Patent ID: 8403908

Claim:
A differential pressure based flow sensor assembly to determine the flow rate of a fluid system comprising: a disposable portion having: a sealed disposable body defining a fluid flow passage forming an inlet and an outlet; a flow restricting element positioned along the fluid flow passage between the inlet and the outlet, wherein the flow restricting element includes an orifice that defines a non-capillary fluid flow path; an impermeable upstream fluid pressure membrane at a location in the fluid flow passage between the inlet and the flow restricting element; and an impermeable downstream fluid pressure membrane at a location in the fluid flow passage between the flow restricting element and the outlet; and a fluid impermeable reusable portion including a housing removably coupled to the disposable portion and having: an upstream fluid pressure sensor to sense an upstream fluid pressure at an upstream location in the fluid flow passage between the inlet and the flow restricting element, the upstream fluid pressure sensor being positioned and adapted to interact with the upstream fluid pressure membrane and thereby generally determine the fluid pressure at the upstream fluid pressure membrane; and a downstream fluid pressure sensor to sense an downstream fluid pressure at a downstream location in the fluid flow passage between the flow restricting element and the outlet, the downstream fluid pressure sensor being positioned and adapted to interact with the downstream fluid pressure membrane and thereby generally determine the fluid pressure at the downstream fluid pressure membrane.