Since the electric butterfly valve is composed of butterfly valve and electric equipment, how to select the electric equipment correctly after the confirmation of butterfly valve is an important factor to meet the engineering needs in actual use. When selecting electric equipment, not only the working environment, electrical control and general skill performance mentioned above should be considered, but also the comprehensive skill performance of electric equipment.
1. Allowable value of stem diameter
When selecting electric equipment for lifting rod valve, pay attention to the allowable valve stem diameter, which is necessary to be less than this value. In addition, the requirements for the height of the valve stem cover (related to the valve pain diameter) should also be put forward when selecting the multi reversing electric equipment. Rotary stem valves may not be equipped with stem cover.
2. Connection between valve and electric equipment
The connection type and size of valve and electric equipment shall comply with national standards: connection of multi reversing valve driving equipment (GB / t12222-1989) and connection of partial reversing valve driving equipment (GB / t12223-1989).
3. Output torque and speed of electric equipment
Output torque value is one of the important skill parameters of electric equipment, and also an important parameter to be selected in use. If the output torque of the selected electric equipment is too large or insufficient when assembling the electric valve, it is not advisable. Due to the general situation, the electric equipment manufacturers need to test and adjust the output torque value when they leave the factory, which is relatively accurate. If the output torque margin is too large, the electric valve will have great potential danger. Once the control and protection failure occurs, it will easily cause valve damage (valve stem bending, valve body cracking) phenomenon, which is very easy to cause pipeline system accidents. Therefore, it is not advisable to select too large output torque margin. If cannot open the valve in the actual operation also belongs to the selection is unreasonable.
As for the confirmation of the output speed of electric equipment, the slower speed should be selected as far as possible when the valve has no strict requirements on its opening and closing time.
Due to the unnecessary faster speed, the motor power will be increased under the same torque requirements, which will not only waste power, improve the project cost, but also increase the volume of electric equipment, resulting in waste in many aspects.
At present, the domestic self-developed electric equipment has a small number of motor standards in each frame number (generally 2-3 standards), and the speed ratio range of gear pair and worm gear pair in the main drive is limited, so the torque and speed grades of each frame number are not much.
4. Allowable maximum thrust of electric equipment
If the axial force of the valve is borne by the electric equipment (i.e. the valve stem nut is in the electric equipment), its thrust value is not allowed to exceed the allowable value of the electric equipment.
5. Maximum number of turns of stem nut
It is necessary to clarify the maximum number of turns of the valve stem nut when selecting the electric equipment of multi reversing valve, so as to correctly select the gear speed ratio of the orientation indication organization in the electric equipment, so as to make the azimuth indication have satisfactory accuracy, and satisfy the investigation on the opening and closing degree of the valve in the process of valve operation, otherwise, it is easy to cause hallucination and affect the normal operation.
At present, some electric equipment of reversing valve has mechanical limit to avoid being unable to judge the valve disc orientation. The corresponding connection requirements of connecting screw hole and keyway orientation between such valve and electric equipment are strict.