◆ Reliable sealing of valve rod: The valve rod adopts a bottom mounted structure with reverse seal, and the sealing force of the reverse seal increases with the increase of the medium pressure, so it can ensure the reliable sealing of the valve rod, and the valve rod will not eject when the valve rod rises abnormally. 　　

1. Allowable value of valve stem diameter When selecting electric device for lifting valve, attention shall be paid to the allowable valve stem diameter, which must be less than this value. In addition, for the multi turn electric device, the requirements for the height of the valve stem cover (related to the valve diameter) should also be put forward when selecting it. Rotary stem valves may not be equipped with valve stem covers.