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Instruction Manual
Form 5300
July 2005
The positioner does not have a remote vent
connection. Refer to the section on vent opening,
purge option, and actuator vent connection for
instructions about a remote vent connection.
Supply Connection
WARNING
Severe personal injury or property
damage may occur if the instrument
air supply is not clean, dry and oil-free.
While use and regular maintenance of
a filter that removes particles larger
than 40 microns in diameter will
suffice in most applications, check
with a Fisher field office and Industry
Instrument air quality standards for
use with corrosive gas or if you are
unsure about the proper amount or
method of air filtration or filter
maintenance.
See figure 12.
Connect a clean, dry, oil-free, non-corrosive air
source to the supply connection of the positioner.
Recommended supply line size is 3/8-inch tubing or
1/4-inch pipe. Use of an appropriate supply air filter
or filter regulator is recommended. Refer to the
positioner specifications, table 1, for supply pressure
requirements.
Supply pressure must not exceed the following
limits:
D For the positioner, do not exceed the maximum
pressure rating of 10.3 bar (150 psig).
D For actuator pressure, refer to the appropriate
actuator instruction manual for maximum allowable
pressures.
D For the valve body assembly, do not exceed
the maximum allowable torque or thrust of the
specific valve.
Output Connections
See figure 12.
Use 3/8-inch tubing between the actuator and
positioner.
3710 and 3720 Positioners
For diaphragm rotary actuators (single-action
output from the positioner): Plug OUTPUT A.
Connect OUTPUT B to the diaphragm casing
connection.
For piston rotary actuators (double-action output
from the positioner): To extend the actuator stem
with increasing instrument input signal, connect
OUTPUT A to the lower actuator cylinder connection
and OUTPUT B to the upper actuator cylinder
connection. To retract the actuator stem with
increasing instrument input signal, connect OUTPUT
A to the upper actuator cylinder connection and
OUTPUT B to the lower actuator cylinder
connection.
Instrument Connection
See figure 12.
Use 3/8-inch tubing to connect the output from the
control device to the INSTRUMENT connection on a
pneumatic positioner. For the electro-pneumatic
positioner, refer to the Electrical Connection section.
Vent Opening, Purge Option, and
Actuator Vent Connection
WARNING
If a flammable or hazardous gas is
used as the supply pressure medium,
personal injury or property damage
could result from fire or explosion of
the accumulated gas. Personal injury
or property damage could also result
from contact with the hazardous gas.
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.
Furthermore, a remote vent pipe from
the enclosure alone cannot be relied
upon to remove all hazardous gas.
Use adequate ventilation and other
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.
15
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