Hach DR/850 Procedures Manual page 287

OXYGEN DEMAND, CHEMICAL,
9.
Insert the
COD/TNT Adapter into
the cell holder by
rotating the adapter until
it drops into place. Then
push down to fully insert
it.
Note: For increased
performance, a diffuser
band covers the light path
holes on the adapter. Do
not remove the diffuser
band.
13.
Place the sample in
the adapter.
Push straight down on
the top of the vial until it
seats solidly into the
adapter.
Note: Do not move the vial
from side to side as this can
cause errors.
10.
Place the blank in
the sample cell adapter.
Push straight down on
the top of the vial until it
seats solidly into the
adapter.
Note: Do not move the vial
from side to side as this can
cause errors.
14.
Tightly cover the
sample cell with the
instrument cap.
Note: Clean the COD vial
with a towel to remove
fingerprints or other marks.
continued
11.
Tightly cover the
sample cell with the
instrument cap.
Note: Clean the COD vial
with a towel to remove
fingerprints or other marks.
Press:
ZERO
The cursor will move to
the right, then the
display will show:
0 mg/L COD
15.
Press:
READ
The cursor will move to
the right, then the result
in mg/L COD will be
displayed.
Note: Standard Adjust may
be performed using a
prepared standard (see
Standard Adjust in Section 1).
Note: Adjust the result for
any sample dilution in
Steps 4 or 6.
287
12.
If the chloride
removal was done, make
sure the filter disc is not
suspended in the middle
of the vial; it can
interfere with the
instrument reading.
Move it with gentle
swirling or by lightly
tapping the vial on the
table top.