JP6807603B2 - Steam sterilizer - Google Patents

Description

The present invention relates to a steam sterilizer that sterilizes an object to be sterilized with saturated steam.

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 vessel) for accommodating the object to be sterilized, and sterilizes 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 to do.
By the way, it is necessary to use saturated steam in order to carry out sterilization reliably, but unsaturated steam that is not saturated steam may be introduced into the sterilization tank for various reasons.

Patent Document 1: In Japanese Patent Application Laid-Open No. 4-122261, correlation data between temperature and pressure showing saturated steam characteristics is stored in advance, and the actual temperature and pressure in the sterilization tank are detected to detect the temperature and pressure in the sterilization tank. A steam sterilizer for determining whether a steam is saturated steam is disclosed.
Then, the steam sterilizer of Patent Document 1 opens a valve that communicates inside and outside the sterilization tank when it is determined to be unsaturated steam, and discharges residual air having a specific gravity larger than that of steam to the outside by the pressure of steam. Operate.

Japanese Unexamined Patent Publication No. 4-122261

In the steam sterilizer of Patent Document 1, when the inside of the sterilization tank reaches a predetermined temperature before the start of the sterilization step, it is determined whether the steam is saturated steam or unsaturated steam based on the correlation data based on the relationship between pressure and temperature. There is.
In this way, if the determination of saturated steam or unsaturated steam is performed only before the actual start of the sterilization process, reliable sterilization cannot be performed if the steam is no longer saturated steam for some reason during the sterilization process. There is a problem.

Further, Patent Document 1 discloses that when it is determined that the vapor is unsaturated vapor, the residual air is discharged to control the vapor so that the vapor becomes saturated.
However, the cause of the unsaturated steam in the sterilization tank is not only the presence of residual air but also other causes. Therefore, the apparatus of Patent Document 1 can surely turn the unsaturated steam into saturated steam. There is a problem that it cannot be done.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to ensure that the state of saturated steam is constantly monitored during the sterilization process and that accurate control is performed when it is determined that the state is not saturated. It is to provide a steam sterilizer for carrying out a sterilization process.

According to the steam sterilization apparatus according to the present invention, a sterilization tank for accommodating an object to be sterilized, a saturated steam pipe for supplying saturated steam introduced from the outside of the apparatus into the sterilization tank, and a periphery of the sterilization tank are provided. , A jacket portion to which the saturated steam pipe or a steam pipe different from the saturated steam pipe is connected, a pressure sensor for measuring the pressure in the sterilization tank, and a temperature sensor for measuring the temperature in the sterilization tank. A drain drain pipe for draining the drain in the sterilization tank, a drain valve for opening and closing the drain drain pipe, an exhaust pipe for exhausting the gas in the sterilization tank, and an exhaust valve for opening and closing the exhaust pipe. The control unit includes a storage device in which a calculation formula for calculating the saturated steam temperature at a predetermined pressure is stored in advance, and a control unit for determining whether or not the steam in the current sterilization tank is saturated steam. , (A): The saturated steam temperature is calculated from the pressure value measured by the pressure sensor based on the above formula. (B): The difference between the current temperature and the saturated steam temperature is calculated by subtracting the saturated steam temperature calculated in the step (a) from the temperature measured by the temperature sensor. (C): When the difference calculated in the step (b) is within the range of the upper limit threshold value or less and the lower limit threshold value or more, it is determined that the steam in the sterilization tank is saturated steam, and the sterilization step is continued as it is. .. (D): When the difference calculated in the step (b) exceeds the upper limit threshold, it is determined that the steam in the sterilization tank is superheated steam, and the temperature of the steam introduced into the jacket portion is lowered. The temperature in the sterilization tank is lowered, and the drain valve is closed to promote the evaporation of the drain. (E): When the difference calculated in the step (b) is less than the lower limit threshold value, it is determined that the steam in the sterilization tank is wet steam or there is a possibility that non-condensable gas remains, and the jacket portion. By raising the temperature of the steam introduced into the sterilizer, the temperature inside the sterilization tank is controlled to rise. (F) be performed :( e) step, (b) If the difference calculated in step is less than the lower limit threshold value, open the exhaust valve, control to perform a degassing operation of the sterilization chamber To do. After performing the degassing operation, saturated steam is supplied until the pressure in the sterilization tank reaches a predetermined pressure. (G): The difference calculated in the steps (b) by executing the steps (a) to (c) during the steps (d) to (f) is within the range of the upper limit threshold and the lower limit threshold or more. In this case, it is determined that the steam in the sterilization tank is saturated steam, the steps (d) to (f) are completed, and the sterilization step is continued. The above steps (a) to (g) are characterized in that they are always executed during the sterilization step.
By adopting this configuration, the operations (a) to (g) are always executed during the sterilization process, so that the steam in the sterilization tank is no longer saturated steam for some reason during the sterilization process. Also, a reliable sterilization process can be performed. Further, since the control is performed based on each cause of the unsaturated steam, it is possible to surely recover from the unsaturated steam state to the saturated steam state.

In addition, the control unit executes the steps (a) to (b) a predetermined number of times in a cycle of negative pressure, steam supply, and steam discharge, and sterilizes after the completion of the conditioning step of discharging the air in the sterilization tank. When the process is executed until the start of the process and the temperature in the sterilization tank reaches the start temperature of the sterilization process, if the difference calculated in step (b) is within the upper limit threshold and the lower limit threshold or more, sterilization is performed. The sterilization step is started by determining that the steam in the tank is saturated steam, and if the difference calculated in the step (b) exceeds the upper limit threshold, the step (d) is executed and the step (d) is executed. b) If the difference calculated in the step (b) is less than the lower limit threshold, the difference calculated in the step (b) is less than the limit threshold even if the step (e) is executed and the step (e) is executed. In this case, the step (f) is executed, and the steps (a) to (c) are executed during the steps (d) to (f), and the difference calculated in the step (b) is equal to or less than the upper limit threshold value. If it falls within the range above the lower limit, it may be determined that the steam in the sterilization tank is saturated steam, the steps (d) to (f) may be terminated, and the sterilization step may be started. ..
According to this configuration, at the start of the sterilization step, it is determined whether or not it is saturated steam, if it is saturated steam, the sterilization step is started, and if it is determined that it is not saturated steam, it becomes saturated steam. The sterilization step can be started after it is determined that the vapor is saturated after performing various operations. Therefore, a reliable sterilization process can be performed.

