Patent ID: 7690391

Claim:
A liquid flow control device comprising: a port or passageway through which liquid flow is to be controlled; a body of a liquid swellable material located in the port or passageway, the body comprising an upstream side surface and a downstream side surface in relation to the direction of liquid flow through the port or passageway, with an annular periphery extending between the upstream and downstream side surfaces; and a layer of sealing material disposed on the body so as to cover the upstream side surface and the annular periphery of the body thus leaving only the downstream side surface of the body exposed to the liquid within the port or passageway, the layer of sealing material preventing contact of the upstream side surface and the annular periphery with the liquid when the body is swollen to close the port or passageway whilst allowing contact of the downstream side surface only of the body with the liquid when the body is in the non-swollen condition allowing liquid flow through the port or passageway.