The GDQ-J-A series normally closed pneumatic high vacuum flapper valve relies on compressed air as the opening and closing power of the valve plate through an electromagnetic directional valve. When power or compressed air is lost, valves with a diameter below DN80 will automatically close the valve relying on spring force. Valves with a diameter above DN100 will quickly close the original air source pressure of the cylinder through the electromagnetic valve group using a one-way valve to achieve automatic valve closure. Thus achieving the function of quickly cutting off the airflow in the vacuum system. The shaft seal structure of pneumatic high vacuum baffle valve can be divided into two types: GDQ-J-A rubber seal and GDQ-J-A (b) corrugated pipe seal. The GDQ-J type is an angle through type, while the GDQ-S type is a three-way type with a pre extraction port. The applicable working medium is air and non corrosive gases.