TABLE OF CONTENTS Mark Adams
Fisher Controls International, Inc., Marshalltown, Iowa
(Process Control Valves)
Len Auer
Rosemount Inc., Eden Prairie, Minnesota (Current-to-Pressure
Transducers for Control-Valve Actuation)
Allen C. Fagerlund
R. A. Engel Technical Center, Fisher Controls International, Inc.,
Marshalltown, Iowa (Control Valve Noise)
Bill Fitzgerald
Fisher Controls Company International, McKinney, Texas
(Control Valve Troubleshooting)
David A. Kaiser
Compumotor Division, Parker Hannifin Corporation, Rohnert
Park, California (Servomotor
Technology in Motion Control Systems)
J. J. Kester
Bodine Electric Company, Chicago, Illinois (Stepper and
Other Servomotors)
S. Longren
Longren Parks, Chanhassan, Minnesota (Servomotors)
Richard H. Osman
AC Drives, Robicon Corporation, Pittsburgh, Pennsylvania
(Solid-State Variable-Speed Drives)
Bert J. Peterson
Fisher Controls International, Inc., Marshalltown, Iowa
(Process Control Valves)
C. Powell
GMFanuc Robotics Corporation, Auburn Hills, Michigan
(Robots)
Marc L. Riveland
Applied Research, Fisher Controls International, Inc.
Marshalltown, Iowa (Control-Valve Cavitation)
by Bert J. Peterson [*]
The control valve, or final control element, is the last device in the control loop. It takes a signal from the process instruments and acts directly to control the process fluid. Control valves maintain process variables such as pressure, flow, temperature, or level at their desired value, despite changes in process dynamics and load. Control valves must be designed to accommodate the needs and characteristics of the process fluid they control. Likewise, the control valve must react to the protocol and needs of the controlling devices in the process control system. The evolution of control valves is in response to the combined forces of the processes they handle...
