Fisher 3710 User manual

D101728X012
Type s 3 710 , 3 72 0 P neumati c P ositioners
Typ
e 3 72 2 C onverter
Incorporates Errata dated August 1994; see page 42
Incorporates Loop Schematics dated December 1994
Figure1. Positioners
W6144/IL
W6058-1/IL
SUPPLY
CONNECTION
    
     
    
     
Instruction Manual
Form 5300
July 1993 Types 3710, 3720, 3722

Types 3710, 3720, 3722
2
Contents
Introduction 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope of Manual 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Description 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Type Number Description 3. . . . . . . . . . . . . . . . . . . .
Positioner to Actuator Mountings List 3. . . . . . . . . .
Specifications 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing the Type 3722 Converter 3. . . . .
Mounting the Positioner 6. . . . . . . . . . . . . . . . .
Connections 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supply Connection 11. . . . . . . . . . . . . . . . . . . . . . . . .
Output Connections 12. . . . . . . . . . . . . . . . . . . . . . . .
Instrument Connection 12. . . . . . . . . . . . . . . . . . . . . .
Vent Opening, Purge Option, and Actuator
Vent Connection 12. . . . . . . . . . . . . . . . . . . . . . . . .
Connecting the Purge Tube 13. . . . . . . . . . . . . . . .
Electrical Connection for the Type 3722
Positioner 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Connections 14. . . . . . . . . . . . . . . . . . . . .
Calibration 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Initial Cam Position 16. . . . . . . . . . . . . . .
Zero and Span Adjustments 17. . . . . . . . . . . . . . . . .
Standard or Beacon Indicator Alignment 18. . . . . .
Changing Positioner Action 19. . . . . . . . . . .
Single-Action/Double-Action 19 . . . . . . . . . . . . . . . . .
Direct-Action/Reverse-Action 19 . . . . . . . . . . . . . . . .
Split-Range Operation 20. . . . . . . . . . . . . . . . . . . . . .
Changing the Spool Valve (To Increase Positioner
Output Capacity) 20. . . . . . . . . . . . . . . . . . . . . . . .
Changing the Span Adjuster Assembly (To Change
Positioner Input Range) 21. . . . . . . . . . . . . . . . . .
Principle of Operation 22. . . . . . . . . . . . . . . . . .
Positioner Maintenance 23. . . . . . . . . . . . . . . .
Replacing the Standard or Beacon Indicator 23. . .
Removing the Type 3722 Converter 23. . . . . . . . . .
Removing the Positioner 23. . . . . . . . . . . . . . . . . . . .
Removing the Feedback Arm Assembly 25. . . . . . .
Disassembling the Feedback Arm Assembly
and Span Adjuster Assembly 25. . . . . . . . . . . . . .
Removing the Feedback Shaft (Cam Shaft) 26. . . .
Disassembling the Spool Valve, Action Block,
and Gasket 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembling the Input Module and
Summing Beam Assembly 27. . . . . . . . . . . . . . . .
Replacing the Input Module Diaphragm 27. . . . . . .
Assembling the Input Module and Summing
Beam Assembly 28. . . . . . . . . . . . . . . . . . . . . . . . .
Assembling the Spool Valve, Action Block, and
Gasket 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assembling the Feedback Shaft (Cam Shaft) 29. .
Replacing the Feedback Arm Assembly
and Span Adjuster Assembly 30. . . . . . . . . . . . . .
Type 3722 Converter Maintenance 30. . . .
Disassembling the Type 3722 Converter 30. . . . . .
Assembling the Type 3722 Converter 30. . . . . . . . .
Testing the Type 3722 Converter Module 31. . . . .
Parts Ordering 31. . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Kits 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts List 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Positioner Common Parts 31. . . . . . . . . . . . . . . . . . .
Diagnostic Connections 35. . . . . . . . . . . . . . . . . . . . .
Type 3722 Electro-Pneumatic Converter 36. . . . . .
Positioner Mounting Parts 37. . . . . . . . . . . . . . . . . . .
Introduction
Scope of Manual
This instruction manual includes installation, operation,
calibration, maintenance, and parts ordering informa-
tion for the Type 3710 pneumatic positioner and Type
3720 electro-pneumatic positioner. This manual also
provides field installation and maintenance information
for the Type 3722 electro-pneumatic converter. Refer
to separate instruction manuals for information on the
actuator, control valve, and other accessories.
Only personnel qualified through training or experience
should install, operate, or maintain the positioner. If
there are any questions concerning the instructions in
this manual, contact your Fisher sales office or sales
representative before proceeding.
Description
The Fisher Controls Type 3710 pneumatic positioner
and the Type 3720 electro-pneumatic positioner are
used with either diaphragm actuators (spring return) or
piston rotary actuators (spring return or double-action)
as shown in figure 1. These positioners provide a
valve ball or disk position for a specific input signal.
These positioners can easily be configured to provide
single- or double-action output for Fisher Controls
rotary actuators.
The Type 3710 pneumatic positioner accepts a pneu-
matic input signal. The Type 3720 electro-pneumatic
positioner accepts a milliampere (mA), direct current

