Negative Results; Tubes And Chambers - LaMotte 2020t/i Manual Del Usuario

As described previously, the
menu and a return to the previous menu. This allows a rapid exit from an inner menu
to the main menu by repeatedly pushing the
time will turn the 2020t/i off .
The display may show the following messages:
Header
Footer
 NEGATIVE RESULTS
There are always small variations in readings with analytical instruments. Often these
variations can be observed by taking multiple readings of the same sample. These
normal variations will fall above and below an average reading. Repeated readings on a
0.00 sample might give readings above and below 0.00. Therefore, negative readings are
possible and expected on samples with concentrations at or near zero. This does not mean
there is a negative concentration in the sample. It means the sample reading was less
than the blank reading. Small negative readings can indicate that the sample was at or
near the detection limit. A large negative reading, however, is not normal and indicates a
problem. Some instruments are designed to display negative readings as zero. In this type
of instrument, if the meter displayed zero when the result was actually a large negative
number there would be no indication that a problem existed. For this reason, the 2020t/i
displays negative numbers for turbidity.
 TUBES AND CHAMBERS
The 2020t/i uses a specifi c tube (Code 0260).
The handling of the tubes is of utmost importance. Tubes must be clean and free from lint,
fi ngerprints, dried spills and signifi cant scratches, especially the central zone between the
bottom and the sample line.
Scratches, fi ngerprints and water droplets on the tube can cause stray light interference
leading to inaccurate results when measuring turbidity. Scratches and abrasions will aff ect
the accuracy of the readings. Tubes that have been scratched in the light zone through
excessive use should be discarded and replaced with new ones.
Tubes should always be washed on the inside and outside with mild detergent prior to use
to remove dirt or fi ngerprints. The tubes should be allowed to air-dry in an inverted position
to prevent dust from entering the tubes. Dry tubes should be stored with the caps on to
prevent contamination.
After a tube has been fi lled 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 fi ngerprints. Always set the
clean tube aside on a clean surface that will not contaminate the tube. It is imperative that
the tubes and light chamber be clean and dry. The outside of the tubes should be dried with
a clean, lint-free cloth or disposable wipe before they are placed in the meter chamber.
EXIT
button allows an exit or escape from the current
Battery Status
More choices are available and can be viewed by scrolling up and/or down
through the display.
Identifi es the current menu and information on calibration curves and
reagent systems if applicable.
In the data logging mode the number of the data point is displayed and the
total number of data points in the memory will be shown. The footer also
shows current time and battery status
EXIT
button. Pushing
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at any