JP5317015B2 - Steam sterilizer - Google Patents

Description

  The present invention relates to a steam sterilizer that sterilizes medical instruments and the like using steam, and an air evacuation method performed in such a steam sterilizer before a sterilization step.

  Conventionally, as disclosed in Patent Document 1 below, as an air evacuation process prior to the sterilization process, it has been proposed to attempt to exclude air from the sterilization tank by introducing and discharging pressurized steam into the sterilization tank. ing. Specifically, by purging the inside of the sterilization tank with pressurized steam, the air is removed from the inside of the sterilization tank. After that, by pressurizing the sterilization tank by introducing pressurized steam and discharging the steam. It has been proposed to further eliminate air from the sterilization tank by repeating the return pressure in the sterilization tank.

  In addition, it is also known to eliminate air from the sterilization tank by repeatedly reducing the pressure in the sterilization tank using a vacuum pump and returning the pressure in the sterilization tank by supplying steam as an air evacuation process before the sterilization process. Yes.

JP-A-9-266943 (Claim 1, Claim 3, Claim 7, Paragraph Nos. 0042-0046)

  As in the invention disclosed in Patent Document 1, after purging the inside of the sterilization tank with steam, immediately pressurizing the inside of the sterilization tank with steam, the boiling evaporation of the condensed water generated by the condensation of the steam does not occur. The amount of steam condensation increases. If the amount of condensed water is large, the object to be sterilized may not be sufficiently dried in the drying step after the sterilization step.

  On the other hand, simply repeating the depressurization in the sterilization tank by the vacuum pump and the return pressure in the sterilization tank by the supply of steam causes the depressurization speed to be slow because there is no steam in the sterilization tank at the first depressurization. That is, when the pressure in the sterilization tank is reduced, it is of course reduced by vacuuming with a vacuum pump, but if there is steam in the sterilization tank, the vacuum pump or the heat exchanger installed on the upstream side as desired Since the vapor from the inside of the sterilization tank condenses, the volume is rapidly reduced, so that the exhaust speed is increased. Therefore, if the pressure in the sterilization tank is reduced without supplying steam, there is no vapor condensation, and the pressure reduction speed becomes slow.

  The problem to be solved by the present invention is to efficiently remove air from the sterilization tank in a short time without excessively generating condensed water.

The present invention has been made in order to solve the above problems, and the invention according to claim 1 is a sterilization tank in which an object to be sterilized is stored, and a gas in the sterilization tank is sucked and discharged to the outside. Depressurizing means for depressurizing the inside of the sterilization tank, return pressure means for introducing outside air into the sterilized tank that has been depressurized to restore the pressure inside the sterilization tank, and steaming means for supplying saturated steam into the sterilization tank And an exhaust means for deriving the gas in the sterilization tank to the outside by a differential pressure from the atmospheric pressure, and as an air exhaust process before the sterilization process, the sterilization tank is not pressurized as the steam temperature exceeds 105 ° C. After the purge operation of supplying steam into the sterilization tank by the steam supply means while allowing the exhaust means to exhaust from the inside of the sterilization tank, the exhaust by the exhaust means and the steam supply by the steam supply means In the stopped state, the destruction by the decompression means. Control means for performing a decompression operation in the tank, the control means, as the air exclusion step, after the decompression operation, the pressure increase in the sterilization tank by the steam supply means and the pressure reduction means or the exhaust means The ascending / depressurizing operation consisting of depressurization in the sterilization tank is performed one or more times, and the final pressurization of the ascending / depressurizing operation is performed by supplying steam into the sterilization tank by the steam supply means, and holding pressure in the subsequent sterilization step It is a steam sterilizer characterized by performing up to 0.5 to 1 times the pressure.

According to the first aspect of the present invention, since the inside of the sterilization tank is decompressed after purging the inside of the sterilization tank with steam, the condensed water generated by the condensation of the steam is boiled and evaporated, so that the condensed water is generated excessively. There is no. Moreover, by purging the inside of the sterilization tank with steam, it is possible to increase the temperature of the object to be sterilized and to eliminate the air in the sterilization tank in parallel, so that the pretreatment time before the sterilization process can be shortened. it can. In addition, steam that is supplied into the sterilization tank for purging and remaining in the sterilization tank, or steam that is supplied into the sterilization tank for purging and condensed once but boiled by subsequent decompression, Although it is sucked in by a decompression means such as a water-sealed vacuum pump, the exhaust rate from the inside of the sterilization tank is increased due to the rapid volume reduction due to recondensing at that time. Can be shortened. Furthermore, according to the invention described in claim 1, after supplying steam into the sterilization tank at the final stage of the air exclusion process, the pressure is 0.5 to 1 times the holding pressure in the sterilization process. The steam is exhausted and the inside of the sterilization tank is decompressed. By exhausting after raising the pressure to 0.5 to 1 times the holding pressure in the sterilization step, a sufficient pressure difference can be secured during this time, and the residual air in the sterilization tank can be driven out.

