An one way valve comprising: a conical shaped valve seat (1)； and a membrane(2) having a hole (3) that is locatedaround the conical valve seat (1), such that a surface (60) of the valve seat(1) seals onto an inner periphery (61) of the hole in themembrane (2), wherein, in use, the membrane (2) is deflected from the surface(60) of the valve seat (1) to provide a fluid pathacross the membrane (2) and allowing fluid to flow from one side of themembrane (2) to the other.
