JP2001070410A - Sterilization processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate air remaining inside a sterilization processing object housing body and to highly and efficiently sterilize a sterilization processing object just by simple steps while miniaturizing and simplifying equipment and reducing the initial cost and the running cost, etc. SOLUTION: This pressure exhaust type sterilization processing method in provided with a pressuring step for removing air inside a sterilization chamber 21 while pressurizing the inside of the sterilization chamber 21, a pressure reducing step for reducing a pressure inside the sterilization chamber by dew- condensing steam inside the sterilization chamber 21 and moving the air inside the sterilization processing object housing body 51 into the sterilization chamber 21 after the pressurizing step and a sterilizing step for making a temperature inside the sterilization chamber 21 reach a sterilization temperature level and keeping the temperature for fixed time after performing each of the preceding steps for one or more times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field for sterilizing articles, and relates to a sterilization method for treating used articles and unsterilized articles.

[0002]

2. Description of the Related Art Pathological bacteria are attached to medical equipment used in medical institutions such as hospitals. Instruments used in laboratories and analytical laboratories handling microorganisms often have such bacteria attached to them. When disposing of these, it is required to sterilize them before disposal.

[0003] As a means for sterilizing various kinds of equipment as described above, a method using high-temperature steam is widely used. Steam sterilization is desirable because it is easy to handle and does not require cost. An apparatus such as an autoclave is often used for this type of steam sterilization. FIG. 1 shows a pressurized exhaust type as an example of a steam sterilization apparatus (autoclave). Hereinafter, this apparatus will be described with reference to FIG.

In FIG. 1, reference numeral 11 denotes an outer tub, reference numeral 21 denotes a sterilization chamber, reference numeral 41 denotes a storage can, reference numeral 51 denotes a sterilized product storage body for storing a sterilized product, reference numeral 52 denotes a sterilized product, and reference numeral 53 denotes water.

[0005] The outer tub 11 is a cylindrical or rectangular tube made of metal, synthetic resin and other materials. Outer tank 1
The upper surface of 1 is opened for taking in and out of an object, and an outer lid 12 is attached here so as to be freely opened and closed. The outer tub 11 is also provided with a cooler 13 on its body. The cooler 13 is of an air-cooled type in which a fan is rotated by a motor, and is electrically controlled. This cooler 13 is shown for explaining the method of the present invention described later, and is not provided in the conventional apparatus.

The sterilization chamber 21 is sometimes called a sterilization pot. The sterilization chamber 21 is made of a material having heat resistance, pressure resistance, corrosion resistance and the like, for example, metal. The sterilization chamber 21 also has an open upper surface, and is provided with an opening / closing lid 22. The sterilization chamber 21 is disposed in the outer tub 11 and is installed therein. The opening / closing lid 22 of the sterilization chamber 21 is attached to the back of the outer lid 12. This means that the upper surface of the outer tub 11 is closed by the outer lid 12 and the upper surface of the sterilization chamber 21 is also closed by the opening / closing lid 22. Therefore, a seal ring 23 for maintaining the airtightness with the opening / closing lid 22 is attached to the upper inner peripheral surface of the sterilization chamber 21. At the lower part in the sterilization chamber 21, an inner bottom 24 having air permeability is provided. The inner bottom 24 is made of, for example, a heat-resistant cage, and another example is made of a heat-resistant perforated plate. The space below the inner bottom 24 in the sterilization chamber 21 is used as a liquid reservoir 25. A well-known heater 26 such as an electric heater is provided inside the liquid reservoir 25. The sterilization chamber 21 also includes a water supply pipe 28 having a water supply valve 27 and a drainage pipe 3 having a drainage valve 29.
0 is connected to the chamber bottom, and an exhaust pipe 32 having an exhaust valve (also serving as an air rejection valve) 31 is connected to the chamber body. Among these, the water supply pipe 28 and the drain pipe 30 communicate with the liquid reservoir 25, and the exhaust pipe 32 communicates with the trunk space (the upper part of the inner bottom 24) of the sterilization chamber 21. Each valve such as the water supply valve 27, the drain valve 29, and the exhaust valve 31 is, for example, an electrically controlled valve, and is, as another example, a manually operated valve. The water supply pipe 28 is connected to a water source. The drain pipe 30 is led to an appropriate drain area, and the exhaust pipe 32 is also led to an appropriate exhaust area. The water supply pipe 28 is shown for explaining the method of the present invention described later, and is not provided in the conventional apparatus.