In the invention according to claim 2, in place of the purge operation, in the decompression operation, the steam supply means does not restore the pressure in the sterilization tank during the decompression of the sterilization tank by the decompression means. temporarily perform steam supply to the sterilization bath, then have further row decompression of the sterilization chamber by the pressure reducing means in a state of stopping the steam supply, even during the temporary steam supply, the vacuum The steam sterilizer according to claim 1 , wherein the operation of the means is continued to reduce the pressure in the sterilization tank .

  According to the invention described in claim 2, by introducing steam in the middle of decompression, the exhaust speed can be increased and the pretreatment time before the sterilization process can be shortened compared to the case where only air is continuously exhausted. it can. For example, when the pressure reducing means is a water-sealed vacuum pump, the exhaust speed drops rapidly at a pressure close to the performance limit. However, if steam is temporarily introduced during the pressure reduction, the steam and the condensed once When the vapor re-evaporated into the water is sucked into the water-sealed vacuum pump, it recondenses and rapidly decreases in volume, so that the exhaust speed from the inside of the sterilization tank can be increased.

  According to the present invention, it is possible to efficiently remove air from the sterilization tank in a short time without generating excessive condensed water.

It is the schematic which shows one Example of the steam sterilizer of this invention. It is a figure which shows an example of the operating method of the steam sterilizer of FIG. 1, and has shown the relationship between the pressure in a sterilization tank, and elapsed time. It is a figure which shows the other example of the operating method of the steam sterilizer of FIG. 1, and has shown the relationship between the pressure in a sterilization tank, and elapsed time. It is a figure which shows the modification of FIG. It is a figure which shows another modification of FIG.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing an embodiment of the steam sterilizer of the present invention. The steam sterilizer 1 according to the present embodiment includes a sterilization tank 2 in which an object to be sterilized is stored, a decompression unit 3 that sucks and discharges the gas in the sterilization tank 2 to the outside, and decompresses the sterilization tank 2. The inside of the sterilization tank 2 is returned to the sterilization tank 2 by the pressure difference between the return pressure means 4 for introducing outside air into the sterilization tank 2 and returning the pressure in the sterilization tank 2, the steam supply means 5 for supplying steam to the sterilization tank 2, and the atmospheric pressure. The exhaust means 6 for deriving the gas to the outside, the drain discharge means 8 for draining from the sterilization tank 2 via the steam trap 7, the pressure sensor 9 for detecting the pressure in the sterilization tank 2, and the sterilization tank 2 And a control means (not shown) for controlling each means based on detection signals of the sensors 9 and 10 and the like.

  The article to be sterilized is not particularly limited, but is typically a medical instrument such as a forceps or a scalpel. Needless to say, the article to be sterilized may be placed in a container or bag such as a cast or sterilization container.

  The sterilization tank 2 is a hollow container that can withstand the decompression of the internal space, and is typically formed in a substantially rectangular box shape. In the sterilization tank 2 of the present embodiment, a door (not shown) for taking in and out the article to be sterilized is provided on the front (on the front side perpendicular to the paper surface). However, doors are provided on the front and the back, respectively, and one door is used as a loading door for putting an object to be sterilized in the sterilization tank 2, and the other door is taken out of the sterilization tank 2 after sterilization. It is good also as a carry-out door for. In either case, the door is closed so that the inside of the sterilization tank 2 can be sealed.

  The outer wall of the sterilization tank 2 is provided with a jacket 11 as a hollow portion for containing steam in order to warm the inside of the sterilization tank 2 from the outside. In this embodiment, the jacket 11 is continuously provided on each of the upper, lower, left and right wall bodies of the sterilization tank 2. Specifically, the steam sterilizer 1 includes a hollow container having a double structure of an inner can 12 and an outer can 13, and the sterilization tank 2 is configured by the inner can 12. The gap is the jacket 11.

