tailieunhanh - CONTROL VALVE HANDBOOK Fourth Edition

Process plants consist of hundreds, or even thousands, of control loops all networked together to produce a product to be offered for sale. Each of these control loops is designed to keep some important process variable such as pressure, flow, level, temperature, etc. within a required operating range to ensure the quality of the end product. Each of these loops receives and internally creates disturbances that detrimentally affect the process variable, and interaction from other loops in the network provides disturbances that influence the process variable | EMERSON Process Management CONTROL VALVE HANDBOOK Fourth Edition FISHER NORTH AMERICA Emerson Process Management Marshalltown Iowa 50158 USA T 1 641 754-3011 F 1 641 754-2830 Fisher EUROPE Emerson Process Management Cernay 68700 France T 33 0 3 89 37 64 00 F 33 0 3 89 37 65 18 Fisher ASIA PACIFIC Emerson Process Management Singapore 128461 Singapore T 65 6777 8211 F 65 6777 0947 Fisher LATIN AMERICA Emerson Process Management Sorocaba Sao Paulo 18087 Brazil T 55 15 238-3788 F 55 15 228-3300 Fisher MIDDLE EAST AFRICA Emerson FZE Dubai United Arab Emirates T 971 4 883 5235 F 971 4 883 5312 Fisher Fisher is a mark owned by Fisher Controls International LLC a member of the Emerson Process Management business division of Emerson Electric Co. The Emerson logo is a trademark and service mark of Emerson Electric Co. All other marks are the property of their respective owners. The contents of this publication are presented for informational purposes only and while every effort has been made to ensure their accuracy they are not to be construed as warranties or guarantees express or implied regarding the products or services described herein or their use or applicability. We reserve the right to modify or improve the designs or specifications of such products at any time without notice. Neither Emerson Emerson Process Management nor any of their affiliated entities assumes responsibility for the selection use and maintenance of any product. Responsibility for the selection use and maintenance of any product remains with the purchaser and end-user. Printed in . Fisher Controls International LLC 2005 D101881X012 ii Preface to Fourth Edition Control valves are an increasingly vital component of modern manufacturing around the world. Properly selected and maintained control valves increase efficiency safety profitability and ecology. The Control Valve Handbook