LaMotte 2020, Instruction Manual

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TURBIDITY TUBES
Turbidity tubes should always be washed prior to use. Use a mild detergent to
remove any dirt or finger prints. Dry the outside of the turbidity tubes with a
clean, lint-free cloth or disposable wipe. Allow the turbidity tubes to air-dry in an
inverted position to prevent dust from entering the tube.
The handling of the turbidity tubes is of utmost importance. Scratches,
fingerprints and water droplets on the turbidity tube or inside the light chamber
can cause stray light interference leading to inaccurate results. It is imperative
that the turbidity tubes and light chamber be clean and dry. Scratches and
abrasions will permanently affect the accuracy of the readings. Tubes can be acid
washed periodically and coated with special silicon oil to mask imperfections in
the glass. After a tube has been filled and capped, it should be held by the cap and
the outside surface should be wiped with a clean, lint-free absorbent cloth until it
is dry and smudge-free. Handling the tube only by the cap will avoid problems
from fingerprints. Always set the clean tube aside on a clean surface that will not
contaminate the tube.
Variability in the geometry and quality
of the glassware is the predominate cause
of variability in results. The special
anti-reflective area on the 2020 tubes allows
more accurate turbidity readings for low NTU
samples. Only 2020 tubes
should be used with the 2020
turbidimeter. Orientation
of the tube in the chamber
will greatly affect the test
results. To obtain the most
accurate results, the tubes
must be positioned so that
the arrow-shaped index mark
on the tube is aligned with
the arrow-shaped index mark
molded into the housing
in front of the light chamber.
This will ensure that the most
accurate results are obtained.
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