Thermo Fisher Scientific TN100 Turbidimeter - Manual (Page 21)

Instruction Manual TN-100/ T-100
16
5. Routine Maintenance
The supplied carrying case is optimal for protecting the instrument. If you do not plan
on leaving the instrument in the supplied carrying case, when not in use, ensure that
the instrument has been turned off and that a clean sample vial fitted with a black cap
has been placed in the sample well. This will ensure that a minimal amount of dust
and/or debris will be able to settle on the optics of the instrument.
5.1
Vials – Handling, Cleaning and Care
Proper measurement of the turbidity of a sample requires the use of a vial that is free of
marks, smudges, scratches and any bacterial growth.
Therefore, sample vials must be handled with absolute care to avoid contamination or
damage, which might change the optical characteristics of the glass. Scratches,
fingerprints, and water droplets on the sample vial or inside the sample well can cause
stray light interference leading to inaccurate readings.
Cleaning the vial is accomplished by washing the interior and exterior of the vial in a
detergent solution. Once cleaned, the vial should be rinsed thoroughly 8 to 10 times
with clean distilled water to eliminate the possibility of detergent buildup and streaking.
Vials can also be acid washed periodically and coated with a special silicone oil to fill
small scratches and mask the imperfections in the glass. Since the silicone oil required
for this application should have the same refractive characteristics as glass, it is
recommended that the oil be obtained from us. Care should be taken not to apply
excessive oil that could attract dirt or contaminate the sample well of the meter. Once
the oil has been applied to the vial, the excess oil should be removed with a lint-free
cloth. The result should be a sample vial surface with a dry appearance, but with all
imperfections filled with oil.
Sample vials should always be handled from the top or by the cap to avoid fingerprints
or smudges. After a vial has been filled with a sample and capped, the outside surface
should be wiped with a clean, lint-free absorbent cloth until it is dry. Cleaned and dried
vials should be stored with the black caps on. The vials can be stored in the carrying
case. During normal operation you may use any typical glass cleaner along with a lint
free cloth or tissue (Kimwipes ® ), to clean the outside of the vials.
Condensation may appear on the vial when your sample is very cold and the relative
air humidity is high. When this happens, the turbidity that you read may be higher than
the actual turbidity due to the light scattered by the condensate on the vial. If you find
yourself in this circumstance, you can alleviate the problem by either coating the vial
with an anti-fogging agent, or by running warm water over the vial for a short period of
time to warm the sample prior to measurement.