Single Point Calibration; Dual Point Calibration - Mettler Toledo InPro 6850i Instructions D'utilisation

InPro 6850 i / 6900 i / 6950 i O
– For correct calibration, a minimum flow rate of
the calibration medium is necessary.
– Make sure that all other parameters, such as
temperature and pressure, are constant.
For continuous applications, we recommend peri-
odic recalibration in line with your requirements
on accuracy, the type of process in operation and
your own experience. The frequency of the need for
re- c alibration depends very much on the specific
application, and therefore appropriate intervals can-
not be exactly defined here.

5.2.3 Single point calibration

By carrying out a single point calibration, the factual
slope of the sensor can be established. The cali-
bration medium can be water with known oxygen
saturation index (e.g. air-saturated water) or air with
known water-vapor saturation (e.g. water-vapor
saturated air).
After the sensor signal has stabilized, the complete
meas u ring system can then be calibrated to the
100 % value of the d esired measurable variable,
e.g. 100 % air, 20.95 % O
(77 °F) and normal pressure (see instruction manual
for the transmitter).

5.2.4 Dual point calibration

By carrying out a dual point calibration both slope
and zero point of the sensor can be established.
a
Important! In case of a dual point calibration,
always start by the zero point calibration before
calibrating the slope.
As a rule, the zero point should be adjusted to zero
manually, or it is automatically performed by the
transmitter (see instruction manual for the transmit-
ter).
Zero-point calibration is recommended:
– when measuring less than 5 ppb in liquids
– when measuring less than 125 ppm (by vol.) in
gases
a
Attention! Incorrect zero point calibration is a
frequent source of measurement error. For correct
calibration, we recommend the use of carbon
dioxide gas with a level of purity of at least
99.9995 %.
After the sensor signal has stabilized (after 6 ...
12 hours), the sensor can be calibrated through
the relevant transmitter to the zero % value of the
desired measurable variable, e.g. 0 % air, 0.0 % O
or 0.0 ppm (see instruction manual for the transmit-
ter).
© 02 / 17 Mettler-Toledo GmbH
Printed in Switzerland
Sensor 12 / 25 mm
2
, or 8.26 ppm at 25 °C
2
InPro 6850 i / 6900 i / 6950 i
19
,
2
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