Types 3710, 3720, 3722
3
W6059-1*/IL
Figure 2. Mounting the Positioner Base Plate
MOUNTING
SCREW
FEEDBACK
SHAFT
MOUNTING
SCREWS
TIE BAR
EXTENSION
(KEY 44) POSITIONER
MOUNTING
PLATE (KEY 43)
(dc), input signal. Refer to the type number description
for an explanation of type numbers.
The Type 3710 pneumatic positioner provides a valve
position for a standard pneumatic input signal. The
positioner may also be split-ranged. See table 2 for
input signal ranges.
The Type 3720 electro-pneumatic positioner provides
a valve position for a milliampere (mA), direct current
(dc), input signal. The positioner may also be split-
ranged. See table 2.
Type Number Description
The following descriptions provide specific information
on the different positioner constructions. If you do not
know the type number of a specific unit, refer to the
nameplate on the positioner (key 5, figure 26).
Type 3710: A pneumatic rotary valve positioner
Type 3720: An electro-pneumatic rotary valve posi-
tioner consisting of a Type 3710 with a Type 3722
attached.
Type 3722: An electro-pneumatic converter used for
conversion of a 4 to 20 milliampere (mA), direct cur-
rent (dc), input signal to a pneumatic input signal for
the pneumatic positioner. Use this unit in combination
with a Type 3710 positioner to make a Type 3720 po-
sitioner.
Positioner to Actuator Mountings List
The positioner mounts directly to the actuator cover
plate of Fisher Controls Types 1051, 1052, and 1061
actuators. See table 3 for actuator sizes.
Figure 2 shows a positioner ready for mounting on a
Fisher Controls piston rotary actuator. A mounting
plate (key 43) is used to mount the positioner base
plate to Fisher Controls Types 1031, 1032, 1051,
1052, 1061, and 1062 actuators. See table 3 for ac-
tuator sizes.
Specifications
Specifications are shown in table 1.
Installing the T ype 3722 Converter
WARNING
Avoid personal injury from sudden
release of process pressure. Before
mounting the Type 3720 electro-
pneumatic positioner or Type 3722
electro-pneumatic converter:
Disconnect any operating lines pro-
viding air pressure, electric power, or a
control signal to the actuator. Be sure
the actuator cannot suddenly open or
close the valve.

Types 3710, 3720, 3722
4
Table1. Specifications
Unless otherwise specified, the specifications listed
are for all positioner type numbers.
Available Configurations
Refer to the type number description
Input Signal(1)
Type 3710:
Standard: J3 to 15 psig (0.2 to 1.0 bar) or J6 to
30 psig (0.4 to 2.0 bar)
Split-Range: J3 to 9 psig (0.2 to 0.6 bar) and 9 to
15 psig (0.6 to 1.0 bar) or J6 to 18 psig (0.4 to 1.2
bar) and 18 to 30 psig (1.2 to 2.0 bar)
Type 3720:
Standard: J4 to 20 mA dc constant current with
30 V dc maximum compliance voltage
Split-Range: J4 to 12 mA dc or 12 to 20 mA dc
Output Signal(1)
Pneumatic pressure as required by the actuator up
to full supply pressure
Action(2):Field-reversible between Jdirect and
Jreverse within the pneumatic positioner
Equivalent Circuit
Type 3720: 120 ohms shunted by three 5.6 V zener
diodes. See figure 10
Typical Performance(1)(4)
Type 3710 Pneumatic Positioner
Independent Linearity: ±0.5% of output span
Hysteresis: 0.5% of output span
Deadband: 0.3% of input span
Type 3720 Electro-Pneumatic Positioner
Independent Linearity: ±1.0% of output span
Hysteresis: 0.6% of output span
Deadband: 0.35% of input span
Electromagnetic Interference (EMI)(1)
Type 3720: When tested per SAMA Standard
PMC 33.1-1978, change in steady-state deviation is
less than ±1% in an electromagnetic field classified
as 3-abc with a field strength of 30 V/m. Positioner
is tested with cover on and with external wiring in
rigid metal conduit.
Maximum Supply Air Demand(3) (Double-Action
Output)
Standard Spool Valve: 60 psig (4.1 bar) supply,
480 scfh (13 normal m3/hour)
High-Capacity Spool Valve: 60 psig (4.1 bar) sup-
ply, 860 scfh (23 normal m3/hour)
Operating Influences(1)
Supply Pressure Sensitivity: A 10% change in
supply pressure changes the valve shaft position less
than the following percentages of valve rotation:
Type 3710: 1.0% at 60 psig supply pressure
Type 3720: 1.5% at 60 psig supply pressure
Supply Pressure(1)
Minimum Recommended: 5 psig (0.3 bar) above
actuator requirement
Maximum: 150 psig (10.3 bar)
Steady-State Air Consumption(3)
Type 3710:
Standard Spool Valve: 23 scfh (0.61 nor-
mal m3/hour) at 60 psig (4.1 bar) supply pressure
High-Capacity Spool Valve: 28 scfh (0.75 nor-
mal m3/hour) at 60 psig (4.1 bar) supply pressure
Type 3720:
Standard Spool Valve: 30 scfh (0.80 nor-
mal m3/hour) at 60 psig (4.1 bar) supply pressure
High-Capacity Spool Valve: 35 scfh (0.93 nor-
mal m3/hour) at 60 psig (4.1 bar) supply pressure
Operative Temperature Limits(1)
J–40 to 180°F (–40 to 80°C) or J–40 to 250°F
(–40 to 121°C)
Housing Classification for Type 3720
NEMA 3R, IEC 529 IP14; Mounting orientation re-
quires converter vent (key 78, figure 27) to be be-
low horizontal
Electrical Classification for Type 3720
Refer to the Hazardous Area Classification bulletin
for specific approvals
Pressure Connections
1/4-inch NPT female
Conduit Connection for Type 3720
J1/2-inch NPT female (standard) or
JM20 female (optional)
Rotary Valve Rotation
J90 degrees (standard)
Approximate Weight
Type 3710: 4.5 pounds (2.04 kg)
Type 3720: 6.0 pounds (2.72 kg)
1. This term is defined in ISA Standard S51.1:1979.
2. For direct action, an increasing input signal extends actuator rod. For reverse action, an increasing input signal retracts actuator rod.
3. Scfh — standard cubic feet per hour (60°F and 14.7 psia). Normal cubic meters per hour (0°C and 1.01325 bar absolute).
4. Typical valves tested using a Fisher Controls Type 1061 size 30 actuator at 60 psig (4.1 bar) supply pressure. Performance may vary with other actuator types and supply pressures.

