US Patent 7150728 Collecting bag having a vent aperture

A collecting bag is provided with a vent aperture to allow for escape of gases which may accumulate in the bag during use. The vent aperture is formed in an extension member that is connected with the bag member. In order to bring the vent aperture from a fully open condition to a fully closed condition, the extension member is folded at least once along a folding line, thereby bringing a first engagement surface into engagement with a second engagement surface. A net element may be positioned between the inlet opening of the bag member and the extension member and a filter device may be positioned within the extension member.