Here are the briefly introduction of the classifications and working principles of some kinds of gate valves.
Overview
The valve industry plays a very important role in the development of national economy as an important link in the preparation of manufacturing industry. The domestic demand and export volume of valve products show an upward trend every month and quarter. The overall situation is good, and the competition among domestic valve enterprises is gradually improving. The valves products are developing in the direction of energy conservation and environmental protection.
Gate valve
The gate valve refers to the valve whose closing part (gate) moves along the vertical direction of the path center line. The gate valve is mainly used for cutting off the medium in the pipeline. The forged steel gate valve is a kind of valve which is widely used. Generally, it is selected for the cut-off device with a DN greater than or equal to 500mm, and sometimes it is also used for the cut-off device with small diameters. As a low-grade gate valve, it is relatively common.
Electric gate valve
The action force distance is further than that of the electric valve. The opening and closing speed of the electric valve can be adjusted. The structure is simple and easy to maintain. Because of the buffer characteristics of the gas itself, it is not easy to be damaged due to jamming. However, there must be air source and its control system is more complex than that of the electric valve. The electric gate valve is sensitive, safe and reliable. Many factories with high control requirements set up compressed air station for pneumatic instrument control elements. The electric one needs electricity. And it can control its flow device.
The electric actuator is easily operated for electric valves, realizing the opening and closing of the valve. It can be divided into two parts. The upper part is the electric actuator, and the lower part is the valve.
There are two kinds of electric valves. One is the angular stroke electric valve. The angular stroke electric actuator is used with the angular stroke valve to realize 90 degrees internal rotations to control the pipeline fluid. The other is the straight stroke electric valve. The straight stroke electric actuator cooperates with the straight stroke valve to make the valve plate up and down to control the pipeline fluid. It is usually used in the equipment with higher automation degree, and the valve is installed horizontally with good adjustment accuracy. Electric valve drive is generally motor, which is more resistant to voltage shock. Solenoid valve can be fast opened and closed, which is generally used in small flow and small pressure. It requires high switching frequency of the electric valve on the contrary. The opening of the electric gate valve can be controlled, and the state can be opened, closed, half opened and closed, which can control the flow of medium in the pipeline. However, the solenoid valve can not meet this requirement.
Flat gate valve
A flat gate valve is a kind of sliding valve with parallel gate closing parts. The closing part can be a single plate or a double plate with an opening mechanism between them. The pressing force from the gate to the valve seat is controlled by the medium pressure acting on the floating gate or floating valve seat. If it is a double gate flat gate valve, the opening mechanism between the two gates can supplement this pressing force.
According to the driving mode, the flat gate valve can be divided into manual flat gate valves, pneumatic flat gate valves and electric flat gate valves. It can be divided into flat gate valve with diversion holes, flat gate valves without diversion holes, flat gate valves of oil fields, flat gate valves of pipelines, flat gate valves of gas, etc. The flat gate valve is suitable for natural gas, petroleum, chemical, environmental protection, city pipeline, gas pipeline and other transportation pipeline, vent system and steam storage device. And it is used as opening and closing device. Z43 single gate valves with diversion holes are suitable for long-distance pipeline of natural gas exploitation and purification.
Stainless steel gate valve
The types of stainless steel gate valves can be divided into wedge gate valves and parallel gate valves according to sealing surface configuration. The wedge gate valve can be divided into the single gate pole type, double gate plate type and elastic gate type. The parallel gate valve can be divided into the single gate plate and double gate plate type. According to the thread position of the valve stem, it can be divided into two types, namely rising stem gate valves and non rising stem gate valves. This kind of valve should be installed horizontally in the pipeline.
When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate is pressed to the valve seat on the other side to ensure the sealing of the sealing surface. That is self sealing. Most gate valves are forced to seal, that is to rely on external force to force the gate to the valve seat to ensure the sealing of the sealing surface. The gate plate of the gate valve moves with the valve stem for linear movement, which is known as rising stem gate valve. Generally, there are trapezoidal threads on the lifting rod. Through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is changed into the operating thrust.
When the valve is opened and the lifting height of the gate is equal to 1:1 of the valve diameter, the fluid passage is completely unblocked. However, this position cannot be monitored during operation. In actual use, the top of the valve stem is used as a mark, that is, the position where it can not be opened is taken as its full open positions. In order to consider the locking phenomenon of temperature changes, the valve is usually turned back 1/2 to 1 turn after opening to the top position. Therefore, the full open position of the valve is determined by the position of the gate.
