Indexing And Matching Sample Cells; Indexing A Single Sample Cell - Hach 2100N Instruction Manual

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SECTION 2,
continued

2.6.3 Indexing and Matching Sample Cells

2.6.3.1

Indexing a Single Sample Cell

1.
Fill the clean cell to the
line with high-quality water,
and cap the sample cell
(refer to Section 2.6.2).
5.
Place an orientation
mark on the sample cell
marking band adjacent to the
index mark. Use this mark to
align the sample cell each
time a measurement is made.
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Precise measurement of multiple, low-turbidity samples requires good laboratory
technique to achieve accuracy and repeatability. Matched sample cells are
required to minimize the effects of optical variation among cells. Alternatively,
use a single sample cell for every measurement to minimize reading variability
caused by cell-to-cell imperfections. Using a single cell provides better accuracy
and precision than matched cells. Once cell orientation in the cell holder is
established, always use the alignment indicated on the cell, regardless of sample
cell choice (refer to Section 2.6.3.1). A Flow-Cell System provides the best
accuracy and reproducibility and is more convenient (see SECTION 5).
Add an orientation mark to a single sample cell as follows:
2.
Wipe the sample cell
clean, and apply a film of
silicone oil (refer to
Section 2.6.1).
3.
Make sure the filter is in
place. Insert the sample cell
into the cell compartment,
and close the cell cover.
Record the reading.
25
4.
Lift the cell
compartment cover, rotate
1
the sample cell (about / of
8
a turn). Close the lid, press
and record the
ENTER
reading. Continue this
procedure until the smallest
NTU reading is obtained.
Note: "door" is displayed when
the sample compartment is
not covered.