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3610J and 3620J Positioners
MINOR LOOP
GAIN ADJ
FLAPPER
NOZZLE
FIXED
RESTRICTION
38A8901-B
B1844-1/IL
Principle of Operation
3610J Series positioners accept a pneumatic input
signal and 3620J Series positioners accept a DC
current input signal from a control device. 3620J
Series electro-pneumatic positioners use a 3622
converter to provide a pneumatic input to the
pneumatic portion (3610J Series) of the positioner.
3610J Series positioners are force-balanced
instruments that provide a control valve position
proportional to the pneumatic input signal. The
following describes the principle of operation for
3610JP and 3620JP positioners. The principle of
operation for 3610J and 3620J positioners is similar
except relay A is not used. The principle of operation
for 3611JP and 3621JP positioners is similar except
the feedback linkage does not use a cam.
26
CROSS-OVER ADJ
RELAY
A
ZERO ADJ
COARSE
SPAN
ADJ
SUMMING BEAM
CAVITY A
CAVITY B
INPUT SIGNAL
PRESSURE
AIR SUPPLY
POSITIONER CAM
END VIEW OF
ROTARY SHAFT
Figure 19. Schematic of the 3610J Positioner
RELAY BEAM
RELAY
B
AIR
SUPPLY
RANGE SPRING
COUNTER SPRING
PIVOT A
INPUT MODULE
PIVOT B
FEEDBACK
LEVER
SPRING AND DIAPHRAGM
ACTUATOR
Refer to the schematic diagrams as indicated:
D 3610J—figure 19
D 3610JP—figure 20
D 3611JP—figure 21
D 3620J—figure 22
D 3620JP—figure 23
D 3621JP—figure 24
For direct action, input signal pressure from a control
device is channeled to cavity A in the input module.
An increase in input signal pressure results in a
downward force on the summing beam, pivoting the
Instruction Manual
SUPPLY PRESSURE
NOZZLE PRESSURE
INPUT SIGNAL
OUTPUT SIGNAL
FINE
SPAN
ADJ
June 2008
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