Xylem photoLab 6100 VIS - Manual (Page 37)

photoLab
®
6100 VIS Operation
37 ba75847e01 08/2009
4.4 Zero adjustment
A valid zero adjustment is required for the calculation of measured values in
the modes, Concentration, Absorbance / % Transmission, Multi wavelengths
and Kinetics. With a zero adjustment, the absorbance of a cell filled with
distilled water ("zero cell") is measured and stored.
Zero adjustment for
absorbance
measurements
The zero adjustment has to be carried out separately for each cell type and
each used wavelength. If necessary, the photometer reminds you that a zero
adjustment is due.
Factory zero
adjustment for
concentration
measurements
For all measurements with WTW test sets (Concentration mode), a factory
zero adjustment is available in the delivery condition. We recommend
replacing it with a zero adjustment of your own.
Note
The cells must be absolutely clean and free of scratches.
Always use a cell of the same type for zero adjustment and measurement of
the sample.
Notes on zero
adjustment
Zero adjustment with round cells:
z Only use clean, scratch-free round cells with distilled water. The minimum
filling level is 20 mm. A ready zero cell is included in the scope of delivery
of the photometer and PhotoCheck (see chapter 8 A
CCESSORIES AND
OPTIONS ).
z A ready zero cell can, in principle, be used any number of times. We
recommend, however, to regularly check the zero cell for visible
contamination and scratches and refill or exchange it if necessary (at least
every 24 months).
Zero adjustment with rectangular cells:
z For rectangular cells, the zero adjustment must be carried out with the
same cell type (manufacturer and glass type [e.g. optical glass, quartz
glass]) that is used for measurement. This is important because cells of
different manufacturers have different absorption behavior. When
changing the cell type repeat the zero adjustment with the new type.
z Prior to zero adjustment, clean the rectangular cell and fill it with distilled
water. The minimum filling level is 20 mm.
z Rectangular cells always have to be inserted in the cell shaft with the
same orientation for measurement and zero adjustment (e.g. cell printing
on the left side ).