JPS63309268A - Sterilizing method - Google Patents

Abstract

PURPOSE:To perform sterilization within an extremely short time and to generate no danger in handling, by injecting a gaseous mixture of gas or steam and air in a pressure resistant container receiving an article to be sterilized and igniting said mixture to explode the same. CONSTITUTION:The lid 4 of a pressure resistant container 2 is opened and an article to be sterilized is inserted in the container 2 to close the lid 4. The valve of a pipe 6 is opened to exclude the air in the pressure resistant container 2 by a vacuum pump and combustible gas is introduced into the container from a pipe 7 while the partial pressure preset corresponding to the pressure within an explosion limit is confirmed by a pressure gauge 13. Subsequently, air is introduced into the container 2 from a pipe 8 to be mixed with the combustible gas while stirred by a fan 5. When a high voltage current is allowed to flow to an ignition plug 12 in this state to generate a spark, the mixed gas explodes. The surface of the article 1 to be sterilized in the pressure resistant container 2 is brought into contact with the flame of about 2,000 deg.C generated by explosion for a short time of several hundred musec unit and all of bacterial thereon are killed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a sterilization method for sterilizing microorganisms attached to objects used in hospitals, food factories, pharmaceutical factories, and others.

(Prior Art) Conventional sterilization methods include heat sterilization, chemical sterilization, and irradiation sterilization.

Heat sterilization involves applying heat to the object to be sterilized using flame, dry heat, high-pressure steam, etc. According to the Japanese Pharmacopoeia, heat sterilization reduces dry ripening by 200%.
The temperature must be maintained at 121°C or higher for 30 minutes or more, and the temperature for widely used high-pressure steam is similarly set at 121°C for 20 minutes. Chemical sterilization uses ethylene oxide and is a method of sterilizing with this gas.

(Problems to be solved by the invention) As mentioned above, in the case of heat sterilization, sterilization takes time;
Furthermore, cooling and drying after sterilization require time, so it takes a considerable amount of time overall. In addition, sterilization with ethylene oxide takes more time than sterilization with high-pressure steam, and furthermore, it uses a gas that is extremely harmful to the human body, so safety and hygiene considerations must be taken when handling it.

The present invention has been made to solve the problems of conventional sterilization methods, and provides a new sterilization method that can be sterilized in a very short time and is not dangerous to handle. The purpose is to

[Structure of the Invention] (Means for Solving the Problems) Therefore, the present invention utilizes the explosion of flammable gas or steam, and the above gas or steam and air are placed in a pressure-resistant container that stores objects to be sterilized. A mixture of gases is injected and ignited to cause an explosion. Gases and steam used include methane, ethylene, LP gas, methanol, ethanol,
Binarized charcoal x etc. can be used.

(Function) When gas is exploded in a pressure-resistant container as in the present invention, the temperature rises instantaneously, and microorganisms are sterilized by the high temperature. Furthermore, depending on the gas or steam used, when the flame is cooled and extinguished, a small amount of incomplete combustion gas is generated, which has a sterilizing effect on microorganisms.

(Example) The figure shows an example of an apparatus for carrying out the present invention, in which an object 1 to be sterilized is placed on a wire mesh 3 provided in a pressure-resistant container 2. This pressure-resistant container 2 can be opened and closed with a lid 4, has a fan 5 inside, and is attached with many pipes each having a valve. A pipe 6 is connected to a vacuum pump (not shown) and sucks air inside the pressure vessel 2, a pipe 7 supplies flammable gas or steam, and a pipe 8 supplies air. Also, 10
A pipe is connected to a high-performance sterilization filter or flame sterilizer 11 to bring the pressure inside the pressure container to atmospheric pressure after an explosion. Further, a spark plug 12 for ignition is provided at the center of the upper part of the pressure container 2. In addition, 13 in the figure is a pressure gauge.

Sterilization using this device begins with 44
Open the lid 4, insert the object to be sterilized, and close the lid 4. Open the valve of the vibro, exhaust the air in the pressure vessel 2 with a vacuum pump (not shown), and pump the flammable gas from the pipe 7 to a preset partial pressure corresponding to the explosion limit while checking with the pressure gauge 13. Next, air is introduced through the pipe 8 and stirred and mixed by the fan 5. When using a flammable liquid such as alcohol as the flammable gas, connect an air washing bottle containing alcohol to the valve of pipe 7, and open the valve to introduce air after the pressure is reduced by a vacuum pump. An explosive gas mixture saturated with alcohol vapor is prepared.

