Model P91PA Poweractor Power Positioner - Invensys

Product Specifications PSS 4-10A1 B
Model P91PA
Poweractor Power Positioner
The P91PA Poweractor Power Positioner provides fast, sensitive, and precise positioning of pneumatic
cylinders, springless diaphragm actuators, and similar devices used with large size control valves.
INTRODUCTION
This power positioner is a pneumatic, force-balance
instrument that is used to position equipment such as
cylinder-operated valves, louvers, and variable-speed
devices. The position is directly proportional to the
output pressure of a pneumatic controller. The
positioner’s main function is to overcome the effect of
friction and process line pressure on the operation of
the valve or similar apparatus.
The output pressure from the controller is applied to
the bellows in the positioner, and not to the cylinder. A
separate supply of high-pressure air, connected to the
pilot valve assembly, is used to operate the cylinder.
For any given controller output, there is but one
corresponding position of the cylinder piston. For the
slightest increase in controller output, full supply
pressure is available to ensure immediate and
accurate positioning of the cylinder piston.
HIGH POWERED DEVICE
Output pressures up to 1035 kPa (150 psi) provide
the power required for tough applications. For
example, approximately 75 kN (16 500 lb) of force is
provided with a 750 kPa (110 psi) on a 356 mm (14
in) bore cylinder.
®

PSS 4-10A1 B
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REVERSIBLE POSITIONER OUTPUT
Positioner output may be reversed from increasing
output to decreasing output by simply inverting the
positioner and changing the length of the spring
holder and stud.
SMOOTH, FAST OPERATION
The close tolerance, micro-finished pilot valve
provides the smooth operation required for fast
action, with a minimum of moving parts.
Accuracy
Positions to better than 1% of total stroke
Sensitivity
Response to signal pressure change of less than 1inch
water pressure
Temperature Limits
–29 to +320°C (–20 to +160°F)
Ambient Temperature Effect
1/2% on output for 55°C (100°F) change
Input Signal
20 to 100 kPa (3 to 15 psi)
Air Supply
1035 kPa (150 psi) maximum
Output Signal
Up to maximum air supply pressure
Relay Bleed Rate
1.3 m 3 /h (0.75 scfm) at 350 kPa (50 psi)
Air Delivery at Standard Conditions (See Table
Below)
For an Air Supply
Pressure of The Air Delivery is
KPa psi m 3 /h scfm
410
620
60
90
12.6
17
STANDARD SPECIFICATIONS
7.4
10
RUGGED CONSTRUCTION
Stroke-force spring is high-quality spring steel wire,
cadmium plated for corrosion resistance. Mechanism
is completely enclosed in weatherproof, gasketed
case.
EASY STROKE AND ZERO ADJUSTMENT
Only a screwdriver is required to change the ratio of
piston movement to input signal, or to adjust zero.
Stroke
Up to 762 mm (30 in)
Case
Cast aluminum
Cover
Cast aluminum, gasketed
Finish
Black enamel, infrared baked
Mounting
FACTORY
With plate bracket and actuating arm for assembly
to MAC Series cylinder
FIELD
With clamp bracket for 25 mm (1 in) hexagonal
column, or 33.3 mm (1.31 in) diameter rod
Stud Length
54 mm (2.125 in), other lengths available to 305 mm
(12 in)
Connections
1/4 NPT
Weight
Approximately 3.2 kg (7 lb)

Controlled Speed of Stroking
Speed control valves in either, or both, cylinder air
lines will provide full area inflow and adjustable
needle restriction for exhaust. Speed control valve
has brass body with stainless steel adjusting screw
and is available in 1/4, 3/8, 1/2, and 3/4 inch sizes.
MODEL CODE
OPTIONAL FEATURES
ORDERING INSTRUCTIONS
PSS 4-10A1 B
Page 3
Description Model
Poweractor Power Positioner
Feedback Kit
P91PA
Feedback Kit for 83 mm (3.25 in) Bore Cylinder Actuator –F1
Feedback Kit for 102 mm (4.00 in) Bore Cylinder Actuator –F2
Feedback Kit for 127 mm (5.00 in) Bore Cylinder Actuator –F3
Feedback Kit for 152 mm (6.00 in) Bore Cylinder Actuator –F4
Feedback Kit for 203 mm (8.00 in) Bore Cylinder Actuator –F5
Feedback Kit for 254 mm (10.00 in) Bore Cylinder Actuator –F6
Feedback Kit for 305 mm (12.00 in) Bore Cylinder Actuator –F7
Feedback Kit for 356 mm (14.00 in) Bore Cylinder Actuator –F8
No Feedback Kit
Optional Selections
–F9
Mounted by Foxboro to a Cylinder Actuator –FM
High Temperature Seals (Applications up to 177°C (350°F) –HT
Mounting Kit (for Pipe, Rod, or Column –PM
Assembled Combination of Model MAC-A84 Cylinder Actuator having a nominal 100 mm (4
in) Bore and 150 mm (6 in) Stroke, and a P91PA Power Positioner. Action is Air-to-Extend
Rod. Assembly includes Floor Mounting Plate. Must specify “–F9” above, No feedback Kit.
–XU
Special Stud Lengths
The standard stud length is 54 mm (2.125 in).
Special lengths to a maximum of 305 mm (12 in) are
also offered.
1. Model Number
2. Factory or Field Mounting
3. Cylinder Stroke
4. Air Range
5. Cylinder Action, Air-to-Extend or Air-to-Retract Rod on Increasing Signal
6. Optional Features
7. Tag and Application

PSS 4-10A1 B
Page 4
The Foxboro Company
33 Commercial Street
Foxboro, MA 02035-2099
United States of America
http://www.foxboro.com
Inside U.S.: 1-888-FOXBORO
(1-888-369-2676)
Outside U.S.: Contact your local
Foxboro representative.
Facsimile (508) 549-4492
An Invensys company
DIMENSIONS – NOMINAL
Foxboro is a registered trademark of The Foxboro Company.
Invensys is a trademark of Invensys plc.
All other brand names may be trademarks of their respective companies.
Copyright 1993 The Foxboro Company
All rights reserved
MB 010 Printed in U.S.A. 0693