Flowserve Cast Flex Wedge Gate Valve - Manual (Page 6)

Cast Flex Wedge Gate Valves FCD ADENIM0010-02
6
1.0 VALVE DESCRIPTION
1.1 Recommended Uses
Anchor/Darling Gate valves are designed to provide isolation of a piping system or a component when closed. They are not
suitable for modulation of flow, i.e. throttling, and should not be used for that purpose.
1.2 Principles of Operation
The principle parts of a flex-wedge gate valve are the body, bonnet, disc, stem and top works (Fig. 1). The body and
bonnet contain the fluid within the system. The gate is positioned by the stem to either block flow through the body or is
raised into the body neck to leave an unobstructed flow passage.
The disc to seat seal in the flex-wedge gate valve is created by a combination of internal pressure and mechanical wedging
force. When the line pressure is high, the differential between the upstream and downstream ports forces the disc against
the downstream seat and creates a seal. At lower line pressures (under approximately 100 psi), the pressure force alone is
not sufficient to create a seal. A
mechanical force resulting from the disc being wedged between the seat rings provides the additional force necessary to
seal.