Hach-Lange EVITA OXY Basic User Manual - Manual (Page 106)

English 106
Calibration
The calibration of the EVITA ® OXY sensor must be done in atmospheric
air. We recommend calibration of the sensor every 6 months.
A calibration can either be triggered by the USC 5000 signal converter
or carried out with help from the TILTCAL
® function of the
OXY transmitter. During the calibration procedure the sensor must be
protected from direct sunlight.
Before the calibration the OXY 1100 sensor must be cleaned thoroughly
(refer to section "Maintenance"). With quick calibration in atmospheric
air a system accuracy of 1 % can be achieved. During the calibration
temperature and air pressure are automatically compensated via an
internal temperature- and air pressure sensor.
The calibration with help of the TILTCAL
® function Hold the transmitter
with the OXY 1100 sensor upward in order to initiate the calibration
procedure through activation of the tilt switch.
Rotate after 5 minutes the transmitter together with the OXY 1100
sensor downward; the transmitter has now completed the calibration
routine. During the calibration the signal is set to a current strength of
4 mA.
Optionally however, a current strength of 20 mA or the last measured
value (hold) can also be set via the USC 5000/7000 signal converter.
Figure 26 Calibration
If the transmitter with the OXY 1100 sensor is rotated downward during
the five-minute calibration period, the calibration procedure is interrupted
and the measurements continue according to the previous calibration
value.
The temperature equalization occurs automatically during the calibration
via a built-in temperature sensor. Furthermore an equalization
for air pressure, relative humidity and salinity also occurs via default
settings. These default values can be changed via the USC signal
converter or via HART®.
Calibration via the USC 5000/7000 signal converter
Select with the key CHANGE in the operator menu the "Calibrate"
menu, and press the key LOCK/UNLOCK (ENTER) to initiate the
calibration procedure.
The relative humidity and the salinity can be compensated whereby you
enter these values via the USC 5000/7000 signal converter (
Figure 34,
page 111 ).
The preset values and the significance of the deviation from these
values are given in
section Appendix I, page 121 .
To achieve a system accuracy of 0.5 %, remove the transmitter from the
medium to be measured and hold it with the OXY 1100 sensor pointing
downward for 1 hour to make sure that the sensor is fully stabilized.
Then the calibration procedure can begin.
Switched Not switched