Hach 2100P ISO Manual page 33

SECTION 2,
2.4.4.1 Assigning Values to Gelex Standards
Note: Correct cell orientation is essential to obtain accurate Gelex values. Always
orient the cell so the diamond mark aligns with the orientation mark on the
instrument.
1. Calibrate the instrument with formazin.
2. Select automatic range mode using the
3. Thoroughly clean the outside of the Gelex vials and apply a thin
coat of silicone oil.
4. Place the 0–10 FNU Gelex standard in the cell compartment so the
diamond on the vial aligns with the orientation mark on the
instrument. Close the lid.
5. Press . Record the value, remove the vial from the instrument
READ
and mark the value on the band near the top of the vial.
6. Repeat steps 3–5 for other Gelex standards. Reassign values tot he
Gelex standards each time the meter is calibrated with formazin.
2.4.4.2 Routine Calibration Check With Gelex
The 2100P ISO Turbidimeter does not require standardization before
every measurement as some turbidimeters do. Periodically, as
experience dictates, check the instrument calibration using the
appropriate Gelex Secondary Standard. Be sure the Gelex standards are
aligned correctly when inserting them (diamond aligns with orientation
mark). If the reading is not within 5% of the previously established
value, recalibrate the instrument with StablCal Stabilized Formazin
Primary Standard or formazin primary standard
page 27).
DO NOT calibrate with Gelex Secondary Standards. Gelex standards
are designed for instrument verification, not calibration.
continued
RANGE
(Section 2.4.3 on
33
key.
®
Standards