Yokogawa Multi Channel Oxygen Analyzer System ZR22/AV550G - Manual (Page 79)

IM 11M12D01-01E 4-13
4. Piping
4.2.7 Piping to Introduce Purge Gas When a Process Gas Alarm Occurs
When a process gas alarm (an input contact signal of unburnt gas detection) occurs, the
averaging converter will cut off the power supply to the heater of the detector, and at the
same time it will send a contact output to activate a solenoid valve for introducing a
purge gas to the detector.
The piping for purging in a system to perform automatic calibration is the same as the
one in the system using flow setting units for manual calibration. As instructed in
Subsection 4.1.7, this piping also requires that a check valve be installed on the
calibration gas inlet of the detector. A typical piping diagram for purging is shown in
Figure 4.13.
It is recommended that each instrument be installed to allow for minimum piping
between the solenoid valve for introducing the calibration gases and the check valve,
and between the solenoid valve for introducing the purge gas and the check valve.
To reference gas flow setting
flowmeter and needlre valve.
To reference gas flow setting flowmeter and needle valve.
Calibration contact outputs
Check valve
Check valve
To calibration gas flow setting needle valve and flowmeter.
Calibration
gas line
Reference
gas line
To calibration gas flow setting
needle valve and flowmeter.
Averaging converter (AV550G)
Heater
Signal
Contact output
Purge gas cylinder
Flowmeter
Pressure regulator Needle valve
Reference
gas line
Calibration
gas line
Solenoid valve
Detector
Power supply
Contact input
Contact output
Analog output
(Averaged and individual outputs)
Stop valve
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: If optional 24 V outputs are specified for solenoid valve (MS Code "/24"), no external power supply for solenoid valves is required.
The solenpid valves are powered from the AV550G Averaging Converter. Never connect external power sources in the wiring for
solenoid valvas.
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Figure 4.13 Typical Piping for Purging