Method and apparatus to assemble a high purity liquid distribution system
A method and apparatus for assembling a high purity liquid distribution system is described. A distal end portion of the tube is heated then pushed over a sleeve so that the distal end portion can have a shrink seal fit over the sleeve to mitigate accidental or inadvertent pull out of the tube from a fitting. Other benefits are also achieved such as minimal flow restriction of the liquid flowing through the joint and the tube.
1. A method of joining a tube fabricated from a perfluoroalkoxy (PFA) material to a sleeve which is fabricated from the PFA material, the method comprising the steps of: heating a heating body to at least 15 degrees Celsius below a softening temperature of the PFA material; disposing a distal end portion of the tube in a hole formed in the heating body until the distal end portion of the tube is in a pliable state; disposing a sleeve on a cylindrical post of a mandrel; removing the distal end portion of the tube out of the hole of the heating body; after the removing step, attaching the tube to the sleeve by disposing the distal end portion of the heated tube over the cylindrical post and the sleeve to facilitate faster cooling of an inner surface of the tube compared to an outer surface of the tube; after the disposing step, removing the attached tube and sleeve from the cylindrical post of the mandrel; allowing the distal end portion of the tube to remain in air which has a temperature between 15 degrees Celsius and 38 degrees Celsius until a temperature of the distal end portion of the tube is below 38 degrees Celsius.
2. The method of claim 1 , further comprising a step of reducing an inner diameter of the tube at a faster rate compared to an outer diameter of the tube to shrink the distal end portion of the tube onto the sleeve.
3. The method of claim 1 , wherein the disposing step includes the step of pushing the distal end portion of the heated tube until a distal end of the distal end portion of the tube contacts a stop flange of the sleeve.
4. The method of claim 2 , wherein the reducing step includes reducing the inner diameter of the tube until a connection percentage between the inner surface of the tube and an outer surface of an enlarged diameter portion of the sleeve and a reduced diameter cylindrical section of the sleeve is equal to or greater than 75%.
5. The method of claim 4 , wherein the connection percentage is between 90% and 96%.
6. The method of claim 1 , wherein the step of removing the attached tube and sleeve from the cylindrical post of the mandrel is performed within 3 seconds after the disposing step.
7. The method of claim 1 , wherein the heating step comprises heating the heating body to a temperature between 250 degrees Celsius and 290 degrees Celsius.
8. The method of claim 1 , comprising a step of performing the disposing step within 10 seconds after the removing the distal end portion step.
9. The method of claim 1 , further comprising a step of gripping the tube with a hand for performing the disposing step.
10. The method of claim 1 , comprising a step of performing the removing the attached tube and sleeve step within 10 seconds after disposing step.