Types 3710, 3720, 3722
5
Table 2. Input Signal Range
POSITIONER TYPE
INPUT SIGNAL RANGE
POSITIONER TYPE Pneumatic Electronic
T ype 3710
w/3 to 15 psig span adj. ass’y
(no color coding)
J3 - 15 psig (0.2 - 1.0 bar)
J3 - 9 psig (0.2 - 0.6 bar) and
9 - 15 psig (0.6 - 1.0 bar),
split-ranging
–––
T ype 3710
w/6 to 30 psig span adj. ass’y
(red color coding)
J6 - 30 psig (0.4 - 2.0 bar)
J6 to 18 psig (0.4 - 1.2 bar)
and
18 - 30 psig (1.2 - 2.0 bar),
split-ranging
–––
T ype 3720
–––
J4 - 20 mA, dc
J4 - 12 mA, dc, or 12 - 20
mA,
dc, split-ranging
T able 3. Positioner to Actuator Mountings
POSITIONER T O ACTUA TOR MOUNTINGS
POSITIONER T O ACTUA TOR MOUNTINGS
Direct Mounting to Actuator Cover Plate(1) Mounting Plate Required
SFisher Type 1051, sizes 30(2), 40, and 60
SFisher Type 1052, sizes 30(2), 40, 60, and 70
SFisher Type 1061, sizes 30, 40, 60, and 68
SFisher Type 1031, sizes 26, 33, 45, 60, and 80
SFisher Type 1032, sizes 45, 70, 185, 280, 425,
680, 1125, 1370, 2585, and 4580
SFisher Type 1051, size 33
SFisher Type 1052, sizes 20, 33
SFisher Type 1061, sizes 80, 100
SFisher Type 1066, sizes 20, 27, and 75
1. Includes purge tube option.
2. The size 30 actuator is no longer manufactured by Fisher Controls. The Types 3710, 3720 positioners are available for field installation on existing size 30 actuators.
DUse bypass valves or completely
shut off the process to isolate the valve
from process pressure. Relieve process
pressure on both sides of the valve.
Drain the process media from both
sides of the valve.
DVent the power actuator loading
pressure and relieve any actuator spring
precompression.
DRelieve any supply or output pres-
sure in the existing positioner.
DWhen installing an
electro-pneumatic positioner or
converter in a hazardous area, turn off
control signals until installation is
complete. Be sure all safety barriers,
connections, and the converter housing
cap and O-ring are properly installed
before supplying a control signal to the
unit.
DUse lock-out procedures to be sure
that the above measures stay in effect
while you work on the equipment.
WARNING
The positioner can provide full supply
pressure to any connected equipment.
To avoid personal injury and equipment
damage, make sure supply pressure
never exceeds the maximum safe work-
ing pressure of any connected equip-
ment.
See figure 3.
To change an existing Type 3710 positioner into a
Type 3720 positioner, install a Type 3722
electro-pneumatic converter. The Type 3722
electro-pneumatic converter mounts over the input and
supply connections of the Type 3710 positioner.
1. Be sure all safety procedures have been followed.
Remove the input and supply connections from the
existing Type 3710 base plate and clean the ports.
2. Locate the two O-rings (key 85, figure 27) and
properly lubricate (key 82) them. Place one O-ring in
the recessed area surrounding the input port on the
positioner base plate. Place the other O-ring around
the supply port.

Types 3710, 3720, 3722
6
Figure3. T ype 3722 Electro-Pneumatic Converter
W6145/IL
EXTERNAL
GROUNDING
SCREW
SUPPLY
CONNECTION
3. Locate the two socket head mounting screws (key
84). Properly orient the converter and secure it to the
positioner base plate with the mounting screws. Be
sure the O-rings remain in place while securing the
converter to the positioner base plate.
4. Connect supply pressure to the converter supply
port.
Mounting the Positioner
Typically, a positioner is ordered with an actuator. At
the factory, the positioner is mounted on the actuator
and calibrated. However, a positioner can be order
separately and mounted on an existing actuator.
To field-mount a positioner to an existing actuator, an
actuator cover plate with mounting holes and purge
tube knockout may be required. Check the existing
actuator cover plate. It must have three positioner
mounting holes and, for specific actuators, a purge
tube knockout. See table 3.
If the proper mounting holes are present, perform the
following mounting procedure and then follow the cal-
ibration procedures in this instruction manual. Refer to
the appropriate instruction manuals for actuator and
valve mounting procedures.
WARNING
Avoid personal injury from sudden re-
lease of process pressure. Before
mounting the positioner:
Disconnect any operating lines pro-
viding air pressure, electric power, or a
control signal to the actuator. Be sure
the actuator cannot suddenly open or
close the valve.
Use bypass valves or completely
shut off the process to isolate the valve
from process pressure. Relieve process
pressure on both sides of the valve.
Drain the process media from both
sides of the valve.
Vent the power actuator loading
pressure and relieve any actuator spring
precompression.
Use lock-out procedures to be sure
that the above measures stay in effect
while you work on the equipment.
When installing a positioner or
converter in a hazardous area, turn off
control signals until installation is com-
plete. Be sure all safety barriers, con-
nections, and the converter housing cap
and O-ring are properly installed before
supplying a control signal to the unit.

