6.2.1 Calibration notes
• Make sure that the instrument is in the same ambient conditions as where it is used.
• Make sure that the standards are at the same ambient temperature as the instrument before use.
• Use only the provided silicone oil. This silicone oil has the same refractive index as the vial glass
and masks minor glass differences and scratches.
• Store the oiling cloth in a plastic storage bag to keep the cloth clean.
• If power is lost during calibration, the new calibration data is lost and the last calibration data is
used.
• In Calibration mode, automatic range and signal averaging on are selected. When calibration is
completed, all operational modes go back to the last settings.
• All nephelometric (turbidity units of measure) calibrations are done at the same time.
• Ratio-on and Ratio-off calibration data is measured and recorded at the same time.
• Clean the USEPA filter assembly before doing a primary calibration, or at least every 3 months
(which is the USEPA-recommended primary calibration interval).
6.2.2 Configure the calibration settings
Change the calibration settings as necessary before the instrument is calibrated. The instrument
must be calibrated when the calibration curve is changed.
1.
Push
Calibration
.
2.
Push
Options
>
Calibration Setup
.
3.
Select the calibration curve range and type of calibration standard.
Option
Description
StablCal RapidCal
(0–40 NTU)
Calibration with 20-NTU StablCal standard (default).
Note: The dark current in the instrument is used as the zero point of the
calibration curve. The calibration curve is linear from 0-40 NTU, thus low
turbidity measurements are very accurate.
StablCal (0–4000
NTU)
Full-range calibration (<0.1 NTU, 20 NTU, 200 NTU, 1000 NTU,
4000 NTU) with StablCal.
Formazin RapidCal
(0–40 NTU)
Calibration with 20-NTU formazin standard.
Note: The dark current in the instrument is used as the zero point of the
calibration curve. The calibration curve is linear from 0-40 NTU, thus low
turbidity measurements are very accurate.
Formazin (0–4000
NTU)
Full-range calibration (20 NTU, 200 NTU, 1000 NTU, 4000 NTU and
dilution water) with formazin.
SDVB (0–4000 NTU)
Full-range calibration (20 NTU, 200 NTU, 1000 NTU, 4000 NTU and
dilution water) with spherical styrene divinylbenzene.
EU Pharm (0–30 NTU)
Full-range calibration (<0.1 NTU, 3 NTU, 6 NTU, 18 NTU, 30 NTU).
4.
Select the remaining calibration options.
Option
Description
Verify after Cal.
Sets the instrument to start a verification immediately after the instrument
is calibrated. When set to on, the verification standard is measured
immediately after a calibration is done. The value of the verification
standard shows on the display as the last standard during calibration.
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