Instrumentation Reference Book, 4th Edition

Chapter 36. Applying Control Valves¹

¹This section originally appeared in different form in Control magazine and is reprinted by permission of Putman Media Inc.

B.G. Liptak and W.H. Boyes

36.1. Introduction

Control valves modulate the flows of process or heat-transfer fluids and stabilize variations in material and heat balance of industrial processes. They manipulate these flows by changing their openings and modifying the energy needed for the flow to pass through them. As a control valve closes, the pressure differential required to pass the same flow increases, and the flow is reduced. Figure 36.1 illustrates the pump curve of a constant-speed pump and the system curve of the process that the pump serves. The elevation (static) head of the process ...