Fisher 3570 User manual

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Fisherr3570 Pneumatic Valve Positioners
Contents
Introduction 1.................................
Scope of Manual 1.............................
Description 2.................................
Valve Positioner Type Numbers 2.............
Specifications 4...............................
Educational Services 4.........................
Installation, Mounting, and Connections 5..........
Installation 5.................................
Diagnostic Test Connections (Optional) 6.....
Connections 7................................
Piping Sizes 7.............................
Vent 8...................................
Supply Pressure Connections 9..............
Cylinder Connections 10....................
Instrument Connection 10..................
Operating Information 11........................
Initial Adjustments 11..........................
Adjustment Procedures 11......................
Changing Positioner Action 12..................
Split Range Operation 15.......................
Initial Range Spring Extension Procedure
for 3570P and 3570PC Positioners 15..........
Principle of Operation 17........................
3570, 3570C, 3570P, 3570PC, and
3571 Valve Positioners 17....................
3572 and 3576 Valve Positioners 18..............
3573 and 3577 Valve Positioners 19..............
Relay Operation 20............................
Maintenance 21................................
Troubleshooting 22............................
Converting a 3570 Valve Positioner to a
3570C Valve Positioner 23....................
Range Spring 24..............................
Disassembly 24............................
Assembly 24..............................
Figure 1. Fisher 3570 Positioner Mounted on
470 Actuator
W5566
Bias Spring 25................................
Disassembly 25............................
Assembly 25..............................
Parts Ordering 25...............................
Parts Kits 26...................................
Positioner Repair Kits 26........................
Diagnostic Test Connection Kits 26...............
Parts List 26...................................
Positioner Common Parts 26....................
Introduction
Scope of Manual
This manual provides installation, operation, adjustment, maintenance, and parts ordering information for Fisher
3570 pneumatic valve positioners. The various product types within this series are described later in this manual. Refer
Instruction Manual
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to figure 1 for a typical mounting of a 3570 positioner. Refer to separate instruction manuals for information
concerning the actuator, valve, and accessories.
Do not install, operate or maintain a 3570 positioner without being fully trained and qualified in valve, actuator, and
accessory installation, operation, and maintenance. To avoid personal injury or property damage, it is important to
carefully read, understand and follow all the contents of this manual, including all safety cautions and warnings. If you
have any questions about these instructions, contact your Emerson Process Management sales office before
proceeding.
Description
3570 pneumatic valve positioners are used with control valve assemblies to provide an accurate valve stem position
that is proportional to the input signal received from a control device. The input signal range can be 0.2 to 1.0 bar (3 to
15 psig), 0.4 to 2.0 bar (6 to 30 psig), or another pneumatic input signal range, as required.
These positioners are normally used with pneumatic piston actuators. However, product types within the 3570 family
can be used with pneumatic, long‐stroke, cylinder actuators or with pneumatic diaphragm actuators.
Valve Positioner Type Numbers
3570 — Pneumatic valve positioner with two relays for use with Fisher 470 and 480 pneumatic piston actuators. See
figure 4. The positioner includes three pressure gauges to monitor input signal, relay output pressure to the top of the
actuator cylinder, and relay output pressure to the bottom (piston underside) of the actuator cylinder.
The 3570 positioner is mounted on the top of the actuator cylinder. The actuator stem position feedback is provided
through extension of the range spring attached to the actuator piston rod.
3570C — Pneumatic valve positioner with automotive tire valves instead of pressure gauges. Tire valves can be used
for clip‐on test pressure gauges. The relay nozzles are locked in place with locknuts to resist unwanted nozzle
movement due to vibration.
3570P — Pneumatic valve positioner with two relays for use with Fisher 490 pneumatic piston actuators. The
positioner includes three pressure gauges to monitor input signal, relay output pressure to the top of the actuator
cylinder, and relay output pressure to the bottom (piston underside) of the actuator cylinder.
The 3570P positioner is mounted alongside the actuator cylinder. Actuator stem position feedback is provided from
the actuator‐valve stem connector through a cable and spool assembly.
3570PC — Pneumatic valve positioner with automotive tire valves instead of pressure gauges. Tire valves can be used
for clip‐on test pressure gauges. The relay nozzles are locked in place with locknuts to resist unwanted nozzle
movement due to vibration.
3571 (Discontinued)— Pneumatic valve positioner with two relays for use with long‐stroke cylinder actuators. The
positioner includes three pressure gauges to monitor input signal, relay output pressure to the top of the actuator
cylinder, and relay output pressure to the bottom (piston underside) of the actuator cylinder.
The 3571 positioner is bracket‐mounted to the side of the actuator. Actuator stem position feedback is provided
through a wire from the actuator‐valve stem connector.
3572 — Pneumatic valve positioner with one relay. The 3572 positioner is normally used on the 472 pneumatic piston
actuator mounted on valve bodies having push‐down‐to‐open (PDTO) action. The positioner includes two pressure
gauges to monitor input signal pressure and relay output pressure to the top of the actuator cylinder.
The 3572 positioner is mounted on the top of the actuator cylinder. Actuator stem position feedback is provided
through an extension of the actuator piston rod.

