Dry compressing vacuum pump having a gas ballast device

摘要

A dry compressing vacuum pump (1) has a continuous or graduated inner compression. A gas ballast device (8) selectively adds a ballast gas to a pumped gas. The gas ballast device has an isolating valve (11), a non-return valve (12) which prevents the escape of gases from the pump through the gas ballast device to the outside, and a pressure differential valve (13).