wtw Turb 550, Operating Manual

Page: 18 / 54

Operation
18
Aligning a marked
cell
A marked cell is aligned as follows:
Aligning an
unmarked cell
An unmarked cell is aligned as follows:
Balancing cells Even insignificant variations in the glass can affect the mea-
sured value. For this reason, always use the same cell or
balance a pair of cells for low turbidity values:
1 Insert the cell in the cell shaft on the turbidity measur-
ing instrument
2 Align the marked cell so that the arrow on the marker
ring points to the marker pin on the casing of the cell
shaft.
1 Insert the cell in the cell shaft on the turbidity measur-
ing instrument
2 Slowly rotate the cell through one complete rotation
(by 360°)
3 Watch the display of the turbidity measuring instru-
ment while rotating the cell. Leave the cell in the po-
sition that gives the lowest display.
1 Fill the first cell with the sample, align it and mark it
(see 4.1.1 M
ARKING AND ALIGNING CELLS
)
2 Press the key to store the measured value
3 Fill the second cell with the same sample and insert
it in the cell shaft
4 Rotate the cell until the same measured value is dis-
played as for the first cell
5 Mark the cell with a marker ring.