Flowserve Cast Globe Valves - Manual (Page 6)

Globe Valves FCD ADENIM0011-00
6
1.0 VALVE DESCRIPTION
1.1 Recommended Uses
Anchor/Darling Globe valves are designed primarily to regulate the volume of flow within a piping system. With the
appropriate disc (for the service) installed, they will throttle fluids with minimal erosion and cavitation. By taking certain
precautions they may also be used for isolation purposes.
1.2 Principles of Operation
The principle parts of a globe valve are the body, bonnet, disc and topworks (Fig. 1). The body and bonnet contain the
fluid within the system. The disc is positioned by the stem in the flow path above the seat. Movement of the stem (in line
with the flow) increases or decreases the annular area between the disc and seat, metering the volume of fluid that
passes between them. When used for isolation purposes the disc to seat seal is created by either a mechanical or an
internal pressure force. When installed with flow under the disc, the stem and topworks provide a mechanical thrust that
holds the disc into the seat against the fluid pressure. With flow over the disc, the differential pressure itself forces the
disc into the seat. The latter situation with the line pressure working towards the seal rather than against it, provides for
more reliable isolation.
FIGURE 1