Hach DR/850 Procedures Manual page 400

SILICA, Ultra High Range,
9.
The display will
show: 2:00 Timer 2
Press:
ENTER
A two-minute reaction
period will begin.
Note: Perform Steps 10-13
within three minutes after
the timer beeps.
13.
Press:
READ
The cursor will move to
the right, then the result
in mg/L silica (SiO )
2
will be displayed.
Note: Use of the Standard
Adjust feature with each
new lot of reagent is highly
recommended. See
Accuracy Check.
continued
10.
When the timer
beeps, place the blank in
the cell holder. Tightly
cover the
sample cell with the
instrument cap.
11.
Press:
ZERO
The cursor will move to
the right, then the
display will show:
0 mg/L SiO2
Note: If Reagent Blank
Correction is on, the
display may flash "limit".
See Section 1.
400
12.
Place the prepared
sample into the cell
holder. Tightly cover the
sample cell with the
instrument cap.