JP4399097B2 - Ethylene oxide gas sterilizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a conditioning process for heating and humidifying the sterilization chamber is performed before the sterilization process is performed, and after the conditioning process is performed, the sterilization process is performed by supplying ethylene oxide gas into the sterilization chamber by the gas supply means. The present invention relates to an ethylene gas sterilizer.
[0002]
[Prior art]
An ethylene oxide gas sterilizer using ethylene oxide gas, which is a sterilization gas, is known as a sterilizer for sterilizing medical instruments used in hospitals and instruments used in experiments and the like.
The ethylene oxide gas sterilization apparatus stores instruments to be sterilized in a sterilization chamber provided to be hermetically sealed, replaces ethylene oxide gas with air in the sterilization chamber, and performs sterilization with ethylene oxide gas.
[0003]
In addition, there are two types of sterilization methods that are carried out in a conventionally known ethylene oxide gas sterilization apparatus, when the sterilization chamber is once evacuated before the sterilization step and when not evacuated. First, a case where the sterilization chamber is once evacuated will be described.
First, before performing sterilization, the ethylene oxide gas sterilizer performs a heating step of heating the sterilization chamber at a predetermined temperature. As a result, the object to be sterilized in the sterilization chamber is raised to a temperature sufficient for sterilization.
[0004]
Next, a humidification step is performed. In the humidification process, first, the air in the sterilization chamber is exhausted until the pressure in the sterilization chamber reaches a predetermined pressure equal to or lower than a predetermined degree of vacuum, and when the pressure in the sterilization chamber reaches the predetermined pressure, the air leaks into the sterilization chamber. A leak test is performed. When it is determined that the leak test is normal, the sterilization chamber is humidified.
In this humidification process, steam is supplied while exhausting the sterilization chamber, and when the temperature reaches a predetermined temperature, the operation of stopping the supply of steam is repeated.
In the present specification, a process including the heating process and the humidification process is referred to as a conditioning process. In other words, the conditioning process is a process for preparing the sterilization chamber and the condition of the object to be sterilized, which is performed before the sterilization process.
[0005]
When the humidification process described above is completed, ethylene oxide gas is supplied into the sterilization chamber, and the sterilization process is started. FIG. 8 shows a pressure transition diagram at this time. Here, the horizontal axis represents time, the vertical axis represents the sterilization chamber pressure, and 0 on the vertical axis represents atmospheric pressure.
Prior to the supply of ethylene oxide gas, the sterilization chamber is once evacuated to a predetermined vacuum level. In this case, due to changes in temperature, atmospheric pressure, etc., the ultimate vacuum varies each time ( Pv, Pv ′).
[0006]
Then, ethylene oxide gas is supplied into the sterilization chamber in a vacuum state, and this ethylene oxide gas is supplied until the pressure in the sterilization chamber reaches a predetermined pressure Ps set in advance with reference to atmospheric pressure. . Specifically, Ps is a gauge pressure of 0.13 MPa. That is, the supply of ethylene oxide gas is controlled to stop when the atmospheric pressure reaches 0.13 MPa with the atmospheric pressure set to 0.
When the supply of ethylene oxide gas is stopped, sterilization is then performed at a preset temperature and a preset time.
[0007]
As described above, the ultimate vacuum in the sterilization chamber varies (Pv, Pv ′). As described above, when the supply of ethylene oxide gas is performed until the predetermined pressure Ps determined by the gauge pressure is reached from different ultimate vacuum degrees, the pressure reaches a lower pressure (2), and the pressure higher than this. In the case (1), a different amount of ethylene oxide gas is supplied each time.
[0008]
Note that FIG. 9 shows a pressure transition diagram of a method of performing the sterilization step without vacuuming the sterilization chamber after simultaneously performing heating and humidification, instead of the method of temporarily pulling the sterilization chamber into a vacuum state as described above.