  The sterilization tank 2 is connected to a decompression means 3 that sucks and discharges the gas in the sterilization tank 2 to the outside and decompresses the sterilization tank 2. The decompression means 3 of this embodiment sucks and discharges the gas in the sterilization tank 2 through the vacuum line 14. The vacuum line 14 may be connected to the bottom of the sterilization tank 2, but is connected to the side of the sterilization tank 2 in the illustrated example.

  The vacuum line 14 is provided with a vacuum valve 15 and a water-sealed vacuum pump 16 in order from the sterilization tank 2 side. Furthermore, the vacuum line 14 may be provided with a heat exchanger between the vacuum valve 15 and the vacuum pump 16 as desired. In this heat exchanger, cooling water is supplied and discharged, and the water and the steam in the vacuum line 14 are indirectly heat-exchanged to cool and condense the steam in the vacuum line 14.

  As is well known, the water-sealed vacuum pump 16 is supplied with water called sealed water. Therefore, water is supplied to the vacuum pump 16 through the sealed water supply valve 17 and discharged. When the vacuum pump 16 is operated, the sealed water supply valve 17 is opened in conjunction with the vacuum pump 16.

  The sterilization tank 2 is connected to a decompression means 4 that introduces outside air into the sterilization tank 2 under reduced pressure to restore the pressure in the sterilization tank 2. The return pressure means 4 of the present embodiment introduces outside air into the sterilization tank 2 under reduced pressure via an air supply line 18. The air supply line 18 is provided with a sterile filter 19, an air supply valve 20, and a check valve 21 in order toward the sterilization tank 2. When the air supply valve 20 is opened in a state where the inside of the sterilization tank 2 is depressurized, the outside air can be introduced into the sterilization tank 2 by the differential pressure, and the inside of the sterilization tank 2 can be decompressed.

  The sterilization tank 2 is connected with steam supply means 5 for blowing steam into the sterilization tank 2. The steam supply means 5 of the present embodiment introduces steam into the sterilization tank 2 through a steam supply line 22 from a steam supply source such as a boiler. The steam supply line 22 is sequentially provided with a pressure reducing valve (not shown) and a steam supply valve 23 toward the sterilization tank 2. By opening and closing the steam supply valve 23, the presence or absence of steam supply into the sterilization tank 2 can be switched.

  Connected to the sterilization tank 2 are an exhaust means 6 for leading the gas in the sterilization tank 2 to the outside by a differential pressure from the atmospheric pressure, and a drain discharge means 8 for draining from the sterilization tank 2 via a steam trap 7. Is done. The exhaust means 6 of the present embodiment guides the gas in the sterilization tank 2 through the exhaust line 24. On the other hand, the drain discharge means 8 of the present embodiment guides the condensed water of the steam supplied into the sterilization tank 2 through the drainage line 25. In the illustrated example, the exhaust line 24 and the drain line 25 are unified as common lines 26 and 27 on the upstream side and the downstream side. A check valve 28 is provided in the downstream common line 27, and a discharge line 29 from the vacuum pump 16 is connected to the downstream thereof via a check valve 30, and an outer can drain discharge line to be described later. 31 is connected.

  An exhaust line 24 and a drain line 25 are provided in parallel between the upstream and downstream common lines 26 and 27. Among them, the exhaust line 24 is provided with an exhaust valve 32, and the drainage line 25 is provided with a steam trap 7 and a check valve 33 in order from the upstream side. As for the exhaust line 24 and the drainage line 25, the upstream common line 26 is connected to the bottom of the sterilization tank 2.

  The sterilization tank 2 is provided with a pressure sensor 9 that detects the pressure in the sterilization tank 2 and a temperature sensor 10 that detects the temperature in the sterilization tank 2. Although the installation position of the pressure sensor 9 is not particularly limited, for example, it is provided on the upper side portion of the sterilization tank 2 as in the illustrated example. On the other hand, the temperature sensor 10 is provided at a predetermined position in accordance with various standards regarding sterilization. In the example of illustration, it is provided in the exit part from the sterilization tank 2 among the common lines 26 of an upstream side.

