Patent ID: 7363941

Claim:
A multi-stage flow control valve, comprising: a valve body having an input port, an internal space extending in a longitudinal direction, and an output port; first and second ceramic guides disposed in the internal space, the second ceramic guide being longitudinally spaced apart from the first ceramic guide to define an intermediate cavity therebetween; a continuous substantially cylindrical ceramic plug to control flow of fluid through the internal space, the ceramic plug extending in the longitudinal direction and being slidably engaged with the first and second ceramic guides; a first set of control surfaces formed in an outer circumferential surface of the ceramic plug, the first set of control surfaces being disposed proximal to the first ceramic guide to contact the fluid in a first staging portion between the input port and the intermediate cavity; and a second set of control surfaces formed in outer circumferential surface the ceramic plug, the second set of control surfaces being disposed proximal to the second ceramic guide to contact the fluid in a second staging portion between the intermediate cavity and the output port.