According to the steam sterilization apparatus according to the present invention, a sterilization tank for accommodating an object to be sterilized, a saturated steam pipe for supplying saturated steam introduced from the outside of the apparatus into the sterilization tank, and a periphery of the sterilization tank are provided. , A jacket portion to which the saturated steam pipe or a steam pipe different from the saturated steam pipe is connected, a pressure sensor for measuring the pressure in the sterilization tank, and a temperature sensor for measuring the temperature in the sterilization tank. A drain drain pipe for draining the drain in the sterilization tank, a drain valve for opening and closing the drain drain pipe, an exhaust pipe for exhausting the gas in the sterilization tank, and an exhaust valve for opening and closing the exhaust pipe. The control unit includes a storage device in which a calculation formula for calculating the saturated steam pressure at a predetermined temperature is stored in advance, and a control unit for determining whether or not the steam in the current sterilization tank is saturated steam. , (A): The saturated vapor pressure is calculated from the temperature measured by the temperature sensor based on the above formula. (B): The difference between the current pressure and the saturated steam pressure is calculated by subtracting the saturated steam pressure calculated in the step (A) from the pressure value measured by the pressure sensor. (C): When the difference calculated in the step (B) is within the range of the upper limit threshold value or less and the lower limit threshold value or more, it is determined that the steam in the sterilization tank is saturated steam, and the sterilization step is continued as it is. .. (D): When the difference calculated in the step (B) exceeds the upper limit threshold, it is determined that the steam in the sterilization tank is superheated steam, and the temperature of the steam introduced into the jacket portion is lowered. The temperature in the sterilization tank is lowered, and the drain valve is closed to promote the evaporation of the drain. (E): When the difference calculated in the step (B) is less than the lower limit threshold value, it is determined that the steam in the sterilization tank is moist steam or there is a possibility that non-condensable gas remains, and the jacket portion. By raising the temperature of the steam introduced into the sterilizer, the temperature inside the sterilization tank is controlled to rise. (F) be performed :( E) step, (B) if the difference calculated in step is less than the lower limit threshold value, open the exhaust valve, control to perform a degassing operation of the sterilization chamber To do. After performing the degassing operation, saturated steam is supplied until the pressure in the sterilization tank reaches a predetermined pressure. (G): The difference calculated in the steps (B) by executing the steps (A) to (C) during the steps (D) to (F) is within the range of the upper limit threshold and the lower limit threshold or more. In this case, it is determined that the steam in the sterilization tank is saturated steam, the steps (D) to (F) are completed, and the sterilization step is continued. The above steps (A) to (G) are characterized in that they are always executed during the sterilization step.
By adopting this configuration, the operations (A) to (G) are always executed during the sterilization process, so that the steam in the sterilization tank is no longer saturated steam for some reason during the sterilization process. Also, a reliable sterilization process can be performed. Further, since the control is performed based on each cause of the unsaturated steam, it is possible to surely recover from the unsaturated steam state to the saturated steam state.

Further, the control unit executes the steps (A) to (B) a predetermined number of times in a cycle of negative pressure, steam supply, and steam discharge, and sterilizes after the completion of the conditioning step of discharging the air in the sterilization tank. If the difference calculated in step (B) is within the range below the upper limit threshold and above the lower limit threshold, it is determined that the steam in the sterilization tank is saturated steam, and the sterilization step is performed. Start, if the difference calculated in step (B) exceeds the upper limit threshold, the step (D) is executed, and if the difference calculated in step (B) is less than the lower limit threshold, the step (D) is executed. If the difference calculated in the step (B) is less than the limit threshold even after the step (E) is executed and the step (E) is executed, the step (F) is executed and (D) to If the difference calculated in step (B) by executing steps (A) to (C) during step (F) is within the range below the upper limit threshold and above the lower limit threshold, the steam in the sterilization tank. It may be characterized in that is determined to be saturated steam, the steps (D) to (F) are completed, and the sterilization step is started.
According to this configuration, at the start of the sterilization step, it is determined whether or not it is saturated steam, if it is saturated steam, the sterilization step is started, and if it is determined that it is not saturated steam, it becomes saturated steam. The sterilization step can be started after it is determined that the vapor is saturated after performing various operations. Therefore, a reliable sterilization process can be performed.

Further, a monitor may be provided, and the control unit may be controlled so as to constantly display the difference between the current temperature and the saturated steam temperature calculated in the step (b) or the step (B).
According to this configuration, the operator can grasp the current state in the sterilization tank in real time.

Further, the control unit may be characterized in that it controls to display the current difference on an indicator displaying a negative numerical value to a positive numerical value.
According to this configuration, the operator can intuitively grasp the current state in the sterilization tank in an instant.

According to the steam sterilizer of the present invention, a reliable sterilization step can be executed by constantly monitoring the state of saturated steam during the sterilization step and executing accurate control when it is determined that the state is not saturated.

It is a piping system diagram of a steam sterilizer. It is a flowchart explaining operation of 1st Embodiment of a steam sterilizer. It is a continuation flowchart of FIG. It is a continuation flowchart of FIG. It is a flowchart explaining the operation before the sterilization process in 1st Embodiment. It is a continuation flowchart of FIG. It is a continuation flowchart of FIG. It is a flowchart explaining operation of 2nd Embodiment of a steam sterilizer. It is a continuation flowchart of FIG. It is a continuation flowchart of FIG. It is a flowchart explaining the operation before the sterilization process in 2nd Embodiment. It is a continuation flowchart of FIG. It is a continuation flowchart of FIG. It is explanatory drawing explaining the example of the saturated steam monitoring screen.

(First Embodiment)
Hereinafter, the steam sterilizer will be described with reference to the drawings.
FIG. 1 is 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, the sterilization tank 32 has a double cylinder structure consisting of an inner cylinder 35 and an outer cylinder 37. The space between the outer wall surface of the inner cylinder 35 and the inner wall surface of the outer cylinder 37 is the jacket portion 34.
The inside of the inner cylinder 35 is configured as a chamber 38 for accommodating an object to be sterilized.

A steam pipe 39 is connected to the jacket portion 34, and steam from the steam pipe 39 is introduced into the jacket portion 34. Since the jacket portion 34 is a portion where steam is introduced to heat the chamber 38, the steam introduced into the jacket portion 34 does not have to be clean saturated steam. Therefore, in the present embodiment, the steam introduced from the steam pipe 39 is referred to as general steam.

The upstream side of the steam pipe 39 is connected to a steam supply device (not shown) provided outside the steam sterilizer 30, and the general steam introduced into the jacket portion 34 is outside the steam sterilizer 30. Supplied from. An on-off valve 40 for opening and closing the steam pipe 39 is provided in the middle of the steam pipe 39.
By introducing general steam into the jacket portion 34, the inside of the sterilization tank 32 (chamber 38) can be heated.

A saturated steam pipe 42 for supplying clean saturated steam is connected to the chamber 38. The saturated steam pipe 42 is provided with an on-off valve 43.
Further, an air supply pipe 44 for supplying air into the chamber 38 is connected between the on-off valve 40 of the saturated steam pipe 42 and the chamber 38. A filter 46 is provided in the air supply pipe 44, and clean air that has passed through the filter 46 can be introduced into the chamber 38. Further, the air supply pipe 44 is provided with a check valve 47 and an on-off valve 48.

