Working principle and structural composition of electric valves, Kle-Valve Wuxi Clariant pneumatic control valves

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The working principle and structural composition of electric valves: The Kle-Valve by Wuxi Clariant Fluid Control valves are devices that consist of an electric drive unit for the valve combined with the valve itself. Electric valves feature a wide range of available power sources, easy operation, and the ability to meet various control requirements; as a result, electric drives play a dominant role among valve drive systems. This article mainly introduces the working principle and structural components of electric valves. Working principle of electric valves: Electric valves use an electric motor as the prime mover. Specially designed three-phase asynchronous motors are usually used. The motor is designed for short-term operation, lacks cooling equipment, and has soft or moderately soft mechanical properties. For applications requiring high reliability, series-wound DC motors are used. For applications that require a change in speed, variable-speed three-phase asynchronous motors are used. The motor drives the valve’s operating element after being slowed down by the main transmission mechanism. There are many structural forms for the main drive mechanism. However, the transmission methods mainly include spur gear transmission, worm gear transmission, spur gear planetary transmission, cycloidal pinion planetary transmission, and harmonic drive, among others. The most common structural configuration for the main drive mechanism is a combination of spur gear transmission and worm gear transmission. The torque output by the main drive mechanism is converted into thrust through trapezoidal threads, which in turn moves the valve shutters (gate valves and globe valves) in a linear motion. Typically, the valve stem nut used for torque-to-thrust conversion is mounted on the valve stem as a component of the valve. At this point, the electric actuator outputs torque to drive the valve stem nut. However, sometimes a trapezoidal thread (valve stem nut) is also provided inside the electric actuator, allowing the electric actuator to directly generate thrust. For valves in which the closing element moves in a rotational motion (ball valves and butterfly valves), the output shaft of the main drive mechanism must pass through a secondary reducer in order to drive the valve’s closing element. Secondary reducers typically use planetary gear drives, worm gear drives, and screw rocker arm drives. The secondary reducer is usually installed in a separate housing before being connected to the electric actuator. Structural components of electric valves: 1. Electric valves are primarily composed of the valve itself and an electric actuator; electric actuators are used in such valves. Its output shaft features a stem nut-type connection; the flange size of the coupling plate is used to drive the stem up and down. Thus, it drives the valve stem to cause the gate to move up and down in a linear motion, thereby achieving the purpose of opening and closing the electric ball valve. 2. The valve electrical assembly is equipped with a manual operating mechanism, which allows the valve to be opened and closed manually in the absence of power; turning the handwheel clockwise closes the valve. Turning counterclockwise opens the valve, which is a pneumatic ball valve. 3. The middle flange of the valve features a self-pressuring sealing structure; its gasket is made of stainless steel, enabling it to provide high-pressure sealing up to 4500 pounds, thus ensuring reliable sealing performance for the ball valve. 4. The gate uses a wedge-type single-gate structure, resulting in a valve with a small size and a compact design – it is a floating ball valve. 5. The valve body features a forge-welded structure, which fundamentally eliminates quality issues caused by casting defects, reduces the rate of defective products, and enhances the reliability of the product. 6. The sealing surfaces of the gate and valve seat are surfaced with cobalt-based cemented carbide. 7. Reverse closing sealing devices are provided on the valve stem and valve cover. When necessary, this reverse seal device can be temporarily used to isolate the medium from the packing box, but it cannot be used to replace the packing. Advantages and disadvantages of electric valves: Advantages of electric valves: high stability, constant thrust, and good resistance to deviation. Disadvantages of electric valves: complex structure and high cost. Daily maintenance of electric valves: 1. Electric valves should be stored in a dry and well-ventilated area, with both ends of the passage blocked off. 2. Electric valves that are stored for long periods should be inspected regularly, cleaned of debris, and coated with rust preventive oil on their working surfaces. 3. After installation, regular inspections should be carried out. The main items to check include: (1) the wear condition of the sealing surfaces. (2) Wear condition of the trapezoidal threads on the valve stem and valve stem nut. (3) Check whether the filler is outdated or ineffective; if damaged, it should be replaced promptly. (4) After the repair and assembly of the electric valve, a sealing performance test should be conducted. For electric valves that are in operation, all valve components should be complete and in good condition. Flange threads and the bolts on the bracket are essential; the threads must be in good condition, with no signs of looseness allowed. The tightening nuts on the handwheel should be tightened promptly if they become loose, to prevent wear at the connection points or loss of the handwheel and nameplate. If the handwheel is lost, it is not allowed to use an adjustable wrench as a substitute; it must be replaced promptly. The packing gland must not be skewed or have no preload clearance. For electric valves in environments prone to contamination by rain, snow, dust, sandstorms, and other pollutants, a protective cover should be installed on their valve stems. The scale on electric valves should remain intact, accurate, and clear. The lead seals, caps, pneumatic accessories, etc., of the electric valve should be complete and in good condition. The insulation jacket should be free of dents and cracks. It is not allowed to strike, stand on, or place heavy objects on operating electric valves ； In particular, non-metallic electric valves and cast iron electric valves should be completely prohibited. Uses of electric valves: They are used for analog regulation of the flow rate of media in pipelines for liquid, gas, and air systems, and they are part of AO control. Electric valves can also be used for two-position on/off control in the management of large valves and ventilation systems. The above is the information on electric valves that the editor has compiled for everyone; it is hoped this will help people gain a deeper understanding of electric valves. Electric valves are both pipeline components and automation components, namely electric actuators. Therefore, in addition to meeting the requirements of the production process for valves, it must also meet the requirements of the production process for automatic devices. The structure of electric valves varies depending on the different components that make up each valve. Kle-Valve, Wuxi Clariant Fluid Control Equipment Co., Ltd. – Further reading: Classification and characteristics of pneumatic ball valves; Differences between Clariant’s pneumatic ball valves and pneumatic control valves