How To Choose The Actuator for Electric Gate Valve?
We all know that electric gate valves are valve equipment that use electric actuators with gate valves. So how should we choose electric actuators when using gate valves? Let’s take a look at Yuechi Electric Manufacturer!
How to Correctly Select an Electric Actuator for an Electric Gate Valve？
Operating torque
The operating torque is the most important parameter for selecting gate valve electric devices. The output torque of the electric actuator should be 1.2 to 1.5 times the maximum operating torque of the gate valve.
There are two main structures of the operating thrust gate valve electric device
one is not equipped with a thrust plate and directly outputs torque; the other is equipped with a thrust plate, and the output torque is converted into output thrust through the valve stem nut in the thrust plate.
Number of turns of the output shaft
The number of turns of the output shaft of the electric device is related to the nominal diameter of the gate valve, the valve stems pitch, and the number of thread heads. It should be calculated according to M=H/ZS (M is the total number of turns that the electric device should meet, H is the gate valve opening height, S is the valve stem transmission thread pitch, and Z is the number of valve stem thread heads).
Valve stem diameter For multi-turn rising stem gate valves
If the maximum valve stem diameter allowed by the electric device cannot pass through the valve stem of the gate valve, it cannot be assembled into an electric gate 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 gate valve. For partial-turn gate valves and non-rising stem gate valves in multi-turn gate valves, although the problem of the valve stem diameter does not need to be considered, the valve stems diameter and the size of the keyway should also be fully considered when selecting so that it can work normally after assembly.
Output speed
If the opening and closing speed of the gate valve is too fast, a water hammer is likely to occur. Therefore, the appropriate opening and closing speed should be selected according to different use conditions.
The gate valve electric actuator has its special requirements, that is, it must be able to limit the torque or axial force.
Usually, the gate valve electric device adopts a torque-limiting coupling. When the specifications of the electric device are determined, its control torque is also determined. Generally, the motor will not be overloaded if it runs within a predetermined time.
However, overload may occur if the following situations occur:
1. The power supply voltage is low and the required torque cannot be obtained, causing the motor to stop rotating;
2. The torque limiting mechanism is incorrectly adjusted to be greater than the stopping torque, resulting in continuous excessive torque, causing the motor to stop rotating;
3. The heat generated by intermittent use exceeds the allowable temperature rise value of the motor;
4. The torque limiting mechanism circuit fails for some reason, causing excessive torque;
5. The ambient temperature is too high, which relatively reduces the thermal capacity of the motor.
VI. Basic overload protection methods are:
1. For overload protection of continuous operation or inching operation of the motor, use a thermostat;
2. For motor stall protection, use a thermal relay;
3. For short circuit accidents, use a fuse or overcurrent relay