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Table 1. Specifications
Available Configurations
See the positioner type number descriptions given
above.
Input Signal
Standard Ranges: 0.2 to 1.0 bar (3 to 15 psig) or 0.4
to 2.0 bar (6 to 30 psig)
Optional Ranges: As desired, within the limits of the
bellows
Split Ranges: Use one‐half of either standard range
when two control valves are operated by one output
signal form a single control device
Output Signal
Type: Pneumatic pressure as required to maintain the
correct valve stem position and seat load
Action: Field‐reversible between direct and reverse
Resolution(1)
0.2% of instrument pressure span
Repeatability(1)
0.3% of total stroke or instrument pressure span
Pressure Connections
Vent: 3/8 NPT
All others: 1/4 NPT
Pressure Indications
3570C and 3570CP Positioners: Tire valves accept
standard pressure gauge chucks (gauges not
supplied)
All Other Types: Gauges supplied per table 3
Bellows Pressure Rating
Standard Bellows: 3.4 bar (50 psig)
Optional Bellows: 6.2 bar (90 psig)
Supply Pressure
Maximum: 10.4 bar (150 psig)
Minimum: 2.4 bar (35 psig)
Supply Medium
Air or Natural Gas
Supply medium must be clean, dry, and noncorrosive
Per ISA Standard 7.0.01
A maximum 40 micrometer particle size in the air
system is acceptable. Further filtration down to 5
micrometer particle size is recommended. Lubricant
content is not to exceed 1 ppm weight (w/w) or
volume (v/v) basis. Condensation in the air supply
should be minimized
Per ISO 8573-1
Maximum particle density size: Class 7
Oil content: Class 3
Pressure Dew Point: Class 3 or at least 10_C less than
the lowest ambient temperature expected
Steady‐State Air Consumption(2)
0.54 normal m3/h (20 scfh) with 6.9 bar (100 psig)
supply pressure
Operative Ambient Temperature Limits(1)
With Nitrile O‐Rings and Diaphragms: –34 to 71°C
(–30 to 160°F)
With Fluorocarbon O‐Rings and Diaphragms
(Optional): 0 to 104°C (32 to 220°F)
Hazardous Area Classification
Complies with the requirements of ATEX Group II
Category 2 Gas and Dust
Meets Customs Union technical regulation TP TC
012/2011 for Groups II/III Category 2 equipment
II Gb c T*X
III Db c T*X
Options
JRestrictor (high‐frequency filter for bellows)
Approximate Weight
2.7 kg (6 pounds) without optional mounting bracket
or actuator/valve assembly
‐ continued ‐

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Table 1. Specifications (Continued)
Declaration of SEP
Fisher Controls International LLC declares this
product to be in compliance with Article 3 paragraph
3 of the Pressure Equipment Directive (PED) 97 / 23 /
EC. It was designed and manufactured in accordance
with Sound Engineering Practice (SEP) and cannot
bear the CE marking related to PED compliance.
However, the product may bear the CE marking to
indicate compliance with other applicable European
Community Directives.
NOTE: Specialized instrument terms are defined in ANSI/ISA Standard 51.1 - Process Instrument Terminology.
1. For a 3570 or 3570C positioner mounted on a 470 or 480 actuator. Values do not apply to other constructions or actuator‐valve combinations.
2. m3/h at 0°C, 1.01325 bar, absolute (Scfh at 60°F, 14.7 psia).
Table 2. Action Under Normal Operating Conditions
POSITIONER ACTION DESIRED PISTON MOTION(1)
Down Up
Direct‐acting Increasing input signal pressure to bellows Decreasing input signal pressure to bellows
Reverse‐acting Decreasing input signal pressure to bellows Increasing input signal pressure to bellows
1. Supply pressure is routed through relays to piston.
Table 3. Pressure Indications
PRESSURE MONITORED
NUMBER OF GAUGES SUPPLIED
STANDARD GAUGE RANGE(1)
Two‐Relay
Positioner
One‐Relay
Positioner
Positioner input signal pressure 1 1 0‐30 psi/0‐0.2 MPa/0‐2 bar or
0‐60 psi/0‐0.4 MPa/0‐4 bar
Cylinder (relay output) pressure 2 1 0‐160 psi/0‐1.1 MPa/0‐11 bar
1. For gauges marked in other units and ranges, consult your Emerson Process Management sales office.
3573 — Pneumatic valve positioner that is similar to The 3572 positioner with the relay output pressure piped to the
bottom (piston underside) of the actuator cylinder. The 3573 positioner is normally used on the 473 pneumatic piston
actuator with valve bodies having push‐down‐to‐close (PDTC) action.
3576 (Discontinued)— Pneumatic valve positioner with one relay for use on direct‐acting pneumatic diaphragm
actuators that require high operating pressures. The 3576 positioner includes two pressure gauges to monitor input
signal pressure and relay output pressure to the top of the actuator diaphragm.
The 3576 positioner is bracket‐mounted to the actuator yoke. Actuator stem position feedback is provided through a
wire from the actuator‐valve stem connector.
3577 (Discontinued)— Pneumatic valve positioner that is similar to 3576 positioner with the relay output pressure
piped to the underside of the actuator diaphragm on reverse‐acting pneumatic diaphragm actuators.
Specifications
Specifications for 3570 positioners are listed in table 1.
Educational Services
For information on available courses for 3570 positioners, as well as a variety of other products, contact:
Emerson Process Management
Educational Services, Registration
Phone: [phone] or [phone]
e‐mail: [email protected]
http://www.emersonprocess.com/education

