Instruction Manual
D200149X012
3610J and 3620J Positioners
September 2017
35
D
Do not remove the actuator from the valve while the valve is still pressurized.
D
Disconnect any operating lines providing air pressure, or a control signal to the actuator. Be sure the actuator cannot
suddenly open or close the valve.
D
When disconnecting any of the pneumatic connections, natural gas, if used as the supply medium, will seep from the
unit and any connected equipment into the surrounding atmosphere. Personal injury or property damage may result
from fire or explosion if appropriate preventative measures are not taken, such as adequate ventilation and the
removal of any ignition sources.
D
Use bypass valves or completely shut off the process to isolate the valve from process pressure.
D
Vent the actuator loading pressure and disconnect positioner supply pressure.
D
For explosion proof applications, disconnect power before removing the converter housing cap in an explosive
atmosphere.
D
Use lock‐out procedures to be sure that the above measures stay in effect while you work on the equipment.
D
Check with your process of safety engineer for any additional measures that must be taken to protect against process
media.
Figure 22. Schematic of Fisher 3620J Positioner
38A6593‐A
B2150
MINOR LOOP
GAIN ADJ
ZERO ADJ
RANGE SPRING
COARSE
SPAN
ADJ
CROSS‐OVER ADJ
RELAY BEAM
RELAY
B
RELAY
A
SUPPLY PRESSURE
NOZZLE PRESSURE
INPUT SIGNAL
OUTPUT SIGNAL
AIR
SUPPLY
FINE
SPAN
ADJ
PIVOT
B
FEEDBACK
LEVER
INPUT MODULE
PIVOT A
FLAPPER
NOZZLE
FIXED
RESTRICTION
CAVITY A
CAVITY B
POSITIONER CAM
END VIEW OF
ROTARY SHAFT
SPRING AND DIAPHRAGM
ACTUATOR
SUMMING BEAM
COUNTER SPRING
FLAPPER
NOZZLE
FIXED
RESTRICTION
MAGNET
COIL 4 TO
20 mA INPUT
SUPPLY