Types 3710, 3720, 3722
7
WARNING
The positioner can provide full supply
pressure to connected equipment. To
avoid personal injury and equipment
damage, make sure the supply pressure
never exceeds the maximum safe work-
ing pressure of any connected equip-
ment.
Note
Mounting, Actuator Types
The positioner mounts directly to the
actuator cover plate of several Fisher
Controls actuators. See table 3. To
directly mount the positioner to an
existing Fisher Controls actuator, you
must use an actuator cover plate with
three positioner mounting holes and the
5/8-inch purge option knockout plug.
See the parts list for the specific actua-
tor cover plate required above to inte-
grally mount the positioner.
See figures 4, 29 for positioner
mounting drawings.
Note
Replacing An Existing Type 3610
Positioner
To mount the positioner to an actuator
with an existing Type 3610 positioner,
remove the Type 3610 positioner and
replace it with an appropriate metal cov-
er plate and four cap screws. For assis-
tance, contact your Fisher Controls
sales office or representative.
1. See figure 5 for a typical actuator. Remove the ac-
tuator travel indicator machine screws, travel indicator,
and actuator cover cap screws.
Note
Rod End Bearing
When removing the actuator cover plate,
take care not to change the position of
the rod end bearing on the end of the
turnbuckle inside the actuator housing.
2. If necessary, install a new cover plate.
a. Remove the existing cap screws and actuator
cover plate from the actuator housing.
b. Remove the retaining ring (e-clip) and hub from
the cover plate.
c. Install the hub and retaining ring into the new
actuator/positioner cover plate.
Note
Cover Plate Orientation
Position the actuator cover plate so the
positioner mounting holes on the new
cover plate allow placement of the posi-
tioner in the desired orientation.
Actuator cover alignment on the Type
1052 actuator can be aided by moving
the actuator slightly away from its ”up”
travel stop using a regulated air source.
If the hole alignment cannot be obtained
in this manner, temporarily loosen the
cap screws that secure the housing to
the mounting yoke and shift the
housing slightly. Do not completely
travel the actuator while the cover is
removed.
Tighten the actuator cap screws before
continuing.
3. Position the new actuator/positioner cover plate so
the positioner mounting holes on the new cover plate
allow placement of the new positioner in the desired
orientation. Secure the new cover plate to the actua-
tor.
4. Install the positioner tie bar (key 42) in place of the
travel indicator on the actuator hub.
Note
Positioner Mounting Alignment
Before installation of the positioner
mounting plate (key 43), review the
mounting drawings (figures 4, 29).
Properly align the positioner mounting
plate before attaching the mounting
plate to the actuator cover plate. Note
that the three positioner mounting holes
must be aligned to match the three
mounting screws which will pass
through the base of the positioner.

Types 3710, 3720, 3722
8
Figure4. Typical Positioner/Actuator Combinations
42B8466-A/DOC
42B8466-A/DOC

Types 3710, 3720, 3722
9
Figure5. Typical Piston Actuator (T ype 1061)
W6147-1/IL
W6146-1/IL
       
    

Types 3710, 3720, 3722
10
Figure 6. Loosening the Cam Locknut
W5916/IL
5. If the specific actuator requires a positioner
mounting plate (key 43), install the mounting plate
using the cap screws (key 45).
6. Unscrew the four captive cover screws and remove
the cover assembly (key 7) from the positioner.
7. See figure 6. Loosen the cam locknut (key 37) and
rotate the feedback shaft (key 38) as necessary to
align the slot in the feedback shaft end with the tie bar
on the actuator hub. Tighten the cam locknut.
8. Align the positioner with the mounting holes in the
new actuator cover plate or positioner mounting plate.
Be sure that the tie bar fits securely into the feedback
shaft end slot. Secure the positioner to the actuator
cover plate or mounting plate using the (hex) socket
head cap screws (key 46).
9. Before installing the positioner cover, properly align
the valve position indicator (standard, low-profile indi-
cator or optional beacon indicator). Follow the stan-
dard or beacon indicator alignment procedure given in
this instruction manual. Then, install the positioner
cover assembly.
Connections
WARNING
The positioner is capable of providing
full supply pressure to connected equip-
ment. To avoid personal injury and
equipment damage, make sure the sup-
ply pressure never exceeds the maxi-
mum safe working pressure of any con-
nected equipment.
To complete the installation of a positioner, connect
tubing and fittings between the positioner and the ac-
tuator. The fittings, tubing, and mounting parts re-
quired depend on the type number and optional equip-
ment such as filter, regulator, and bypass valve.
Positioner pressure and electrical connection locations
are shown in figure 7. All pressure connections are
1/4-inch NPT female. Use 3/8-inch tubing or 1/4-inch
pipe for all tubing connections.

