Hach DR/700 Procedures Manual page 130

OXYGEN DEMAND, CHEMICAL,
7.
Press: ZERO
The display will
count down to 0.
Then the display will
show 0.00 mg/L, and
the zero prompt will
turn off.
10.
Press:
READ
The display will
count down to 0.
Then the display will
show the results in
mg/L COD.
Note: For most accurate
results with samples
near 150 mg/L COD,
repeat the analysis with
a diluted sample.
8.
Clean the outside
of the sample vial
with a towel.
42-46
continued
9.
Place the sample
vial into the adapter
with the Hach logo
facing the front of the
instrument.