Sealing constant-pressure device for sealing container and keeping constant pressure

The utility model discloses a sealing constant-pressure device for sealing container and keeping constant pressure, comprising a chamber with a variable volume, a connection pipeline and an accessory device, wherein the materials in a served target container are separated from the outside world and the pressure in the target container keeps constant; when the sealing constant-voltage device is used, a sealing system with a communicated volume space is formed by the chamber with a variable volume, the connection pipeline and the accessory device; the volatilization loss of the materials in the system and the corresponding environment pollution can be reduced or avoided; the loss of protection gas can be also reduced or avoided; simultaneously, the sealing constant-pressure device can meet a special demand that the served target container is sealed at a pressure lower or higher than the atmosphere. The sealing constant-pressure device has the advantages of simple structure, easy installation and maintenance. In