Non-return valve

A non-return valve comprising:

• a valve body including a fluid passageway which defines a fluid inlet and a fluid outlet located on a low pressure and a high pressure side of the valve, respectively, the fluid passageway being adapted to allow a flow of fluid from the inlet to the outlet;
• and
• a valve diaphragm in the form of a conical-shaped diaphragm having a collapsible located at or adjacent its apex which is orientated in a downstream flow direction and directed toward the high pressure side of the valve, said diaphragm being connected across the fluid passageway, and being rotationally symmetrical about a longitudinal axis which passes through its apex, said diaphragm tapering in wall thickness toward said apex and further being constructed of a resiliently flexible material wherein upon insertion of a nozzle through the collapsible aperture the diaphragm closes about the nozzle to prevent fluid escape whereas upon retraction of the nozzle the diaphragm itself initiates closure of the collapsible aperture, said closure being further promoted by fluid on the high pressure side of the valve to thus prevent fluid flowing in a reverse direction toward the inlet whereas the application of pressure using the nozzle, exceeding atmospheric pressure and that on the high pressure side, to an inlet side of the diaphragm deflects the diaphragm to expose the aperture and allow fluid to flow through the passageway from the inlet to the outlet only.