3、 The electric on-off butterfly valve also has excellent sealing performance. It has the line design of sealing valve, which can absolutely guarantee the sealing. This design can prevent air from entering without air leakage. Secondly, it also has the design of friction surface, which will produce certain resistance in the friction process. This design can make the sealing better. 　　

1. Allowable value of valve stem diameter When selecting electric equipment, pay attention to the allowable valve stem diameter, and the valve stem diameter must be less than this value. In addition, the requirements for the height of the valve stem cover (related to the valve diameter) should also be put forward when selecting multi reversing electric equipment. Rotary stem valves may not be equipped with valve stem covers.