Assembly of a flexible tube and a fitting body and a method thereof

1. An apparatus for joining a rigid tube and a flexible tube, the apparatus comprising:

a fitting body comprising:

a shoulder portion extending out, the shoulder portion comprising a cavity and a threaded portion on an outer surface, and

the guide tube extending from the fitting body through the cavity in the same direction as the threaded portion, the guide tube for engaging with the flexible tube;

a sealing assembly arrangement coaxially over the flexible tube and engaged with the fitting body, the sealing assembly arrangement configured to clamp down against the outer surface of the flexible tube at multiple locations due to radial pressure, the sealing assembly comprising a compression nut comprising an inner threaded portion configured to engage with the threaded portion of the fitting body, a first taper portion for reducing an inner diameter of the compression nut, and a second taper portion at a lateral distance from the first taper portion for further reducing the inner diameter of the compression nut;

a ferrule configured to engage with the shoulder of the fitting body and clamp down at a first location of the outer surface of the flexible tube due to radial pressure caused by the compression nut being moved toward the fitting body;

a first collet configured to clamp down at a second location of the outer surface of the flexible tube due to radial pressure caused by the compression nut being moved toward the fitting body, the ferrule and the first collet forming a combination collet; and

a second collet configured to clamp down at a third location on the outer surface of the flexible tube due to radial pressure caused by the compression nut being moved toward the fitting body.

2. The apparatus of claim 1 , wherein the combination collet is a monolithic structure.

3. The apparatus of claim 1 , wherein:

the ferrule is configured to clamp down at the first location of the outer surface of the flexible tube due to radial pressure between the ferrule and the shoulder of the fitting body caused by the compression nut being moved toward the fitting body, and

the first collet comprises a first clamping portion for engaging with the first taper portion such that the first clamping portion clamps down at the second location of the outer surface of the flexible tube due to radial pressure between the first taper portion and the first clamping portion caused by the compression nut being moved toward the fitting body.

4. The apparatus of claim 1 , wherein the second collet comprises a second clamping portion for engaging with the second taper portion such that the second clamping portion clamps down at the third location on the outer surface of the flexible tube due to radial pressure between the second taper portion and the second clamping portion caused by the compression nut being moved toward the fitting body.

5. The apparatus of claim 1 , wherein the guide tube comprises a rigid tube that is coaxially positioned through the fitting body such that a first end of the rigid tube extends from one side of the fitting body and a second end of the rigid tube extends from the opposite side of the fitting body.

6. A method comprising:

introducing a ferrule, a first collet, a second collet, and a compression nut to an outer surface of a flexible tube, the ferrule and the first collet forming a combination collet, the compression nut comprising an inner threaded portion, a first inner taper portion, and a second inner taper portion;

sliding a first end of the flexible tube over a guide tube of a fitting body toward a shoulder of the fitting body such that at least a portion of the flexible tube is inside the shoulder of the fitting body; and

fastening the inner threaded portion of the compression nut onto an outer threaded portion on the shoulder of the fitting body such that a plurality of radial pressure caused by the first inner taper portion and the second inner taper portion of the compression nut causes the ferrule to clamp down at a first location of the outer surface of the flexible tube, the first collet to clamp down at a second location of the outer surface of the flexible tube, and the second collet to clamp down on a third location on the outer surface of the flexible tube.

7. The method of claim 6 , wherein fastening the inner threaded portion of the compression nut onto the outer threaded portion of the shoulder of the fitting body generates a first radial pressure from the first inner taper portion of an inner wall of the compression nut, causing the first collet of the combination collet to clamp down at the second location on the outer surface of the flexible tube.

8. The method of claim 7 , wherein fastening the inner threaded portion of the compression nut onto the outer threaded portion of the shoulder of the fitting body further generates a second radial pressure from the second inner taper portion of the compression nut, causing the second collet to clamp down at the third location on the outer surface of the flexible tube, the third location at a lateral distance from the second location.

9. The method of claim 8 , wherein fastening the inner threaded portion of the compression nut onto the outer threaded portion of the shoulder of the fitting body further generates a third radial pressure from a taper portion on an inner wall of the shoulder of the fitting body, causing the ferrule of the combination collet to clamp down at the first location on the outer surface of the flexible tube, the first location being inside the shoulder of the fitting body.

10. The method of claim 8 , wherein the second radial pressure is generated before the third radial pressure is generated.

11. The method of claim 8 , wherein the second radial pressure and the third radial pressure are generated concurrently.

12. The method of claim 8 , wherein the combination collet is a monolithic structure.