Vent - Fisher 3570 Instruction Manual

3570 Positioners
September 2015
Figure 4. Typical Location of Fisher 3570 Positioner Parts and Adjustments
RANGE SPRING
(SPAN ADJUSTMENT)
CYLINDER
BOTTOM
PRESSURE
INSTRUMENT
PRESSURE
VENT CONNECTION
3/8 NPT
ZERO ADJUSTMENT
FRONT VIEW
W4025
NOTES:
1 ON SOME CONSTRUCTIONS, TWO NOZZLES AND ADJUSTMENTS ARE REQUIRED.

Vent

WARNING
Personal injury or property damage could result from fire or explosion of accumulated gas, or from contact with hazardous
gas, if a flammable or hazardous gas is used as the supply pressure medium.
The positioner/actuator assembly does not form a gas‐tight seal, and flammable or hazardous gas could leak from the
assembly. Therefore, if the assembly is enclosed install a remote vent line from the enclosure. However, a remote vent pipe
alone cannot be relied upon to remove all hazardous gas. Use adequate ventilation, and necessary safety measures. Vent
line piping should comply with local and regional codes and should be as short as possible with adequate inside diameter
and few bends to reduce case pressure buildup.
CAUTION
When installing a remote vent pipe, take care not to overtighten the pipe in the vent connection. Excessive torque will
damage the threads in the connection.
Note
The vent connection is always plugged with a pipe plug for 3570P and 3570PC positioners when mounted on 490 actuators.
8
CLEAN‐OUT
PLUNGER
HORIZONTAL
RELAY
CYLINDER
(TOP CONNECTION)
(O‐RING, KEY 33)
CYLINDER
TOP PRESSURE
RELAY NOZZLE
(OUTPUT PRESSURE
ADJUSTMENT) 1
CYLINDER (BOTTOM
BELLOWS POSTS
CONNECTION) (1/4 NPT)
W4027
Instruction Manual
D200137X012
BELLOWS
VERTICAL
RELAY
SUPPLY
CONNECTION
(NOT SHOWN)
(1/4 NPT)
INSTRUMENT
CONNECTION
(INPUT SIGNAL)
(1/4 NPT)
BACK VIEW