An exhaust pipe 50 for discharging drain, steam, and air in the chamber 38 is connected to the bottom of the chamber 38.
Further, a drain in the jacket portion 34 and an exhaust pipe 52 for discharging steam are connected to the bottom portion of the jacket portion 34.
These two exhaust pipes 50 and 52 merge on the downstream side to form one exhaust pipe 53, which can be discharged to the outside.

A vacuum pump exhaust pipe 55 is provided, which branches off from the exhaust pipe 50 of the chamber 38 and connects to the vacuum pump 54. An on-off valve 56 and a check valve 57 are provided between the vacuum pump 54 and the exhaust pipe 50 of the vacuum pump exhaust pipe 55.
Since the gas in the chamber 38 discharged through the exhaust pipe 50 is in a state where vapor, liquid, and liquid water are mixed, the vacuum pump 54 is preferably a water-sealed type. Therefore, the vacuum pump 54 is connected to the vacuum pump water supply pipe 59 provided with the on-off valve 61 and the vacuum pump exhaust / drain pipe 58. A check valve 60 is provided in the exhaust / drain pipe 58 for the vacuum pump.

An exhaust pipe 62 is provided separately from the vacuum pump exhaust pipe 55, branching from the exhaust pipe 50 of the chamber 38. The exhaust pipe 62 is provided with an exhaust valve 63 and a check valve 64.

The exhaust pipe 50 of the chamber 38 is provided with a drain valve 65, a drain trap 66, and a check valve 67 before merging with the exhaust pipe 53.
Further, the exhaust pipe 52 from the jacket portion 34 is provided with a drain trap 68 and a check valve 69.

A temperature sensor 70 for measuring the temperature inside the chamber and a pressure sensor 72 for measuring the pressure inside the chamber are provided in the chamber 38.
The temperature sensor 70 and the pressure sensor 72 are connected to the control unit 74. The control unit 74 has a central processing unit such as a CPU and a memory such as a ROM and a RAM, and executes operation control of the entire device based on a preset program.

The temperature sensor 70 and the pressure sensor 72 constantly measure the temperature and pressure from the end of the conditioning process to the start of the sterilization process and during the sterilization process, and are measured by the temperature and pressure sensor 72 measured by the temperature sensor 70. The pressure value is constantly input to the control unit 74.
The control unit 74 constantly determines whether or not the steam in the chamber 38 is saturated steam during the sterilization process, and if it is determined that the steam is not saturated steam, the chamber 38 is filled with saturated steam based on predetermined conditions. Perform each control as follows. The details of this control will be described later.

Further, a storage device 76 is provided, and the storage device 76 stores in advance a calculation formula for calculating the saturated steam temperature at a predetermined pressure. However, the storage device 76 may be provided separately from the control unit 74, or may be included in the control unit 74.

A monitor 77 is connected to the control unit 74. The monitor 77 is composed of a touch panel monitor. The operator can touch the monitor 77 to input the operation content, and can display the operation management screen and the history management screen. Further, the monitor 77 can display a monitoring screen of saturated steam during the sterilization process.

The overall operation of the steam sterilizer 30 of the present embodiment will be described with reference to FIGS. 2 to 4.
The steam sterilizer 30 executes a conditioning step (step S100) for discharging the air in the chamber 38 as a preliminary step of the sterilization step.
In the conditioning step, the control unit 74 drives the vacuum pump 54 to create a negative pressure in the chamber 38, and then stops the operation of the vacuum pump 54. Then, the control unit 74 opens the on-off valve 43 and supplies saturated steam into the chamber 38.

When the control unit 74 determines that the pressure in the chamber 38 has reached a preset predetermined pressure based on the pressure in the chamber 38 by the pressure sensor 72, the on-off valve 43 is closed to supply saturated steam. Stop.
Then, the control unit 74 drives the vacuum pump 54 to discharge the steam in the chamber 38, and makes the inside of the chamber 38 a negative pressure.
The control unit 74 repeats such a cycle of negative pressure, steaming, and steam discharge a predetermined number of times to eliminate the non-condensable gas in the chamber 38. After the removal of the non-condensable gas is completed, the control unit 74 supplies saturated steam into the chamber 38 until the pressure inside the chamber 38 reaches a predetermined pressure.

The control unit 74 executes a cycle of negative pressure, steam supply, and steam discharge a predetermined number of times to complete the conditioning step, and then opens the on-off valve 43 based on the temperature detected by the temperature sensor 70 in the chamber 38. Saturated steam is supplied to the chamber 38, and the temperature of the chamber 38 is controlled to reach a predetermined temperature. The control unit 74 starts the sterilization step (step S102) when the temperature of the chamber 38 reaches a predetermined temperature.

During the sterilization step (step S102), the control unit 74 maintains the inside of the chamber 38 at a predetermined temperature and a predetermined pressure, and sterilizes the object to be sterilized in the chamber 38.
Even during the sterilization process, the temperature of the temperature sensor 70 is constantly input to the control unit 74, and the control unit 74 determines whether or not the steam is saturated based on the measured temperature in the chamber 38. Judgment as to whether or not it is saturated steam is performed through the following steps.

The control unit 74 calculates the saturated steam temperature at a predetermined pressure value from the calculation formula stored in the storage device 76 (step S104). In the present embodiment, the saturated steam temperature at the pressure value measured by the pressure sensor 72 is calculated. As the calculation formula, an approximate formula of Clausius-Clapeyron's formula or an approximate formula of Teten's formula can be adopted.

The control unit 74 subtracts the saturated steam temperature calculated from the calculation formula from the measured temperature measured by the temperature sensor 70 (step S106). Let x be the difference at this time.
That is, x = (measured temperature)-(calculated saturated steam temperature).
The control unit 74 determines whether or not the difference x is within a predetermined range. The control unit 74 sets the upper limit threshold value a and the lower limit threshold value b in advance as the allowable range of the value of x, and compares the value of x, the value of a, and the value of b (step S108).

When x> a, as shown in FIG. 3, the control unit 74 determines that the steam in the chamber 38 is superheated steam (step S112). In the case of superheated steam, since the amount of water is small with respect to the temperature, the control unit 74 closes the drain valve 65 of the exhaust pipe 50 so that the drain collects in the chamber 38. Further, the control unit 74 controls so as to throttle the on-off valve 40, reduces the amount of general steam supplied to the jacket unit 34, and controls the temperature of the chamber 38 to decrease (step S114).

