Vacuum sterilization process and devices

Abstract

Vacuum sterilization process with the application of vapour of a mixture of peracetic acid with hydrogen peroxide and residual gas plasma from atmospheric air, excited by pulsed electrical discharge; operational devices and methods used in the sterilization process, preferably a process of sterilization in vacuum, dry, and at low temperature (room temperature).

Description

TECHNICAL FIELD [0001] The present invention relates to a sterilization process, operational devices and respective methods applied for the sterilization of various different items of apparatus and products, using vacuum techniques, the application of sterilizing gas and plasma. More particularly, this invention makes use of gas from a solution of peracetic acid or hydrogen peroxide evaporated under vacuum, with the partial separation of water from the solution for sterilization, as well as the use of plasma from residual atmospheric air for the elimination of residues, with temperature monitoring and control. BACKGROUND ART [0002] Among chemical methods of sterilization, the use of hydrogen peroxide and peracetic acid is acquiring considerable prominence. This is due to their bactericidal, sporicidal, and fungicidal properties, which have been known for many years (BAULDRY, M. G. C., The bactericidal, fungicidal and sporicidal properties of hydrogen peroxide and peracetic acid, Jou...

AI Technical Summary

Benefits of technology

[0016] An object of the present invention is to provide a sterilization process which, in association with the operational devices and respective methods, differs from the commercial processes and patents referred to heretofore, and presents numerous advantages, being:

[0017] 1.) The initial plasma, formed with the residual gas from filtered atmospheric air by means of the present process, is applied in order to establish an adequate temperature and to enhance the active principle of the sterilizing gas which is to be injected;

[0018] 2.) The excitation of the plasma used is effected by means of a pulsed DC power source instead of the radio frequency (RF) source referred to in the documents referred to heretofore. The pulsed DC signal is especially selected so as to avoid excessive heating at the plasma generating electrode, and has the advantage over RF of not requiring impedance couplers. Consequently, the excitation of the plasma is simpler and is less dependent on the type of charge (metal, glass ceramics, or plastic) and the design format of the electrode. Another advantage is the lower cost of manufacture.

Problems solved by technology

Despite the high diversity of the sterilization systems which use peracetic acid and hydrogen peroxide and ethylene oxide, there are still a number of problems of operational and financial nature, as well as risks of contamination of the materials and the environment during the process.

For example, application in diluted form requires large volumes of the sanitizing liquid, the materials cannot be packed, and sterile water is required for the rinsing, as well as a clean area for drying, thus incurring in the risk of re-contamination.

These systems incur high energy consumption, as a function of the use of heater devices.

The process with ethylene oxide requires long periods of sterilization, as well as aeration, since this substance is highly toxic.

The difficulty with penetration of the hydrogen peroxide in the environment with restricted diffusion is due to the presence of water vapour which, because it reaches the area concerned first, has a higher vapour pressure, which turns it into a barrier to penetration by the hydrogen peroxide vapour.

Depending on the geometric shape of the electrodes and the articles which are to be sterilized, this coupling may prove difficult, and consequently incur losses of energy and heating of the source, as well as the cost of the RF source being increased excessively with the increasing of its power, so making the sterilization processes substantially more expensive;

Damage to the vacuum system, incurred by the action of highly reactive gases during the process of evacuation after the exposure period and the diffusion of the sterilizing gas.

This consequently requires a substantial number of handling procedures in the vacuum system, and a reduction in the service life of these items of equipment; and

Inefficiency of the process of sterilizing areas of restricted diffusion due to the injection of the aqueous solution of hydrogen peroxide or peracetic acid in the plasma sterilization system.

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