Flow Control Valve

An example assembly includes: a valve body having a cavity therein, wherein the valve body comprises internal threads formed in a first-handed direction and an external feature; a knob having an internal feature configured to engage with the external feature of the valve body to allow the internal feature of the knob to move past the external feature of the valve body in a linear direction when assembling the knob on the valve body; and a needle disposed in the cavity of the valve body and having external threads formed in the first-handed direction and engaging with the internal threads of the valve body, the needle being coupled to the knob such that rotation of the knob and the needle results in linear movement of the needle within the valve body due to engagement of the external threads of the needle with the internal threads of the valve body. 1. An assembly comprising:a valve body having a cavity therein, wherein the valve body comprises internal threads formed in a first-handed direction and an external feature;a knob having an internal feature configured to engage with the external feature of the valve body to allow the internal feature of the knob to move past the external feature of the valve body in a linear direction when assembling the knob on the valve body; anda needle disposed in the cavity of the valve body and having external threads formed in the first-handed direction and engaging with the internal threads of the valve body, the needle being coupled to the knob such that rotation of the knob and the needle results in linear movement of the needle within the valve body due to engagement of the external threads of the needle with the internal threads of the valve body.2. The assembly of claim 1 , wherein the external feature of the valve body comprises respective external threads and the internal feature of the knob comprises respective internal threads claim 1 , wherein the respective external threads of the valve body and the respective internal ...