9 - Control Valves

Abstract

This chapter discusses control valves, which can be broken into two major classifications—process and fluid power. Process valves control the flow of gases and liquids through a process system, and fluid-power valves control pneumatic or hydraulic systems. Process-control valves are available in a variety of sizes, configurations, and materials of construction, and the common types are—ball, gate, butterfly, and globe valves. The configuration of fluid power control valves varies with their intended application. The more common configurations include one-way, two-way, three-way, and four-way. As with process-control valves, actuators used to control fluid-power valves have a fundamental influence on performance. The actuators must provide positive, real-time response to control inputs. The primary types of actuator used to control fluid-power valves are mechanical, pilot, and solenoid. Although there are limited common control valve failure modes, the dominant problems are usually related to leakage, speed of operation, or complete valve failure.