Types 3710, 3720, 3722
11
Figure 7. Connections
34B0693-A
B2386-1/IL
The conduit connection to the converter is 1/2-inch
NPT female with an M20 connection, optional.
The positioner does not have a remote vent connec-
tion. Refer to the section on vent opening, purge op-
tion, and actuator vent connection for instructions
about a remote vent connection.
Supply Connection
WARNING
Personal injury or property damage may
occur from an uncontrolled process if
the supply medium is not clean, dry,
oil-free, or non-corrosive gas. Industry
instrument air quality standards
describe acceptable dirt, oil, and
moisture content.
Because differences in air quality can
cause a variety of problems in pneumat-
ic control operation, Fisher Controls has
no technical basis to recommend the
level of filtration equipment required to
prevent performance degradation of
pneumatic equipment. A filter or filter
regulator capable of removing particles
of 40 microns in diameter should be suf-
ficient for most applications.
Use appropriate filtration equipment and
establish a maintenance cycle to moni-
tor positioner operation.
See figure 7.

Types 3710, 3720, 3722
12
Connect a clean, dry, oil-free, non-corrosive air source
to the supply connection of the positioner. Recom-
mended supply line size is 3/8-inch tubing or 1/4-inch
pipe. A supply air filter or a filter regulator capable of
removing particles 40 microns in diameter is recom-
mended. Refer to the positioner specifications, table 1,
for supply pressure requirements.
Supply pressure must not exceed the following limits:
For the positioner, do not exceed the maximum
pressure rating of 150 psig (10.3 bar).
For actuator pressure, refer to the appropriate
actuator instruction manual for maximum allowable
pressures.
For the valve body assembly, do not exceed the
maximum allowable torque or thrust of the specific
valve.
Output Connections
See figure 7.
Use 3/8-inch tubing between the actuator and position-
er.
For diaphragm rotary actuators (single-action out-
put 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 OUT-
PUT 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 ac-
tuator cylinder connection.
Instrument Connection
See figure 7.
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 posi-
tioner, refer to the electrical connections section.
Vent Opening, Purge Option, and
Actuator Vent Connection
WARNING
If a flammable, toxic, or reactive 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 flammable, toxic, or
reactive gas.
The positioner/actuator assembly does
not form a gas-tight seal and flammable,
toxic, or reactive gas could leak from
the assembly. Therefore, if the assembly
is enclosed, install a remote vent line
from the enclosure. Furthermore, a re-
mote vent pipe from the enclosure alone
cannot be relied upon to remove all haz-
ardous gas.
Use adequate ventilation and other nec-
essary safety measures. Vent line piping
should comply with local and regional
codes and should be as short as pos-
sible with adequate inside diameter and
few bends to reduce case pressure
buildup.
See figure 8.
The positioner does not have an external vent connec-
tion. A unit exhausts actuator pressure through a
screened hole (vent opening, figure 7) located in the
positioner base plate. Do not restrict the vent opening.
Restricting the vent opening can produce a pressure
buildup in the positioner case and degrade positioner
performance.
A purge tube (key 58, figure 8) is available as an op-
tion when mounting the positioner on selected Fisher
Controls actuators. One end of the purge tube with an
O-ring (key 59) installs in the actuator cover plate. The
other end of the purge tube with an O-ring installs in
the vent opening in the positioner base plate. When
the purge tube is used, it relays actuator exhaust pres-
sure from the positioner into the actuator housing.
Within the actuator and positioner assembly, exhaust
pressure takes the following course:
The actuator exhaust pressure vents from the
actuator through the positioner spool valve into the
positioner case.
The exhaust pressure then exits the positioner
case through the vent opening.
The purge tube carries the exhaust pressure into
the actuator housing.
The exhaust pressure then purges the actuator
housing and dissipates from the housing.

Types 3710, 3720, 3722
13
Figure 8. Mounting the Positioner Base Plate with Purge T ube
W6073/IL
PURGE TUBE (KEY 58)
O-RINGS (KEY 59)
LONG-BLADED SCREW
DRIVER THROUGH VENT
Most actuators manufactured by Fisher Controls do
not have vent openings. The exhaust pressure simply
dissipates from within the actuator housing. However,
the Types 1051, 1052, and 1061 actuators feature an
operational screened vent connection when a metal
access plate is specified for the actuator housing.
When using the purge option, remember: The actuator
and positioner assembly is not airtight. However, if you
use the optional purge tube to connect the positioner
to the actuator and the actuator has a vent opening,
leave open the 1/4-inch NPT vent connection in the
actuator housing to prevent pressure buildup in the
positioner case.
If the 1/4-inch NPT vent connection is available, a vent
line can be installed from the actuator. However, the
valve/actuator/positioner assembly is not airtight.
Maintain adequate ventilation and observe other safe-
ty measures.
For help in selecting the purge option for positioner/
actuator combinations, contact your Fisher sales office
or representative.
Connecting the Purge Tube
The positioner mounts directly to the actuator cover
plate of Fisher Controls Types 1051, 1052, and 1061
actuators. See table 3 for actuator sizes.
With an integral mounting, a purge tube (key 58), with
two O-rings (key 59), can be used to relay actuator
exhaust pressure from the positioner into the actuator
housing. If the current actuator cover plate does not
have the positioner mounting holes and purge tube
knockout, order a new cover plate. See the parts list
for the specific actuator cover plate required for each
actuator.
1. The actuator cover plate features a purge tube
knockout. Locate the knockout and use appropriate
tools to open this hole in the cover plate.
2. Install the actuator cover plate and then insert the
purge tube with O-ring into the purge tube hole in the
cover plate.
Note
Purge Tube Installation
When mounting a positioner to an ac-
tuator with the purge tube installed,
guide the purge tube into the vent open-
ing in the positioner base plate by re-
moving the vent screen (key 41) and
then inserting an appropriate tool such
as a screwdriver through the vent open-
ing into the purge tube.
When the positioner is secured to the
actuator, install the vent screen.
3. Before mounting the positioner, be sure the second
O-ring is properly fitted to the end of the purge tube.
Use care when mounting the positioner. Be sure the
purge tube with O-ring fits into the vent opening on the
rear of the positioner base plate.