After executing step S114, the control unit 74 is left in that state for a certain period of time, and then determines whether or not the steam in the chamber 38 has become saturated steam. That is, the control unit 74 calculates the saturated steam temperature at the predetermined pressure value from the calculation formula stored in the storage device 76 (step S116), and then calculates from the calculation formula from the measured temperature measured by the temperature sensor 70. The saturated steam temperature is subtracted (step S118). Let x be the difference at this time.
That is, x = (measured temperature)-(calculated saturated steam temperature).
The control unit 74 determines whether or not the difference x is within a predetermined range. The control unit 74 sets the upper limit threshold value a and the lower limit threshold value b in advance as the allowable range of the value of x, and compares the value of x, the value of a, and the value of b (step S120).

Nevertheless, if a> x, the operation of step S114 is continued, and if a ≧ x ≧ b, the drain valve 65 and the on-off valve 40 are opened to stop the storage of drain and the jacket portion of general steam. The supply amount to 34 is returned to the normal state (step S122). Then, the process returns to step S104 of FIG. 2 and the sterilization step is continued.

When x <b, as shown in FIG. 4, the control unit 74 determines that the steam in the chamber 38 is either wet steam or residual non-condensable gas (step S124). However, it is not judged to be either wet steam or residual non-condensable gas.
Next, the control unit 74 opens the on-off valve 40 to increase the amount of general steam supplied to the jacket unit 34 (step S126). As a result, the temperature inside the chamber 38 can be raised, so that the state of the wet steam can be eliminated in the case of the wet steam.

After the execution of step S126, the control unit 74 leaves it in that state for a certain period of time, and then determines whether or not it has become saturated steam. That is, the control unit 74 calculates the saturated steam temperature at the predetermined pressure value from the calculation formula stored in the storage device 76 (step S128), and then calculates from the calculation formula from the measured temperature measured by the temperature sensor 70. The saturated steam temperature is subtracted (step S130). Let x be the difference at this time.
That is, x = (measured temperature)-(calculated saturated steam temperature).
The control unit 74 compares the value of x with the value of b, and if the difference x is equal to or greater than the lower limit threshold value b, the control unit 74 determines that the moist steam has been eliminated (step S132). ..

When it is determined that the steam has become saturated, the on-off valve 40 is throttled to return the amount of general steam supplied to the jacket portion 34 to the normal state (step S134). Then, the process returns to step S104 of FIG. 2 and the sterilization step is continued.

Even if the amount of general steam supplied to the jacket portion 34 is increased, if x <b, it is judged that there is a possibility that non-condensable gas may remain instead of wet steam, and the on-off valve 40 is throttled. The amount of general steam supplied to the jacket portion 34 is returned to the normal state (step S136), the exhaust valve 63 is opened, and the degassing operation in the chamber 38 is executed (step S138).
Since the inside of the chamber 38 is under positive pressure during the sterilization step, the air (non-condensable gas) in the chamber 38 can be discharged by opening the exhaust valve 63.

After executing step S138, the control unit 74 is left in that state for a certain period of time, and then opens the on-off valve 43 while measuring the pressure in the chamber 38 with the pressure sensor 72 until the pressure in the chamber 38 reaches a predetermined pressure. Supply saturated steam (step S140). Then, the process returns to step S104 of FIG. 2 and the sterilization step is continued.

In FIG. 2, when a ≧ x ≧ b, the control unit 74 determines that the steam in the chamber 38 is saturated steam, continues the sterilization step until a predetermined time elapses, and the predetermined time elapses. By the way, the sterilization step is completed (step S122).
After the sterilization is completed, the control unit 74 opens the exhaust valve 63, exhausts the steam in the chamber 38 by the positive pressure in the chamber 38, and then drives the vacuum pump 54 when the inside of the chamber 38 becomes atmospheric pressure. The steam in the chamber 38 is exhausted.

Further, although the above-described saturated steam monitoring control has been described when it is executed during the sterilization process, the control unit 74 checks whether or not the saturated steam is saturated steam between the end of the conditioning process and the start of the sterilization process. , The sterilization step may be started when it is determined that the vapor is saturated.
This operation will be described with reference to FIGS. 5 to 7.
After the conditioning step is completed, the chamber 38 is filled with saturated steam, and in order to raise the temperature in the chamber 38 to the sterilization start temperature, the control unit 74 supplies the saturated steam to the chamber 38, and the chamber 38 is filled. The temperature is controlled to reach the sterilization start temperature (step S150).

The control unit 74 calculates the saturated steam temperature at a predetermined pressure value from the calculation formula stored in the storage device 76 during the heating of the chamber (step S152). In the present embodiment, the saturated steam temperature at the pressure value measured by the pressure sensor 72 is calculated. As the calculation formula as described above, an approximate formula of Clausius-Clapeyron's formula or an approximate formula of Teten's formula can be adopted.

The control unit 74 subtracts the saturated steam temperature calculated from the calculation formula from the measured temperature measured by the temperature sensor 70 (step S154). Let x be the difference at this time.
Further, the control unit 74 determines whether or not the temperature in the chamber 38 measured by the temperature sensor 70 has reached the sterilization start temperature (step S156) while calculating the difference x, and reaches the sterilization start temperature. Continue heating and calculating the difference x until.

When the sterilization start temperature is reached, the control unit 74 compares the value of x, the value of a, and the value of b to see if there is a difference x in the preset upper threshold a and lower threshold b. Step S158).
When a ≧ x ≧ b, the control unit 74 determines that the steam in the chamber 38 is saturated steam, and starts the sterilization step (step S160).

When x> a, as shown in FIG. 6, the control unit 74 determines that the steam in the chamber 38 is superheated steam (step S162). In the case of superheated steam, since the amount of water is small with respect to the temperature, the control unit 74 closes the drain valve 65 of the exhaust pipe 50 so that the drain collects in the chamber 38. Further, the control unit 74 controls so as to throttle the on-off valve 40, reduces the amount of general steam supplied to the jacket unit 34, and controls the temperature of the chamber 38 to decrease (step S164).

After the execution of step S164, the control unit 74 is left in that state for a certain period of time, and then determines whether or not the steam in the chamber 38 has become saturated steam. That is, the control unit 74 calculates the saturated steam temperature at the predetermined pressure value from the calculation formula stored in the storage device 76 (step S166), and then calculates from the calculation formula from the measured temperature measured by the temperature sensor 70. The saturated steam temperature is subtracted (step S168). Let x be the difference at this time.
The control unit 74 determines whether or not the difference x is within a predetermined range. The control unit 74 sets the upper limit threshold value a and the lower limit threshold value b in advance as the allowable range of the value of x, and compares the value of x, the value of a, and the value of b (step S170).

Nevertheless, if a> x, the operation of step S164 is continued, and if a ≧ x ≧ b, the drain valve 65 and the on-off valve 40 are opened to stop the storage of drain and the jacket portion of general steam. The supply amount to 34 is returned to the normal state (step S172). Then, the control unit 72 starts the sterilization step (step S174).