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Installation, Mounting, and Connections
Installation
WARNING
D Always wear protective clothing, gloves, and eyewear when performing any installation operations to avoid personal
injury.
D Personal injury or property damage may result from fire or explosion if natural gas is used as the supply medium and
preventive measures are not taken. Preventive measures may include, but are not limited to, one or more of the
following: Remote venting of the unit, re‐evaluating the hazardous area classification, ensuring adequate ventilation,
and the removal of any ignition sources. For information on remote venting of this positioner, refer to page 8.
D Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
D If installing this into an existing application, also refer to the WARNING at the beginning of the Maintenance section of
this instruction manual.
The positioner is usually mounted on the actuator at the factory. However, if the positioner and actuator are ordered
separately, it is necessary to mount the positioner on the actuator. Before mounting the positioner, be certain the
O‐ring (key 33, figure 10) is in place in the cylinder (top connection) in the base of the positioner.
For appropriate actuator/positioner combinations, refer to the positioner type number descriptions given earlier in
this instruction manual.
D For 3570, 3570C, 3572, and 3573 positioners, mount the positioner with two cap screws (key 32, figure 10). If the
range and bias springs are not installed in the positioner, refer to the range spring and bias spring procedures in the
Maintenance section.
Insert the threaded end of the spring retainer (key 19, figure 2) into the center of the range spring (see figure 2). Then,
insert a screwdriver into the center of the range spring and extend the spring until the spring retainer can be screwed
into the top of the actuator piston rod extension. Tighten the spring retainer into the top of the actuator piston rod
extension. If the range spring and/or bias spring is not installed in the positioner, refer to the procedures for either
spring in the Maintenance section.
D For 3570P and 3570PC positioners, attach the positioner extension and positioner to the cylinder mounting plate
with the two cap screws (key 100, figure 13). Make the required pressure connections as described in the following
procedure. Go to the initial range spring extension procedures for 3570P and 3570PC positioners.
D For 3571, 3576, and 3577 positioners, insert two cap screws through the holes in the mounting bracket (key 55,
figure 12) to attach the positioner to the actuator mounting boss. Attach the hex drive stud to the actuator‐valve
stem connection. Attach the end bearing (key 56E, figure 12) to the hex drive stud.

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Figure 2. Bias and Range Springs for Zero and Span Adjustments
AJ7270‐C
1H8907‐C
1J2233‐C
B2402
ZERO ADJUSTMENT
EFFECTIVE LENGTH EFFECTIVE LENGTH
OVERALL
LENGTH
SPRING LOCK BELLOWS
BEAM TRAVEL
STOP (E‐RING)
BEAM
SPRING RETAINER SPACER
SPRING RETAINER SPACER
(IF REQUIRED) (KEY 235)
SPRING RETAINER
(KEY 19)
RANGE SPRING
(KEY 18)
(OPTIONAL)
PISTON ROD EXTENSION
LOCKNUTS
SPRING
RETAINER
BIAS SPRING
BIAS SPRING POST
NOTE:
BOTTOM OF BIAS SPRING POST THREAD MUST BE POSITIONED
AS SHOWN FOR PROPER POSITION OF E‐RING TRAVEL STOPS.
Diagnostic Test Connectors (Optional)
Diagnostic test connectors are available from the factory, when the unit is ordered, or they can be installed on an
existing control valve assembly in the field. These connectors are especially useful for “quick” connections when using
the FlowScannertvalve diagnostic system. The FlowScanner is a portable, microprocessor‐based diagnostic and
calibration system specifically designed for use with pneumatically‐operated control valves.
To support diagnostic testing of the control valve assembly, the connectors, piping, and other hardware can be
installed between the 3570 positioner and the actuator. A typical connector installation is shown in figure 3. For
connectors, refer to the FlowScanner Diagnostic Connection kit listing in the parts list.
The hardware used includes 3/4 NPT pipe nipple, pipe tee, and pipe bushings with a 1/8 NPT pipe bushing for the
connector. The connector consists of 1/8 NPT body and body protector (see figure 3).
1. Before assembling the pipe nipple, pipe tee, pipe bushings, actuator piping, and connector body, apply sealant to
all threads.
2. Position the pipe tee, connector body, and body protector for easy access when doing diagnostic testing.

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Figure 3. Diagnostic Test Connections
12B8044‐A
A6112
PIPE NIPPLE
TO BOTTOM
CYLINDER
PIPE TEE
GAUGE
ACTUATOR
377 TRIP VALVE
(OPTIONAL)
PIPE NIPPLE TO
INSTRUMENT CONNECTION
PIPE NIPPLE
TO SUPPLY
CONNECTION
3570
POSITIONER BODY PROTECTOR
BODY
PIPE BUSHING
STEM
REQUIRED WHEN
PURCHASED WITH GAUGE
FROM 377
TRIP VALVE
Connections
Piping Sizes
All pressure connections on 3570 positioners are 1/4 NPT (internal). Use 3/8‐inch pipe or tubing for supply, cylinder
(bottom connection), and instrument (input signal) connections. For the remote vent pipe, if one is required, use 19
mm (3/4‐inch) (minimum inside diameter) pipe for runs up to 6.09 meters (20 feet). For vent piping runs from 6.09 to
30.5 meters (20 to 100 feet), use 25.4 mm (1‐inch) (minimum inside diameter) pipe. Refer to figure 4 for the locations
and sizes of connections.

