
presumed that the amount of light from a light source may decrease to a level of 40
or less over
a period of at least 10 years because the deterioration of a light source is not linear. If an error
occurs after only a few years, it can be judged that other causes may exist.
Span calibration
Prior to span calibration, it is necessary to select a turbidity standard substance.
Conventionally, refined powders of Kaolin and Formazin have been used. For tap water,
Polystyrene Latex (PSL) is used.
For these turbidity standard substances, use commercial products or HORIBA Advanced
Techno's consumables.
Moreover, an optional span solution is also available as a substitute for the span calibration
liquid. If span solution is used, pour the span solution into the Liquid span bottle and shake
and mix it strongly before putting it in place. By doing this, signals indicating that the span
solution is used as a substitute for the standard solution can be obtained. However, even if an
already-known turbidity liquid is poured into the Liquid span bottle, span calibration cannot be
performed according to that value.
To use a Liquid span bottle, attach it to a turbidity meter already calibrated with a turbidity
standard substance beforehand. Then, test the measured value that is indicated at this point.
From the next time, perform span calibration with reference to this value.
The span solution components are refined Kaolin, a trace amount of dispersant (sodium
pyrophosphate), and sterilizing agent (hydrogen peroxide).
Put the Liquid span bottle in zero water. As the value of the Liquid span bottle changes, retest
it once a year.
Pour a Kaolin solution of 5 degrees or higher into the Liquid span bottle. If a solution with a low
turbidity is poured, particles will adhere to the wall surfaces and the turbidity will change over
time. For span calibration of turbidity, use a standard solution of 2 degrees or higher. It is
possible that errors may become larger in a standard solution that is closer to the zero point.
Note
Put the Liquid span bottle in zero water. If it remains in the air, calibration cannot be performed.
A solution of 0.3 times to 0.9 times the measurement range is suitable for the turbidity of a span
calibration liquid.
Prior to span calibration, clean the inside of the cell adequately and rinse it with clean water.
Perform calibration using the span calibration liquid of an already-known turbidity.
At the time of shipment from the factory, it is calibrated with Formazin. Other turbidity standard
substances may be calibrated and shipped upon request. In this case, they need to be
calibrated by the user.
Adjust the span coefficient for the measured value so that it is equal to the turbidity of the
standard solution.
Once
Once