When x <b, as shown in FIG. 7, the control unit 74 determines that the steam in the chamber 38 is either wet steam or residual non-condensable gas (step S175). However, it is not judged to be either wet steam or residual non-condensable gas.
Next, the control unit 74 opens the on-off valve 40 to increase the amount of general steam supplied to the jacket unit 34 (step S176). As a result, the temperature inside the chamber 38 can be raised, so that the state of the wet steam can be eliminated in the case of the wet steam.

After the execution of step S176, the control unit 74 leaves it in that state for a certain period of time, and then determines whether or not it has become saturated steam. That is, the control unit 74 calculates the saturated steam temperature at the predetermined pressure value from the calculation formula stored in the storage device 76 (step S178), and then calculates from the calculation formula from the measured temperature measured by the temperature sensor 70. The saturated steam temperature is subtracted (step S180). Let x be the difference at this time.
The control unit 74 compares the value of x with the value of b, and if the difference x is equal to or greater than the lower limit threshold value b, it is determined that the wet steam has been eliminated (step S182).

When the control unit 74 can determine that the steam has become saturated, the on-off valve 40 is throttled to return the amount of general steam supplied to the jacket unit 34 to the normal state (step S184). Then, the sterilization step is started (step S185).

Even if the amount of general steam supplied to the jacket portion 34 is increased, if x <b, it is judged that there is a possibility that non-condensable gas may remain instead of wet steam, and the on-off valve 40 is throttled. The amount of general steam supplied to the jacket portion 34 is returned to the normal state (step S186), the exhaust valve 63 is opened, and the degassing operation in the chamber 38 is executed (step S188).
Since the inside of the chamber 38 is under positive pressure during the sterilization step, the air (non-condensable gas) in the chamber 38 can be discharged by opening the exhaust valve 63.

After executing step S188, the control unit 74 is left in that state for a certain period of time, and then opens the on-off valve 43 while measuring the pressure in the chamber 38 with the pressure sensor 72 until the pressure in the chamber 38 reaches a predetermined pressure. Supply saturated steam (step S190). Then, the control unit 74 returns to step S182, compares the value of x with the value of b, and if the difference x is equal to or higher than the lower limit threshold value b, the residue of the non-condensable gas is eliminated. Judge. When the difference x becomes equal to or higher than the lower limit threshold value b, the operation of step S184 is not executed and the sterilization step is started (step S185).

(Second Embodiment)
Next, the overall operation in the second embodiment will be described with reference to FIGS. 8 to 10.
The same components as the components of the first embodiment are designated by the same reference numerals, and the description thereof may be omitted.
The present embodiment is different from the first embodiment in that the control during the sterilization step is executed by calculating the saturated vapor pressure from the temperature in the chamber 38.

The steam sterilizer 30 executes a conditioning step (step S200) for discharging the air in the chamber 38 as a preliminary step of the sterilization step.
In the conditioning step, the control unit 74 drives the vacuum pump 54 to create a negative pressure in the chamber 38, and then stops the operation of the vacuum pump 54. Then, the control unit 74 opens the on-off valve 43 and supplies saturated steam into the chamber 38.

When the control unit 74 determines that the pressure in the chamber 38 has reached a preset predetermined pressure based on the pressure in the chamber 38 by the pressure sensor 72, the on-off valve 43 is closed to supply saturated steam. Stop.
Then, the control unit 74 drives the vacuum pump 54 to discharge the steam in the chamber 38, and makes the inside of the chamber 38 a negative pressure.
The control unit 74 repeats such a cycle of negative pressure, steaming, and steam discharge a predetermined number of times to eliminate the non-condensable gas in the chamber 38. After the removal of the non-condensable gas is completed, the control unit 74 supplies saturated steam into the chamber 38 until the pressure inside the chamber 38 reaches a predetermined pressure.

The control unit 74 executes a cycle of negative pressure, steam supply, and steam discharge a predetermined number of times to complete the conditioning step, and then opens the on-off valve 43 based on the temperature detected by the temperature sensor 70 in the chamber 38. Saturated steam is supplied to the chamber 38, and the temperature of the chamber 38 is controlled to reach a predetermined temperature. The control unit 74 starts the sterilization step (step S202) when the temperature of the chamber 38 reaches a predetermined temperature.

During the sterilization step (step S202), the control unit 74 controls the opening degree of the on-off valve 43 based on the pressure detected by the pressure sensor 72 in the chamber 38, and the inside of the chamber 38 reaches a predetermined pressure. To control. Further, the control unit 74 introduces general steam into the jacket unit 34 and controls the inside of the chamber 38 to reach a predetermined temperature.

The control unit 74 maintains the inside of the chamber 38 at a predetermined temperature and a predetermined pressure, and sterilizes the object to be sterilized in the chamber 38.
Even during the sterilization process, the temperature of the pressure sensor 72 is constantly input to the control unit 74, and the control unit 74 determines whether or not the steam is saturated based on the measured pressure in the chamber 38. Judgment as to whether or not it is saturated steam is performed through the following steps.

The control unit 74 calculates the saturated steam pressure at a predetermined temperature from the calculation formula stored in the storage device 76 (step S204). In this embodiment, the saturated vapor pressure at the temperature measured by the temperature sensor 70 is calculated. As the calculation formula, an approximate formula of Clausius-Clapeyron's formula or an approximate formula of Teten's formula can be adopted.

The control unit 74 subtracts the saturated steam pressure calculated from the calculation formula from the measured pressure measured by the pressure sensor 72 (step S206). Let y be the difference at this time.
That is, y = (measured pressure)-(calculated saturated vapor pressure).
The control unit 74 determines whether or not the difference y is within a predetermined range. The control unit 74 sets the upper limit threshold value c and the lower limit threshold value d in advance as the allowable range of the value of y, and compares the value of y, the value of c, and the value of d (step S208).

When y> c, as shown in FIG. 9, the control unit 74 determines that the steam in the chamber 38 is superheated steam (step S212). In the case of superheated steam, since the amount of water is small with respect to the temperature, the control unit 74 closes the drain valve 65 of the exhaust pipe 50 so that the drain collects in the chamber 38. Further, the control unit 74 controls so as to throttle the on-off valve 40, reduces the amount of general steam supplied to the jacket unit 34, and controls the temperature of the chamber 38 to decrease (step S214).

After the execution of step S214, the control unit 74 is left in that state for a certain period of time, and then determines whether or not the steam in the chamber 38 has become saturated steam. That is, the control unit 74 calculates the saturated vapor pressure at a predetermined temperature from the calculation formula stored in the storage device 76 (step S216), and then calculates from the calculation formula from the measured pressure measured by the pressure sensor 72. The saturated steam pressure is subtracted (step S218). Let y be the difference at this time.
That is, y = (measured pressure)-(calculated saturated vapor pressure).
The control unit 74 determines whether or not the difference y is within a predetermined range. The control unit 74 sets the upper limit threshold value c and the lower limit threshold value d in advance as the allowable range of the value of y, and compares the value of y, the value of c, and the value of d (step S220).

