The term “vacuum system” and “vacuum suction drain” refers to special pneumatic conveyors. Generally speaking, in such conveyors transportation takes place in that a pressure difference is applied to the material to be conveyed, i.e. the material to be conveyed is entrained in the fluid flow generated as a result of the pressure difference, wherein generally speaking air is used as the transport medium.
Especially in aircraft, vacuum systems are used for the transportation of waste from the cabin, for example from toilets or galleys, to a central waste collecting tank. In this arrangement the material to be conveyed is conveyed to the waste collecting tank by way of a pipeline network, i.e. vacuum suction drains. Negative pressure in the waste collecting tank in relation to the cabin pressure provides the required pressure difference.
In aircraft with pressurized cabins the pressure difference between the cabin and the environment is used directly to generate the negative pressure for pneumatic conveyance. When this pressure difference is insufficient, e.g. on the tarmac or at low altitudes, the required pressure difference is generated by a compressor.
In the case of toilets with a pneumatic conveyor system in aircraft systems, often a loud noise level arises. This noise is even noticed by the passengers in the cabin and is perceived by passengers to be uncomfortable.
DE 10 2005 013 566 A1 and US 2012/0014757 A1 describe an arrangement for adapting the transportation behavior of material to be conveyed through drains of a vacuum system wherein a valve is arranged in a vacuum suction drain.