Also in this case, ethylene oxide gas is supplied from atmospheric pressure 0 to a predetermined set pressure Ps with reference to atmospheric pressure. However, the pressure in the sterilization chamber increases with heating and humidification in the sterilization chamber, and this pressure increase varies vertically. Therefore, as shown in FIG. 9, when ethylene oxide gas supply is started when Po is small (1) and when ethylene oxide gas supply is started when Po 'is large (2) ), When the pressure is finally supplied up to the set pressure Ps, a different amount of ethylene oxide gas is supplied each time.
[0009]
[Problems to be solved by the invention]
When ethylene oxide gas is supplied from the pre-gas supply pressure, such as the ultimate vacuum level, which varies, to the set pressure set by the gauge pressure, ethylene oxide gas must not be supplied above the minimum level required for sterilization. Therefore, there is no problem as to whether or not sterilization is performed reliably.
However, even if the temperature and time for sterilization are set in the same way, the amount of ethylene oxide gas supplied will vary somewhat, so the sterilization conditions are not reproducible and the conditions of the sterilization state are managed. There is a problem that management is inconvenient for recording.
Further, when there is variation in the supply amount of ethylene oxide gas, ethylene oxide gas may be supplied more than necessary, so that there is a problem that ethylene oxide gas is wasted.
[0010]
Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide an ethylene oxide gas sterilization apparatus that prevents variations in the amount of ethylene oxide gas supplied when ethylene oxide gas is supplied into the sterilization chamber. Is to provide.
[0011]
[Means for Solving the Problems]
That is, according to the ethylene oxide gas sterilization apparatus of the present invention, a sterilization chamber in which an object to be sterilized is stored, a gas supply means for supplying ethylene oxide gas into the sterilization chamber, and a conditioning for heating and humidifying the sterilization chamber In the ethylene oxide gas sterilization apparatus, comprising the control means for performing control and controlling the supply of ethylene oxide gas into the sterilization chamber by the gas supply means and performing the sterilization process after the conditioning process is performed. A measuring means for measuring an end-time pressure in the sterilization chamber at the end, and measuring a current pressure in the sterilization chamber at any time during the supply of ethylene oxide gas into the sterilization chamber by the gas supply means, and a conditioning step from the current pressure Subtracting means to calculate the increased pressure value by subtracting the end pressure at the end, and supply to the sterilization chamber The storage means in which the supply pressure value corresponding to the predetermined amount of the ethylene oxide gas is set and recorded in advance, and the supply pressure value in which the increased pressure value calculated by the subtraction means is recorded in the storage means A comparison means for comparing whether or not the value matches the value, and the control means compares the supply pressure value when the increase pressure value matches the supply pressure value as a result of comparison by the comparison means. The gas supply means is controlled to stop the supply.
By adopting this configuration, a certain amount of ethylene oxide gas to be supplied can always be supplied into the sterilization chamber even if the pressure in the sterilization chamber at the end of the conditioning process varies. For this reason, the reproducibility of the sterilization operation can be improved, which is convenient for management of sterilization conditions and the like.
[0012]
In the conditioning step, a vacuum pump that exhausts until the pressure in the sterilization chamber is equal to or lower than a predetermined vacuum degree, the measuring means measures the pressure in vacuum at the end of the conditioning step, the subtracting means, If the increased pressure value is calculated by subtracting the vacuum pressure from the current pressure, even if the vacuum inside the sterilization chamber is once evacuated before the start of the sterilization process, A certain amount of ethylene oxide gas can always be supplied into the sterilization chamber. For this reason, the reproducibility of the sterilization operation can be enhanced, which is convenient for management of sterilization conditions and the like.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
FIG. 1 is a piping diagram showing the configuration of an ethylene oxide gas sterilizer (hereinafter simply referred to as a sterilizer).
First, the structure of the sterilization apparatus of this embodiment is demonstrated based on FIG.
[0014]
Reference numeral 20 denotes a can having a sterilization chamber 21. The can body 20 is formed in a double can structure including an outer cylinder 20a and an inner cylinder 20b, and can be sealed even when the inside is set to a high pressure.
