Booster Stage - Emerson Fisher 846 Instruction Manual

Type 846 and Model 3311
4 to 20 MA
INPUT
ELECTRONIC CIRCUIT
MAGNETIC ACTUATOR
PILOT STAGE

BOOSTER STAGE

TO VALVE ACTUATOR
3 TO 15 PSI
A6324-1/IL
OUTPUT, TYPICAL
Figure 4-1. Functional Parts Block Diagram
REGULATED
AIR SUPPLY
REGULATED
AIR SUPPLY
A6645/IL
Booster Stage
The receiver nozzle pressure controls the booster
stage, which has a poppet valve design. An increase
in receiver nozzle pressure positions the valving in
the booster stage to produce an increase in the
transducer output signal. A decrease in the receiver
nozzle pressure positions the valving in the booster
stage to allow exhaust to occur, decreasing the
output signal.
4–2
SOLID-STATE
PRESSURE
SENSOR
HIGH OUTPUT PRESSURE
LOW OUTPUT PRESSURE
Figure 4-3. Deflector/Nozzle Pilot Stage Operation (Direct Action)
W6287/IL
Figure 4-2. Detail of Deflector/Nozzle Pilot Stage
DEFLECTED NOZZLE
FLOW PATTERN
The booster stage operates using a 3:1 pressure
gain from the pilot stage. High flow rate capability is
achieved by large flow area poppet design and
internal porting having low flow resistance. The
booster stage design provides very good stability in
high vibration applications, and the poppet valve
technology provides resistance to plugging.
Instruction Manual
Form 5739
February 2002
PRESSURE TO
BOOSTER STAGE
PRESSURE TO
BOOSTER STAGE