US Patent 7384439 Vents for fluid systems

A vent for a fluid system includes a chamber through which fluid can flow along either a first flow path or a second flow path, in which the resistance to fluid flow is relatively high when the fluid follows the first flow path and relatively low when the fluid follows the second flow path. In a preferred embodiment the chamber is substantially cylindrical and has two ports, one of which is substantially coaxial with the chamber and the other of which is substantially tangential to the chamber. The fluid flow, at least when flowing the first flow path, may include a component of higher density than the fluid, and the flow of fluid along the first flow path may act to separate the higher density component from the fluid.