Hach-Lange 2100 N IS Laboratory Turbidimeter User Manual - Manual (Page 17)

Measure the Gelex secondary turbidity standards
Measure the Gelex secondary turbidity standards each time the instrument is calibrated and record the new values on the Gelex vials with a water
soluble marker.
1. Clean the Gelex
vials with a soft, lint-free
cloth to remove water
spots and fingerprints. 2. Apply a small bead
of silicone oil from the
top to the bottom of the
vial. 3. Use the oiling cloth
to apply the oil equally
to the surface of the
vial. Remove the
excess oil. Make sure
that the vial is almost
dry. 4. Push RANGE to
select automatic
ranging.
The Auto Range light
turns on. 5. Push UNITS AVG to
turn signal averaging
off.
The UNITS AVG light
turns off. 6. Push UNITS/Exit to
select the NTU
measurement mode.
The NTU light turns on.
7. Put the 0–2 NTU
Gelex vial in the sample
cell holder with the
triangle on the vial
aligned with the
reference mark on the
sample cell holder.
Close the cover. 8. Read the value
when stable. Remove
the vial from the
instrument. 9. Record the value on
the white diamond
space on the vial using
a water soluble marker.
Record on the vial if
Ratio was on or off
when the vial was
measured. 10. Do steps 7–10 for
the other Gelex vials
(but not the stray light
standard). Measure
from lowest to highest
NTU.
English 15