Functions
The flange stop valve is a forced sealing valve, so when the valve is closed, pressure must be applied to the valve disc to force the sealing surface not to leak. When the medium enters the valve from below the valve disc, the resistance that the operating force needs to overcome is the friction between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the valve diameter of the stem must be large, otherwise, the valve stem will bend. Flanged globe valves are easy to operate and the threaded seat ring provides easy access for repair or replacement. Packing swing bolts on most valves simplifies packing replacement. All-bolt bonnet construction makes disassembly faster.
Types
1. According to the position of the valve stem thread
- External thread type
- Internal thread type
2. According to the flow direction of the medium
- Straight-through
- DC type
- Angular
3. According to sealing method
- Packing seal
- Bellows seal