VALVE FUNCTIONS AND BASIC PARTS
The following important information in this chapter is summarized below:
Valve Functions and Basic Parts Summary
There are four basic types of flow control elements employed in valve design.
Move a disc, or plug into or against an orifice (for example, globe or
needle type valve).
Slide a flat, cylindrical, or spherical surface across an orifice (for example,
gate and plug valves).
Rotate a disc or ellipse about a shaft extending across the diameter of an
orifice (for example, a butterfly or ball valve).
Move a flexible material into the flow passage (for example, diaphragm
and pinch valves).
Valve stem leakage is usually controlled by properly compressing the packing
around the valve stem.
There are seven basic parts common to most valves.