Expansion valve with a plug and a flow selector

A valve device for fluid, particularly for pressurized gas comprising:

• a body with a longitudinal axis, an inlet at a lower portion of said body, an outlet at an upper portion of said body and a passage connecting said inlet with said outlet;
• a blocker movable along a direction substantially parallel to said longitudinal axis and cooperating with a stationary seat in said passage so as to be able to close said passage;
• a manually controlled rotary control member arranged at an upper portion, preferably at the top, of said body;
• a conversion device for converting the rotary movement of said control member into a translational movement along said longitudinal axis, said conversion device being connected to said control member and being adapted to displace said blocker in order to open or close said passage as a function of the manipulation of said control member, wherein said conversion device is arranged in an isolated chamber of said passage, preferably vented to the atmosphere, said passage surrounding said chamber.