The invention relates to a ventilating device (2) for liquid containers (1), in particular for liquid containers (1) for an aqueous urea solution, including a housing (3) which can be mounted at an opening of the liquid container (1) and has a first opening (4) to the liquid container (1) and a second opening (5) to the surroundings of the liquid container (1), a diaphragm (6) which is arranged within the housing (3), is permeable to air, is impermeable to liquid and is configured in such a way that a deformation of the diaphragm (6) takes place by a pressure change in the liquid container (1), as a result of which the volume within the housing (3) within the diaphragm (6) changes, with the result that the displaced volume leaves the housing (3) via the second opening (5) to the surroundings of the liquid container (1). Furthermore, the invention relates to a liquid container (1) having a ventilating device (2) according to the invention.

A valve apparatus for use in an interior of a fuel tank, a fuel tank including the valve apparatus, and a motor vehicle including the fuel tank. The valve apparatus includes a substantially flat housing defining a channel between an inlet orifice and an outlet orifice, and a membrane arranged to seal the channel. The membrane is configured to be impermeable to liquid fuel and permeable to fuel vapor.

A fuel tank system includes: a fuel tank; a canister; a vent pipe; a valve member that is provided at the vent pipe and is sectioned into a tank-side main chamber, a canister-side main chamber and a back pressure chamber; a pipe configured to open an interior of the canister to the atmosphere; a negative pressure pump that is provided at the pipe, and applies negative pressure through the canister and the vent pipe to a fuel tank interior; a judging means for judging absence/presence of perforation of the fuel tank from behavior of air pressure at a time when negative pressure is generated at the negative pressure pump; and a negative pressure application path that communicates the pipe with the back pressure chamber, and that is configured to apply negative pressure from the negative pressure pump to the back pressure chamber without the negative pressure going through the canister.

A valve assembly includes a housing having an inner chamber, a float assembly provided within the inner chamber, and an elongated membrane. The inner chamber is provided with a vent orifice in fluid communication with a vent outlet. The float assembly is movable along a longitudinal axis of the housing, and includes an angled platform disposed on an upper surface of the float assembly. The membrane includes a first end secured to a first attachment of the float assembly, a second end provided opposite the first end and secured to a second attachment of the float assembly, and a slack portion associated with the second end.