Calibration Verification; Optical System Check; Prepare A Sample Cell - Hach 2100AN IS User Manual

7. Push RATIO to 8. Put the 0–2 NTU
select Ratio on or off. Gelex vial in the sample
cell holder with the
Ratio must be on for
triangle on the vial
Gelex standards
aligned with the
greater than 40 NTU.
reference mark on the
For the 0–2 and
sample cell holder.
0–20 NTU Gelex
Close the cover.
standards, select the
Ratio function that the
instrument will operate
in.

Calibration verification

At intervals, measure the Gelex secondary turbidity standard that is
closest in value to the turbidity range to be measured. Do the steps in
Measure the Gelex secondary turbidity standards
change the value that is recorded on the vial.
Turn Ratio on if the Gelex vial is greater than 40 NTU. Select the Ratio
setting recorded on the Gelex vial for vials less than 40 NTU.
If the measured value is within ±5% of the value recorded on the Gelex
vial, calibration is verified. If not, calibrate the instrument.
®
Note: The StablCal primary turbidity standards can also be used to do a
calibration check. Prepare the StablCal vials before use. Refer to
StablCal standards on page 13. Do not use the < 0.1 NTU StablCal vial as it does
not have an accurately identified NTU value. The instrument is calibrated if the
measured value is within ±5% of the StablCal value.
9. Read the value 10. Record the value
when stable. Remove on the white diamond
the vial from the space on the vial using
instrument. a water soluble marker.
Record on the vial if
Ratio was on or off
when the vial was
measured.

Optical system check

At intervals, measure the Gelex stray light standard to inspect the
integrity of the optical system. Do the steps in
on page 16, but do not light standard
on the vial.
If the value measured is similar to the value recorded on the Gelex stray
light standard (within ±0.02 NTU), the instrument works correctly. If not,
contact Customer Service.

Prepare a sample cell

Prepare the
Use a clean sample cell(s) for sample measurement.
Note: As an alternative, a flow cell can be used for sample measurement. Refer to
Using a flow cell
11. Do steps 7–10 for
the other Gelex vials
(but not the stray light
standard). Measure
from lowest to highest
NTU.
on page 15, but do not change the value that is recorded
on page 31.
Measure the Gelex stray
English 17