Hach 2100AN Instrument Manual page 81

SECTION 9,
continued
9.2.1.1 Color Measurement and Calibration Procedure
1.
Insert the appropriate
Filter Assembly in the
filter assembly
compartment. Use the
455-nm Filter Assembly
for Color measurement
(Pt-Co CU).
Note: Flow-Cell Kit use is
recommended. A Flow-Cell
system is required to achieve
cited instrument accuracy
and reproducibility
specifications.
Note: Instrument warm-up
stabilization time for Color
measurement is 30 minutes.
Typical application is to leave
the instrument on 24 hours a
day.
Before measuring Color, calibrate the instrument using a blank solution and a
known standard. Hach recommends a blank solution of deionized water and a
standard of 15 or 500 Platinum Cobalt (Pt-Co) Color Units. After inserting the
455-nm Color Filter Assembly in the instrument, calibrate the Color Unit using
Section 9.2.1.1.
Use the following procedure to make color measurements or recalibrate. To make
measurements based on the existing calibration, reestablish the zero reference
point and insert sample cells containing sample.
2.
Press the
UNITS/EXIT
key until the units display
reads . Press the
-----CU
key. The
CAL/ZERO
display reads
"ZERO"
.
CU
Note: The instrument is
simultaneously zeroed for
Color, Transmittance, and
Absorbance modes.
3.
Using the manual
Flow-Cell Kit, insert the
Flow-Cell Assembly into
the cell holder. Press the
inlet and outlet tubes into
the slots on the
instrument's top enclosure
and cover with the flow-
cell light cover.
Note: Refer to Section 5.2.1
on page 51.
Note: Thoroughly clean the
Flow Cell (see Section 5.2.5
on page 63). After cleaning,
apply a thin coat of silicone
oil to the outside of the cell
(see Section 2.3.2.1 on
page 19).
Note: The instrument's cell
cover does not close when
the Flow Cell is installed.
81
4.
Carefully pour
250 mL of deionized
water into the Inlet
Reservoir.
Note: Flow rate through the
Flow Cell is controlled by
adjusting the height of the
Collection Drain Assembly
on the Support Rod (see
Section 5.2.1.4 on page 53).
Note: Always slowly pour
sample down the inside edge
of the reservoir to minimize
entrapment of air bubbles in
the sample.