North American TwinBed ® II Simplified Control System Schematic
Sheet 4343-9
Auxiliary Flue 20% POC
Injector Gas Blocking Solenoid Valve Closed
Exhaust (80% POC)
Gas Flow Control Valve
Gas
GCV Open
GCV Closed
"A" Firing
"B" Exhausting
Burner Gas block- ing solenoid valve open
Electronic Fuel/Air Ratio Control
Burner Gas
Injector Gas
Burner
Regenerator
CACV Open
CACV Closed
Combustion Air Blower
Purge Differential Pressure Switch
ECV Open
PS
ECV Closed
Exhaust Temp Control Valve T/C
Exhaust Fan
LEGEND:
Combustion Air Flow Control Valve
symbol - meaning
CACV
- combustion air cycle valve
To Exhaust Temperature Control Loop and High Tempera- ture Switch
ECV GCV
- exhaust cycle valve
- gas cycle valve - solid line indicates pressurized - dashed line indicates venting - black solenoid indicates energized valve - white solenoid indicates de-energized valve
Air/Exhaust Cycle Control Solenoid Valve Cycle Permissive
To Cycle Reversal Logic and Regenerator High Temperature Switch (typ)
S
S
S
S
S
- vent port with silencer - plugged valve port
Solenoid Valve
S
S
- thermocouple
Compressed Air
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