4.7
4.6 Autocalibration valve installation
As a general guide, two externally powered three way valves are required for each transducer
to be calibrated. One switches between sample gas and the second 'calibration' valve (which
switches between calibration gas 1 and calibration gas 2).
Autocalibration valves may be controlled either by the RS232 output (see Section 3.3) or by
relays on the rear panel of the analyser (refer to Section 3.2 and Section 3.6).
Figure 4.3 and Figure 4.4 show typical installations and assume that, in the de-energised
states, the lower port on the valves will be normally open (NO). The latter figure actually
demonstrates the potential to utilise independent autocalibration even when several
transducers are on a single sample stream (ref 4900D).
NOTE
The CAL1/CAL2 valve is only used during calibration. In the case of fully
independent autocalibration, it is permitted to connect all CAL1/CAL2 valves to one
relay, and configure the software accordingly. However, a dedicated SAMPLE/CAL
solenoid/relay is required for each group.
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