JP6966077B2 - Gas sterilizer - Google Patents

Description

The present invention relates to a gas sterilizer using a gas such as saturated steam or sterilizing gas as a sterilizing agent.

In hospitals, pharmaceutical companies, food companies, chemical companies, etc., it is necessary to sterilize various articles as objects to be sterilized. There are various types of sterilizers for performing sterilization, but steam sterilizers use steam as a sterilizer, so they have the advantages of being non-toxic, easily available, and relatively easy to manage. Yes, it has been often used in the past.

The steam sterilizer is provided with a sterilization tank (pressure vessel or pressure-resistant airtight container) for accommodating the object to be sterilized, and the sterilization of the object to be sterilized by introducing saturated steam at a predetermined temperature (predetermined pressure) into the sterilization vessel for a predetermined time. Perform the action.

The steam sterilizer of Patent Document 1 is provided with an absolute pressure sensor for measuring absolute pressure, and is provided with a three-way valve for selectively connecting either the inside of the sterilization chamber or the atmosphere to the absolute pressure sensor, prior to the vacuum process. Alternatively, after the sterilization process, the absolute pressure sensor is controlled to connect to the atmosphere to measure the atmospheric pressure, and after the sterilization process is completed, the three-way valve is controlled so that the absolute pressure sensor is connected to the inside of the sterilization chamber. It is disclosed to measure the internal pressure of the sterilization chamber.

Further, as a sterilizer, in addition to the steam sterilizer as described above, a gas sterilizer using a gas such as ethylene oxide gas, hydrogen peroxide gas, or carbon dioxide gas is also known.
For example, a gas sterilizer as shown in Patent Document 2 uses ethylene oxide gas as a sterilizer. This gas sterilizer introduces ethylene oxide gas into a sterilization tank whose pressure is below a predetermined pressure by a vacuum pump, calculates the gas concentration based on the pressure value in the sterilization tank, and requires sterilization based on the calculated gas concentration. I try to set the time.

Japanese Patent No. 5869966 Japanese Unexamined Patent Publication No. 2012-35013

In the steam sterilizer of Patent Document 1, both the atmospheric pressure and the internal pressure are confirmed by one absolute pressure sensor, but it is not possible to reliably detect the high pressure abnormality of the internal pressure of the sterilization chamber at the time of sterilization. Since the pressure difference between the sterilization chamber pressure and the atmospheric pressure cannot be accurately determined, there is a problem that there is a risk of danger when opening and closing the door.

When the pressure in the sterilization chamber is measured using the gauge pressure sensor, the pressure difference between the sterilization chamber pressure and the atmospheric pressure can be reliably measured.
However, in the gauge pressure sensor, when calculating the saturated steam temperature, the temperature must be calculated based on the assumed standard atmospheric pressure, and there is a problem that the saturated steam temperature cannot be calculated accurately.

In the case of a gas sterilizer as in Patent Document 2, the gas concentration in the sterilization tank is an important factor for sterilization performance. Then, how long the sterilization time should be set according to the gas concentration in the sterilization tank. Further, in the case of a gas sterilizer, it is necessary to calculate the remaining amount of air in the sterilization tank and the gas suction pressure, which are calculated based on the pressure inside the sterilization tank measured by the gauge pressure sensor. However, since the pressure inside the sterilization tank by the gauge pressure sensor is a value based on the assumed standard atmospheric pressure, there is a problem that the remaining amount of air in the sterilization tank and the gas suction pressure may have a slight error. ..

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a sterilizer capable of accurately measuring various values such as temperature and remaining amount of air.

According to the gas sterilizer according to the present invention, in a gas sterilizer in which steam, gas or other gas is used as a sterilizer, a sterilization tank provided with a door for opening and closing an opening and accommodating an object to be sterilized inside. A first sensor that measures the pressure in the sterilization tank with absolute pressure, a second sensor that measures atmospheric pressure with absolute pressure, and a pressure value in the sterilization tank measured by the first sensor. A control in which the atmospheric pressure value measured by the second sensor is input and the pressure difference between the sterilization tank internal pressure and the atmospheric pressure is calculated by comparing the input atmospheric pressure value with the atmospheric pressure value. It is characterized by having a part and.
By adopting this configuration, the absolute pressure sensor can be used, and all the disadvantages of the absolute pressure sensor and the gauge pressure sensor can be eliminated. That is, the pressure difference between the internal pressure of the sterilization tank and the atmospheric pressure can be accurately calculated by using two absolute pressure sensors.

Further, a monitor controlled by the control unit is provided, and the control unit determines that the door can be opened and closed if the calculated pressure difference is within a predetermined range, and the calculated pressure difference is obtained. If is out of the predetermined range, it may be determined that the door cannot be opened and closed, and the determination result may be controlled to be displayed on the monitor.
According to this configuration, safety when opening and closing the door can be ensured.