Reference numeral 22 denotes an air filter for introducing clean air into the can 20. Clean air that has passed through the air supply pipe 24 from the air filter 22 is introduced into the sterilization chamber 21 through the intake valve 23.
[0015]
The ethylene oxide gas is enclosed in a cylinder (denoted as EOG in the drawing) and supplied into the sterilization chamber through a gas supply pipe 25 to which the cylinder is connected.
The gas supply pipe 25 is connected so that ethylene oxide gas can be introduced into the sterilization chamber 21 via the gas filter 27, the gas supply valve 30, and the vaporizer 26. In addition, the gas supply pipe 25 and the air supply pipe 24 are connected so as to become one on the way. A safety valve 29 is provided here.
Further, in order to humidify the inside of the sterilization chamber 21, a steam generator (not shown) is connected to the sterilization chamber 21 via the humidification valve 32.
[0016]
The gas supply means in the claims is a concept including a cylinder, a gas supply valve 30, a gas supply pipe 25, and the like.
[0017]
Reference numeral 34 denotes a vacuum pump. The vacuum pump 34 is connected to an exhaust pipe 36 extending outward from the sterilization chamber 21, and draws air in the sterilization chamber 21 to form a vacuum state.
The can body 20 is provided with at least two temperature sensors.
One of them is an outer cylinder temperature sensor 38, which measures the temperature of the outer cylinder 20a.
The other of the two temperature sensors is an inner cylinder temperature sensor 39. The inner cylinder temperature sensor 39 measures the temperature in the inner cylinder 20b.
Reference numeral 40 denotes a pressure sensor. The pressure sensor 40 is connected to the inner cylinder 20b so that the pressure in the sterilization chamber 21 can be measured.
[0018]
Reference numeral 42 denotes a CPU as control means. Here, the subtracting means and the comparing means referred to in the claims are a function of the CPU 42, and the CPU 42 includes the subtracting means and the comparing means.
The CPU 42 is connected to storage means 44 (memory) composed of ROM, RAM, and the like, and based on the sterilizer control program stored in advance in the storage means 44, each of the gas supply valves 30, the intake valves 23, The operation of the sterilizer is controlled by operating the humidifying valve 32 or the like.
Further, each of the vacuum pumps 34, the outer cylinder temperature sensor 38, the inner cylinder temperature sensor 39, and the pressure sensor 40 described above are connected to the CPU 42. The measuring means referred to in the claims includes the pressure sensor 40 and the CPU 42.
[0019]
In the storage means 44, a supply pressure value corresponding to a predetermined amount of ethylene oxide gas to be supplied is set and recorded in advance.
This supply pressure value is not based on the atmospheric pressure like the gauge pressure or on the basis of the degree of vacuum 0 like the absolute pressure. The pressure just before the gas supply is subtracted from the current pressure in the sterilization chamber. It is to adapt to the value.
This supply pressure value may be provided so that it can be changed by the user, but may be provided so that it cannot be changed by a preset supply pressure.
The supply pressure value is such a value that a larger amount is supplied into the sterilization chamber than at least the amount of ethylene oxide gas that can be sterilized.
[0020]
Reference numeral 48 denotes display means. The display means 48 includes a CRT monitor or a liquid crystal monitor capable of displaying characters, or a simple lamp provided so as to be able to determine the number of processes currently being performed. Such display means 48 is connected to the CPU 42, and the display contents and the like are controlled and displayed by the CPU 42.
Reference numeral 50 denotes a setting switch connected to the CPU 42. The setting switch 50 is provided so that the user can set the operation time of each process or the sterilization temperature.
[0021]
As described in the prior art, there are two types of sterilization apparatuses. One of them is a method in which the sterilization chamber is once evacuated before performing the sterilization step, and the other is a method in which the sterilization chamber is not evacuated but sterilized.
In the normal sterilization, the former method is used, but the latter method is often used when sterilizing an optical apparatus or the like that cannot withstand a vacuum state.
Of these two methods, the user can select either method by operating the setting switch 50 or the like.
