1、 Introduction to the structure of electric gate valves:
(1) What is an electric valve:
Simply put, an electric valve uses an electric actuator to control the valve, thereby achieving the opening and closing of the valve. It can be divided into two parts: the upper part is an electric actuator, and the lower part is a valve.
(2) There are two types of electric valves:
One type is an angle stroke electric valve: it is used by an angle stroke electric actuator in conjunction with an angle stroke valve to achieve a 90 degree internal rotation of the valve to control the flow of the pipeline; Another type is a straight stroke electric valve: it is used by a straight stroke electric actuator in conjunction with a straight stroke valve to achieve up and down movement of the valve plate to control the flow of the pipeline. Usually used in conjunction with highly automated equipment, the horizontal installation and adjustment accuracy of this valve is above.
2、 Principle:
(1) Operating principle of electric valve:
Electric valves are usually connected by electric actuators and valves, and become electric valves after installation and debugging. The electric valve uses electrical energy as power to connect the electric actuator to drive the valve, achieving the opening and closing and regulating actions of the valve.To achieve the purpose of switching or regulating the pipeline medium.
(2) Electromagnetic valve is a type of electric valve; It uses the magnetic field generated by the electromagnetic coil to pull the valve core, thereby changing the on-off of the valve body. When the coil is powered off, the valve core relies on the pressure of the spring to retract.
(3) Structural characteristics of electric gate valves:
① The valve adopts a pressure self tightening sealing or valve body, valve cover gasket sealing structure, which is trustworthy! Safe and reliable use.
② The valve disc adopts a double gate structure with a universal top in the middle, which can automatically adjust the sealing surface of the valve disc and valve seat to ensure the sealing of the valve. At the same time, this structure is easy to maintain, saves costs, and has good valve disc interchangeability.
③ The sealing surfaces of the valve disc and valve seat are made of cobalt chromium tungsten hard alloy by plasma spray welding. The sealing surface has high hardness, wear resistance, scratch resistance, and long service life.
④ The valve stem is made of nitrided steel with surface nitriding treatment, high hardness, scratch resistance, corrosion resistance, and long service life.
⑤ The electric device is equipped with torque control mechanism, on-site operation mechanism, and manual and electric switching mechanism. In addition to on-site operation, remote operation, PLC control, and intelligent control of 4-20mA current input and output can also be carried out.
⑥ The manual valve is opened by a manual mechanism or a handwheel upon impact. Reduce valve operating force.
⑦ Valves can be installed at any position in the pipeline, and carbon steel or alloy steel valves can be selected based on the temperature of the medium and medium.
3、 The application range of electric gate valves:
(1) Oil and natural gas transmission pipelines. The flat gate valve with a diversion hole is also convenient for cleaning pipelines.
(2) Transportation pipelines and storage equipment for finished oil.
(3) Wellhead devices for oil and natural gas extraction, also known as Christmas tree valves.
(4) Pipes with suspended particles in the medium.
(5) Urban gas transmission pipelines.
(6) Water supply engineering.
4、 Regarding the operating mechanism of pneumatic gate valves:
(1) The opening and closing direction of pneumatic valves should always be clockwise.
(2) Due to the frequent manual opening and closing of pneumatic valves in the pipeline network, the number of opening and closing revolutions should not be too large, even for large diameter valves, it should be within 200-600 revolutions.
(3) In order to facilitate the opening and closing operation of a person, the maximum opening and closing torque should be 240N-m under pipeline pressure conditions.
(4) The opening and closing operating end of pneumatic valves should be square tenon, with standardized dimensions and facing the ground, so that people can operate directly from the ground. Valves with wheels are not suitable for underground pipeline networks.
(5) Display panel for the degree of opening and closing of pneumatic valves:
① The scale lines for the degree of opening and closing of pneumatic valves should be cast on the gearbox cover or the shell of the display panel after changing direction, all facing the ground, and the scale lines should be brushed with fluorescent powder to show eye-catching;
② The material of the indicator dial needle can be made of stainless steel plate under good management, otherwise it is painted steel plate, and aluminum sheet should not be used for production;
③ The indicator dial needle is eye-catching and firmly fixed. Once the opening and closing adjustment is accurate, it should be locked with rivets.
(6) If the pneumatic valve is buried deep and the distance between the operating mechanism and display panel from the ground is ≥ 1.5m, an extension rod facility should be installed and firmly fixed to facilitate observation and operation from the ground. That is to say, the valve opening and closing operation in the pipeline network is not suitable for downhole operations.
5、 Performance testing of pneumatic gate valves:
(1) When manufacturing a certain specification of valve in bulk, an authoritative organization should be entrusted to conduct the following performance tests
① The opening and closing torque of the valve under working pressure;
② Under working pressure, the number of consecutive opening and closing times that can ensure the valve is tightly closed;
③ Detection of flow resistance coefficient of valves under pipeline water transmission conditions.
(2) Valves should undergo the following inspections before leaving the factory:
① When the valve is open, the valve body should withstand an internal pressure test of twice the working pressure value of the valve;
② Under the closed condition of the valve, both sides shall withstand 1.1 times the working pressure of the valve, without leakage; But for metal sealed butterfly valves, the leakage value should not exceed the relevant requirements.
6、 Internal and external anti-corrosion of pneumatic valves
(1) The inside and outside of the valve body (including the gearbox) should first be shot blasted and rust removed, striving to electrostatic spray powder non-toxic epoxy resin with a thickness of over 0.3mm. When it is difficult to electrostatic spray non-toxic epoxy resin on oversized valves, similar non-toxic epoxy paint should also be brushed and sprayed.
(2) The interior of the valve body and various parts of the valve plate require comprehensive anti-corrosion. On the one hand, immersion in water will not rust, and electrochemical corrosion will not occur between two metals; On the other hand, the smooth surface reduces the water resistance.
(3) The hygiene requirements for anti-corrosion epoxy resin or paint inside the valve body should be tested by corresponding authoritative authorities.The chemical and physical properties should also meet relevant requirements.
