The present invention relates to the sterilization of phases comprising gases and/or vapors and suspended particles. The invention is directed to a device for sterilization of streams of the mentioned matter.
As various pathogenic microbes and substances are being treated in dedicated facilities, such as laboratories, research facilities, hospitals, glove boxes and other special containment areas, and also in equipment for biowaste destruction, it is of increasing importance to ensure that none of these agents escapes outside such facilities or equipment at any time during the various processing stages. Autoclaves are typically used for sterilization of various media, equipment, tools and waste materials.
During use of such equipment or facilities, gases and vapors, typically air and steam, are led both into the facility and out of it. A particular case is the exhaust from an autoclave used for sterilization. During an operational process, the autoclave goes through various cycles of evacuation and repressurization, whereby the risk of still viable hazardous agents escaping through an exhaust channel is obvious, in particular during the early stages of the process when the specified sterilization temperature has not yet been reached. To decrease this risk, filters are often arranged in the exhaust line. An effective way of ensuring that the exhaust stream is sterile is to provide an incinerator in the exhaust line, but open flame incinerators are not easy to operate and not cost-effective, and they pose other risks.
Sterilization in the context of the present discussion includes the killing of microbes including bacteria and viruses so as to render them non-pathogenic, as well as the destruction of other biological agents that may cause harmful effects. Exhaust fluids in this context mean gases which are non-condensable under the normal operational conditions of the device to which the exhaust line is connected, such as atmospheric gases, as well as condensable vapors, and also any particles suspended in these, and which exit a facility or equipment in order to be sterilized in accordance with the invention.
In International patent application WO2008/105696, a device and process for treating an autoclave exhaust stream are disclosed. The invention disclosed in WO2008/105696 is based on the arrangement of two filters in series in the exhaust line, and a heater between the filters for evaporating condensate that tends to form in the line. With the use of the heater, the condensate can be driven through a hydrophobic filter which will not allow liquid water through, and the condensate can also be heated to sterilization temperature.
In international patent application WO 98/16263 are disclosed a method and apparatus for sterilizing air to be used for e.g. pneumatic medical instruments, cleanrooms and aircraft cabins. The device comprises a replaceable filter.
In order to ensure maximum sterility, according to the present invention a device has been developed in which exhaust fluid from equipment or a facility for treating biologically active material is heated to a temperature at least sufficient to kill or denature hazardous agents, and conveyed through a filter which is heated, preferably by the fluid, to essentially the same temperature. The relevant temperature is maintained during operation in both the fluid and the filter. Since the filter is dimensioned to trap microbial agents like bacteria and viruses and the temperature of the filter surfaces is sufficient for sterilization, microbial agents are bound to come into contact with said surfaces and a very high degree of sterilization certainty is reached.
According to the invention, a device is provided which has a body, an inlet port, a space provided with a heat source for heating a fluid flowing through the space which comprises a meandering channel for ensuring effective heat transfer, at least one metal filter unit which can be heated to the desired fluid temperature which is at least 400 ° C., and an exit port for fluid which has passed through the filter unit(s).
The filter unit or units are seamlessly joined to the body of the device by welding without the use of gaskets. Eliminating the gaskets makes possible the utilization of temperatures in excess of 600° C.
In the following, the invention is described in detail with reference to the attached drawings.
The outlet 6 of the heating section leads to a filtering section 7, in which is provided a filter unit 8. A single filter unit is shown in
Preferably, the material of the filter unit is stainless steel. Other metal alloys may be used as required, taking into account the desirability to obtain a seamless, welded structure.
Suitable metal filter units are available from e.g. the Pall Corporation, New York.
During operation, the filter unit is essentially in thermal equilibrium with the heated fluid flowing through it. According to a preferred embodiment of the invention, the thermal equilibrium is achieved by including in the process a preconditioning stage, during which a vacuum pump pulls sterile, filtered atmospheric air through the heating and filter section.
In
With the filter unit at operating temperature, agents entering the device encounter already in the heating section a temperature which is normally sufficiently high to eliminate the viability of bacteria and viruses, and to effect degeneration of biologically active structures like pyrogens and prions where applicable. The relevant temperature is determined by the skilled person according to the conditions and biological agents involved in each case. The fluid temperature at the downstream end of the heating section is above 400° C.; preferably above 600° C.
Finally, surface contact with the filter unit or units at essentially the same temperature ensures that no viable harmful agents are released to the atmosphere.
After the fluid stream has passed through the unit, it may be cooled by spraying water into the stream through a nozzle, or in any other suitable way, as is known to the skilled person.
The device according to the invention may be used for sterilizing a fluid leaving a processing device or facility, but it may also be used for decontamination of inflowing fluid to a facility or apparatus if necessary.
The efficiency of the device for sterilization according to the present invention was tested. The device used in the tests corresponds to that shown in
The test results are shown in Table 1 below.
(*The presence of the heating section and/or filter unit in the device: yes (+), no (−)
(**Zero (0) means that no endotoxin was present in the outcoming fluid
As can be seen from Table 1, the device for sterilization of a fluid phase according to the present invention combines two effective sterilization operations (heating and filtration). The arrangement provides redundancy, since effective sterilization occurs even if one component, heating or filtration, would fail.
Number | Date | Country | Kind |
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11397510.6 | May 2011 | EP | regional |