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Figure 4. Typical Location of Fisher 3570 Positioner Parts and Adjustments
CYLINDER
BOTTOM
PRESSURE
W4025
W4027
CLEAN‐OUT
PLUNGER
HORIZONTAL
RELAY
CYLINDER
(TOP CONNECTION)
(O‐RING, KEY 33)
CYLINDER
TOP PRESSURE
ZERO ADJUSTMENT
INSTRUMENT
PRESSURE
VENT CONNECTION
3/8 NPT
NOTES:
1 ON SOME CONSTRUCTIONS, TWO NOZZLES AND ADJUSTMENTS ARE REQUIRED.
CYLINDER (BOTTOM
CONNECTION) (1/4 NPT)
INSTRUMENT
CONNECTION
(INPUT SIGNAL)
(1/4 NPT)
SUPPLY
CONNECTION
(NOT SHOWN)
(1/4 NPT)
VERTICAL
RELAY
BELLOWS
RELAY NOZZLE
(OUTPUT PRESSURE
ADJUSTMENT)
BELLOWS POSTS
FRONT VIEW BACK VIEW
1
RANGE SPRING
(SPAN ADJUSTMENT)
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.

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The connection marked VENT (see figure 4) should be left open if the actuator is installed in the vertical position.
However, the vent must be protected against the entrance of any foreign material that could plug it. Check the vent
periodically to be certain it is not plugged.
If the actuator is mounted in other than the vertical position, be sure there is a vent and drain at the lowest point of the
positioner. To do this, remove the pipe plug (key 36, figure 10) from the cover. Then, position the cover in such a way
that the hole in the cover is at the lowest point. Plug the vent connection because the positioner is now vented
through the cover.
Note
A remote vent is not possible with 3570P, 3570PC, 3571, 3576, and 3577 positioners.
If a remote vent is required, the vent line must be as short as possible with a minimum number of bends or elbows.
Vent line piping should have a minimum inside diameter of 19 mm (3/4‐inch) for runs up to 6.09 meters (20 feet) and
a minimum inside diameter of 25.4 mm (1‐inch) for runs from 6.09 to 30.5 meters (20 to 100 feet).
Supply Pressure Connections
WARNING
Personal injury or property damage may occur from an uncontrolled process if the supply medium is not clean, dry, oil‐free
air, or noncorrosive gas. While use and regular maintenance of a filter that removes particles larger than 40 micrometers in
diameter will suffice in most applications, check with an Emerson field office and industry instrument air quality standards
for use with corrosive air or if you are unsure about the proper amount or method of air filtration or filter maintenance.
WARNING
To avoid personal injury or property damage resulting from the sudden release of pressure, do not install the valve
assembly where service conditions could exceed the limits given in this manual or on the appropriate nameplates. Use
pressure‐relieving devices as required by government or accepted industry codes and good engineering practices.
WARNING
If the supply pressure medium is corrosive, make sure the tubing and instrument components that contact the corrosive
medium are of suitable corrosion‐resistant material. The use of unsuitable materials might result in personal injury or
property damage due to the uncontrolled release of the corrosive media.
The connection marked SUPPLY (see figure 4) must be provided with clean, dry air or a noncorrosive gas. Install a
40‐micrometer filter and suitable equipment to dry the supply medium. Establish a maintenance cycle to ensure that
the regulator and filter are working correctly.
CAUTION
The maximum allowable supply pressure to prevent damage to the components of the positioner, actuator, and valve is
normally stamped on the actuator nameplate. Use a suitable supply pressure regulator to reduce the supply pressure
source to the value stamped on the nameplate.

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If this maximum supply pressure value is not available, use a supply pressure that does not exceed any of the following:
D The maximum supply pressure for the positioner as shown in table 1.
D The maximum pressure rating of the actuator, from the appropriate actuator instruction manual.
D The maximum allowable valve plug stem load for the specific valve body assembly being used. Contact your
Emerson Process Management sales office for valve plug stem load information, if required.
D For diaphragm actuators, refer to the actuator instruction manual for the recommended supply pressure and use
the larger value of the range listed.
The recommended supply pressure for use with piston actuators is the highest available supply pressure between
3.4 bar (50 psig) and the maximum limit determined by the actuator and positioner specifications. Selecting the
highest pressure within the limits will minimize load error and will maximize stroking speed and thrust. For the lowest
supply pressure that will assure satisfactory performance, the factors of valve plug unbalance force, valve plug seating
force, and frictional force must be considered in the following relationship:
Supply
pressure, = 98
bar
(Valve
unbalance,
kg)
++
(Seating
force,
kg)
(Frictional
force,
kg) + 0.7 bar
(Area of the actuator piston,
in square mm)
[]
or
Supply
pressure, =
psig
(Valve
unbalance,
pounds)
++
(Seating
force,
pounds)
(Frictional
force,
pounds) + 10 psig
(Area of the actuator piston,
in square inches)
[]
Consult your Emerson Process Management sales office for the appropriate values for specific actuators, valves, and
service conditions. The 0.7 bar (10 psig) is added to the equation to account for an approximate 0.7 bar (10 psi)
differential pressure loss in the positioner. For spring‐return piston actuators, the pressure required to compress the
actuator spring completely must also be considered.
Cylinder Connections
1. The connection marked CYLINDER (see figure 4) is connected at the factory to the lower part of the cylinder
(bottom) or to the lower diaphragm casing if the positioner is used with a pneumatic diaphragm actuator.
2. The cylinder top connection is a pressure passage located in the bottom of the positioner base (key 1, figure 10). On
3570 and 3570C positioners, an O‐ring (key 33, figure 10) is used between the bottom of the positioner and the top
of the actuator. On 3570P, 3570PC, 3571, 3576, and 3577 positioners, a mounting bracket (key 55, figure 12) is
required. This mounting bracket connects to the bottom of the base. An O‐ring (key 33, figure 10) is placed
between the base and mounting bracket. This mounting bracket provides a 1/4 NPT connection for the positioner
output. This connection is made at the factory if the positioner is ordered mounted to the actuator or if the
mounting bracket is installed.
Instrument Connection
The connection marked INSTRUMENT (see figure 4) connects to the output signal connection of the control device.
The positioner operates only on a pneumatic input signal; the input signal range is marked on the nameplate (key 23,

