Valves

Abstract

This chapter focuses on several factors that need to be considered during the selection of valves and actuators. One of the factors is that a valve satisfactory in one location might not be satisfactory in another location even if conditions are only slightly different. Other factors include that manufacturers of several styles of valves might make some good ones and some poor ones, models are changed from time to time and a valve, once poor, might now be good, and, finally, it is extremely difficult to write specifications to comply with the law, allow competitive bidding, and still obtain a satisfactory valve. Valves require the incorporation of safety features to prevent damage from malfunctioning equipment that ensures the completion of an automatic control system. These safety features could be arranged to prevent the operation of an unprimed pump, to prevent the operation of a pump against a closed control valve that does not open on schedule, or to limit excessive pumping when discharging to a broken pipe. Isolation valves are either fully closed or fully opened. Valves that remain in one position for extended periods become difficult to operate unless they are "exercised" from time to time. Valves should be exercised at least once each year (more often if the water is corrosive or dirty), and the required exercise. a check valve is usually (but not always) required to prevent reverse flow and prevent runaway reverse pump speeds when the pump is shut off, keep the pipeline full of water to prevent the entrance of air, and minimize water hammer and surges for pump start-up and shut-down. © 2008 Elsevier Ltd All rights reserved.

Department(s)

Civil, Architectural and Environmental Engineering

International Standard Book Number (ISBN)

978-185617513-5

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 Elsevier, All rights reserved.

Publication Date

01 Dec 2008

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