Abstract: There is provided a seal configuration for use in connection with vacuum systems. The seal configuration finds particular use in vacuum waste flush systems, such as those used in passenger transport vehicles that have on-board lavatories with vacuum toilet systems. The seal configuration generally provides an offset configuration, which can result in a larger seal on the vacuum side. This can slightly delay the opening of the waste side seal with respect to the vacuum side seal of the system, proving an improved vacuum environment. This can also give the flow of waste a more direct transition across a vacuum plate as it flows through a flush valve.