Valve

A valve comprising:

• a housing comprising a tubular side wall, the side wall having first and second ends and surrounding an internal space, a first end wall at the first end of the side wall, defining one end of the internal space, a second end wall at the second end of the side wall, the second end wall having a centrally located aperture arranged to provide fluid communication between said internal space and the exterior of the housing, and at least one passage extending through the side wall at a location adjacent the second end wall and arranged to provide fluid communication between the exterior of the housing and said internal space;
• a valve element located within said internal space, the valve element contacting the side wall and the first end wall and substantially filling all of said internal space except for a portion thereof adjacent said second end of the side wall, at least the part of the valve element in contact with the side wall being formed of an elastomer;
• and
• a seat in the form of a boss surrounding the centrally located aperture of the second end wall and extending toward the first end wall;
• wherein the valve element is deformable from a first condition in which it is spaced from said seat and allows fluid communication between said at least one passage and said aperture, to a second condition in which a part of the valve element engages the seat, thereby closing said aperture and preventing fluid communication between said at least one passage and said aperture.