[0007] The storage can 41 having an open top is used for storing the sterilized product storage body 51 therein. Storage can 41
Are mainly made of heat-resistant metal. As a typical example, the sterilized product storage body 51 for collecting the sterilized product 52 is formed of a sterilization bag made of a sheet material having heat resistance and corrosion resistance. The sterilized product 52 as an object of the sterilization process corresponds to a medical instrument, an analytical instrument, and various other items. Since bacteria, viruses, and other microorganisms adhere to such a sterilized product 52, such fungi also adhere to the sterilized product container 51 packed with the bacteria, viruses, and other microorganisms. However, when accommodating the sterilized product storage body 51 to which the bacteria are attached in the housing can 41 and handling it, the direct contact with the sterilized product storage body 51 is avoided, and the sterilized product storage body 51 is damaged. It is also a preparation for when you do. In that sense, the storage can 41 can be said to be a container for protection. A representative example of the water 53 supplied into the liquid reservoir 25 is clean water.

[0010] The sterilization process of the sterilized product 52 using the apparatus shown in FIG. 1 is as follows. The opening / closing lid 22 is opened in the liquid reservoir 25 of the sterilization chamber 21, and a certain amount of water 53 is put therein. The sterilized product 52 is put in the sterilized product storage body 51, and the sterilized product storage body 51 is stored in the storage can 41. Such a storage can 41 is also placed in the sterilization chamber 21 immediately before the operation. At this time,
The mouth of the sterilized product storage body 51 in the storage can 41 is open as shown in FIG. During operation, the outer tub 11 and the sterilization chamber 2
After closing 1 with the outer lid 12 and the opening / closing lid 22, the inside of the sterilization chamber 21 is exhausted through the exhaust pipe 32 while the water 53 in the liquid reservoir 25 is heated by the heater 26. In such a case, the water 53 in the liquid reservoir 25 evaporates in the sterilization chamber 21,
The vapor permeates the inner bottom 24 and spreads upward. In addition, the steam tends to enter the inside of the sterilized product storage body 51 from the opened mouth thereof. However, if air remains in the sterilized product storage body 51, such steam does not sufficiently enter. The following is a sterilized product 52
In order to kill the bacteria adhered to the chamber, the exhaust pipe 32 is closed, the inside of the sterilization chamber 21 is set to the sterilization set temperature using the steam generated by the heater 26, and the temperature is maintained for a certain time. However, when air remains in the sterilized product storage body 51, it takes a considerable time until the temperature in the bag reaches the sterilization temperature.

FIG. 3 shows a change in the sterilization chamber 21 and a change in the sterilized product storage body 51 with temperature and pressure on the vertical axis and time on the horizontal axis in the conventional method. FIG. 3 also shows the operating states of the heater 26 and the exhaust valve 31. The conventional method can be said as follows with reference to FIG. That is, in the case of the conventional method, the temperature in the sterilization chamber 21 increases in the air elimination step _S01 . In particular,
Since attained temperature by an amount which is pressurized with air exclusion step S ₀₁ is increased, the temperature inside the sterilization chamber 21 comes to exceed 100 ° C.. Thereafter, the temperature rise step _{S 02} or sterilization step _{S 03} the sterilization chamber 21 by passing through a 1
A temperature of 21 ° C. is reached. At this time, the sterilized product storage body 5
The temperature in 1 also increases in proportion to the temperature in sterilization chamber 21. The sterilization step _S03 ends after the temperature of 121 ° C. is maintained for about 20 minutes. Then, only the exhaust step _S04 is performed as post-processing.