  Further, the steam sterilizer 1 includes an outer can steam line 34 for supplying steam into the jacket 11 and an outer can drain discharge line 31 for draining condensed water of the steam. The outer can steam line 34 is connected to the upper portion of the outer can 13 and supplies steam into the jacket 11 (more specifically, in the cavity between the outer can 13 and the inner can 12). Whether or not steam is supplied into the sterilization tank 2 via the outer can vapor line 34 is switched by opening and closing an outer can vapor valve 35 provided in the outer can vapor line 34. On the other hand, the outer can drain discharge line 31 is connected to the bottom of the outer can 13 and includes a steam trap 36 and a check valve 37 in order. The steam sterilizer 1 further includes an outer can pressure sensor 38 that detects the pressure in the jacket 11.

  The steam sterilizer 1 further includes control means. The control means is a controller (not shown) that controls the decompression means 3, the decompression means 4, the steam supply means 5, the exhaust means 6, and the like based on the detection signals of the sensors 9, 10, 38, the elapsed time, and the like. is there. Specifically, in addition to the vacuum valve 15, the vacuum pump 16, the sealed water supply valve 17, the air supply valve 20, the steam supply valve 23, the exhaust valve 32, the pressure sensor 9 and the temperature sensor 10, the outer can steam valve 35 and the outside The can pressure sensor 38 is connected to the controller. The controller sterilizes the sterilized material in the sterilization tank 2 according to a predetermined procedure (program) as described below.

  Hereinafter, the operation method of the steam sterilizer 1 of the present embodiment will be specifically described. FIG. 2 is a diagram illustrating an example of an operation method of the steam sterilizer 1 of the present embodiment, and shows the relationship between the pressure in the sterilization tank 2 and the elapsed time.

  In the initial state (standby state), the air supply valve 20 and the exhaust valve 32 are open, the other valves 15, 17, 23, and 35 are closed, and the vacuum pump 16 stops operating. From this initial state, in this embodiment, the air exclusion process S1, the steam supply process S2, the sterilization process S3, the exhaust process S4, and the drying process S5 are sequentially performed. Further, before the air exclusion step S1, the steam sterilizer 1 supplies steam into the jacket 11 and maintains the jacket 11 at a predetermined pressure. Specifically, the outer can steam valve 35 is opened to supply steam into the jacket 11, and the pressure inside the jacket 11 is monitored by the outer can pressure sensor 38, while the inside of the jacket 11 is kept at a predetermined pressure (this predetermined pressure is After that, the opening and closing of the outer can steam valve 35 is controlled so as to maintain the first predetermined pressure. Such control is continuously performed also in each process after air exclusion process S1. The first predetermined pressure is set according to the sterilization temperature (the holding temperature in the sterilization step S3).

  By such control, after the inside of the jacket 11 is equilibrated at the first predetermined pressure, the article to be sterilized is accommodated in the sterilization tank 2, the door of the sterilization tank 2 is closed, and the air exclusion process S1 is started. . In the air evacuation step S1, first, a purge operation S11 in the sterilization tank 2 using steam is performed for a predetermined time using the steam supply means 5 and the exhaust means 6. That is, the steam supply means 5 supplies steam into the sterilization tank 2 while allowing the exhaust means 6 to exhaust from the sterilization tank 2, and the purge operation S11 in the sterilization tank 2 is performed for a predetermined time. More specifically, the air supply valve 20 is closed, the steam supply valve 23 and the exhaust valve 32 are opened, steam is supplied from the steam supply line 22 into the sterilization tank 2, and the gas in the sterilization tank 2 is exhausted. Eject from 24. Thereby, the temperature rise of the object to be sterilized in the sterilization tank 2 and the air removal from the sterilization tank 2 can be achieved in parallel.

  In the purge operation S11, the exhaust valve 32 is opened, so that the inside of the sterilization tank 2 is maintained at substantially atmospheric pressure. Thereby, even if the steam supplied into the sterilization tank 2 from the steam supply line 22 is maintained at, for example, 0.3 MPa (saturation temperature 143.7 ° C.) on the primary side (upstream side) of the steam supply valve 23, It expands in the sterilization tank 2 to lower the temperature, and becomes steam of 100 to 105 ° C. Therefore, the temperature difference between the steam in the sterilization tank 2 and the object to be sterilized can be suppressed, and excessive condensation of the steam can be prevented.

