Measurement Of Low Turbidity Values; Indexing And Matching Sample Vials; Indexing A Single Sample Vial - Lovibond TB 300 IR Mode D'emploi

Note:
The dilution of the water sample may alter the characteristics of the suspended
particles and produce erroneous results.

2.3.8.3 Measurement of low turbidity values

Accurate and repeatable measurements of low turbidity values depend on exact measurement
techniques.
• Use a clean, unscratched and indexed vial.
• Rinse the vial three times with the sample. Add the water sample to the mark.
• Allow the vial to stand for 1 -5 minutes so that bubbles can disappear.
• Carefully invert the vial (so that settled particles disperse in the sample).
• Place the vial in the sample chamber and press the Read/Avg key.
• Perform multiple measurements, until a reproducible value is displayed (leave the vial in
the sample chamber).
Note the smallest consistent and reproducible value.

2.3.8.4 Indexing and matching sample vials

Matched sample vials are required to minimise the effects of optical variation from glass vial
to glass vial. Alternatively an indexed single sample vial can be used for every measurement.
Once vial orientation in the sample chamber is located, always use this new orientation mark
for all measurements independent of the white pre-printed triangle mark.

2.3.8.5 Indexing a single sample vial

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10. Place the cover on the instrument.
11. Press [Read/Avg] or [Read] key.
12. Note the displayed result.
Note:
Assume the indication "Underrange" is equal to 0.00 NTU.
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Fill a clean and dry vial up to the mark with dilution
water (see chapter 2.3.7.1 Preparing Dilution Water).
Cap the vial.
Hold the vial by the cap and clean it with the supplied cleaning
tissue to remove water spots and finger prints.
Switch the turbidimeter on.
Place the vial in the sample chamber.
Make sure that the marks are aligned.
Place the cover on the instrument.
Press [Read/Avg] or [Read] key.
Note the displayed result.
Rotate the vial in the sample chamber about 45°.
Repeat this procedure until the smallest NTU value is obtained.
Mark the vial at this point. Use this orientation mark for all further
measurements.
TB300 IR 6 03/2022