[0010]

As in the above-described conventional method, it is difficult to completely eliminate the air in the sterilized product storage body 51 simply by performing the air removing step _S01 . This is a common problem of the conventional method employing the pressurized exhaust type. The sterilized product storage body 51 in which air remains as described above
In this case, the high-temperature steam does not sufficiently reach every corner, and the inside of the sterilized product storage body 51 does not reach a predetermined sterilization temperature. Occurs. That is, not all bacteria can be killed. Since the surviving bacteria proliferate over time, each of the sterilized products 52 in the bag is propagated by the proliferated bacteria.
Are contaminated in a chain. Of course, if the inside of the sterilization chamber 21 is evacuated over a long period of time, sufficient exhaustion of the sterilized product storage body 51 can be expected. However, if the time taken for air removal is too long, the total time required for the sterilization treatment becomes longer, and the work efficiency is reduced. In addition, energy loss during the sterilization process is large. As a countermeasure against this, it is conceivable to use vacuum evacuation means, but in such a case, the equipment cost and the operating cost are increased by the use of such means, and the equipment becomes large and complicated.

[0011]

SUMMARY OF THE INVENTION In view of the above technical problems, the present invention eliminates air remaining in a sterilized product storage body while reducing the size and simplicity of equipment and reducing initial costs and running costs. An object of the present invention is to provide a sterilization method capable of highly and efficiently sterilizing a sterilized product only by steps.

[0012]

The sterilization method according to the present invention is characterized by the following means for achieving the intended object. In other words, the problem solving means according to the first aspect of the present invention is to store a sterilized product storage container containing a sterilized product and having a bag opening open in a sterilization chamber, and keep the sterilization chamber airtight. Then, in a pressurized and exhausted sterilization method in which the sterilized product in the sterilized product storage is brought into contact with high-temperature steam in the sterilization chamber to perform steam sterilization, the inside of the sterilization chamber is evacuated while pressurizing the inside of the sterilization chamber. Pressurizing step, and, after the pressurizing step, depressurizing the inside of the sterilizing chamber by condensing steam in the sterilizing chamber to move the air in the sterilized object storage into the sterilizing chamber, After performing the preceding step one or more times, the sterilization step for allowing the temperature in the sterilization chamber to reach the sterilization temperature range and maintaining the temperature for a certain period of time. To.

[0013]

The sterilization method according to the present invention has a pressurizing step, a depressurizing step, and a sterilizing step. As an example of the embodiment, each step is performed in the order of a pressurizing step → a depressurizing step → a sterilizing step. In the first pressurization step, the internal pressure of the sterilization chamber is increased by opening the exhaust valve. Although the pressure inside the sterilization chamber increases during the pressurization step, the sterilization chamber communicates with the outside (atmosphere), which has a lower pressure. Therefore, during the pressurizing step, the air in the sterilization chamber is eliminated due to the pressure difference between the inside and outside of the chamber. However, in the case of the sterilized product storage container that is open in the sterilization chamber, it is difficult to eliminate the internal air. In the next pressure reduction step, the pressure in the sterilization chamber is reduced by closing the exhaust valve. In this decompression step, the inside of the sterilization chamber becomes relatively low pressure, and the inside of the sterilized product storage body becomes relatively high pressure. Therefore, when air remains in the sterilized product storage, the residual air is drawn out of the sterilized product storage into the sterilization chamber. When the pressurizing step is performed again immediately after the depressurizing step, the residual air drawn from the sterilized product storage is exhausted to the outside of the sterilizing chamber. It is therefore desirable to repeat the pressurizing and depressurizing steps before the sterilization step. In the sterilization step after completion of both steps, the temperature in the sterilization chamber is allowed to reach the sterilization temperature range, and the temperature is maintained for a certain time. When the temperature in the sterilization chamber is increased to a high temperature and a high pressure by this sterilization step, a high-temperature gas (steam) reaches all corners of the sterilized product storage body after the residual air removal processing is completed. Each of the sterilized products in the sterilized product container is highly sterilized in order to sufficiently contact the high-temperature steam in such a sterilization temperature range. Although the method of the present invention relates to an improvement in the pressurized and evacuated sterilization method, from another viewpoint, it can be said to be a vacuum evacuated sterilization method of a type not using a vacuum device.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sterilization method according to the present invention will be described with reference to the accompanying drawings.

The method of the present invention is carried out using the apparatus (autoclave) illustrated in FIG. The apparatus used in the method of the present invention is provided with a cooler 13 and a water supply pipe 28 which are not present in the conventional apparatus. Apparatus / sterilized product storage body 51 in FIG.
The sterilized product 52 and others have already been described. Therefore, the description regarding FIG. 1 will be omitted by referring to the above-described contents.

