HACH LANGE ORBISPHERE 3654, Руководство пользователя, Страница: 36 / 58

34
Calibrations
Ensure that normal measurement mode is selected in the Measurement Mode menu of the
WIN3654 program (see
Measurement mode on page 32 ).
Calibration must only be carried out once the TC sensor is giving a stable measurement.
Expose the membrane to the calibration sample until this stable reading is obtained. This
usually takes about 5 minutes.
For calibration it is important that the sensor's membrane is at the same temperature as the
calibration sample. Therefore, allow some sample to pass through the flow chamber for 3
minutes before calibrating.
6.2.1 Calibration setup
Ensure that the purge gas is flowing at the recommended rate through the sensor by placing the
purge gas exit tubing into water. This rate should be more than four bubbles during the purge
which lasts for 4 seconds.
This purge cycle is repeated every 20 seconds.
The calibration procedure requires a source of pure gas (regulated by a pressure valve)
connected to the central entry port of the flow chamber, an accurate pressure gauge (better than
± 2%) at the exit of the flow chamber, a needle valve to control the flow on exit, and a beaker of
water to monitor the gas flow.
Figure 10 above illustrates the calibration setup.
Figure 10 Calibration setup diagram