Differences in Gate Shape
The wedge gate valve's gate sealing surface is designed to be wedge-shaped, forming a certain angle with the gate's centerline. This design increases the positive pressure on the wedge gate's sealing surface as the valve stem thrust increases during valve closing, achieving a positive seal. This design is particularly suitable for sealing low-pressure media.
In contrast, the gate's inlet and outlet sealing surfaces of a slab gate valve are parallel to the gate's centerline. Sealing is primarily achieved by the medium pushing the floating gate or floating seat.
Differences in Valve Stem Driving Torque
Because a wedge gate valve relies on the valve stem to push the wedge gate downward to achieve a positive seal, its stem driving torque is relatively high.
In contrast, a slab gate valve uses medium pressure to press the gate against the valve seat to achieve a seal, resulting in less torque on the valve stem.
Differences in the Limit Control Methods of the Electrically Controlled Switch
Electric wedge gate valves typically use a torque switch to control the closing process, ensuring that the valve stem continuously pushes the gate and applies the appropriate sealing pressure to the valve seat. The closing of a flat gate valve is primarily controlled by a travel switch, which precisely controls the position of the gate disc to achieve closing.
Adaptability to Media Containing Suspended Particulates
When a wedge gate valve is open, the gate disc and valve seat are separated. During closing, particles can enter the sealing surface, affecting or even damaging the seal.
The gate disc and valve seat of a flat gate valve maintain a tight fit during opening and closing, preventing particles from entering the sealing surface.
Impact of Temperature Differences on the Gate Disc
In environments with large temperature differences,
wedge gate valves may experience gate sticking due to thermal expansion and elongation of the valve stem.
Slab gate valves, on the other hand, are not affected by this, and even stem elongation does not affect the sealing performance of the gate disc.
Comparison of Other Features
1. Compared to rising-stem gate valves, the stem of a wedge gate valve is typically exposed and lacks a protective cover, while the stem of a flat gate valve is equipped with a protective cover to protect it from dust and rain.
2. In the packing and gate positions, wedge gate valves usually do not add sealing grease, while flat gate valves add grease to increase lubrication, reduce wear and improve sealing effect.