In this state, when a high voltage current is applied to the ignition plug 12 and a spark is generated, the mixed gas explodes.

The surface of the object to be sterilized inside the pressure-resistant container 2 is in contact with the flame of about 2000°C generated by the explosion for a short period of several hundred milliseconds.
All microorganisms are sterilized.

The flame caused by the explosion of the gas comes into contact with the object to be sterilized and the inner wall of the pressure-resistant container, and is cooled and extinguished. At this time, a small amount of incomplete combustion gas is generated. These gases are ethylene oxide when the flammable gas is ethylene, and are aldehydes when the flammable gas is alcohol. Since all of these have a sterilizing effect on microorganisms, the object 1 to be sterilized is sterilized not only by the high temperature caused by the explosion but also by this gas.

Since the pressure inside the pressure vessel 2 is slightly reduced due to the explosion, the valve of the pipe 1O is then opened and atmospheric air is introduced through the filter 11 to bring the inside of the pressure vessel to atmospheric pressure. Thereafter, the lid 4 is opened and the object 1 to be sterilized is taken out. Since the explosion ends within one second, this sterilization process is completed in an extremely short time.

Although the pressure inside the pressure vessel 2 increases due to the explosion, the pressure within the pressure vessel 2 increases, but the maximum is about 7 atmospheres, so the production of the pressure vessel 2 is easy. Moreover, since the high pressure generated by the explosion is evenly applied to the objects to be sterilized placed in the pressure container 2, there is no risk of them being destroyed or damaged by the explosion pressure.

The results of an experiment using methane, ethylene, methanol, ethanol, and carbon disulfide as flammable gases or vapors using a pressure vessel 2 with a volume of 3.5 L are described below.

In addition, spore-forming bacteria (Bac 111us), which is the most resistant to heat and is designated as an indicator bacteria, is used to determine sterilization.
A sample was used in which spores (10 spores) of 5tearother+*ophillus were adhered to a filter paper. After sterilizing this sample, a prescribed culture solution was added and cultured at 55° C. for more than one week, and the presence or absence of contamination of the solution was visually determined.

Table 1 No matter which gas or steam was used, it was effective at equivalent concentrations to air. However, the concentration of gas and vapor is methane 7
If the amount is insufficient compared to air (as in 13% methane), or in excess (as in 13% methane), the flame temperature will not rise sufficiently and it will be ineffective. In this example, the pressure (initial pressure) in the pressure container before ignition is set to atmospheric pressure.

Steam is used when the object to be sterilized is placed on a wire mesh 3, but the object to be sterilized is placed in a test tube with a diameter of IC 1 and a length of 5 C.
The test results for % methane and 6.5% ethylene showed that when the initial pressure was atmospheric pressure, methane was ineffective but ethylene was effective. Therefore, we conducted a test by increasing the initial pressure of methane to 2 atmospheres, which proved to be effective.

The reason why atmospheric pressure was ineffective against the objects inside the test tube was because the explosion flame was cooled on the inside surface of the test tube.
Increasing the initial pressure increases the explosion flame temperature and the flame duration, so it is also effective against objects to be sterilized inside test tubes. In the case of ethylene, the fact that it is effective even at atmospheric pressure is due to the sterilizing effect of ethylene oxide, which is a by-product during extinguishing inflammation. Due to its chemical structure, methane does not produce incomplete combustion gas that has a sterilizing effect.

Sterilization using gas or steam explosion requires that the average temperature inside the pressure container be 1000° C. or higher and last for 200 m5 or more. The duration of the temperature of 1000°C or higher becomes longer if the pressure vessel is larger or the initial pressure is higher.

Taking this into consideration, the initial pressure may be selected in accordance with the size of the pressure vessel.

[Effects of the invention] As described above, in the present invention, sterilization is performed using explosion of gas or steam, so sterilization can be performed in an extremely short time compared to conventional methods. The amount of energy required to do so is minute.

Furthermore, compared to the widely used sterilization using high-pressure steam, the present invention does not require a steam generator, and the structure of the pressure-resistant container is simpler and cheaper than the conventionally used autoclave.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for carrying out the method of the invention. 1: Item to be sterilized, 2: Pressure-resistant container, 3: Wire mesh, 4: Lid, 5:
Fan, 122 spark plugs.

Claims (1)

[Claims] A sterilization method characterized by inserting an object to be sterilized into a pressure-resistant container, injecting a mixed gas of flammable gas or combustible liquid vapor and air into the pressure-resistant container, and causing the mixture to explode.