Dual Point Calibration - Mettler Toledo InPro 6000 Bedienungsanleitung

18
Process calibration is performed when a reliable con-
trol value is available and process pressure is known.
Process pressure is only needed if the system is mea-
suring in saturation (% air or % O
units. During this calibration the phase values of the
calibration curve are adjusted.
Process scaling is performed mainly in biopharma ap-
plications after sterilization (autoclaving) when the
user desires to set the system to an initial value. Dur-
ing this calibration the phase values of the sensor are
not adjusted, only the displayed values and the nA out-
puts are rescaled to the desired value.
Note: For process calibration the operator can use ei-
ther the process pressure or the calibration pressure,
depending on how the reference value is taken.
After the sensor signal has stabilized, the complete
measurement system can be calibrated to the desired
variable, e.g. % air, % O
tion manual for the transmitter).
Note: For this type of calibration an accurate refer-
ence value and correct pressure settings are essen-
tial.

5.3.6 Dual point calibration

To receive a maximum accuracy of the measured val-
ues over the full measuring range, a dual point calibra-
tion is required.
A dual point calibration is required after replacement of
the OptoCap.
By carrying out a dual point calibration both phase
angles at zero oxygen (phi 0) and at hundred percent
oxygen (phi 100) of the sensor can be established.
Point 1: Slope correction (with air or other calibration
media with known O
After the sensor signal has stabilized, the complete
meas uring system can then be calibrated to the 100 %
value of the desired measurable variable, e.g. 100 %
air, 20.95 % O
normal pressure (see instruction manual for the
transmitter).
Point 2: Zero point
After the sensor signal has stabilized, the sensor can
be calibrated to the 0% value of the desired measur-
able variable, e.g. 0% air, 0.0 % O
25 ˚C / 77 ˚F (see instruction manual for the transmit-
ter).
Note: Incorrect zero point calibration is a frequent
source of measurement error. For correct calibra-
tion, we recommend the use of nitrogen gas or oth-
er oxygen-free medium with a level of purity of at
least 99.995 %.
InPro 6000 optical O
52 206 256
InPro 6000 Series Optical O
value)
2
, or 8.26 ppm at 25 °C (77 °F) and
2
sensors
2
2
) or gas (ppm gas)
2
, ppm or ppb (see instruc-
2
© 07 / 12 Mettler-Toledo AG
Printed in Switzerland
Sensors 12 mm
, or 0 ppm at
2