In the embodiment of the sterilization method according to the present invention, that is, in the sterilization processing of the sterilized product 52 using the apparatus shown in FIG. 1, a pressurizing step, a depressurizing step, and a sterilizing step are performed after a preparation stage.

At the preparation stage, a fixed amount of water 53 is put in the liquid reservoir 25 of the sterilization chamber 21 as described above.
As described above, the storage can 41 containing the sterilized product storage body 51 containing the sterilized product 52 is stored in the sterilization chamber 21 immediately before the operation. At this time, the storage can 41
The inside of the sterilized product storage body 51 is open as shown in FIG.

In the first pressurization step, the outer tub 11 and the sterilization chamber 21 are closed by the outer lid 12 and the opening / closing lid 22, and after the exhaust valve 31 is opened, the water 53 in the liquid reservoir 25 is heated by the heater 26. Here, the steam generated in the sterilization chamber 21 permeates the inner bottom 24 and reaches the upper part of the chamber. Moreover, since the amount of generated steam exceeds the amount of exhaust in the sterilization chamber 21, the pressure in the sterilization chamber 21 increases. If the internal pressure of the sterilization chamber 21 exceeds the external pressure (atmospheric pressure) in this pressurizing step, the pressure difference causes the air in the sterilization chamber 21 to be naturally removed. That is, the gas in the sterilization chamber 21 flows out of the sterilization chamber 21 through the exhaust pipe 32 in which the exhaust valve 31 is open.

In the next pressure reduction step, for example, the power of the heater 26 is turned off, the exhaust valve 31 is closed, and the cooler 13 is operated. As a cooling means other than the cooler 13, after the drain valve 29 of the drain pipe 30 is temporarily opened to extract the water (high temperature) 53 in the liquid reservoir 25, the water supply pipe 28 with the water supply valve 27 opened. Fresher water (low temperature) 53 is put into the liquid reservoir 25. Also at the time of this water exchange, the heater 26 is turned off,
The exhaust valve 31 is closed. In yet another example, both are performed. In the case of the cooling means by the cooler 13, the temperature of the wall of the sterilization chamber 21 receiving the cool air from the rotating fan drops, and the vapor in the sterilization chamber 21 contacts the chamber wall and condenses and becomes water droplets. The pressure in 21 decreases. Even with the cooling means by replacing the water 53, when high-temperature water is extracted and low-temperature water is newly supplied,
Since the steam in the sterilization chamber 21 that has come into contact with the low-temperature water becomes similar to the above, the pressure in the sterilization chamber 21 decreases. When these air-cooling means and water-cooling means are used in combination, the depressurization step speed is increased as is obvious. When the pressure inside the sterilization chamber becomes low, the pressure inside the sterilized product storage container becomes relatively high, and thus the inside of the sterilized product storage 51 is sucked into the sterilization chamber 21 until the internal pressures of both are balanced.
If air remains in the sterilized product storage body 51, the residual air is drawn out of the sterilized product storage body 51 into the sterilization chamber 21.

In the re-pressurizing step performed after the depressurizing step, the processing operation according to the content described in paragraph [0018] is performed, and when the depressurizing step is performed again after the re-pressing step, the paragraph number [ 0019]. Each of these pressurizing and depressurizing steps may be performed multiple times,
In proportion to the number of times, the efficiency of removing the residual air in the sterilized product storage body 51 increases.

After the required number of pressurizing and depressurizing steps are performed, in a sterilizing step that is performed subsequent to the final depressurizing step, the water 25 in the liquid reservoir 25 is set with the valves 27, 29, and 31 closed. Is heated by the heater 26, the high-temperature steam generated thereby causes the inside of the sterilization chamber 21 to reach the sterilization set temperature, and the temperature in the sterilization chamber 21 is maintained at the sterilization set temperature for a certain period of time. The heater 26 is appropriately turned on and off to maintain the set sterilization temperature. According to the sterilization step, the bacteria adhering to the sterilized product 52 are also killed by the high-temperature steam at the set sterilization temperature that has entered the sterilized product storage body 51.

After the sterilization step, a final exhaust step is performed. In this evacuation step, the sterilization chamber 2
The temperature of the inside of 1 rapidly drops due to the exhaust.

