1. Field of the Invention
The present invention pertains to gate valves, and in particular to resilient seat gate valves.
2. Description of the Related Art
Resilient seat gate valves are employed in the transport of clean water. The valve gate or closure member is typically in the form of a wedge made of cast iron material so as to be sufficiently rugged so as to be suitable for high pressure and high flow applications. In a resilient seat gate valve, the outer surface of the valve wedge is coated with an elastomeric material so as to offer a bubble-tight seal even at elevated operating pressures. The valve wedge is operated by turning a threaded stem so as to advance or retract the valve wedge within the waterway of the valve housing. Upon valve closure, the resilient material on the edge forms a bubble-tight seal with the internal surface of the valve body. Dirt or other contamination in the valve operating system can lead to incomplete sealing of the wedge or other malfunction.
It is an object of the present invention to provide a resilient seat gate valve.
Another object of the present invention is to provide a resilient seat gate valve having an improved wedge operator system which readily overcomes the deleterious effects of contamination introduced either during construction or entrained within product carried to the valve.
These and other objects of the present invention which will become apparent from studying the appended description and drawings are provided in a valve arrangement, that comprises a valve housing that defines a water passageway and a valve seat within the valve passageway. A valve wedge disposed within the housing passageway moves along a direction of operation between a closed position in contact with the valve seat to block flow of water through the valve passageway and an open position allowing flow of water through the valve passageway. A pair of spaced apart tracks are disposed within the valve housing on either side of the wedge and extend along the direction of operation. A pair of opposed wings carried on the valve wedge, travel in each track. A valve stem coupled to the valve wedge moves the valve wedge in opposite reciprocating directions between valve open and valve closed positions. Rollers are carried on the wings for rolling engagement with the tracks and scraper blades are carried on the wings adjacent the rollers to scrape contamination from the tracks. The tracks may be provided with or without a liner. If a wing is provided without rollers because of a light loading application, for example, the track is preferably provided without a liner. A light loading condition may arise, for example, at the upper end of a horizontally oriented valve arrangement. However, under heavy loading conditions as, for example, at the bottom end of a horizontally operated valve arrangement, it is preferred that the wings be provided with load bearing rollers. In this instance, it is also preferred that the track be provided with a liner of generally U-shaped cross-section and made of a rugged material such as stainless steel.