Hach DR 900 Manuel D'utilisation page 7

Install the sample cell and cell adapter
The instrument has one cell compartment which can use one adapter for
different sample cell types. Make sure to install the sample cell in the
correct orientation and in a consistent orientation so that the results are
more repeatable and precise. Refer to
cap before the instrument zero is set or a measurement is made to
prevent light interferences. Refer to
Figure 4. Close the instrument
Figure 5.
Figure 4 Sample cell orientation
1 1-cm/10-mL plastic sample cell
2 1-inch (25 mm) glass sample cell
3 16-mm glass test vial
4 Orientation mark
5 Orientation position (clockwise)
6 Sample cell adapter
English 7