Needle valve for flow control

1. A method of providing fluid flow control in a needle valve assembly, comprising:

providing a needle valve assembly comprising a motor, an internally threaded valve body, and an externally threaded plunger threadably engaged with the internally threaded valve body and rotatably and reciprocally driven by the motor, the motor and the plunger including respective gears and the gear ratio of the gear of the plunger to the gear of the motor being at least 1:1, the valve body including a fluid inlet, a fluid outlet, and a flow chamber therebetween, the flow chamber including a flow chamber wall and a flow chamber outlet, the plunger including a flexible needle member that reciprocates within the flow chamber outlet to provide variable flow control therethrough, the flexible needle member including a lip seal that engages the flow chamber wall during reciprocation of the plunger and flexible needle member to provide a seal therebetween;

supplying fluid flow to the fluid inlet of the needle valve assembly;

providing variable flow control in the needle valve assembly through reciprocation of the flexible needle member in the flow chamber outlet;

sealingy engaging the flow chamber wall with the lip seal of the flexible needle member to prevent fluid flow therebeween.

2. The method of claim 1 , wherein the flexible needle member is a one-piece member with the lip seal integrally formed therein.

3. The method of claim 1 , wherein the motor is a stepper motor including at least 24 steps/revolution.

4. The method of claim 1 , wherein the motor is a stepper motor.

5. A method of providing fluid flow control in a needle valve assembly, comprising:

providing a needle valve assembly comprising a motor, an internally threaded valve body, and an externally threaded plunger threadably engaged with the internally threaded valve body and rotatably and reciprocally driven by the motor, the valve body including a fluid inlet, a fluid outlet, and a flow chamber therebetween, the flow chamber including a flow chamber wall and a flow chamber outlet the plunger including a flexible needle member that reciprocates within the flow chamber outlet to provide variable flow control therethrough, the flexible needle member including a lip seal that engages the flow chamber wall during reciprocation of the plunger and flexible needle member to provide a seal therebetween;

supplying fluid flow to the fluid inlet of the needle valve assembly;

providing variable flow control in the needle valve assembly through reciprocation of the flexible needle member in the flow chamber outlet;

sealingy engaging the flow chamber wall with the lip seal of the flexible needle member to prevent fluid flow therebeween,

wherein the needle valve assembly is part of a flow control mechanism of a gas separation device for separating oxygen gas from air, and the method includes separating oxygen gas from air using the gas separation device and controlling product flow in a flow control mechanism using the needle valve assembly.

6. The method of claim 5 wherein the flexible needle member is a one-piece member with the lip seal integrally formed therein.

7. The method of claim 5 wherein the motor is a stepper motor including at least 24 steps/revolution.

8. The method of claim 5 wherein the motor and the plunger include respective gears and the gear ratio of the gear of the plunger to the gear of the motor is at least 1:1.

9. The method of claim 5 wherein the motor is a stepper motor, and the motor and the plunger include respective gears.

10. A needle valve assembly for providing fluid flow control, comprising:

a motor;

an internally threaded valve body; and

an externally threaded plunger threadably engaged with the internally threaded valve body and rotatably and reciprocally driven by the motor, the motor and the plunger including respective gears and the gear ratio of the gear of the plunger to the gear of the motor being at least 1:1;

wherein the valve body including a fluid inlet, a fluid outlet, and a flow chamber therebetween, the flow chamber including a flow chamber wall and a flow chamber outlet, the plunger including a flexible needle member reciprocating within the flow chamber outlet to provide variable flow control therethrough, the flexible needle member including a lip seal engageable with the flow chamber wall during reciprocation of the plunger and flexible needle member to provide a seal therebetween.

11. The needle valve assembly of claim 10 , wherein the flexible needle member is a one-piece member with the lip seal integrally formed therein.

12. The needle valve assembly of claim 10 , wherein the motor is a stepper motor including at least 24 steps/revolution.

13. The needle valve assembly of claim 10 wherein the motor is a stepper motor.

14. A needle valve assembly for providing fluid flow control, comprising:

motor;

an internally threaded valve body; and

an externally treaded plunger threadably engaged with the internally threaded valve body and rotatably and reciprocally driven by the motor,

wherein the valve body including a fluid inlet, a fluid outlet, and a flow chamber therebetween, the flow chamber including a flow chamber wall and a flow chamber outlet, the plunger including a flexible needle member reciprocating within the flow chamber outlet to provide variable flow control therethrough, the flexible needle member including a lip seal engageable with the flow chamber wall during reciprocation of the plunger and flexible needle member to provide a seal therebetween,

wherein the needle valve assembly is part of a flow control mechanism of a gas separation device for separating oxygen gas from air.

15. The method of claim 14 , wherein the flexible needle member is a one-piece member with the lip seal integrally formed therein.

16. The method of claim 14 , wherein the motor is a stepper motor including at least 24 steps/revolution.

17. The method of claim 14 , wherein the motor and the plunger include respective gears and the gear ratio of the gear of the plunger to the gear of the motor is at least 1:1.

18. The method of claim 14 , wherein the motor is a stepper motor, and the motor and the plunger include respective gears.