Vacuum drying process used for manufacturing dialyzer
AssigneeFresenius USA, Inc.
InventorsMarion Andersen, Marvin Lyon, G. Neivell Allan, Wade Paskett
Life of this patent
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Abstract
A method of sterilizing and drying a dialyzer or other device, wherein a vacuum drying phase is interrupted by interspersed pulses of air or other gas. The pulses lessen the evaporative cooling effect, to thereby reduce differential shrinkage that can structurally damage the dialyzer.
Claims24
A method for destroying pathogens in a device including a first material joined to a second material and for preventing delamination of the first and second materials, the first material having a first coefficient of thermal expansion and the second material having a second coefficient of thermal expansion different from the first coefficient, the method comprising:
- (a) applying heated steam to the device at a first pressure in a chamber to destroy pathogens;
- (b) removing said steam and any condensate from said chamber by applying a second pressure to the device, wherein said second pressure is lower than said first pressure;
- (c) interspersing said second pressure with at least one pulse of a third pressure that is between said first pressure and said second pressure, said pulse being accomplished by adding a gas to the chamber at a first flow rate for about two minutes, and then adding the gas at a second flow rate, the second flow rate being greater than the first flow rate;
- and
- repeating steps (b) and (c) at least two more times, wherein the at least three pulses of the third pressure control a temperature differential between the first and second materials and prevent delamination of the first material from the second material.
A method of drying a device including a first material joined to a second material and of preventing delamination of the first and second materials, the first material having a first coefficient of thermal expansion and the second material having a second coefficient of thermal expansion different from the first coefficient, the method comprising:
- (a) positioning the device in a chamber;
- (b) applying a pressure less than atmosphere to the chamber in at least three pulses, each pulse including reducing the chamber pressure to a first pressure less than atmosphere and then increasing the chamber pressure to a second pressure less than atmosphere by adding a gas to the chamber at a first flow rate for about two minutes, and then adding the gas at a second flow rate, the second flow rate being greater than the first flow rate,
- wherein said at least three pulses control a temperature differential between the first and second materials and prevent delamination of the first material from the second material.
A method of drying a dialyzer that has been subjected to steam sterilization so as to lessen differential shrinkage caused by differential cooling rates in the dialyzer between a housing and a potting material joined to the housing to help prevent delamination of the housing and potting materials, the method comprising:
- (a) placing the dialyzer in a chamber;
- (b) applying a partial vacuum to the dialyzer to allow evaporation of water into the vacuum to thereby evaporatively cool surfaces from which said water evaporates;
- (c) increasing the pressure in said chamber to reduce evaporation of said water and to thereby reduce evaporative cooling from said surfaces by adding a gas to said chamber at a first flow rate for about two minutes, and then adding the gas at a second flow rate, the second flow rate being greater than the first flow rate;
- and
- (d) repeating steps (b) and (c) at least two more times, wherein increasing the pressure at least three times controls a temperature differential between the housing and the potting material and prevents delamination of the housing from the potting material.
A method of sterilizing a device including a first material joined to a second material and of preventing delamination of the first and second materials of the device, the first material having a first coefficient of thermal expansion and the second material having a second coefficient of thermal expansion different from the first coefficient, the method comprising:
- (a) inserting the device into an autoclave;
- (b) introducing steam into the autoclave to sterilize the device;
- (c) applying vacuum pressure to the autoclave until a pressure within the autoclave reaches approximately negative 0.9 bar;
- (d) adding a gas to the autoclave at a first flow rate for about two minutes, and then adding the gas at a second flow rate, the second flow rate being greater than the first flow rate, the pressure within the autoclave reaching approximately negative 0.3 bar after adding the gas;
- (e) after adding the gas, maintaining the pressure within the autoclave at approximately negative 0.3 bar for about one minute;
- and
- (f) repeating steps (c) through (e) multiple times.
Dependencies are inferred from the claim text.