Common problems in the selection of electric valves

Simply put, an electric regulating valve uses an electric actuator to operate a gate valve, thereby opening and closing the gate valve. It can be divided into two parts: the upper part is the electric actuator, and the lower part is the gate valve. It is also called a central air conditioning valve.

The electric regulating valve is a product in automatic control valves. It can not only complete the power switch function, but also complete the valve position adjustment function of the electric regulating valve. The stroke of the electric actuator can be divided into 90° angular stroke and straight stroke. Special requirements can reach 180°, 270°, 360° full stroke. The application of angular stroke electric actuator with angular stroke valve completes the 90° rotation of the gate valve to conduct liquid in the pipeline; the application of straight stroke electric actuator with straight stroke valve completes the left and right position of the multi-hole plate to conduct liquid in the pipeline.

The following aspects should be noted when selecting an electric valve:

1. The actual operating torque is a basic parameter for selecting valve electrical devices. The output torque of the electrical equipment should be 1.2 to 1.5 times the actual maximum operating torque of the gate valve.

2. The server structure of the actual operating thrust valve electric device has two types: one type does not have a thrust plate and outputs torque immediately; the other type is equipped with a thrust plate, which converts the output torque into output thrust according to the valve stem nut in the thrust plate.

3. The number of output shaft rotations of the valve electrical device is related to the nominal diameter of the gate valve, the valve stem pitch, and the number of external threads. It should be calculated according to M = H/ZS (M is the total number of rotations that the electrical equipment should reach, H is the relative height of the gate valve, S is the thread pitch of the valve stem transmission system, and Z is the number of external threads of the valve stem).

4. Valve stem diameter For multi-rotation rising stem gate valves, if the large valve stem diameter allowed by the electric equipment cannot be assembled into an electric valve according to the equipped gate valve valve stem. Therefore, the nominal diameter of the hollow output shaft in the electric equipment must exceed the valve stem diameter of the non-rising stem gate valve. For partial rotation gate valves and non-rising stem valves in multi-rotation gate valves, although the basis of the valve stem diameter does not need to be considered, the valve stem diameter and the health groove specifications should also be considered when selecting, so that it can work normally after assembly.

5. If the output speed is faster than the gate valve, it is easy to cause water hammer. Therefore, a reasonable opening and closing rate should be selected according to different application standards.

6. Valve electric devices have special requirements, that is, the torque or axial force must be limited. Valve electric devices usually choose torque-limited couplings. After the specifications and models of the electrical equipment are clarified, the operating torque is clarified.