[0022]
(First embodiment)
Next, FIG. 2 shows a pressure transition diagram in the case of the sterilization process using the sterilization apparatus of the present embodiment, and the first implementation based on a method of temporarily evacuating the sterilization chamber before performing the sterilization process. A form is demonstrated.
Sterilization consists of a plurality of different steps.
First, the heating process A is performed first. In the heating step A, an object to be sterilized in the sterilization chamber 21 is heated for a time preset by the user via the setting switch 50 under atmospheric pressure.
Following the heating step A, a humidification step B is performed. In the humidification process B, first, the inside of the sterilization chamber 21 is lowered to a predetermined degree of vacuum or less by forced exhaust by the vacuum pump 34. At this time, the vacuum pump 34 stops exhausting in a state where the air is drawn to the maximum. Next, steam is supplied into the sterilization chamber 21 while operating the vacuum pump 34 again. Subsequently, the supply of steam is stopped when the inside of the sterilization chamber 21 reaches a predetermined temperature, and the operation of supplying steam again is repeated when the temperature inside the sterilization chamber 21 becomes equal to or lower than the predetermined temperature. By this operation, the inside of the sterilization chamber 21 is humidified.
[0023]
After the humidification step B, a sterilization step C is performed.
First, in the sterilization process C, ethylene oxide gas is supplied by a pressure set in advance in the sterilization chamber 21.
When ethylene oxide gas is supplied for the set pressure, sterilization is performed for a preset time at a temperature preset by the user using the setting switch 50 before starting the sterilization process.
[0024]
After the sterilization process C is completed, a cleaning process D is performed. In the cleaning process D, pulse cleaning D1 is first performed, and then blow cleaning D2 is performed. Both the pulse cleaning D1 and the blow cleaning D2 are operated for a set time preset by the user using the setting switch 50 before starting the sterilization process.
Here, the pulse cleaning is to alternately perform forced exhaust in the sterilization chamber 21 and intake of outside air into the sterilization chamber 21, and blow cleaning refers to forced exhaust in the sterilization chamber 21 and introduction of outside air. This is a cleaning method in which the weight of the exhaust is increased and the sterilization chamber 21 is maintained in a negative pressure state while performing the above.
By performing such a cleaning process D, the ethylene oxide gas in the sterilization chamber 21 and the ethylene oxide gas adhering to the object to be sterilized can be efficiently and reliably removed.
[0025]
Although the entire sterilization process ends when the cleaning process D ends, an aeration process E may be added after the cleaning process D.
The aeration process E is performed in order to surely remove the ethylene oxide gas adhering to the article to be sterilized by simultaneously performing forced exhaust and intake of air in the sterilization chamber 21. The aeration process E is performed until the set time previously set by the setting switch 50 by the user ends or until the user forcibly ends.
[0026]
Next, the supply of ethylene oxide gas in the present embodiment will be described in more detail based on FIG. 3 and FIG. FIG. 3 is a flow chart summarizing the gas supply process until the gas supply is completed in the sterilization process C, including the heating process A and the humidification process B shown in FIG. These are pressure transition diagrams at the time of gas supply.
First, the conditioning process is started in step S100. In the conditioning process, the heating process A and the humidification process B as described above are performed, and the vacuum pump 34 is forcibly evacuated so that the inside of the sterilization chamber 21 is below a predetermined degree of vacuum.
When the inside of the sterilization chamber 21 becomes a predetermined vacuum level or less, the conditioning process ends, and the process proceeds to step S104.
[0027]
In step S <b> 104, the reached vacuum pressure P <b> 1 in the sterilization chamber 21 is measured by the pressure sensor 40. This vacuum pressure P1 is the end pressure described in the claims.
And it transfers to step S106 and gas supply is started. The gas is supplied by the CPU 42 operating the gas supply valve 30 and the like.
In step S108, a preset supply pressure value X is read from the storage means 44, and in the next step S110, the pressure sensor 40 measures the current pressure Px in the sterilization chamber during gas supply.
