Liquid chromatography conduit assemblies having high pressure seals
Described is a tubing assembly which includes a permanently deformable outer tube, an intermediate tube and an inner tube. A radial seal is provided by a uniform radial crimp having a non-zero longitudinal length at a longitudinal location on the tubing assembly. In some embodiments one or both ends of the assembly have a uniform radial crimp and are polished so that the ends of two or more of the tubes are substantially flush with each other to thereby block the passage of fluids between the ends of the tubes. In other embodiments the uniform radial crimps are at other longitudinal locations where a high pressure seal is desired. The longitudinal length and the depth of each uniform radial crimp can be formed to accommodate the requirements of a particular application so that leakage along the tubing assembly is prevented and void volume is reduced or eliminated.
1. A liquid chromatography tubing assembly comprising:
an outer tube comprising a metal;
an intermediate tube comprising a polymeric material and disposed within the outer tube; and
first inner tube disposed within the intermediate tube, wherein the outer tube is deformed by a uniform radial crimp at a longitudinal location along the outer tube to form a fluid-tight seal between the first inner, intermediate and outer tubes, and wherein the uniform radial crimp has a base region over which a diameter of the outer tube is reduced for a longitudinal length greater than 6 mm.
2. The liquid chromatography tubing assembly of claim 1 further comprising a second inner tube disposed in the intermediate tube.
3. The liquid chromatography tubing assembly of claim 2 , wherein the first inner tube has an inner diameter that is different from an inner diameter of the second inner tube.
4. The liquid chromatography tubing assembly of claim 1 wherein the first inner tube comprises one of steel and fused silica.
5. The liquid chromatography tubing assembly of claim 1 wherein the polymeric material comprises one of polyetheretherketone, polytetrafluoroethylene, and polyimide.
6. The liquid chromatography tubing assembly of claim 1 wherein the metal comprises one of hardened steel and annealed steel.
7. A liquid chromatography tubing assembly comprising:
an outer tube comprising a metal;
an intermediate tube comprising a polymeric material and disposed within the outer tube; and
first inner tube disposed within the intermediate tube, wherein the outer tube is deformed by a uniform radial crimp at a longitudinal location along the outer tube to form a fluid-tight seal between the first inner, intermediate and outer tubes, and wherein the uniform radial crimp has a base region over which a diameter of the outer tube is reduced for a longitudinal length greater than one millimeter.
8. The liquid chromatography tubing assembly of claim 7 further comprising a second inner tube disposed in the intermediate tube.
9. The liquid chromatography tubing assembly of claim 8 , wherein the first inner tube has an inner diameter that is different from an inner diameter of the second inner tube.
10. The liquid chromatography tubing assembly of claim 7 wherein the first inner tube comprises one of steel and fused silica.
11. The liquid chromatography tubing assembly of claim 8 wherein the polymeric material comprises one of polyetheretherketone, polytetrafluoroethylene, and polyimide.
12. The liquid chromatography tubing assembly of claim 7 wherein the metal comprises one of hardened steel and annealed steel.