Nevertheless, if c> y, the operation of step S214 is continued, and if c ≧ y ≧ d, the drain valve 65 and the on-off valve 40 are opened to stop the storage of drain and the jacket portion of general steam. The supply amount to 34 is returned to the normal state (step S222). Then, the process returns to step S204 of FIG. 8 and the sterilization step is continued.

When y <d, as shown in FIG. 10, the control unit 74 determines that the steam in the chamber 38 is either wet steam or residual non-condensable gas (step S224). However, it is not judged to be either wet steam or residual non-condensable gas.
Next, the control unit 74 opens the on-off valve 40 to increase the amount of general steam supplied to the jacket unit 34 (step S226). As a result, the temperature inside the chamber 38 can be raised, so that the state of the wet steam can be eliminated in the case of the wet steam.

After the execution of step S226, the control unit 74 leaves it in that state for a certain period of time, and then determines whether or not it has become saturated steam. That is, the control unit 74 calculates the saturated vapor pressure at a predetermined temperature from the calculation formula stored in the storage device 76 (step S228), and then calculates from the calculation formula from the measured pressure measured by the pressure sensor 72. The saturated steam pressure is subtracted (step S230). Let y be the difference at this time.
That is, y = (measured pressure)-(calculated saturated vapor pressure).
The control unit 74 compares the value of y with the value of d, and if the difference y is equal to or greater than the lower limit threshold value d, the control unit 74 determines that the wet steam has been eliminated (step S232). ..

When it is determined that the steam has become saturated, the on-off valve 40 is throttled to return the amount of general steam supplied to the jacket portion 34 to the normal state (step S234). Then, the process returns to step S204 of FIG. 8 and the sterilization step is continued.

Even if the amount of general steam supplied to the jacket portion 34 is increased, if y <d, it is judged that there is a possibility that non-condensable gas may remain instead of wet steam, and the on-off valve 40 is throttled. The amount of general steam supplied to the jacket portion 34 is returned to the normal state (step S236), the exhaust valve 63 is opened, and the degassing operation in the chamber 38 is executed (step S238).
Since the inside of the chamber 38 is under positive pressure during the sterilization step, the air (non-condensable gas) in the chamber 38 can be discharged by opening the exhaust valve 63.

After executing step S238, the control unit 74 is left in that state for a certain period of time, and then opens the on-off valve 43 while measuring the pressure in the chamber 38 with the pressure sensor 72 until the pressure in the chamber 38 reaches a predetermined pressure. Saturated steam is supplied (step S240). Then, the process returns to step S204 of FIG. 8 and the sterilization step is continued.

In FIG. 8, when c ≧ y ≧ d, the control unit 74 determines that the steam in the chamber 38 is saturated steam, continues the sterilization step until a predetermined time elapses, and the predetermined time elapses. By the way, the sterilization step is completed (step S222).
After the sterilization is completed, the control unit 74 opens the exhaust valve 63, exhausts the steam in the chamber 38 by the positive pressure in the chamber 38, and then drives the vacuum pump 54 when the inside of the chamber 38 becomes atmospheric pressure. The steam in the chamber 38 is exhausted.

Further, although the above-described saturated steam monitoring control has been described when it is executed during the sterilization process, the control unit 74 checks whether or not the saturated steam is saturated steam between the end of the conditioning process and the start of the sterilization process. , The sterilization step may be started when it is determined that the vapor is saturated.
This operation will be described with reference to FIGS. 11 to 13.
After the conditioning step is completed, the chamber 38 is filled with saturated steam, and in order to raise the temperature in the chamber 38 to the sterilization start temperature, the control unit 74 supplies the saturated steam to the chamber 38, and the chamber 38 is filled. The temperature is controlled to reach the sterilization start temperature (step S250).

The control unit 74 calculates the saturated steam pressure at a predetermined temperature from the calculation formula stored in the storage device 76 during the heating of the chamber (step S252). In this embodiment, the saturated vapor pressure at the temperature measured by the temperature sensor 70 is calculated. As the calculation formula as described above, an approximate formula of Clausius-Clapeyron's formula or an approximate formula of Teten's formula can be adopted.

The control unit 74 subtracts the saturated steam pressure calculated from the calculation formula from the measured pressure measured by the pressure sensor 72 (step S254). Let y be the difference at this time.
Further, the control unit 74 determines whether or not the temperature in the chamber 38 measured by the temperature sensor 70 has reached the sterilization start temperature (step S256) while calculating the difference y, and reaches the sterilization start temperature. The heating and the calculation of the difference y are continued until.

When the sterilization start temperature is reached, the control unit 74 compares the value of y, the value of c, and the value of d to see if there is a difference y in the preset upper threshold c and lower threshold d. Step S258).
When c ≧ y ≧ d, the control unit 74 determines that the steam in the chamber 38 is saturated steam, and starts the sterilization step (step S260).

When y> c, as shown in FIG. 12, the control unit 74 determines that the steam in the chamber 38 is superheated steam (step S262). In the case of superheated steam, since the amount of water is small with respect to the temperature, the control unit 74 closes the drain valve 65 of the exhaust pipe 50 so that the drain collects in the chamber 38. Further, the control unit 74 controls so as to throttle the on-off valve 40, reduces the amount of general steam supplied to the jacket unit 34, and controls the temperature of the chamber 38 to decrease (step S264).

After executing step S264, the control unit 74 is left in that state for a certain period of time, and then determines whether or not the steam in the chamber 38 has become saturated steam. That is, the control unit 74 calculates the saturated vapor pressure at a predetermined temperature from the calculation formula stored in the storage device 76 (step S266), and then calculates from the calculation formula from the measured pressure measured by the pressure sensor 72. The saturated steam pressure is subtracted (step S268). Let y be the difference at this time.
The control unit 74 determines whether or not the difference y is within a predetermined range. The control unit 74 sets the upper limit threshold value c and the lower limit threshold value d in advance as the allowable range of the value of y, and compares the value of y, the value of c, and the value of d (step S270).

Nevertheless, if y> c, the operation of step S264 is continued, and if c ≧ y ≧ d, the drain valve 65 and the on-off valve 40 are opened to stop the accumulation of drain and the jacket portion of general steam. The supply amount to 34 is returned to the normal state (step S272). Then, the control unit 72 starts the sterilization step (step S274).

When y <d, as shown in FIG. 13, the control unit 74 determines that the steam in the chamber 38 is either wet steam or residual non-condensable gas (step S275). However, it is not judged to be either wet steam or residual non-condensable gas.
Next, the control unit 74 opens the on-off valve 40 to increase the amount of general steam supplied to the jacket unit 34 (step S276). As a result, the temperature inside the chamber 38 can be raised, so that the state of the wet steam can be eliminated in the case of the wet steam.

