Method of cleaning passageways using a mixed phase flow of a gas and a liquid

Abstract

A method of cleaning surfaces using a mixed phase cleaning mixture of an aqueous solution and a flow of gas sufficient to produce droplets of the liquid which are entrained by the gas for a time sufficient to clean tubing of various lengths and geometries and porous membranes to remove biofilm, debris and contaminants.

Description

[0001] This application is a continuation-in-part of copending application Ser. No. 08 / 880,662.[0002] This invention relates to a method for removing biofilm, debris, contaminants and the like from the surfaces of passageways, including passageways which have irregular or complex shapes or whose walls are permeable, using a mixed-phase cleaning solution. BACKGROUND OF THE INVENTION [0003] Interior surfaces of passageways such as small-bore tubing, pipes, ducts and the like, which may carry fluids such as liquids, gases, slurries or aerosols, are very difficult to clean and to maintain in a clean condition. When the flow path is long and narrow, or hard to reach, it is difficult to clean the surfaces by conventional liquid phase flushing because such a long, narrow passageway limits liquid flow velocities by creating a high resistance to flow. As a result, shear stresses which could aid in the removal of contaminants from such surfaces are limited. Low flow velocities also limit the ...

AI Technical Summary

Benefits of technology

This method achieves complete removal of biofilm and debris with reduced chemical and thermal stress, extending the life of medical devices and improving their performance, while being cost-effective and environmentally friendly.

Problems solved by technology

Interior surfaces of passageways such as small-bore tubing, pipes, ducts and the like, which may carry fluids such as liquids, gases, slurries or aerosols, are very difficult to clean and to maintain in a clean condition.

When the flow path is long and narrow, or hard to reach, it is difficult to clean the surfaces by conventional liquid phase flushing because such a long, narrow passageway limits liquid flow velocities by creating a high resistance to flow.

As a result, shear stresses which could aid in the removal of contaminants from such surfaces are limited.

Low flow velocities also limit the usefulness of solvents for the same reasons.

Cleaning of small diameter passageways is also difficult because of the nature of certain types of residues.

Removal of biofilm from passageways is also necessary for other applications, including medical, industrial and food service applications, because such biofilms are the main cause of high bacterial counts and high levels of endotoxins.

However, removing biofilm from fluid passageways is quite difficult, which makes disinfecting the surface more difficult as well.

However, these agents do not readily diffuse into the entire thickness of the biofilm.

Thus these treatments are generally only partially effective, and the original levels of viable bacteria return quite rapidly.

However, in addition to the fact that autoclaving does not actually remove debris from the handpiece, this autoclaving procedure can be damaging to the turbine and various seals in the handpiece.

While this may flush non-adherent biofilm and debris from passageways, it can be shown that it provides little or no removal of adherent biofilm and debris such as blood, mucous and the like.

While this is a useful method of distributing a cleaning solution, it does not ensure complete cleaning of adherent debris.

Simple spraying does not ensure that these conditions are met.

It can be estimated that prior art techniques which use a total of only a drop or two of liquid would not provide enough liquid for the surface area of a dental handpiece tube to achieve significant re-formation of droplets.

Infections arising from the use of endoscopic devices have been reported and traced to the inefficient cleaning and debris removal by conventional methods.

However, this method is time-consuming and suffers from inefficiency in removing all pathogens and other debris, as well as being subject to variations in technique from one operator to another.

Such substances decrease the thermal efficiency of heat exchangers.

Cleaning permeable membranes is more difficult than cleaning solid surfaces, because whatever is held back by the membrane can lodge either immediately at the membrane exposed surface or within the membrane pore structure, with the surfaces within the membrane pore structure being more difficult to clean.

Some medical devices contain materials or components which suffer damage from one or more of these processes, or there may be times when for other reasons it may be impractical to use them.

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