Electric butterfly valve is made up by butterfly valve and electric actuator, therefore, after the butterfly valve is determined, how to correctly choose electric actuator to meet the engineering need in practical use is becoming important.
1. Allowed value of stem diameter
For lifting lever valve, you should pay attention to the allowed value of stem diameter when choosing its electric actuator, and the real value can not beyond the allowed valve. In addition, for multi-turn electric actuator, the request about the height of stem cover should be put forward. Besides, rotating rod valve can not be installed with stem cover.
2. The connection between valve and electric actuator
The connection type and size between valve and electric actuator should confirm to the national standard. GB/T12222-1989 is the connection of multi-turn valves while GB/T12223-1989 is the connection of partial multi-turn valves.
3. The output torque of electric actuator
The output torque value is one of the important technological parameters of electric actuator, as well as in practical use. When equipping an
electric valve, it is not desirable if the output torque of the electric actuator is excessive or insufficient. Generally, its manufacturers will test and adjust the output torque value before leaving the factory, so the value of electric actuator is relatively accurate. If the output torque allowance is too big, it will cause great potential danger to electric valve. And once the control protection is fail, the valve will be easily damaged (such as bent stem, cracked body) and causes pipeline system accidents.
4. The maximum thrust value of electric actuator
If the valve axial force is borne by electric actuator (that is, the stem nut is installed in electric actuator), then the thrust value is not allowed to exceed the allowable values of electric actuator.
5. The maximum circle number of stem nut
The maximum circle number of stem nut must be illustrated when choosing electric actuator of multi-turn valves during working process. So that people can correctly match the gear ratio of position indicating actuator and make the position indicator work effectively in the process of observing the open and close situation of a
valve. Otherwise, it will be easy to cause illusion problem and affect the normal work of the valve.
At present, some of the electric actuators have mechanical limits so as to judge the disc position. This type of valve has a strict corresponding relation with connecting screw hole and keyway position.
