Nephelometric Measurement Procedure - Hach 2100AN Instrument Manual

SECTION 2,
continued

2.2.1 Nephelometric Measurement Procedure

1.
Collect a
representative sample in a
clean container. Fill the
sample cell to the line
(approximately 30 mL).
Handle the sample cell by
the top. Cap the sample
cell.
Note: Instrument warm-up
stabilization time with Ratio
on is 30 minutes and with
Ratio off is 60 minutes.
Typical application is to leave
the instrument on 24 hours a
day.
5.
Place the sample cell
in the instrument cell
compartment, close
the lid.
Note: For immediate update
of the display, press .
ENTER
2.
Hold the sample cell
by the cap, and wipe to
remove water spots and
finger prints.
6.
Select manual or
automatic ranging by
pressing the key.
RANGE
3.
Apply a thin bead of
silicone oil from the top to
bottom of the cell—just
enough to coat the cell
with a thin layer of oil.
Using the oiling cloth
provided, spread the oil
uniformly. Then wipe off
the excess. The cell should
appear nearly dry with
little or no visible oil.
Note: See Section 2.3.2 on
page 18.
7.
Select the appropriate
signal averaging setting
(on or off) by pressing the
key.
SIGNAL AVG
Note: See Section 3.1.3 on
page 34 for more information.
16
4.
Install the appropriate
filter module.
Note: The USEPA filter
typically is used for this
application.
Note: Alternatively, an
860 nm filter can be
purchased for non-EPA
reporting.
RATIO
8.
Select the appropriate
Ratio setting (on or off) by
pressing the key.
RATIO
Note: Values > 40 NTU
require Ratio on.
Note: See Section 3.1.6 on
page 34 for more information.