Types 3710, 3720, 3722
14
4. Secure the positioner to the mounting plate using
the (hex) socket head cap screws (key 46).
5. Install the vent screen in the positioner base plate.
Electrical Connection for Type 3720
Positioner
WARNING
In explosion-proof applications, discon-
nect power before removing the con-
verter housing cap.
In Class I, Division 1 explosion-proof
applications, install rigid metal conduit
and a conduit seal no more than
18 inches (457 mm) from the converter.
Personal injury or property damage may
result from explosion if the seal is not
installed.
For intrinsically-safe installations, refer
to Fisher loop schematics or to instruc-
tions provided by the barrier manufac-
turer for proper wiring and installation.
Use the 1/2-inch NPT (or M20 thread) conduit connec-
tion for field wiring installation. Refer to figures 9 and
10 when connecting field wiring from the control de-
vice to the converter. Connect the positive wire from
the control device to the converter’s positive ( + ) ter-
minal and the negative wire from the control device to
the converter’s negative ( – ) terminal.
Do not overtighten the terminal screws. Maximum
torque is 4 pounds force per inch (4 lbfSin.) or
0.45 Newton-meters (0.45 NSm).
Diagnostic Connections
See figure 11.
For diagnostic testing of control valve packages
(valve, actuator, positioner, and accessories), special
connectors and hardware are available. The hardware
required for diagnostic connections includes 3/4-inch
NPT pipe nipples and pipe tees with a 1/8-inch NPT
pipe bushing for the connector. The connector con-
sists of a 1/8-inch NPT body and body protector. If the
diagnostic connectors are ordered for a positioner with
gauges, 1/8-inch stems are also included.
Install connectors and hardware between the position-
er and the actuator.
Figure 9. Field Wiring Diagram
21B2335-D
A5578-1/IL
Figure 10. Circuit Schematic
A5577*/IL
1. Before assembling the pipe nipple, pipe tee, pipe
bushing, actuator piping, and connector body, apply
sealant (key 64) to all threads.
2. Assemble connectors and hardware. Remove stan-
dard piping connections, if necessary, and install the
diagnostic connections.
DType 3720: For a diagnostic connection to the
instrument pressure output from the converter module,
remove the 1/8-inch NPT pipe plug (key 86) from the
Type 3722 converter housing. Apply sealant (key 83)
to the threads of the 1/8-inch NPT connector body and
install it directly into the housing.
DTypes 3710, 3720: For diagnostic connections
made up of a pipe nipple, pipe tee, pipe bushing, and
connector body, turn the pipe tee to position the con-
nector body for easy access when doing diagnostic
testing.

Types 3710, 3720, 3722
15
Figure 1 1. Diagnostic Connections
13B8743-A
B2414/IL
12B8055-A
B2385/IL

Types 3710, 3720, 3722
16
Figure 12. Loosening the Cam Locknut
W5916/IL
Calibration
The following calibration procedures are for Type 3710
pneumatic positioner adjustment. For the Type 3720
electro-pneumatic positioner, there are no adjustments
within the Type 3722 converter portion of the position-
er. All adjustments are accomplished within the pneu-
matic portion of the positioner.
WARNING
Avoid personal injury or equipment
damage from sudden release of process
fluid. Before calibration:
Use bypass valves or completely
shut off the process to isolate the valve
from process pressure.
Release process pressure from
both sides of the valve.
Setting the Initial Cam Position
Before trying any calibration procedure, follow these
instructions to position the cam (key 36) with respect
to the valve position.
1. Unscrew the four captive cover screws (key 8) and
remove the positioner cover assembly (key 7).
2. See figure 12. Inspect the cam (key 36) and loosen
the cam locknut (key 37).
3. Disconnect the positioner output tubing at the ac-
tuator and attach a regulated air source or other
means of positioning the actuator.
4. Position the actuator to correspond with the initial
valve position at minimum instrument input signal.
Stroke the actuator to the final valve position and note
the direction of actuator shaft rotation. Return the ac-
tuator to its initial valve position.
5. See figure 13. Position the cam on the roller for the
desired input signal range, for example, 0 - 100%, and
insure that the arrow on the cam corresponds with the
direction of actuator shaft rotation for increasing input
signal. Tighten the cam locknut, leaving a gap of
approximately 0.031 inches (0.80 mm) between the
cam and roller.
6. Reconnect the output tubing to the actuator.