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figure 10). The maximum allowable input signal for positioners with standard or optional bellows is in table 1 (bellows
pressure rating). The instrument connection is made at the factory when a complete control valve assembly with a
valve‐mounted control device is ordered. Otherwise, make field connections to the positioner from an appropriate
control device. Refer to table 1 and the nameplate for input signal pressure ranges.
Operating Information
Initial Adjustments
Normally, no adjustments are necessary upon initial installation. The positioner is set at the factory for the travel, input
signal range, and action specified in the order. Adjustment is necessary when operating conditions are changed, when
the unit has been dismantled and reassembled, or when the control valve travel does not correspond to the desired
input signal range. If the operating conditions have not changed but the positioner requires adjustment, refer to the
adjustment procedures in this section. If the operating conditions have changed a new range spring, bias spring, and
springer retainer/spacer may be required. Contact your Emerson Process Management sales office for assistance in
determining if a new range spring, bias spring, and spring retainer/spacer are required. Refer to the Range Spring, Bias
Spring, and Spring Retainer/Spacer Selection for 3570 Pneumatic Valve Positioners Instruction Manual Supplement
(D104021X012).
Adjustment Procedures
Refer to figure 2. 3570 positioners have three adjustments:
D The bias spring. It is the zero adjustment which determines the starting point of the valve plug travel.
D The range spring. It is the span adjustment which determines the full valve plug travel for a given input signal range.
D The relay nozzle adjustment. This adjustment determines the steady‐state positioner output pressure.
To illustrate the use of the various adjustments, assume that the positioner has been repaired or has become
completely out of adjustment. Assume also that the input signal range is 0.2 to 1 bar (3 to 15 psig). Proceed as follows:
1. Make sure the input signal range and the valve travel stamped on the nameplate agree with the present operating
conditions.
2. Loosen the four thumb screws on the underside of the positioner base and remove the cover.
3. Provide a means for varying the input signal pressure from zero to 0.07 or 0.14 bar (1 or 2 psig) above the higher
value of the input signal range (see table 1). Provide an accurate means of measuring the input signal pressure.
Check the accuracy of the positioner instrument pressure gauge (see figure 4). The gauge accuracy is ±0.04 bar
(±0.6 psig) on a 0 to 2 bar (0 to 30 psig) gauge, and ±0.08 bar (±1.2 psig) on a 0 to 2 bar (0 to 60 psig) gauge. This
accuracy is measured at the mid‐point of the full range of the scale.
4. Set the input signal pressure at the mid‐point of its range [0.6 bar (9 psig) in this example]. Observe the valve travel
indicator scale attached to the yoke. The indicator disk should be somewhere between the open and closed
positions.
5. Loosen the locknut directly below the bias spring seat (see figure 2) and adjust the bias spring up or down until the
valve travel indicator disk shows that the valve plug is somewhere between the open and closed positions. Upward
movement of the bias spring adjustment causes downward travel of the valve stem.

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6. For positioners with two relays (3570, 3570C, 3570P, 3570PC, and 3571 positioners), observe the relay output
pressures. If the cylinder gauges are present as shown in figure 4, read the cylinder top and cylinder bottom gauges
or use clip‐on test pressure gauges. The two relay output pressures should be approximately equal [within 0.3 bar (5
psig)] and should be approximately 75 percent of the supply pressure. For example, if the supply pressure is 7 bar
(100 psig), the two relay output pressures should be within 0.3 bar (5 psig) of each other, and should be
approximately 5.2 bar (75 psig).
CAUTION
The relays in the 3570C and 3570PC positioners use a locknut (key 29P, figure 10) on the nozzle (key 29Q). If the nozzle is
rotated when the locknut is tight, damage to the relay diaphragm might result. Always use a wrench on the nozzle to
prevent it from turning while loosening or tightening the locknut.
If the relay output pressures are not at the values mentioned, adjust the nozzles. Counterclockwise rotation of either
nozzle will move the nozzle closer to the beam and will increase relay output pressure.
For all 3570 positioners, examine the end of the beam near the bias spring (see figure 2). The beam should be
approximately centered between the two E‐ring travel stops. Observing the caution above for 3570C and 3570PC
positioners, rotate the nozzle(s) to center the beam between the E‐rings. For positioners with two relays, the relay
output pressures must be approximately equal [within 0.3 bar (5 psig)] and approximately 75 percent of supply
pressure after the beam is centered.
7. Apply an input signal equal to the low value of the input signal range [0.2 bar (3 psig) in this example]. Adjust the
bias spring (see figure 2) up or down until the valve travel is at the starting point.
8. Loosen the spring lock (see figure 2) and slowly increase the input signal toward the high end of the input signal
range [1.0 bar (15 psig) in this example]. If the valve travel is less than its expected range, increase the travel by
adjusting the range spring counterclockwise. If the valve travel reaches the end of its expected range with an input
signal less than the high value of the input signal range, decrease the travel by adjusting the range spring clockwise.
9. Repeat steps 7 and 8 until the valve plug or travel indicator action corresponds to the input signal requirements of
the application [0.2 to 1.0 bar (3 to 15 psig) in this example].
10. Lock the range spring and the bias spring seat in position. The positioner is then ready for operation.
11. If the positioner is unstable and adjustment does not correct the problem, it might be due to unwanted fluctuations
in the input signal. A restrictor assembly (key 47, figure 10) can be installed in the input signal circuit to dampen
these fluctuations. The restrictor might help to minimize instability. To take the restrictor out of service, exchange
the location of the restrictor with that of the bellows mounting screw (key 46, figure 10).
12. Replace the cover (key 39) on the positioner.
Changing Positioner Action
The instructions given below are to be used after the springs have been changed or if no spring change is required.
Numbered parts mentioned in this section are shown in figure 5 unless otherwise noted.