[0028]
In step S112, the supply pressure value X is compared with the pressure supplied so far. That is, by subtracting the vacuum pressure P1 from the current pressure Px, an increase pressure value Px-P1 is calculated as to how much pressure has increased since the vacuum, and the increase pressure value Px-P1 and the supply pressure value X are calculated. The comparison is made from time to time.
When the increased pressure value Px−P1 reaches the supply pressure value X, the process proceeds to step S114 to stop the gas supply, and the gas supply ends.
[0029]
In this way, since a supply pressure value is set so that a predetermined amount of ethylene oxide gas is supplied in advance so that a constant amount of gas is always supplied at the start of the sterilization process, a constant amount of ethylene oxide gas is always set. Can be supplied.
[0030]
(Second Embodiment)
FIG. 5 shows a pressure transition diagram of the second embodiment in which sterilization is performed without evacuating the sterilization chamber.
First, the heating / humidification step a is performed. In the heating / humidification step a, the object to be sterilized in the sterilization chamber 21 is heated for a time set in advance by the user via the setting switch 50 under the atmospheric pressure 0, and at the same time, the user enters the sterilization chamber 21 beforehand. The supplied water is vaporized and the inside of the sterilization chamber 21 is humidified. This warming / humidifying step a is a conditioning step referred to in the claims.
The sterilization step b is performed after the heating / humidification step a.
First, in the sterilization step b, ethylene oxide gas is supplied by a pressure set in advance in the sterilization chamber 21.
When ethylene oxide gas is supplied for the set pressure, sterilization is performed for a preset time at a temperature preset by the user using the setting switch 50 before starting the sterilization process.
[0031]
After the sterilization step b is completed, a cleaning step c is performed.
Although the entire sterilization process is completed when the cleaning process c is completed, an aeration process d may be added after the cleaning process c.
The aeration step d is performed in order to surely remove the ethylene oxide gas adhering to the article to be sterilized by simultaneously performing forced exhaust and intake of air in the sterilization chamber 21. The aeration step d is performed until the set time previously set by the setting switch 50 by the user ends or until the user forcibly ends.
[0032]
Next, the supply of ethylene oxide gas in the present embodiment will be described in more detail based on FIG. 6 and FIG.
FIG. 6 is a flowchart summarizing the gas supply process, and FIG. 7 is a pressure transition diagram during gas supply.
First, the conditioning process is started in step S120. In the conditioning process, the heating / humidification process a as described above is performed to heat the article to be sterilized.
If heating is performed for a predetermined time in step S122, the conditioning process ends, and the process proceeds to step S124.
[0033]
In step S124, the current pressure P0 in the sterilization chamber when ethylene oxide gas is supplied is measured by the pressure sensor 40. This P0 is the end pressure described in the claims.
And it transfers to step S126 and gas supply is started. The gas supply is performed by the CPU 42 operating the gas supply valve 30 and the like.
In step S128, the CPU 42 reads the preset supply pressure value Y from the storage means 44, and in the next step S130, the pressure sensor 40 measures the current pressure Py in the sterilization chamber during gas supply.
[0034]
In step S132, the supply pressure value Y is compared with the pressure supplied up to now. That is, by subtracting the pressure P0 at the time of ethylene oxide gas supply from the current pressure Py, an increase pressure value Py-P0 is calculated as to how much pressure has increased since the gas supply, and this increase pressure value Py-P0 and supply The pressure value Y is compared at any time.
When the increased pressure value Py-P0 reaches the supply pressure value Y, the process proceeds to step S134 to stop the gas supply, and the gas supply ends.
[0035]
In this way, a predetermined amount of ethylene oxide gas is supplied in advance so that a constant amount of gas is always supplied during the sterilization process, instead of supplying gas until the pressure value from atmospheric pressure is reached. Since such a supply pressure is set in advance, a certain amount of ethylene oxide gas is always supplied, and the reproducibility of the sterilization operation is good.
[0036]
While the present invention has been described in detail with reference to a preferred embodiment, the present invention is not limited to this embodiment, and it goes without saying that many modifications can be made without departing from the spirit of the invention. .
