Patent ID: 8065924

Claim:
A differential pressure based flow sensor assembly to determine the flow rate of a fluid system comprising: a disposable portion having: a body defining a fluid flow passage forming an inlet and an outlet, the body having a base portion and a lid portion; a flexible fluid pressure membrane disposed along the fluid flow passage between the inlet and the outlet, the fluid pressure membrane being secured between the base portion and the lid portion of the body; and a flow restricting element positioned in the fluid flow passage between the inlet and the outlet; wherein lid portion has a first opening and a second opening, and the fluid pressure membrane has a first area and a second area adapted to be aligned with the first opening and the second opening respectively of the lid portion; wherein the fluid pressure membrane defines an opening between the first area and the second area for receiving the flow restricting element; and a reusable portion having: an upstream fluid pressure sensor disposed outside the fluid flow passage and adapted to be pressed upon by the first area of the fluid pressure membrane through the first opening of the lid portion in order to sense an upstream fluid pressure at an upstream location in the fluid flow passage between the inlet and the flow restricting element; and a downstream fluid pressure sensor disposed outside the fluid flow passage and adapted to be pressed upon by the second area of the fluid pressure membrane through the second opening of the lid portion in order to sense a downstream fluid pressure at a downstream location in the fluid flow passage between the flow restricting element and the outlet.