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Figure 5. Bellows Mounting for Direct and Reverse Action
A1088‐1
RESTRICTOR
2
2
2
2
2
2
33
1
1
1
1
1
BEAM
BEAM
BELLOWS BASE
BELLOWS BASE
PEDESTAL PEDESTAL
REVERSE
ACTION
DIRECT
ACTION
BELLOWS TOP VIEW
WITH OPTIONAL RE
STRICTOR
1—MOUNTING SCREW
2—MOUNTING SCREW
3—BELLOWS POST
WARNING
The following procedures require taking the positioner, actuator, and control valve assembly out of service. To avoid
personal injury or property damage caused by uncontrolled process pressure, provide a temporary means of control for the
process before taking the assembly out of service.
Before removing the input signal and supply pressure connections from the positioner, remove the input signal and supply
pressure sources from the connections. The sudden release of pressure can cause personal injury or property damage.
Note
Changing the positioner action might require changing the bias spring and/or the spring retainer. Contact your Emerson Process
Management sales office for assistance in determining if a new bias spring and/or spring retainer are required. Refer to instruction
manual supplement D104021X012.
Changing to Reverse Action
1. Bypass the control valve and shut off the input signal line and the supply pressure line to the positioner.
2. Loosen the four thumb screws on the underside of the positioner base and remove the cover.

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3. Two bellows posts are provided. The posts are screwed into storage holes in the positioner base immediately above
the CYLINDER and INSTRUMENT connections. Unscrew these posts.
Note
An optional restrictor (see the top view in figure 5) can be found in place of one of the bellows mounting screws (number 1). If so,
note the location of the restrictor and replace it in the same location during reassembly. The restrictor has a hex head; the
mounting screws do not.
4. Remove the four mounting screws (numbers 1 and 2) and lift out the bellows assembly.
5. Screw the bellows posts (number 3) into the holes where the screws (number 1) originally were.
6. Invert the bellows and replace the screws (numbers 1 and 2).
7. Refer to the adjustment procedures to check operation of the positioner.
8. Make a notation on the action label (key 43, figure 10) that the action of the positioner has been changed.
9. Replace the cover (key 39) on the positioner.
Changing to Direct Action
1. Bypass the control valve and shut off the input signal line and the supply pressure line to the positioner.
2. Remove the positioner cover by loosening the four thumb screws on the underside of the base.
Note
An optional restrictor (see the top view in figure 5) can be found in place of one of the bellows mounting screws (number 1). If so,
note the location of the restrictor and replace it in the same location during reassembly. The restrictor has a hex head; the
mounting screws do not.
3. Remove the four mounting screws (numbers 1 and 2), bellows, and bellows posts (number 3).
4. Invert the bellows and reinstall it in the positioner. Secure the bellows with the four screws (numbers 1 and 2).
Screw the bellows posts into the storage holes provided in the base immediately above the cylinder and instrument
connections.
5. Refer to the adjustment procedures to check the operation of the positioner. If the input signal range has not been
changed, adjustment of the range spring might not be necessary.
6. Make a notation on the positioner action label (key 43, figure 10) that the action of the positioner has been
changed.
7. Replace the cover (key 39) on the positioner.

