Wet Labs ac-s, Руководство пользователя

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ac-s User’s Guide (ac-s) Revision F 9 Feb. 2006 17
a
clean
is the clean water offset value supplied with the ac meter
a
’
clean
is the corrected clean water offset
a
air
is the factory supplied air value
a
’
air
is the field obtained air values
Alternatively, the offset air value difference can be applied directly to the data as a post-
processing step. Obtaining air values in the field is a much more straightforward process
than obtaining clean water values. This is a powerful technique that can track and
compensate for instrument drift and filter aging. Care must be taken when implementing
this technique since a drop of water or smudge on the windows will result in a reading
quite different from the factory air values. This difference might be interpreted as
instrument drift. By iterating this process several times (re-cleaning the instrument and
obtaining a new set of air values), you will gain experience in differentiating true
instrument drift from smudged optics.
Caution
Back up the factory DEV file before making any modifications to it.
Effective air calibration requires:
1. The instrument’s optical path is clean and dry.
2. The instrument’s optical path is completely shielded from ambient light.
To perform air tracking we recommend the following basic procedures.
1. Remove flow tubes and clean and dry completely. Remove the sleeves from the flow
tubes to assure there is no trapped moisture. Allow the flow tubes to sit in a dry
environment with good air flow.
2. Clean and completely dry the optical windows of the instrument. If the optics have
not been cleaned for some time, clean with a mild solution of detergent and distilled
water, rinse, and wipe dry. Follow with a single wipe across each window with an
ethanol-soaked lens tissue (or other low water content alcohol-type solvent) and then
a single wipe with a dry tissue. If the windows are already fairly clean, simply use the
ethanol wipe procedure. You may wish to apply a stream of pressurized air or
nitrogen around the windows to force moisture from the window mount.
WARNING
Beware of using standard air compressor air. It can blow oil all over the optics.
3. Allow the unit to sit open for an hour or two to assure that it dries.
4. Reassemble and insert flow tubes.
5. Turn on meter and allow it to warm up about 5 minutes.