Types 3710, 3720, 3722
17
Figure 13. Proper Cam Position
A6045/IL
Figure 14. Features and Adjustments
W5947
NAMEPLATE
AREA
SCREENED
VENT
OPENING
ZERO ADJ PIVOT
SPAN ADJ
SHAFT
(THREADED ROD)
ZERO ADJUSTER
LOCK NUT
ZERO ADJUSTER
FEEDBACK
ARM ASSY
NOTES:
THE SPAN ADJ ASSY IS MADE UP OF THE RANGE SPRING, SPAN ADJ SHAFT (THREADED ROD), AND SPAN ADJ KNOB.
THE SPAN ADJ ASSY FEATURES A RED COLOR-CODED RANGE SPRING FOR A 6 TO 30 PSIG INPUT SIGNAL
SPAN ADJ ASSY ACTION BLOCK MOUNTING SCREW HOLE
SPOOL VALVE
INPUT MODULE
SUMMING BEAM
MOUNTING
SCREW
HOLE
CAM
MOUNTING SCREW HOLE
1
2
1
2
Zero and Span Adjustments
See figure 14.
1. To start this procedure, if necessary, unscrew the
four captive cover screws (key 8) and remove the
cover assembly (key 7).
2. Apply supply pressure.
3. Provide a way to check the input signal. Apply the
minimum input signal. For example:
For a Type 3710 pneumatic positioner, if the in-
put signal range is 3 to 15 psig (0.2 to 1.0 bar), apply
3 psig (0.2 bar).
For a Type 3720 electro-pneumatic positioner, if
the input signal range is 4 to 20 mA, apply 4 mA to the
Type 3722 converter.

Types 3710, 3720, 3722
18
NOTES:
RETAINING RING (E-CLIP) (KEY 12) IS NOT SHOWN.
THE SHAFT OF THE INDICATOR (KEY 15) PASSES THROUGH THE POSITIONER COVER
AND FITS OVER THE END OF THE FEEDBACK SHAFT (CAM SHAFT) (KEY 38).
Figure 15. Standard Indicator
W6061/IL
1
2
FEEDBACK SHAFT
(CAM SHAFT) (KEY 38) INDICATOR (KEY 15) INDICATOR SCALE (KEY 14)
1
2
Note
Key 35
The zero adjustment locknut and zero
adjustment knob are identical parts,
key 35.
4. Loosen the zero adjustment locknut (key 35) and
turn the zero adjustment knob (key 35) until the actua-
tor travels the valve to the proper position. This valve
position must correspond to the minimum input signal.
Tighten the zero adjustment locknut before proceeding
to step 5.
5. Slowly increase the input signal until the input
reaches the maximum input signal. Observe the ac-
tuator travel and valve position as the input increases.
Determine the actuator/valve position at the maximum
input signal.
6. After observing the actuator/valve travel at maxi-
mum input signal, return the input signal to the mini-
mum input signal before turning the span adjustment
knob.
If the actuator/valve travel, observed in step 5,
stopped short of the required valve position at maxi-
mum input signal, increase the actuator/valve travel by
rotating the positioner span adjustment knob toward
the zero adjustment nut (key 35) to add active spring
coils to the range spring.
If the actuator/valve travel, observed in step 5,
reaches the required valve position before the input
signal reaches the maximum input signal, decrease
the actuator/valve travel by rotating the positioner
span adjustment knob away from the zero adjustment
nut (key 35) to remove active spring coils from the
range spring.
7. After turning the span adjustment knob to change
actuator travel, re-zero the positioner using the proce-
dure given in steps 4 and 5, above.
8. Increase the input signal until the input reaches the
maximum input signal. Observe the actuator/valve
travel as the input increases. Repeat steps 3 through
8 until the actuator travel corresponds to the input sig-
nal range.
9. Properly align the indicator and replace the posi-
tioner cover assembly.
Standard or Beacon Indicator Alignment
Note
Indicator
The standard, low-profile indicator con-
sists of the indicator cover (key 14), in-
dicator (key 15) with internal retaining
ring (e-clip) (key 12), and separate point-
er (key 13) recessed into the indicator.
An O-ring (key 15A) fits over the molded
Phillips slot in the indicator to retain the
pointer.
The optional beacon indicator consists
of an external unit (key 10) with external
retaining ring (key 12) and extension
shaft (key 11).
See figure 15.

