Hach DR/850, Procedures Manual, Page: 227 / 460

227
17.
Add the contents
of one pillow of
Monochlor F to the cell
for the Free Ammonia
measurement.
Cap and shake the cell
about 20 seconds to
dissolve the reagent.
Note: The reaction period
indicated in step 11 must be
complete before the
addition of Monochlor F to
the cell for free ammonia
measurement.
18.
Cap and shake the
cell about 20 seconds to
dissolve the reagent.
A green color will form
if ammonia or
monochloramine is
present.
19.
Press:
TIMER ENTER
A five-minute reaction
period will begin.
Note: The color
development time depends
on the sample temperature.
See Table 1.
20.
After the timer has
expired, press:
EXIT
21.
Place the Free
Ammonia cell into the
instrument so that the
cell tab is at the
two-o’clock position.
Make sure the sample
cell tab is completely
seated in the cell holder
slot.
Tightly cover the sample
cell with the instrument
cap.
22.
Press:
READ
The cursor will move
to the right, then
the result in mg/L free
ammonia as nitrogen
(NH
3
–N) or chosen units
will be displayed.
FA
10
mL
5
mL
FA
Tab
Slot
FA
Nitrogen, Free Ammonia and Chloramine (Mono), continued