Further, the control unit compares the values measured by the first sensor and the second sensor when the door is opened, and if the values do not match, the first sensor It may be characterized in that it is determined that either the sensor or the second sensor is abnormal.
According to this configuration, it is generally difficult to detect an abnormality in the pressure sensor in the sterilizer, but it is possible to easily detect an abnormality in the sensor.

According to the sterilizer of the present invention, various values such as temperature and remaining air can be accurately calculated by using the absolute pressure sensor.

It is a piping system diagram of the steam sterilizer of 1st Embodiment. It is a piping system diagram of the ethylene oxide gas sterilization apparatus of the 2nd Embodiment.

(First Embodiment)
Hereinafter, a steam sterilizer as an example of a gas sterilizer will be described with reference to the drawings.
FIG. 1 is an example of a piping system diagram of the steam sterilizer according to the first embodiment.
The steam sterilizer 30 includes a sterilization tank 32 that houses the object to be sterilized and performs sterilization treatment. The sterilization tank 32 is composed of a pressure vessel or a pressure-resistant airtight vessel in order to raise the internal pressure to a predetermined sterilization pressure.

Further, since the sterilizer 32 of FIG. 1 shows a schematic configuration viewed from the side, the steam sterilizer originally has a double cylinder structure consisting of an inner cylinder and an outer cylinder. However, the illustration of this double cylinder structure is not shown. It is omitted, and the structural description of the double cylinder structure is also omitted in the following description.
Further, the opening of the sterilization tank 32 has a door 31 that can seal the inside of the sterilization tank 32.

A saturated steam pipe 34 provided with an on-off valve 35 is connected to the sterilization tank 32. As a result, saturated steam from the saturated steam pipe 34 is introduced into the sterilization tank 32. The upstream side of the saturated steam pipe 34 is connected to a saturated steam supply device (not shown) provided outside the steam sterilizer 30.
The saturated steam introduced into the sterilization tank 32 is pure steam and is clean steam containing no impurities.

Further, an air supply pipe 36 for supplying compressed air into the sterilization tank 32 is connected between the on-off valve 35 of the saturated steam pipe 34 and the sterilization tank 32. A filter 38 is provided in the air supply pipe 36, and clean air that has passed through the filter 38 can be introduced into the sterilization tank 32. Further, the air supply pipe 36 is provided with an on-off valve 39.

An exhaust pipe 40 for discharging drain, steam, and air in the sterilization tank is connected to the bottom of the sterilization tank 32.
An on-off valve 42 and a vacuum pump 44 are connected to the branch pipe 41 branched from the exhaust pipe 40.

Further, since the gas in the sterilization tank 32 to be discharged is in a state where steam and water as a liquid are mixed, the vacuum pump 44 is preferably a water-sealed type. Therefore, a water supply pipe 46 is connected between the vacuum pump 44 and the on-off valve 42 via the tank 48. The water supply pipe 46 is provided with an on-off valve 47.

In the exhaust pipe 40, a first pressure sensor 50 is provided on the downstream side of the branch pipe 41, and two on-off valves 51 and 52 are provided in series further downstream of the first pressure sensor 50. An automatic relief valve 54 is provided in parallel with the on-off valve 52 on the downstream side.
The downstream side of the on-off valve 52 and the downstream side of the automatic relief valve 54 merge with the drainage / exhaust pipe 55 of the vacuum pump 44.

Further, the air supply pipe 36 is also provided with a branch pipe 56 that branches on the upstream side of the filter 38. The branch pipe 56 is provided with an on-off valve 57, which joins the drain / exhaust pipe 55 of the vacuum pump 44 on the downstream side of the on-off valve 57.

Further, the first pressure sensor 50 is connected to the control unit 58, and the measured pressure value is input to the control unit 58.
A second pressure sensor 60 having an open end is connected to the control unit 58. The second pressure sensor 60 having an open end measures the atmospheric pressure regardless of the piping, and inputs the measured atmospheric pressure value to the control unit 58.
The control unit 58 has a central processing unit such as a CPU and a memory such as a ROM and RAM, and executes operation control of the entire device based on a preset program.

Both the first pressure sensor 50 and the second pressure sensor 60 use an absolute pressure sensor. The absolute pressure expresses the pressure with the pressure at the time of absolute vacuum as 0. On the other hand, the gauge pressure is a pressure based on atmospheric pressure.

Further, a temperature sensor 64 for measuring the temperature inside the sterilization tank 32 is provided. The temperature sensor 64 is connected to the control unit 58, and the measured temperature data is input to the control unit 58.