[0037]
【The invention's effect】
According to the ethylene oxide gas sterilization apparatus according to the present invention, since the ethylene oxide gas is supplied until the increased pressure value matches the supply pressure value, a constant amount of ethylene oxide gas can always be supplied, and the sterilization operation can be performed. It can be performed with good reproducibility. For this reason, it is convenient for management to record and manage the sterilization state. In addition, the ethylene oxide gas is not supplied and wasted.
It also has a vacuum pump that can evacuate the air in the sterilization chamber until a predetermined degree of vacuum is reached. The measuring means measures the vacuum pressure at the end of the conditioning process, and the subtracting means measures the vacuum pressure from the current pressure. By subtracting and calculating the increased pressure value, even when there is a variation in the degree of vacuum, a constant amount of ethylene oxide gas can be always supplied, and sterilization can be performed with good reproducibility. . For this reason, it is convenient for management to record and manage the sterilization state. In addition, the ethylene oxide gas is not supplied and wasted.
[Brief description of the drawings]
FIG. 1 is a piping system diagram of an ethylene oxide gas sterilization apparatus according to the present invention.
FIG. 2 is a pressure transition diagram illustrating the entire sterilization operation of the first embodiment.
FIG. 3 is a flowchart for explaining an ethylene oxide gas supply method according to the first embodiment;
FIG. 4 is a pressure transition diagram when supplying ethylene oxide gas according to the first embodiment.
FIG. 5 is a pressure transition diagram illustrating the entire sterilization operation of the second embodiment.
FIG. 6 is a flowchart for explaining an ethylene oxide gas supply method according to a second embodiment.
FIG. 7 is a pressure transition diagram when supplying ethylene oxide gas according to the second embodiment.
FIG. 8 is a pressure transition diagram when the sterilization chamber is evacuated when supplying a conventional ethylene oxide gas.
FIG. 9 is a pressure transition diagram when the sterilization chamber is not evacuated when a conventional ethylene oxide gas is supplied.
[Explanation of symbols]
20 can body 21 sterilization chamber 22, 27 filter 23 intake valve 24 air supply pipe 25 gas supply pipe 26 vaporizer 29 safety valve 30 gas supply valve 32 humidification valve 34 vacuum pump 36 exhaust pipe 38, 39 temperature sensor 40 pressure sensor 42 CPU ( Control means)
44 Storage means (ROM, RAM, etc.)
48 Display means 50 Setting switch

Claims (2)

A sterilization chamber for storing articles to be sterilized;
Gas supply means for supplying ethylene oxide gas into the sterilization chamber;
And a control unit that performs a conditioning process for heating and humidifying the sterilization chamber, and controls the sterilization process by supplying ethylene oxide gas into the sterilization chamber by the gas supply unit after the conditioning process is performed. In ethylene oxide gas sterilizer,
Measuring means for measuring the end pressure in the sterilization chamber at the end of the conditioning process and measuring the current pressure in the sterilization chamber as needed during the supply of ethylene oxide gas into the sterilization chamber by the gas supply means;
Subtracting means for subtracting the end pressure at the end of the conditioning process from the current pressure to calculate an increased pressure value;
A storage means in which a supply pressure value corresponding to a predetermined amount of ethylene oxide gas to be supplied into the sterilization chamber is set and recorded;
Comparing means for comparing whether or not the increased pressure value calculated by the subtracting means matches the supply pressure value recorded in the storage means,
The control means includes
As a result of comparison by the comparison means, when the increased pressure value matches the supply pressure value, the ethylene oxide gas sterilization apparatus controls the gas supply means to stop the supply of ethylene oxide gas. . A vacuum pump for exhausting until the pressure in the sterilization chamber becomes a predetermined vacuum level or less during the conditioning step;
The measuring means measures the pressure in vacuum at the end of the conditioning process,
2. The ethylene oxide gas sterilizer according to claim 1, wherein the subtracting unit calculates an increased pressure value by subtracting the vacuum pressure from the current pressure.

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