FIG. 2 shows changes in the sterilization chamber 21 with respect to the above embodiment of the present invention, with temperature and pressure on the vertical axis and time on the horizontal axis. In FIG. 2, S _{11 to} S
₁₄ pressurization _step, S 21 _{to S 23} are vacuum step,
S ₃₁ represents sterilization _{step, S 41} is a pumping step, respectively. “Cooling” in FIG. 2 corresponds to the cooling by the air cooling / water cooling, and “heating” in FIG. 2 corresponds to the heating by the heater 26.

In each step of the method of the present invention, each temperature in the sterilization chamber 21 and the sterilized product storage body 51 changes as shown in FIG. When attention is paid to the main temperatures among these, in each of the pressurizing steps S _{11 to} S ₁₄ , the temperature in the sterilization chamber 21 exceeds 100 ° C. because the attained temperature increases by the amount of pressurization. and it is, the temperature in the sterilization chamber 21 and sterilized product container 51 when the sterilization step S ₃₁ is reached respectively 121 ° C..

The residual air in the sterilized product storage body 51 tends to decrease as the number of pressurizing and depressurizing steps is increased. Therefore, the number of times of the pressurizing step and the depressurizing step may be set according to the capacity of the sterilized product storage body 51, whereby the air in the sterilized product storage body 51 can be almost completely eliminated. When almost no residual air remains in the sterilized product storage body 51, the sterilized product 52 is highly sterilized by steam sterilization.

In the evacuation method for sterilization and the sterilization method of the present invention, each step from the start to the end of the operation can be fully automated by combining the illustrated apparatus with a control panel (eg, a microcomputer). .

As described above, the sterilized product 52 includes medical instruments and analytical instruments as well as various other items. Such a sterilized product 52 is sterilized after use and before disposal, and may be sterilized before use. The container for processing the sterilized product 52 is the sterilized product storage body 51. The sterilized object storage body 51 is usually a bag made of a sheet material having heat resistance and corrosion resistance, but may be a container having heat resistance and corrosion resistance. In such a case, the container has a top surface opened like a flask or a beaker, for example.

[0028]

The sterilization method according to the present invention includes a pressurizing step, a depressurizing step, and a sterilizing step, and the air in the sterilized object storage is almost completely eliminated by the pressurizing step and the depressurizing step before the sterilizing step. Therefore, after both of these steps, the sterilized product in the sterilized product storage can be highly sterilized simply by performing the sterilizing step. In addition, expensive pressurizing equipment and vacuum equipment for pressurizing and depressurizing the inside of the sterilization chamber are not used. This means that the equipment can be downsized and simplified. Nevertheless, since the step times such as the pressurizing step and the depressurizing step are short, a large amount of time is not required until the sterilization step, and the sterilization processing efficiency is improved. When this time is short, waste of heat energy can also be suppressed. Therefore, according to this method, initial costs and running costs for the sterilization treatment are generally low.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing an embodiment of the method of the present invention together with an apparatus used for the method.

FIG. 2 is an explanatory diagram showing an example of each step in the method of the present invention.

FIG. 3 is an explanatory diagram showing each step in a conventional method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Outer tank 12 Outer lid 13 Cooler 21 Sterilization chamber 22 Opening / closing lid 23 Seal ring 24 Inner bottom 25 Liquid reservoir 26 Heater 27 Water supply valve 28 Water supply pipe 29 Drainage valve 30 Drainage pipe 31 Exhaust valve 32 Exhaust pipe 41 Storage can 51 Sterilization treated container 52 sterilized product 53 water S ₁₁ to S ₁₄ pressurization step S ₂₁ to S ₂₃ vacuum step S ₃₁ sterile step S ₄₁ pumping step

Claims (1)

[Claims] 1. A sterilized product storage container containing a sterilized product and having an open mouth is placed in a sterilization chamber, and the sterilization chamber is kept airtight. In a pressurized / exhaust-type sterilization method for performing steam sterilization by bringing a processed product into contact with high-temperature steam in a sterilization chamber, a pressurizing step for removing air from the sterilization chamber while pressurizing the sterilization chamber, Then, after performing decompression of the inside of the sterilization chamber by condensing the vapor in the sterilization chamber to move the air in the sterilized product housing into the sterilization chamber, and performing each of these preceding steps one or more times A sterilization step of causing the temperature in the sterilization chamber to reach a sterilization temperature range and maintaining the temperature for a certain period of time.