A monitor 62 is connected to the control unit 58. The monitor 62 is composed of a touch panel monitor. The operator can touch the monitor 62 to input the operation content, and can display the operation management screen and the history management screen.
Further, the monitor 62 can display a monitoring screen of saturated steam during the sterilization step of opening and closing the door 31, as will be described later.

Hereinafter, the calculation of the pressure in the sterilization tank 32 based on the pressure sensor in the present embodiment will be described.
The pressure value input from the first pressure sensor 50 and the atmospheric pressure value input from the second pressure sensor 60 are constantly input to the control unit 58.
To determine whether the steam in the sterilization tank 32 is filled with saturated steam, the control unit 58 calculates the saturation temperature from a calculation formula stored in advance based on the pressure value of the first pressure sensor 50, and determines the temperature. It can be determined by comparing whether or not the temperature measured by the sensor 64 matches the calculated saturation temperature.

Further, the detection of the high pressure abnormality in the sterilization tank 32 cannot be determined only by the pressure value from the first pressure sensor 50. This is because the inside of the sterilization tank 32 is isolated from the outside, so it cannot be determined by absolute pressure whether or not it is abnormal.
Therefore, the control unit 58 constantly compares the pressure value from the first pressure sensor 50 with the atmospheric pressure value from the second pressure sensor 60 to calculate the pressure difference between the sterilization tank internal pressure and the atmospheric pressure. When the pressure difference (when the internal pressure of the sterilization tank 32 is larger than the atmospheric pressure) is equal to or more than a predetermined value, the control unit 58 determines that the inside of the sterilization tank 32 has a high pressure abnormality.
When the control unit 58 determines that the inside of the sterilization tank 32 has a high pressure abnormality, the control unit 58 displays that fact on the monitor 62. Further, the control unit 58 may not only display the high voltage abnormality on the monitor 62 but also notify the operator's hearing that the high pressure abnormality is present by, for example, sounding an alarm sound. ..

Further, when the door 31 is opened after the sterilization step and the drying step are completed, it is necessary to confirm the pressure difference between the internal pressure of the sterilization tank 32 and the atmospheric pressure. This is because it is dangerous to open the door 31 when there is a pressure difference between the internal pressure of the sterilization tank 32 and the atmospheric pressure.
Therefore, the control unit 58 determines that the door 31 can be opened and closed if the pressure value of the first pressure sensor 50 and the pressure difference of the second pressure sensor 60 are within a predetermined range, and the calculated pressure difference is calculated. If it is outside the predetermined range, it can be determined that the door 31 cannot be opened or closed.
Then, the control unit 58 can control the determination result to be displayed on the monitor 62. In this way, the operator can safely open and close the door 31 by displaying on the monitor 62 whether or not the door can be opened and closed.

Further, the control unit 58 compares the value measured by the first pressure sensor 50 with the value measured by the second pressure sensor 60 while the door 31 is open, and if the values do not match, the control unit 58 compares the value measured by the first pressure sensor 50 with the value measured by the second pressure sensor 60. , It can be determined that any one of the first pressure sensor 50 and the second pressure sensor 60 is abnormal.
Then, when it is determined that any one of the two pressure sensors is abnormal, the control unit 58 may control so as to display the fact on the monitor 62.

(Second Embodiment)
The above-described embodiment was for a saturated steam sterilizer, but an embodiment of an ethylene oxide gas sterilizer will be described below as an example of the gas sterilizer.
The same components as those in the above-described embodiment are designated by the same reference numerals, and the description thereof may be omitted.

FIG. 2 is a piping system diagram of the ethylene oxide gas sterilizer 70.
Ethylene oxide gas is introduced from a cylinder (not shown) or a gas supply pipe 72 connected to the outside. The gas supply pipe 72 is provided with a plurality of on-off valves 74 and 75, and a filter 76 is provided between them.
Further, the gas supply pipe 72 is connected to the vaporizer 78. The vaporizer 78 is configured to heat the gas in the gas supply pipe 72 by the steam pipe 80.

The gas supply pipe 72 coming out of the vaporizer 78 merges with the air supply pipe 84 and is connected to the sterilization tank 32. The air supply pipe 84 is provided with a filter 85 and an on-off valve 86.

The steam pipe 80 is provided with an on-off valve 82 on the upstream side of the vaporizer 78, and is branched into a pipe introduced into the vaporizer 78 and a pipe introduced into the sterilizer tank 32. An on-off valve 83 is provided on the side introduced into the sterilization tank 32.

Further, a branch pipe 88 that branches from the upstream side of the on-off valve 82 of the steam pipe 80 to the drainage / exhaust pipe 55 is provided. An on-off valve 87 is provided in the middle of the branch pipe 88.