Overview
The valve industry plays a very important role in the development of national economy as an important link in the preparation of manufacturing industry. The domestic demand and export volume of valve products show an upward trend every month and quarter. The overall situation is good, and the competition among domestic valve enterprises is gradually improving. The valves products are developing in the direction of energy conservation and environmental protection.
Gate valve
The gate valve refers to the valve whose closing part (gate) moves along the vertical direction of the path center line. The gate valve is mainly used for cutting off the medium in the pipeline. The forged steel gate valve is a kind of valve which is widely used. Generally, it is selected for the cut-off device with a DN greater than or equal to 500mm, and sometimes it is also used for the cut-off device with small diameters. As a low-grade gate valve, it is relatively common.
Electric gate valve
The action force distance is further than that of the electric valve. The opening and closing speed of the electric valve can be adjusted. The structure is simple and easy to maintain. Because of the buffer characteristics of the gas itself, it is not easy to be damaged due to jamming. However, there must be air source and its control system is more complex than that of the electric valve. The electric gate valve is sensitive, safe and reliable. Many factories with high control requirements set up compressed air station for pneumatic instrument control elements. The electric one needs electricity. And it can control its flow device.
The electric actuator is easily operated for electric valves, realizing the opening and closing of the valve. It can be divided into two parts. The upper part is the electric actuator, and the lower part is the valve.
There are two kinds of electric valves. One is the angular stroke electric valve. The angular stroke electric actuator is used with the angular stroke valve to realize 90 degrees internal rotations to control the pipeline fluid. The other is the straight stroke electric valve. The straight stroke electric actuator cooperates with the straight stroke valve to make the valve plate up and down to control the pipeline fluid. It is usually used in the equipment with higher automation degree, and the valve is installed horizontally with good adjustment accuracy. Electric valve drive is generally motor, which is more resistant to voltage shock. Solenoid valve can be fast opened and closed, which is generally used in small flow and small pressure. It requires high switching frequency of the electric valve on the contrary. The opening of the electric gate valve can be controlled, and the state can be opened, closed, half opened and closed, which can control the flow of medium in the pipeline. However, the solenoid valve can not meet this requirement.
Flat gate valve
A flat gate valve is a kind of sliding valve with parallel gate closing parts. The closing part can be a single plate or a double plate with an opening mechanism between them. The pressing force from the gate to the valve seat is controlled by the medium pressure acting on the floating gate or floating valve seat. If it is a double gate flat gate valve, the opening mechanism between the two gates can supplement this pressing force.
According to the driving mode, the flat gate valve can be divided into manual flat gate valves, pneumatic flat gate valves and electric flat gate valves. It can be divided into flat gate valve with diversion holes, flat gate valves without diversion holes, flat gate valves of oil fields, flat gate valves of pipelines, flat gate valves of gas, etc. The flat gate valve is suitable for natural gas, petroleum, chemical, environmental protection, city pipeline, gas pipeline and other transportation pipeline, vent system and steam storage device. And it is used as opening and closing device. Z43 single gate valves with diversion holes are suitable for long-distance pipeline of natural gas exploitation and purification.
Stainless steel gate valve
The types of stainless steel gate valves can be divided into wedge gate valves and parallel gate valves according to sealing surface configuration. The wedge gate valve can be divided into the single gate pole type, double gate plate type and elastic gate type. The parallel gate valve can be divided into the single gate plate and double gate plate type. According to the thread position of the valve stem, it can be divided into two types, namely rising stem gate valves and non rising stem gate valves. This kind of valve should be installed horizontally in the pipeline.
When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate is pressed to the valve seat on the other side to ensure the sealing of the sealing surface. That is self sealing. Most gate valves are forced to seal, that is to rely on external force to force the gate to the valve seat to ensure the sealing of the sealing surface. The gate plate of the gate valve moves with the valve stem for linear movement, which is known as rising stem gate valve. Generally, there are trapezoidal threads on the lifting rod. Through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is changed into the operating thrust.
When the valve is opened and the lifting height of the gate is equal to 1:1 of the valve diameter, the fluid passage is completely unblocked. However, this position cannot be monitored during operation. In actual use, the top of the valve stem is used as a mark, that is, the position where it can not be opened is taken as its full open positions. In order to consider the locking phenomenon of temperature changes, the valve is usually turned back 1/2 to 1 turn after opening to the top position. Therefore, the full open position of the valve is determined by the position of the gate.
Next: Design of High-pressure Slab Gate Valves for High-sulfur Natural Gas (Part Three)
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