Selection of electric valve

by:Lianke Valve     2022-08-22
In pipeline engineering, the correct selection of electric valves is one of the guarantee conditions to meet the requirements of use. Here, I will introduce to you a selection of electric valves, their functional characteristics and the working environment in which electric valves can be used. What is an electric valve? The electric valve simply uses the electric actuator to control the valve, so as to realize the opening and closing of the valve. It can be divided into upper and lower parts, the upper part is the electric actuator, and the lower part is the valve. Also called air conditioning valve. The electric valve is a high-end product in the automatic control valve. It can not only realize the switching function, but also realize the valve position adjustment function. The stroke of the electric actuator can be divided into two types: 90° angular stroke and straight stroke. Special requirements can also meet the full stroke of 180°, 270° and 360°. The angular stroke electric actuator is used in conjunction with the angular stroke valve to realize the internal rotation of the valve to control the on-off of the pipeline fluid; the straight stroke electric actuator is used with the straight stroke valve to realize the up and down action of the valve plate to control the pipeline fluid on-off. Technical principle The electric valve is usually connected by an electric actuator and a valve, and becomes an electric valve after installation and debugging. The electric valve uses electric energy as power to connect the electric actuator to drive the valve to realize the opening and closing and adjustment of the valve. So as to achieve the purpose of switching or adjusting the pipeline medium. The electric valve is generally driven by a motor. It takes a certain amount of time to complete the opening or closing action, and it can be adjusted. Compare withstand voltage shocks. Solenoid valves are quick-opening and quick-closing, and are generally used in places with small flow and small pressure that require a large switching frequency; electric valves are the other way around. The opening of the electric valve can be controlled, and the state is open, closed, half-open and half-closed, which can control the flow of the medium in the pipeline, but the solenoid valve cannot meet this requirement. The three-wire electric valve has three lines of F/R/N, F represents the forward action (or open action) control line, R represents the reverse action (or close action) control line, and N represents the ground wire. Solenoid 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, the coil is de-energized, and the valve core is retracted by the pressure of the spring. What types of electric valves are there? 1. Electric valves can be divided into on-off electric valves and regulating electric valves according to the valve position function; 2. According to the valve position, they can be divided into electric ball valves and electric butterfly valves; 3. According to the shape of the valve body It can be divided into: ordinary electric valve and micro electric valve; 4. The electric valve is conventionally switch type and regulating type; 5. According to the wiring, it is also divided into three-wire and two-wire system. Two-wire and three-wire systems are available. Working environment of electric valve In addition to the pipeline parameters, electric valve should pay special attention to the environmental conditions of its work, because the electric device in the electric valve is an electromechanical device, and its working conditions are greatly affected by its working environment. Usually, the working environment of the electric valve is as follows: 1. Indoor installation or outdoor use with protective measures; 2. Outdoor open-air installation, eroded by wind, sand, rain and dew, sunlight, etc.; 3. It is flammable, easy to Explosive gas or dust environment; 4. Environment in wet tropics and dry tropics; 5. The temperature of the pipeline medium is as high as 480°C or more; 6. The ambient temperature is below -20°C. 7. Easily flooded or submerged in water; 8. Environment with radioactive substances (nuclear power plants and radioactive material test devices); 9. Environment on ships or docks (with salt spray, mold, humidity); 10. Vibration 11. Occasions that are prone to fire; for the electric valve in the above environment, the structure, material and protective measures of the electric device are different. Therefore, the corresponding valve electric device should be selected according to the above working environment. The following points should be paid attention to when selecting an electric valve: 1. Operating torque Operating torque is the most important parameter for selecting the valve electric device, and the output torque of the electric device should be 1.2 to 1.5 times the maximum operating torque of the valve. 2. There are two main structures for operating the thrust valve electric device: one is not equipped with a thrust plate, and the torque is directly output; the other is equipped with a thrust plate, and the output torque is converted into an output thrust through the valve stem nut in the thrust plate. 3. The number of rotations of the output shaft The number of rotations of the output shaft of the valve electric device is related to the nominal diameter of the valve, the pitch of the valve stem, and the number of thread heads, which should be calculated according to M=H/ZS (M is the total value that the electric device should meet. The number of turns, H is the opening height of the valve, S is the thread pitch of the valve stem drive, and Z is the number of thread heads of the valve stem). 4. Stem diameter For multi-turn rising stem valves, if the maximum stem diameter allowed by the electric device cannot pass through the valve stem of the equipped valve, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the valve stem of the rising stem valve. For part-turn valves and dark-stem valves in multi-turn valves, although there is no need to consider the passage of the diameter of the valve stem, the diameter of the valve stem and the size of the keyway should also be fully considered during selection.Make it work properly after assembly. 5. If the opening and closing speed of the output speed valve is too fast, it is easy to produce water hammer. Therefore, the appropriate opening and closing speed should be selected according to different use conditions. 6. The valve electric device has its special requirements, that is, it must be able to limit the torque or axial force. Usually valve electric devices use torque-limiting couplings. After the specification of the electric device is determined, its control torque is also determined. Welcome to call Lianke Valve Co.,Ltd., we will answer your questions. Tel: +86-577-8585 9626. Lianke Valve Co.,Ltd. is a company dedicated to valve innovation and manufacturing, striving to bring better valves to everyone.
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