After the execution of step S276, the control unit 74 leaves it in that state for a certain period of time, and then determines whether or not it has become saturated steam. That is, the control unit 74 calculates the saturated vapor pressure at a predetermined temperature from the calculation formula stored in the storage device 76 (step S278), and then calculates from the calculation formula from the measured pressure measured by the pressure sensor 72. The saturated steam pressure is subtracted (step S280). Let y be the difference at this time.
The control unit 74 compares the value of y with the value of d, and if the difference y is equal to or greater than the lower limit threshold value d, it is determined that the wet steam has been eliminated (step S282).

When the control unit 74 can determine that the steam has become saturated, the on-off valve 40 is throttled to return the amount of general steam supplied to the jacket unit 34 to the normal state (step S284). Then, the sterilization step is started (step S285).

Even if the amount of general steam supplied to the jacket portion 34 is increased, if y <d, it is judged that there is a possibility that non-condensable gas may remain instead of wet steam, and the on-off valve 40 is throttled. The amount of general steam supplied to the jacket portion 34 is returned to the normal state (step S286), the exhaust valve 63 is opened, and the degassing operation in the chamber 38 is executed (step S288).
Since the inside of the chamber 38 is under positive pressure during the sterilization step, the air (non-condensable gas) in the chamber 38 can be discharged by opening the exhaust valve 63.

After executing step S288, the control unit 74 is left in that state for a certain period of time, and then opens the on-off valve 43 while measuring the pressure in the chamber 38 with the pressure sensor 72 until the pressure in the chamber 38 reaches a predetermined pressure. Saturated steam is supplied (step S290). Then, the control unit 74 returns to step S282, compares the value of y with the value of d, and if the difference y is equal to or higher than the lower limit threshold value d, the residual non-condensable gas is eliminated. Judge. When the difference y becomes equal to or higher than the lower limit threshold value d, the operation of step S284 is not executed and the sterilization step is started (step S285).

(Other embodiments)
In each of the above-described embodiments, general steam is introduced into the jacket portion, but saturated steam may be supplied to the jacket portion and saturated steam may be supplied from the jacket portion into the chamber.

(Monitor saturated steam monitoring screen)
The saturated steam monitoring screen displayed on the monitor 77 will be described with reference to FIG. The screen display is characterized in that the difference between the current temperature and the saturated steam temperature described in the first embodiment can be displayed by an indicator.

In the uppermost column 80 of the display screen on the monitor 77 of FIG. 14, the operation pattern and the registration No. , The process name is displayed. When an abnormality occurs in the device, the control unit 74 controls the color of the column 80 to be displayed in a color different from that in the normal operation so as to notify the operator of the abnormality.
Further, in the column 82 in the second row from the top, the accumulated time for sterilizing the air filter is displayed, and the operator can be notified of the replacement time of the air filter.
In the center column 84, the set value and the current value of each timer and each counter are displayed.

The theoretical steam temperature range indicator 86 is displayed at the lower right of the central column 84.
This theoretical steam temperature range indicator 86 (hereinafter, simply referred to as an indicator) displays the value of the difference between the current temperature and the saturated steam temperature in real time from the end of the conditioning step to the sterilization step and during the sterilization step. Is. The indicator 86 has a semicircular shape with scales of 0 in the 12 o'clock direction, 1 in the 1 o'clock direction, 2 in the 2 o'clock direction, and 3 in the 3 o'clock direction. , A scale of -3 is arranged in the 9 o'clock direction. The unit of this scale is ° C.
The control unit 74 controls so that the tip of the needle 87 points to the position of the scale corresponding to the calculated value according to the calculated difference value.

For example, in FIG. 14, the tip of the needle 87 points to −1.4. This is because the control unit 74 calculated the difference between the current temperature and the saturated steam temperature and calculated that the difference value was -1.4 (° C.), so that the tip of the needle 87 was between 10 o'clock and 11 o'clock. It is controlled so that it faces the relevant part.

By looking at such an indicator 86, the operator can intuitively instantly determine whether the internal state of the chamber 38 is saturated steam, superheated steam, moist steam or non-condensable gas. I can grasp it.
If the needle 87 of the indicator 86 points to 0, it can be determined that the vapor is ideally saturated. In addition, when it points in the positive direction, it can be determined that there is little dampness. If the positive value is large, it can be determined that the steam is superheated. When the needle 87 of the indicator 86 points in the minus direction, it can be determined that there is a lot of dampness or a non-condensable gas is present. When the negative value is large, it can be determined that a large amount of wet steam or non-condensable gas remains.

As an example of the indicator 86, the one that displays the difference between the current temperature and the saturated steam temperature in real time has been described, but the difference between the current pressure and the saturated steam pressure may be displayed in real time.

Further, as an example of the indicator 86, an example in which the needle points to a corresponding numerical value has been described as in the analog type, but the display method is not limited to such an embodiment. For example, a configuration such as displaying only numerical values such as a digital type may be adopted.

30 Steam sterilizer 32 Sterilization tank 34 Jacket part 35 Inner cylinder 37 Outer cylinder 38 Chamber 39 Steam pipe 40 On-off valve 42 Saturated steam pipe 43 On-off valve 44 Air supply pipe 46 Filter 47 Check valve 48 On-off valve 50 Exhaust pipe 52 Exhaust pipe 53 Exhaust pipe 54 Vacuum pump 55 Vacuum pump Exhaust pipe 56 On-off valve 57 Check valve 58 Exhaust / drain pipe for vacuum pump 59 Water supply pipe for vacuum pump 60 Check valve 61 On-off valve 62 Exhaust pipe 63 Exhaust valve 64 Check valve 65 Drain Valve 66 Drain trap 67 Check valve 68 Drain trap 69 Check valve 70 Temperature sensor 72 Pressure sensor 74 Control unit 76 Storage device 80 Column 82 Column 84 Column 86 Theoretical steam temperature range indicator 87 Needles

Claims (8)