Types 3710, 3720, 3722
19
1. Locate the indicator/extension shaft (key 11 or key
15) inside the front cover. To align the indicator, rotate
the indicator/extension shaft to match the position of
the feedback shaft extending from the cam (key 36).
2. Install the cover assembly (key 7) so that the indi-
cator/extension shaft joins with the feedback shaft.
The standard indicator (key 15) features a molded
Phillips slot that protrudes through the indicator cover
(key 14). If necessary, use a small, Phillips head
screwdriver to align the indicator with the feedback
shaft.
3. Inspect the indicator, pointer, and scale. Make sure
the proper valve position is shown. Follow the proce-
dures given in this instruction manual to travel the
valve from fully opened to fully closed. Make sure the
indicator properly displays the valve travel.
If the indicator is not properly aligned, continue with
the following procedure.
4. If the indicator pointer and indicator scale are
slightly out of alignment, loosen the four machine
screws (key 3) that hold the indicator scale to the posi-
tioner cover. Turn the scale to properly align it with the
pointer. Tighten the four screws and travel the valve to
confirm proper valve position indication.
5. If the pointer in the standard, low-profile indicator is
positioned in the wrong quadrant, loosen the four ma-
chine screws (key 8) that hold the indicator scale (key
14) to the positioner cover. Remove the indicator scale
and O-ring (key 15A). Then, carefully lift the pointer
(key 13) from the indicator (key 15). Place the pointer
in the proper position and re-install the O-ring, indica-
tor scale, and screws. Make sure the indicator scale
and pointer are now properly aligned by traveling the
valve.
6. If the internal scale of the beacon indicator is not
properly aligned, remove the four machine screws that
hold the beacon indicator (key 10) to the positioner
cover. Properly orient the beacon cover and replace
the screws. Make sure the beacon cover and scale
are now properly aligned by traveling the valve.
Changing Positioner Action
WARNING
Avoid personal injury or equipment
damage from sudden release of process
fluid. Before changing positioner action:
Disconnect any operating lines pro-
viding air pressure, electric power, or a
control signal to the actuator and acces-
sories. Be sure the actuator cannot sud-
denly open or close the valve.
Use bypass valves or completely
shut off the process to isolate the valve
from process pressure. Relieve process
pressure on both sides of the valve.
Drain the process media from both
sides of the valve.
Vent the actuator loading pressure.
Use lock-out procedures to be sure
that the above measures stay in effect
while you work on the equipment.
Single-Action/Double-Action
See figure 16 for positioner output connections. See
figure 18 for the positioner schematic.
Use 3/8-inch tubing between the positioner and actua-
tor.
For single-action output, plug positioner OUTPUT
A. Refer to the actuator instruction manual for the spe-
cific connection for positioner OUTPUT B. Connect
positioner OUTPUT B to the actuator connection for
single-action. For Fisher Controls diaphragm actua-
tors, this connection is known as the diaphragm casing
connection.
For double-action output (with direct-action), refer
to the actuator instruction manual for the specific con-
nections for positioner OUTPUT A and B. Connect
positioner OUTPUT A to the actuator cylinder connec-
tion where actuator air pressure is exhausted during
the initial actuator stroke. Connect positioner OUTPUT
B to the actuator cylinder connection where supply
pressure enters the actuator during the initial actuator
stroke. For Fisher Controls piston actuators, OUTPUT
A connects to the lower actuator cylinder connection
and OUTPUT B connects to the upper actuator cylin-
der connection.
Direct-Action/Reverse-Action
This section explains changing the positioner action
from direct to reverse or reverse to direct. With direct-
action, the actuator stem extends as the input signal to
the positioner increases. With reverse-action, the ac-
tuator stem retracts as the input signal to the position-
er increases.
See figure 16.
1. Turn off supply pressure. Reverse the piping con-
nections between the actuator and the positioner out-
put connections (OUTPUT A and OUTPUT B).

Types 3710, 3720, 3722
20
Figure 16. Output Connections
A6056/IL
For single-action output, disconnect piping from
OUTPUT B. Unplug OUTPUT A and connect the
piping to it. Plug OUTPUT B.
For double-action output, disconnect piping from
both positioner outputs. Connect piping from OUTPUT
A to OUTPUT B. Connect piping from OUTPUT B to
OUTPUT A.
It may be necessary to bend new lengths of tubing if
rigid tubing is used.
2. After reversing the piping connections, remove the
positioner cover assembly (key 7) and reverse the
cam (key 36). To reverse the cam, unscrew the cam
locknut (key 37). Remove the cam, turn it over, and
reinstall it, making sure the cam is positioned for the
proper input signal range.
3. Set the initial cam position following the cam align-
ment procedure given in this manual. Tighten the cam
locknut.
4. Turn on supply pressure. Perform the zero and
span adjustment procedure given in this manual.
5. Replace the positioner cover assembly.
Split-Range Operation
The positioner can be used for split-range operation
with the input signal from a single control device split
between two positioner/actuator/control valve pack-
ages. One positioner will fully stroke one actuator with
an input signal range from:
3 to 9 psig (0.2 to 0.6 bar)
9 to 15 psig (0.6 to 1.0 bar)
6 to 18 psig (0.4 to 1.2 bar)
18 to 30 psig (1.2 to 2.0 bar)
1. Turn off supply pressure. Remove the positioner
cover assembly (key 7).
2. Loosen the cam locknut (key 37). Rotate the cam
to the desired split-range value: either “0-50%” or
“50-100%”.
3. Before tightening the cam locknut, perform the cam
alignment procedure given in this manual.
4. Turn on supply pressure. Perform the zero and
span adjustment procedure given in this manual. Use
the proper input signal range to match the cam split-
range value selected in step 2, above.
5. Replace the positioner cover assembly.
Changing The Spool Valve (To Increase
Positioner Output Capacity)
WARNING
Avoid personal injury or equipment
damage from sudden release of process
fluid. Before changing the spool valve:
Disconnect any operating lines pro-
viding air pressure, electric power, or a
control signal to the actuator and acces-
sories. Be sure the actuator cannot sud-
denly open or close the valve.
Use bypass valves or completely
shut off the process to isolate the valve
from process pressure. Relieve process
pressure on both sides of the valve.
Drain the process media from both
sides of the valve.
Vent the actuator loading pressure.
Use lock-out procedures to be sure
that the above measures stay in effect
while you work on the equipment.
A high-capacity spool valve is available as an option.
Use of the high-capacity spool valve permits increased
actuator stroking speed. See table 2 for outputs for the
standard and high-capacity spool valves.
1. Turn off supply pressure. Release actuator pres-
sure. Remove the positioner cover assembly (key 7).