Valve electric device is to realize the valve remote control, automated operation of the key equipment, its movement process can be accurately regulated by the size of the stroke, torque or axial thrust. The performance and application effect of the valve electric device depends largely on the type of valve, work specification and specific location in the pipeline or equipment. Core Composition of Electric Device The electric device usually consists of the following key components: – Specialized motor: with strong overload capacity, high starting torque, low moment of inertia, suitable for short-term intermittent work. – Deceleration mechanism: Used to reduce the output speed of the motor to adapt to the valve’s operating requirements. – Stroke control mechanism: to ensure that the opening and closing position of the valve is accurate. – Torque limiting mechanism: to prevent the torque (or thrust) from exceeding the preset value and protect the safety of the equipment. – Manual-electric switching mechanism: to realize the convenient switching between manual and electric operation. – Opening degree indicator: visualize the position of the valve in the opening and closing process. How to choose the electric actuator according to the type of valve 1. Angular stroke electric actuator (corner less than 360 degrees): for butterfly valves, ball valves, plug valves and so on. This type of actuator through less than a week of rotation (usually 90 degrees) can complete the valve opening and closing control. According to the different ways of mounting interface, it is divided into direct-connected type and base crank type. – Directly connected: the output shaft of the actuator is directly connected to the valve stem. – Base crank type: the output shaft is connected to the valve stem through a crank. 2. Multi-turn electric actuator (angle greater than 360 degrees): applicable to gate valves, Globe valves and so on. This type of actuator requires multiple turns to realize the opening and closing control of the valve. 3. straight stroke electric actuator: applicable to single-seat adjustment valves, double-seat adjustment valves, etc. The output shaft of the actuator carries out linear movement. The output shaft of the actuator carries out linear movement, not rotation. Determine the mode of electric actuator according to the control requirements 1. switching electric actuator (open-loop control): used to simply open or close the valve, without precise control of media flow. According to the structure form, it is divided into split structure and integrated structure. – Split structure: the control unit is separated from the actuator, and an external control unit is required. Installation is complex, high maintenance costs. – Integration structure: control unit and actuator are integrated, easy to install and maintain. 2. Regulating electric actuator (closed-loop control): not only with the switching function, but also to accurately control the valve and regulate the flow of media. When selecting, it is necessary to consider the type of control signal (e.g. current, voltage), the working form (electric open type, electric close type) and the protection measures against loss of signal. Selection according to the use of the environment and grade According to the use of the environment and grade requirements, the valve electric device can be divided into ordinary, outdoor, explosion-proof, outdoor explosion-proof, etc., in order to meet the safety needs of different scenarios. Determine the actuator output according to the required torque of the valve The torque required for valve opening and closing determines the output torque size of the electric actuator. This parameter is usually provided by the valve user or manufacturer. When selecting a model, it should be ensured that the output torque of the electric actuator is at least 1.2 to 1.5 times the maximum torque of the valve operation to ensure that the valve can open and close properly. Correct selection of the basis of the valve electric device – operating torque: is the key parameter in the selection of electric devices, should ensure that the electric device output torque to meet the valve operation of the maximum torque of 1.2 to 1.5 times. – Operation thrust: the host structure of the electric device has two kinds, one directly output torque, the other through the thrust disk converted to output thrust. – The number of turns of the output shaft: related to the nominal diameter of the valve, stem pitch, the number of threaded heads, need to be calculated according to the formula. – Stem diameter: for open stem valves, the hollow output shaft inner diameter of the electric device must be greater than the outer diameter of the valve stem. For partially rotary valves and dark stem valves, it is also necessary to consider the stem diameter and keyway size to ensure normal operation. – Output speed: the opening and closing speed of the valve is too fast may lead to water strike phenomenon, so it should be based on the use of conditions to choose the appropriate opening and closing speed. By comprehensively considering the above factors, you can choose the most suitable valve electric device for your industrial application to ensure the accuracy and safety of valve control.
Valve electric device: a must for driving valve control
