21 PNEUMATIC RELAYS INCLUDING SIGNAL SELECTOR RELAYS, SIGNAL LIMITING RELAYS, CHARACTERIZING RELAYS AND FIXED RATIO RELAYS; PNEUMATIC CONTROL STATIONS INCLUDING ADJUSTABLE RATIO RELAYS, AUTOMATIC MANUAL TRANSFER STATIONS, AUTOMATIC MANUAL TRANSFER STATIONS, MANUAL LOADING STATIONS, AND INDICATING CONTROL STATIONS; PNEUMATIC ACTUATORS INCLUDING ON-OFF BURNER VANE ACTUATORS, POSITIONED BURNER VANE ACTUATORS, GENERAL PURPOSE ACTURATORS; ELECTRIC BURNER VANE ACTUATORS, PNEUMATIC FLOW TRANSMITTERS; CIRCULAR CHART RECORDERS; ELECTRIC COMBUSTION CONTROL SYSTEMS; AND STEAM TEMPERATURE CONTROL SYSTEMS