Even in a gas sterilizer such as the ethylene oxide gas sterilizer 70, a first pressure sensor 50 is provided on the downstream side of the branch pipe 41 in the exhaust pipe 40, and the first pressure sensor 50 is provided. It is connected to the control unit 58, and the measured pressure value is input to the control unit 58.
A second pressure sensor 60 having an open end is connected to the control unit 58. The second pressure sensor 60 having an open end measures the atmospheric pressure regardless of the piping, and inputs the measured atmospheric pressure value to the control unit 58.

In the gas sterilizer, when measuring the gas concentration in the sterilizer 32, the pressure in the sterilizer 32 is measured. This is because the concentration can be calculated from the temperature and pressure.
Therefore, when measuring the gas concentration, the control unit 58 constantly compares the pressure value from the first pressure sensor 50 with the atmospheric pressure value from the second pressure sensor 60 to determine the internal pressure in the sterilization tank and the atmospheric pressure. The pressure difference can be calculated and used as the pressure value in the sterilization tank 32.
As described above, even in the gas sterilizer, the pressure in the sterilization tank 32 can be reliably measured by using the absolute pressure sensor without using the gauge pressure sensor.

Further, in the gas sterilizer, each step is executed in the order of preheating step, pressure leak test, vacuum leak test, pulse heating step, humidification step, and gas supply step before the start of the sterilization step.
At this time, in the sterilization tank 32, the amount of water supplied by the recovery pressure at the time of humidification is estimated and measured by the first pressure sensor 50 which is an absolute pressure sensor when shifting to the humidification step after the completion of the heating step. The remaining amount of air in the sterilization tank 32 can be accurately calculated based on the pressure value.

Further, although it is necessary to calculate an accurate gas concentration during the sterilization step, the accurate gas concentration is calculated based on the pressure value in the sterilization tank 32 measured by the first pressure sensor 50 which is an absolute pressure sensor. be able to.

Further, by arranging the temperature sensors at various places in the sterilization tank 32, it is possible to calculate the accurate gas concentration distribution in the sterilization tank 32.

30 Steam sterilizer 31 Door 32 Sterilization tank 34 Saturated steam piping 35 On-off valve 36 Air supply pipe 38 Filter 39 On-off valve 40 Exhaust pipe 41 Branch pipe 42 On-off valve 44 Vacuum pump 46 Water supply pipe 47 On-off valve 48 Tank 50 First pressure sensor 51 On-off valve 52 On-off valve 54 Automatic relief valve 55 Drainage / exhaust pipe 56 Branch pipe 57 On-off valve 58 Control unit 60 Second pressure sensor 62 Monitor 64 Temperature sensor 70 Ethylene oxide gas sterilizer 72 Gas supply pipe 74 On-off valve 76 Filter 78 Vaporization Vessel 80 Steam piping 82 On-off valve 83 On-off valve 84 Air supply pipe 85 Filter 86 On-off valve 87 On-off valve 88 Branch pipe

Claims (3)

In a saturated steam sterilizer
A sterilization tank with a door that opens and closes the opening and stores the object to be sterilized inside
A first sensor that measures the pressure in the sterilization tank as an absolute pressure,
A second sensor that measures atmospheric pressure in absolute pressure,
A temperature sensor that measures the temperature inside the sterilization tank and
The temperature data in the sterilization tank measured by the temperature sensor is input, and the pressure value in the sterilization tank measured by the first sensor and the atmospheric pressure value measured by the second sensor are input. It has a control unit for calculating the pressure difference between the sterilization tank internal pressure and the atmospheric pressure by comparing the input sterilization tank internal pressure value with the atmospheric pressure value.
The control unit calculates the saturation temperature from a calculation formula stored in advance based on the pressure value of the first sensor, and the temperature in the sterilization tank measured by the temperature sensor coincides with the calculated saturation temperature. By comparing whether or not to do so, it is determined whether or not the steam in the sterilization tank is filled with saturated steam.
A saturated steam sterilizer, characterized in that, when the pressure difference is equal to or greater than a predetermined value, the control unit determines that the inside of the sterilization tank has a high pressure abnormality. A monitor controlled by the control unit is provided.
The control unit
If the calculated pressure difference is within a predetermined range, it is determined that the door can be opened and closed.
If the calculated pressure difference is out of the predetermined range, it is determined that the door cannot be opened or closed.
The saturated steam sterilizer according to claim 1, wherein the determination result is controlled so as to be displayed on the monitor. The control unit compares the values measured by the first sensor and the second sensor when the door is opened, and if the values do not match, the first sensor and the second sensor. The saturated steam sterilizer according to claim 1 or 2, wherein any one of the second sensors is determined to be abnormal.

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