Overview of the Expansion and Contraction Gate Valve
Plate gate valve is a kind of single gate plate valve or double gate plate valve with expansion mechanism. Plate gate valve is prone to leakage under low medium pressure. To ensure the good sealing of the valve under full pressure, sufficient preload must be applied to the valve seat. However, with large preload and high medium pressure, frequent opening and closing of the valve might make the sealing surface wear too quickly, affecting the service life of the valve. Meanwhile, iron cast and steel cast material are usually used for gate valve. They are very heavy, not suitable for some mobile applications. That’s why expansion and contraction type lightweight gate valve is designed. It reduces the weight of plate gate valve, improves the sealing performance and service life.
The valve is a symmetrical flat valve body structure. It combines the valve body and valve cover of ordinary gate valve into one. And the sanitary valve body is designed into a flat square. This kind of design reduces the structural size of the valve body, saves the number of connecting bolts between valve body and valve cover, effectively reducing the weight of the valve.
The valve seat uses stand-alone design, combining the valve seat and valve interface of ordinary gate valve into one. For the same valve body, replacing different valve seats can simply change the type of interface of the valve. This effectively improves the commonality and maintainability of valve body, while avoiding the problem in which deformation of the valve body under high pressure results in poor sealing performance of the valve.
In order to increase the sealing performance of the gate valve under low pressure, solve the leakage problem under low pressure, reduce the friction between gate plate and the sealing ring of the valve seat, prolong the service life of the gate valve, the gate valve sealing is designed into steel ball topped mechanical expansion and contraction sealing mechanism. When the gate valve closes, the steel ball topped mechanism props open the two gate plates, presses tight the sealing surface, produces sealing pressure, achieving the effect of double-sided forced sealing. When the gate valve opens, the steel ball topped mechanism contracts, the gate plate moves inward and leaves the sealing surface, reducing the friction between the gate plate and the sealing ring of the valve seat during the opening and closing process.
The opening indicator of magnetic gate valve uses the magnet on the gate plate to drive the pointer of the magnetic induction meter installed outside the gate valve to display the opening. In the case of different opening of the valve, the magnet mounted on the gate plate has different distance and direction from the indicators. And the magnetic induction pointer on the instrument also produces induction of different intensity and direction. According to this, the pointer indicates the different opening of the valve