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Split Range Operation
3570 valve positioners are suitable for split range operation. In split range operation, two or more control valves are
operated by one output signal from a single control device. When two control valves are split ranged, one valve
strokes fully with one half the input signal range and the second valve strokes fully with the other half of the input
signal range.
Valve positioners shipped from the factory for split range operation are constructed and adjusted accordingly. If it is
necessary to convert an existing positioner to one suitable for split range operation, consult your Emerson Process
Management sales office to determine the new parts required (refer to instruction manual supplement
D104021X012). For most changes, a new range spring and possibly a new bias spring will be required. A new range
spring retainer might also be required for 3570, 3570C, 3572, and 3573 positioners.
When corresponding with your Emerson sales office, supply all information possible about the desired operating
conditions and the serial numbers of the control valve assembly. This information will facilitate the proper selection of
the required parts.
To change an existing valve positioner to one suitable for split range operation, refer to the range and bias spring
removal and replacement procedures in the Maintenance section. Be certain the required new parts are on hand
before beginning any maintenance operation.
Initial Range Spring Extension Procedures for 3570P And 3570PC
Positioners
This procedure must be performed whenever the range spring has been changed or the positioner has been removed.
Key numbers used in this procedure are shown in figure 13 except where indicated.
1. With the cap screw (key 87) removed, hook the small ball of the positioner cable (key 91) into the slot of the smaller
portion of the cable spool (key 96). Wind the cable on the spool until the coils of the range spring (key 18, figure 10)
are slightly separated. Be certain the cable is wound so that it comes off the side of the spool opposite the access
opening and that the cable cannot cross itself on the spool.
2. Install the ball end of the actuator cable (key 92) into the slot of the large portion of the spool that is closer to the
access opening. Wrap the cable on the spool as many times as possible, then bring the cable out through the
bottom of the positioner extension. Be certain the cable is wound so that it comes off the side of the spool opposite
the access opening and that the cable cannot cross itself on the spool. Attach the cable to the cable strap (key 93),
leaving approximately a 0.8 mm (1/32‐inch) gap between the cable eye and cap screw head (key 94).
3. With the actuator piston rod completely retracted and the range spring coils slightly separated, attach the cable
strap to the actuator feedback arm. Use the set of cable‐strap holes closest to the range spring. Turn the spring cap
(key 86) one turn counterclockwise and install one cap screw (key 87).
4. Adjust the range spring (key 18, figure 10) to obtain full travel for the input signal range (span adjustment). Refer to
step 7 of the adjustment procedures. Adjustment of the bias spring (zero adjustment) does not need to be done at
this time.
5. Remove the screw from the spring cap and slowly release the torsion spring force by turning the spring cap
clockwise. Disconnect the cable strap from the actuator and remove all range spring extension by rotating the cable
spool.

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6. Rotate the cable spool to obtain the correct initial range spring extension. Each full revolution of the spool extends
the range spring 50.8 mm (2 inches) [6.4 mm (1/4‐inch) for 1/8 revolution]. If the initial range spring extension is
not specified, calculate it using one of the equations given below. Round off the amount of extension (e) obtained
from the equation to the next higher 6.4 mm (1/4 inch).
T
1.87 (Pn)
(standard bellows)
e=
T
1.25 (Pn)
(optional high pressure bellows)
e=
where:
e = initial range spring extension required in mm
T = actuator travel in mm
Pn= input signal span in bar (for example, 0.8 bar for a 0.2 to 1 bar input signal range)
or where:
e = initial range spring extension required in inches
T = actuator travel in inches
Pn= input signal span in psi (for example, 12 psi for a 3 to 15 psig input signal range)
7. If necessary, move the actuator cable ball to the spool slot nearer the access opening. With the actuator piston rod
fully retracted and the range spring at the correct initial extension, attach the cable strap to the actuator feedback
arm. Use the set of cable strap holes that is closest to the tapped holes in the feedback arm.
8. Refer to the positioner adjustment procedures.

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Principle of Operation
3570, 3570C, 3570P, 3570PC, and 3571 Valve Positioners
Refer to the schematic diagram in figure 6. The pneumatic output signal from a control device is piped to the
positioner bellows. For explanation purposes, assume this signal has increased. The bellows expands and moves the
beam, which pivots around a fixed point and simultaneously uncovers the nozzle of relay B and covers the nozzle of
relay A. The nozzle pressure in relay A increases due to the restriction created by the beam covering the nozzle.
Through relay action, the pressure to the top of the piston increases. At the same time, relay B reacts to the change in
beam position to decrease the pressure to the underside of the piston. These unbalanced pressures move the actuator
piston down.
In the 3570 and 3570C positioners, the piston movement is fed back to the beam by means of a range spring, which is
connected to the beam and to the piston rod extension. In the 3570P, 3570PC, and 3571 positioners, the feedback is
provided to the range spring by a cable or wire that is connected to the actuator‐valve stem connector. The downward
movement of the piston rod extension extends the range spring until the torque on the beam balances the torque
exerted by the instrument bellows.
Figure 6. Schematic Diagram of Fisher 3570 Positioner with a 470 Pneumatic Piston Actuator
BOTTOM CYLINDER PRESSURE
NOZZLE PRESSURE
TOP CYLINDER PRESSURE
SUPPLY PRESSURE
INPUT SIGNAL PRESSURE
YOKE
RELAY “A”
BELLOWS REVERSED POSITION
RELAY “B”
RANGE SPRING
CYLINDER
R = RESTRICTION
A1067‐1
BIAS SPRING
SUPPLY
R
INPUT
SIGNAL
R
SUPPLY
As the input signal decreases, the reverse action takes place. The bellows contracts, and as the beam pivots, it covers
the nozzle of relay B and uncovers the nozzle of relay A. Through relay action, the pressure below the piston increases
and the pressure above the piston decreases to move the piston upward.

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3572 and 3576 Valve Positioners
Refer to the schematic diagram in figure 7, which shows the 3572 positioner mounted on a 472 pneumatic piston
actuator. For the 3576 positioner, the principle of operation is identical to the 3572 positioner but the actuator can be
a direct or reverse acting pneumatic diaphragm actuator.
Figure 7. Schematic Diagram of Fisher 3572 Positioner with a 472 Pneumatic Piston Actuator
CR4006‐A
A1084‐1/IL
BELLOWS
REVERSED
POSITION
RANGE SPRING
BIAS SPRING
CYLINDER
INPUT
SIGNAL
R
R = RESTRICTION
PISTON
RELAY A
YOKE
SUPPLY
INPUT SIGNAL PRESSURE
SUPPLY PRESSURE
TOP CYLINDER PRESSURE
NOZZLE PRESSURE
The pneumatic output signal from a control device is piped to the positioner bellows. For explanation purposes,
assume this signal has increased. The bellows expands and moves the beam, which pivots around a fixed point and
covers the relay nozzle. The nozzle pressure in the relay increases due to the restriction created by the beam covering
the nozzle. Through relay action, the pressure above the piston overcomes the force exerted by the actuator spring,
and the piston moves downward. This changes the valve plug position.
In the 3572 positioner, piston movement is fed back to the beam by means of a range spring, which is connected to
the beam and the piston rod extension. As the piston rod extension moves downward, the range spring is extended
until the torque of the beam balances the torque exerted by the instrument bellows.