A sterilization tank that houses the object to be sterilized and
Saturated steam piping that supplies saturated steam introduced from outside the equipment into the sterilization tank,
A jacket portion provided around the sterilization tank and connected to the saturated steam pipe or a steam pipe different from the saturated steam pipe.
A pressure sensor that measures the pressure in the sterilization tank and
A temperature sensor that measures the temperature inside the sterilizer and
A drain drain pipe for draining the drain in the sterilization tank and
A drain valve that opens and closes the drain drain pipe,
An exhaust pipe for exhausting the gas in the sterilization tank and
An exhaust valve that opens and closes the exhaust pipe,
A storage device in which a calculation formula for calculating the saturated steam temperature at a predetermined pressure is stored in advance, and
It is equipped with a control unit that determines whether the steam in the current sterilization tank is saturated steam.
The control unit
(A): The saturated steam temperature is calculated from the pressure value measured by the pressure sensor based on the above calculation formula.
(B): The difference between the current temperature and the saturated steam temperature is calculated by subtracting the saturated steam temperature calculated in the step (a) from the temperature measured by the temperature sensor.
(C): When the difference calculated in the step (b) is within the range of the upper limit threshold value or less and the lower limit threshold value or more, it is determined that the steam in the sterilization tank is saturated steam, and the sterilization step is continued as it is. ..
(D): When the difference calculated in the step (b) exceeds the upper limit threshold, it is determined that the steam in the sterilization tank is superheated steam, and the temperature of the steam introduced into the jacket portion is lowered. The temperature in the sterilization tank is lowered, and the drain valve is closed to promote the evaporation of the drain.
(E): When the difference calculated in the step (b) is less than the lower limit threshold value, it is determined that the steam in the sterilization tank is wet steam or there is a possibility that non-condensable gas remains, and the jacket portion. By raising the temperature of the steam introduced into the sterilizer, the temperature inside the sterilization tank is controlled to rise.
(F) be performed :( e) step, (b) If the difference calculated in step is less than the lower limit threshold value, open the exhaust valve, control to perform a degassing operation of the sterilization chamber To do. After performing the degassing operation, saturated steam is supplied until the pressure in the sterilization tank reaches a predetermined pressure.
(G): The difference calculated in the steps (b) by executing the steps (a) to (c) during the steps (d) to (f) is within the range of the upper limit threshold and the lower limit threshold or more. In this case, it is determined that the steam in the sterilization tank is saturated steam, the steps (d) to (f) are completed, and the sterilization step is continued.
A steam sterilizer that constantly executes the above steps (a) to (g) during the sterilization step. The control unit
The steps (a) to (b) are executed from the end of the conditioning step of discharging the air in the sterilization tank to the start of the sterilization step by executing the cycle of negative pressure, steaming, and steam discharge a predetermined number of times .
When the temperature inside the sterilization tank reaches the sterilization process start temperature,
When the difference calculated in step (b) is within the range of the upper limit threshold value or less and the lower limit threshold value or more, it is determined that the steam in the sterilization tank is saturated steam, and the sterilization step is started.
If the difference calculated in the step (b) exceeds the upper limit threshold value, the step (d) is executed.
If the difference calculated in the step (b) is less than the lower limit threshold value, the step (e) is executed.
If the difference calculated in the step (b) is less than the limit threshold even after the step (e) is executed, the step (f) is executed.
If the difference calculated in step (b) by executing steps (a) to (c) during steps (d) to (f) is within the range of the upper limit threshold or higher and the lower limit threshold or higher, sterilization is performed. The steam sterilizer according to claim 1, wherein the steam in the tank is determined to be saturated steam, the steps (d) to (f) are completed, and the sterilization step is started. Equipped with a monitor
The steam sterilizer according to claim 1 or 2, wherein the control unit controls so as to constantly display the difference between the current temperature and the saturated steam temperature calculated in the step (b). The steam sterilizer according to claim 3, wherein the control unit controls so as to display the current difference on an indicator displaying a negative value to a positive value. A sterilization tank that houses the object to be sterilized and
Saturated steam piping that supplies saturated steam introduced from outside the equipment into the sterilization tank,
A jacket portion provided around the sterilization tank and connected to the saturated steam pipe or a steam pipe different from the saturated steam pipe.
A pressure sensor that measures the pressure in the sterilization tank and
A temperature sensor that measures the temperature inside the sterilizer and
A drain drain pipe for draining the drain in the sterilization tank and
A drain valve that opens and closes the drain drain pipe,
An exhaust pipe for exhausting the gas in the sterilization tank and
An exhaust valve that opens and closes the exhaust pipe,
A storage device in which a calculation formula for calculating the saturated vapor pressure at a predetermined temperature is stored in advance, and
It is equipped with a control unit that determines whether the steam in the current sterilization tank is saturated steam.
The control unit
(A): The saturated steam pressure is calculated from the temperature measured by the temperature sensor based on the above calculation formula.
(B): The difference between the current pressure and the saturated steam pressure is calculated by subtracting the saturated steam pressure calculated in the step (A) from the pressure value measured by the pressure sensor.
(C): When the difference calculated in the step (B) is within the range of the upper limit threshold value or less and the lower limit threshold value or more, it is determined that the steam in the sterilization tank is saturated steam, and the sterilization step is continued as it is. ..
(D): When the difference calculated in the step (B) exceeds the upper limit threshold, it is determined that the steam in the sterilization tank is superheated steam, and the temperature of the steam introduced into the jacket portion is lowered. The temperature in the sterilization tank is lowered, and the drain valve is closed to promote the evaporation of the drain.
(E): When the difference calculated in the step (B) is less than the lower limit threshold value, it is determined that the steam in the sterilization tank is moist steam or there is a possibility that non-condensable gas remains, and the jacket portion. By raising the temperature of the steam introduced into the sterilizer, the temperature inside the sterilization tank is controlled to rise.
(F) be performed :( E) step, (B) if the difference calculated in step is less than the lower limit threshold value, open the exhaust valve, control to perform a degassing operation of the sterilization chamber To do. After performing the degassing operation, saturated steam is supplied until the pressure in the sterilization tank reaches a predetermined pressure.
(G): The difference calculated in the steps (B) by executing the steps (A) to (C) during the steps (D) to (F) is within the range of the upper limit threshold and the lower limit threshold or more. In this case, it is determined that the steam in the sterilization tank is saturated steam, the steps (D) to (F) are completed, and the sterilization step is continued.
A steam sterilizer that constantly executes the steps (A) to (G) during the sterilization step. The control unit
The steps (A) to (B) are executed from the end of the conditioning step of discharging the air in the sterilization tank to the start of the sterilization step by executing the cycle of negative pressure, steaming, and steam discharge a predetermined number of times .
If the difference calculated in step (B) is within the range below the upper limit threshold value and above the lower limit threshold value, it is determined that the steam in the sterilization tank is saturated steam, and the sterilization step is started.
If the difference calculated in the step (B) exceeds the upper limit threshold value, the step (D) is executed.
If the difference calculated in the step (B) is less than the lower limit threshold value, the step (E) is executed.
If the difference calculated in the step (B) is less than the limit threshold even after the step (E) is executed, the step (F) is executed.
If the difference calculated in step (B) by executing steps (A) to (C) during steps (D) to (F) is within the range of the upper limit threshold or higher and the lower limit threshold or higher, sterilization is performed. The steam sterilizer according to claim 5, wherein the steam in the tank is determined to be saturated steam, the steps (D) to (F) are completed, and the sterilization step is started. Equipped with a monitor
The steam sterilizer according to claim 5 or 6, wherein the control unit controls so as to constantly display the difference between the current pressure and the saturated steam pressure calculated in the step (B). The steam sterilizer according to claim 7, wherein the control unit controls to display the current difference on an indicator displaying a negative value to a positive value.