Calibrating The 2100An (Using Formazin Standards) - Hach 2100AN Instrument Manual

SECTION 3,
continued

3.2.4 Calibrating the 2100AN (using Formazin Standards)

1.
Insert the EPA filter
module.
Note: Clean the filter before
performing a primary
calibration, or at least every
3 months (which is the
USEPA recommended
calibration frequency).
Note: To clean the filter, use
glass cleaner, lens cleaner,
or isopropyl alcohol, and a
cotton-tipped swab.
2.
Press .
CAL/Zero
The CAL mode
annunciator lights, and the
small green LED digits in
the mode display flashes
. The NTU value of the
00
dilution water used in the
previous calibration is
displayed.
Note: Ratio on and Ratio off
calibration data are
measured and recorded
simultaneously.
Note: Calibration for EBC
and NEPH units of measure
is set automatically via the
NTU calibration.
Note: Upon entering the
Calibration Mode, Automatic
Range, Signal Averaging On,
Ratio on and NTU units are
automatically selected. Upon
completion of calibration, all
operational modes are
restored to precalibration
settings.
3.
Fill a clean sample
cell to the line (approx.
30 mL) with dilution
water. Wipe the cell clean
and apply a thin film of
silicone oil (refer to
Section 2.3.2 on page 18).
Note: For best accuracy use
matched sample cells for all
measurements during
calibration (refer to
Section 2.3.4.2 on page 22).
An alternative may be to use
the same cell for all
standards.
Note: A portion of the same
dilution water used for
preparing standards must be
used in this step.
Note: To exit the calibration
procedure at any time without
changing any stored value,
press .
UNITS/Exit
39
4.
Place the sample cell
into the cell holder, and
close the cell cover.
Note: Install all matched vials
with the orientation mark
aligned with the cell holder
reference mark.