Page 114 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities
P. 114
PIPING
2.64 CHAPTER TWO
FIGURE 2.34 Typical ball valves.
BUTTERFLY VALVES
A butterfly valve has a wafer-shaped body with a thin rotating disk as the closing device.
Like the ball valve, the butterfly operates with a one-quarter turn from fully opened to fully
closed. The disk is always in the flow path, but since it is relatively thin, it offers little restric-
tion to the flow. When the valve is closed, the disk edge fits tightly against a ring-shaped
liner (seat).
These valves generally have one-piece bodies that fit sandwich-style between two pipe
flanges. The two most common body types are wafer body and lug body, illustrated in Fig. 2.35.
The wafer body is placed between pipe flanges, and the flange bolts surround the valve body.
The lug body has protruding lugs that provide bolt holes matching those in the flanges.
FIGURE 2.35 Butterfly valves. (a) Wafer body; (b) lug body.
Downloaded from Digital Engineering Library @ McGraw-Hill (www.accessengineeringlibrary.com)
Copyright © 2009 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.
