Heat disinfection of a water supply

Details Heat disinfection of a water supply Heat disinfection of a water supply

1999-12-09

2001-06-26

Drodge, Joseph W. (Department: 1723)

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

C210S097000, C210S138000, C210S321690, C210S646000, C210S764000, C134S022110, C422S028000

Reexamination Certificate

active

06251279

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to systems for heat disinfection of fluid supply systems for dialysis clinics.
2. Description of the Prior Art
Traditionally, the fluid supply systems to dialysis clinics have been constructed of metal piping and/or PVC plastic piping which has been permanently installed in the walls and other cavities of the building in which the dialysis clinic is located. Often there are long distances of hundreds of feet between the ultrapure water and dialysate fluids sources utilized for the clinic, and the dialysis machines themselves, thus resulting in very long lengths of such piping in the supply system.
The fluid supply systems of dialysis clinics must be frequently monitored for the presence of bacteria and endotoxins, and periodically the fluid supply systems must be disinfected.
Traditional fluid supply systems for dialysis clinics have been disinfected by chemical means. The PVC plastic piping which has traditionally utilized in such systems cannot withstand the temperatures involved in heat disinfection with hot water.
To the extent that heat disinfection has been tried in prior art systems, those systems have relied on extremely expensive plastic materials such as polytetrafluoroethylene (Teflon®) piping which is cost prohibitive for most applications.
The prior art has also included isolated equipment components, such as the dialysis machines themselves, which have sometimes been fabricated from materials suitable for heat disinfection. Such a component is shown, for example, in U.S. Pat. No. 5,591,344 to Kenley et al.
What the prior art has not provided, is a complete system including extensive piping runs constructed from affordable materials in combination with suitable processes for heat disinfection of such a system in a reliable and economical manner.
SUMMARY OF THE INVENTION
The present invention provides just such an improved system. A method of heat disinfecting a fluid supply system for a dialysis machine is provided which includes the steps of providing the fluid supply system with a cross linked polyethylene and/or polypropylene plastic conduit; providing a source of hot water; and flowing the hot water through the plastic conduit for a sufficient time and at a sufficient temperature to disinfect the plastic conduit.
The cross linked polyethylene plastic conduit can be provided in very long continuous lengths of flexible conduit which can be unrolled from a coil of such conduit in lengths in excess of 100 feet. Various straight sections of conduit and fittings to be utilized with such a system are preferably constructed from polypropylene plastic. The polypropylene material is suitable from both the economic standpoint and its compatibility with the heat disinfection processes.
In one embodiment, the heat disinfection process includes the application of hot water at a temperature of at least 190° F. and for a time of from 15 minutes to one hour. If the temperature is increased to at least 220° F., the time can be reduced to no more than half hour.
Depending upon the construction of the system, it may be necessary to bypass certain heat sensitive components of the system. For example, conventional reverse osmosis units may not be suitable for heat disinfection and thus, may need to be bypassed.
The heated water for use in the disinfection process is preferably provided by passing ultrapure water through one side of a heat exchanger, while passing a second fluid from a low pressure boiler through the other side of the heat exchanger to heat the ultrapure water.
Modified techniques are provided for use in systems utilizing a centralized bicarbonate mixing devices. When such a device is present, the bicarbonate solution must first be flushed from the system.
It is therefore, an object of the present invention to provide improved methods and apparatus for disinfection of a fluid supply system for a dialysis clinic.
Another object of the present invention is the provision of fluid supply systems utilizing cross linked polyethylene plastic conduit which can be heat disinfected.
Still another object of the present invention is the provision of systems including a heat exchanger for heating ultrapure water via heat exchange with a fluid from a low pressure boiler.
Still another object of the present invention is the provision of procedures for heat disinfection wherein heat sensitive components of a system may be bypassed.
Still another object of the present invention is the provision of procedures for heat disinfection of a fluid supply system including a centralized bicarbonate mixing device.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the following disclosure when taken in conjunction with the accompanying drawings.


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Appendix B to ANSI/AAMI ST35-1991, copyright 1996 by the Association for the Advancement of Medical Instrumentation.
Exhibit “A” is a two page document prepared by Applicants and entitled Heat Disinfectable Permeate Loop, Nashville, TN VA, undated.
Exhibit A is a brochure of Gambro entitled Water for Dialysis.
Exhibit B is a 510 K Summary for this same machine that was described in Exhibit A. Exhibit B is dated Sep. 23, 1998.
Exhibit C is another brochure entitled “The Gambro CWP100WRO H”. This brochure is dated on its last page as year 2000, thus the brochure Exhibit C does not appear in itself to be prior art. It does, however, appear to describe the same system as described in Exhibits A and B and is thus disclosed in the interest of complete disclosure.

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