Knowledge of Forged Steel Valve Electric Actuators-part two
Jan 24, 2019
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3. Electric device classified according to the operating environment and explosion-proof grade
According to the operating environment and explosion-proof grade requirements, the electric device of the forged steel valve can be divided into ordinary type, outdoor type, explosion-proof type, outdoor explosion-proof type, etc.
The output torque of the electric actuator is determined based on the torque required for the forged steel valve. The torque required for the forged steel valve to open and close determines the output torque of the electric actuator. It is usually recommended by the user or chosen by the forged valve manufacturer. An actuator manufacturer is only responsible for the output torque of the actuator. The torsion force required for the normal opening and closing of the forged steel valve is determined by factors such as the diameter of the forged steel valve and the working pressure. However, due to the difference in the machining accuracy and assembly process of the valve manufacturer, the torque required for the forged steel valves of same specification produced by different manufacturers is also different, even the torque of the forged steel valves of same specification produced by the same valve manufacturer is also different. If the torque of the actuator you selected is too small, the forged valve cannot be normally opened and closed. Therefore, for the electric actuator, a reasonable torque range is critical.
4. The basis for correct selection of the forged steel valve driving devices Operating torque:
The operating torque is the most important parameter for selecting the electric device of the forged steel valve. The output torque of the electric device should be 1.2~1.5 times of the maximum operating torque of the forged steel valve.
Operating thrust:
There are two types of main components of the valve electric device: one is that the thrust plate is not allocated and the torque is directly output; the other is to configure the thrust plate, and the output torque is converted into the output thrust through the stem nut in the thrust plate.
Rotation number of the output shaft:
The number of turns of the output shaft of the valve electric device is related to the nominal diameter of the forged valve, the pitch of the valve stem and the number of threads. It should be calculated according to M=H/ZS (M is the total number of rotations that the electric device should meet, and H is the height for valve opening, S is the stem transmission thread pitch, and Z is the number of stem thread ).
Diameter of valve stem:
For multi-turn type rising stem valves, if the maximum stem diameter allowed by the electric device cannot pass through the valve stem of the forged valve, it cannot be assembled into an electric forged valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the rising stem forged valve. For some of the rotary valves and the non-rising stem valves in the multi-turn forged valves, although the problem of whether the diameter of the stem can pass through the valve stem of the forged valve is put aside, the diameter of the stem and the size of the key groove should be fully considered in the selection, so that the forged valve can work normally after assemble.
Output rotational speed:
If the opening and closing speed of the forged valve is too fast, water hammer is likely to occur. Therefore, the appropriate opening and closing speed should be selected according to different conditions of use.