A needle valve having improved economy of manufacture and assembly is disclosed in which the tapered end of the needle moves axially with respect to a valve seat having a cylindrical opening but does not rotate. Ball ValvesAn adjusting means, in turn, is rotated to cause the axial movement of the needle and an alignment means, preferably a sphere, is interposed between the needle and the adjusting means to provide alignment between the two components. The needle itself is also spring biased away from the valve seat. Needle ValvesA needle valve for control of the flow of a gas, said needle valve comprising a valve housing, said valve housing having an inlet and an outlet and defining a flow path for the flow of gas between said inlet and said outlet, a valve seat in said flow path,BUTTERFLY VALVES a needle having a distal tapered end and a proximal end, said proximal end having a countersink formed as a frustro-conical indentation, said distal end positioned within said valve seat and movable toward and away from said seat to decrease and increase, respectively, the flow of gas through said seat passing from said inlet to said outlet, bias means adapted to bias said needle away from said valve seat, an adjusting means threadedly engaged within said valve housing, said adjusting means being rotatable with respect to said housing to move said adjusting means laterally within said valve housing with respect to said valve seat, and a sphere positioned between the proximal end of said needle and said adjusting means, said adjusting means contacting said sphere in a point contact and said sphere contacting said frusto-conical countersink of said proximal end of said needle at a circular line contact aligning said adjusting means and said proximal end of said needle and allowing the lateral movement of said adjusting means, but not the rotational movement, to laterally move said needle with respect to said valve seat to control the flow of the fluid passing therethrough. The needle valve of the present invention overcomes the aforedescribed difficulties by providing a valve wherein the needle itself does not rotate as it moves axially with respect to the valve seat to control the flow of the fluid. Instead, the tapered needle moves within the cylindrical seat only axially along its longitudinal axis. The needle itself is moved by a second component, an adjustment screw that is threadedly engaged to the valve housing and which is rotated to advance or retract the needle with respect to its seat. A self centering means, in the preferred form of a sphere, is interposed between the adjustment screw and the needle such that alignment of the adjustment screw and needle is readily accomplished without expensive and time consuming procedures. Further a spring biasing means biases the needle toward the retracted position, that is, the needle is biased to move away from its valve seat. The needle is physically aligned with respect to its seat by an internal guide that restrains the needle at a location near the distal end of the needle, that is adjacent or near to the valve seat. A further guide contains the proximal end of the needle so that the needle is well supported within the valve housing for precise movement with respect to its valve seat. Thus, the problems associated with nonconcentric needles is alleviated since the needle itself does not rotate as it moves with respect to its seat and therefore once aligned in its internal guides, its movement remains true within the valve housing and thus with respect to the valve seat. Additionally, misalignment of the adjustment screw is also compensated by having a self centering means, such as a sphere, that is interposed between the adjustment screw and the needle.

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