Valve for pressurized environments

A valve subjected to pressurized environments of the type including a tubular body and a valve stem received with the tubular body, the valve stem shiftable along the axis of the tubular body, the head whereof is provided or not with a sealing lining adapted for cooperating, in a sealed manner, with a corresponding seat of the valve body, said stem acting depending on a predetermined pressure, against a coiled spring housed in a chamber of circular cross-section, coaxial with the tubular body and disposed between a bearing zone situated at a first end of the chamber and the stem, to return the latter toward the seat, with a predetermined force, wherein the return spring comprises:

• a return spring first end comprising a return spring first end first turn with a diameter similar to a diameter of the chamber at the first end of the chamber, said first return spring first end first turn being arranged so as to bear on the bearing zone, and
• a return spring second end including a return spring second end first turn, the return spring second end first turn being smaller than the return spring first end first turn, the return spring second end first turn connected with the shank or the head of the stem, the return spring second end further including a return spring second end large turn for centering and radial stabilization in said chamber, the return spring second end large turn being coaxial with the return spring second end first turn and having a diameter similar to a second diameter of the chamber at a second end of the chamber opposite to the first end of the chamber,
• wherein the return spring first end comprises a return spring first end second end turn coaxial with the return spring first end first turn, said return spring first end second end turn connecting with the shank or the head of the stem, the return spring first end second end turn being smaller than the return spring first end first turn.