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In the 3576 positioner, the feedback is provided to the range spring by a wire that is connected to the actuator‐valve
stem connector.
As the input signal decreases, the reverse action takes place. The bellows contracts, and as the beam pivots, it
uncovers the relay nozzle. Through relay action, the pressure on top of the piston decreases, and the force of the
actuator spring moves the piston upward.
3573 and 3577 Valve Positioners
Refer to the schematic diagram in figure 8, which shows the 3573 positioner mounted on a 473 pneumatic piston
actuator. For the 3577 positioner, the principle of operation is identical to the 3573 positioner, but the actuator can be
direct or reverse acting.
Figure 8. Schematic Diagram of Fisher 3573 Positioner with 473 Pneumatic Piston Actuator
CR4007‐A
A1082‐1/IL
INPUT SIGNAL PRESSURE
SUPPLY PRESSURE
BOTTOM CYLINDER PRESSURE
NOZZLE PRESSURE
INPUT
SIGNAL
R
R = RESTRICTION
PISTON
YOKE
SUPPLY
BELLOWS
REVERSED
POSITION
RANGE SPRING
BIAS
SPRING
CYLINDER
RELAY
The pneumatic output signal from a control device is piped to the positioner bellows. For explanation purposes,
assume this signal has increased. The bellows expands and moves the beam, which pivots around a fixed point and
uncovers the relay nozzle. The nozzle pressure decreases due to the uncovering of the nozzle by the beam. Through

Instruction Manual
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relay action, the pressure to the underside of the piston decreases. The force exerted by the actuator spring
overcomes the force of the pressure below the piston, and the piston moves downward. This changes the valve plug
position.
In the 3573 positioner, piston movement is fed back to the beam by means of a range spring, which is connected to
the piston rod extension. The downward movement of the piston rod extension extends the range spring until the
torque of the beam balances the torque exerted by the instrument bellows.
In the 3577 positioner, feedback is provided to the range spring by a wire that is connected to the actuator‐valve stem
connector.
As the input signal decreases, the reverse action takes place. The bellows contracts, and as the beam pivots, it covers
the relay nozzle. Through relay action, the pressure on the underside of the piston increases to overcome the force
exerted by the actuator spring, and the piston moves upward.
Relay Operation
Refer to figure 9, which shows a sectional view of a typical relay.
Supply pressure reaches the relay(s) through passages in the positioner base and is channeled to fixed restriction R and
to point A between the supply valve B and the balancing O‐ring of the relay valve. The fixed restriction is an integral
part of the relay restriction plug and wire assembly G. The orifice in nozzle F is larger than the fixed restriction. This
allows the supply pressure to bleed to atmosphere faster than it enters the unit through the fixed restriction when the
beam flapper is away from the nozzle.
Assume that a change in the input signal causes the beam flapper to cover the nozzle of a relay. The supply pressure
flows through fixed restriction R into the chamber between the two relay diaphragms. Due to the restricting effect of
the flapper over the nozzle, pressure builds up in the chamber between the diaphragms, forcing the diaphragm head
assembly E downward to open supply valve B, allowing output pressure to increase.
The supply pressure flows past supply valve B to increase the output pressure to the actuator cylinder. The cylinder
pressure (relay output pressure) also acts on the area D. This provides an air feedback that returns the diaphragm head
assembly E and the movable nozzle F to their original positions, thus preventing any further increase in output
pressure. The feedback arrangement and the movable nozzle ensure accurate and stable positioning of the actuator
piston without introducing cycling or over‐correction. After any change in the output pressure, supply valve B and
exhaust valve C always return to the closed position to put the nozzle back in its original, or equilibrium, position. The
spring behind supply valve B aids in closing the valve as the diaphragm head assembly is forced upward.
When the beam flapper moves away from the nozzle F, the supply pressure bleeds out at a greater rate than it enters
through the fixed restriction R. The pressure then decreases in the chamber between diaphragms. The force of the
cylinder pressure acting on area D pushes diaphragm head assembly E upward, opening exhaust valve C. Cylinder
pressure bleeds through the exhaust port to atmosphere. As the cylinder pressure decreases and the force on area D
decreases, the force of the nozzle pressure in the chamber between the diaphragms returns the assembly to its
original position. The unit is again in equilibrium, but at a lower nozzle pressure and a lower output pressure.
Each relay has a 4:1 ratio between the nozzle pressure and the output pressure. For example, a 0.7 bar (10 psig) nozzle
pressure change, produces a 2.7 bar (40 psig) output pressure change; a 1.4 bar (20 psig) nozzle pressure change
produces an 5.5 bar (80 psig) output pressure change. With a constant input signal pressure, the internal parts of the
relay are at equilibrium with the supply and exhaust valves closed.