  After the purge operation S11 is continued for a predetermined time, the exhaust by the exhaust means 6 and the steam supply by the steam supply means 5 are stopped. Specifically, the steam supply valve 23 and the exhaust valve 32 are closed. And decompression operation S12 in the sterilization tank 2 by the decompression means 3 is performed up to a predetermined pressure (this predetermined pressure is referred to as a second predetermined pressure). Specifically, the vacuum valve 15 is opened, the sealed water supply valve 17 is opened, and the vacuum pump 16 is operated simultaneously. As a result, the pressure in the sterilization tank 2 is reduced. The pressure sensor 9 monitors the pressure in the sterilization tank 2, and the pressure in the sterilization tank 2 is reduced until the pressure in the sterilization tank 2 reaches the second predetermined pressure. The second predetermined pressure is set as appropriate, but is set to, for example, −90 kPa to −95 kPa in the present embodiment.

  After the purge operation S11, the inside of the sterilization tank 2 is not pressurized (= heated up) by the steam supply by the steam supply means 5, but is decompressed by the decompression means 3, so that the self-evaporation of the condensed water in the sterilization tank 2 occurs. Condensate is not generated excessively. In addition, it is supplied into the sterilization tank 2 for the purge operation S11 and is supplied into the sterilization tank 2 for the purge operation S11 or vapor remaining in the sterilization tank 2, and once condensed, but is re-applied by the subsequent decompression. The evaporated vapor is sucked by the water-sealed vacuum pump 16 and recondensed by the sealed water of the vacuum pump 16. Due to the rapid volume reduction due to this recondensation, the gas in the sterilization tank 2 is further sucked into the vacuum pump 16 and the exhaust speed from the sterilization tank 2 is further increased.

  After such a depressurization operation, an ascending / depressurizing operation S15 including a pressure increasing operation S13 in the sterilization tank 2 by the steam supply means 5 and a pressure reducing operation S14 in the sterilization tank 2 by the pressure reducing means 3 is performed once or more as desired. The In FIG. 2, the ascending / depressurizing operation S15 is performed only once, but may be performed a plurality of times. Alternatively, in some cases, such ascending / depressurizing operation S15 may not be performed, and immediately after the depressurizing operation S12 immediately after the purge operation S11, the process may proceed to the next step. That is, after the pressure reducing operation S12 immediately after the purge operation S11, steam may be supplied into the sterilization tank 2 until the inside of the sterilization tank 2 reaches a sterilization pressure (steaming step S2).

  The pressure increasing operation S13 in the pressure increasing / decreasing operation S15 is performed by opening the steam supply valve 23 while the vacuum valve 15, the air supply valve 20 and the exhaust valve 32 are closed. Thereby, steam is supplied into the sterilization tank 2, and the pressure in the sterilization tank 2 rises. During the pressure increase in the sterilization tank 2, the pressure sensor 9 monitors the pressure in the sterilization tank 2, and when the pressure reaches the pressure increase target pressure, the steam supply valve 23 is closed and the process proceeds to the pressure reduction operation S14. Although the pressure increase target pressure is the atmospheric pressure in FIG. 2, it may be less than the atmospheric pressure or a pressure exceeding the atmospheric pressure (however, a pressure not exceeding the sterilization pressure). Further, when the pressure increasing / decreasing operation S15 is performed a plurality of times, the pressure increase target pressure in each time may be the same or different.

  The depressurization operation S14 in the ascending / depressurizing operation S15 is performed by opening the vacuum valve 15 and the sealed water supply valve 17 and operating the vacuum pump 16 with the air supply valve 20, the steam supply valve 23 and the exhaust valve 32 closed. . Thereby, the vapor | steam in the sterilization tank 2 is exhausted, and the pressure in the sterilization tank 2 falls. During the pressure reduction in the sterilization tank 2, the pressure sensor 9 monitors the pressure in the sterilization tank 2, and when the pressure reaches the pressure reduction target pressure, the vacuum valve 15 and the sealed water supply valve 17 are closed and the vacuum pump 16 is stopped. . However, when the pressure increase target pressure is set to a pressure exceeding atmospheric pressure in the pressure increasing operation S13 and the inside of the sterilization tank 2 is in a pressurized state, the vacuum valve 15, the air supply valve 20, and the steam supply valve 23 are closed. The pressure in the sterilization tank 2 can be lowered by opening the exhaust valve 32 and exhausting the vapor from the sterilization tank 2. When the pressure reduction target pressure is less than atmospheric pressure, when the sterilization tank 2 is at or just before atmospheric pressure, the exhaust valve 32 is closed, the vacuum valve 15 and the sealed water supply valve 17 are opened, and the vacuum pump 16 is operated. The sterilization tank 2 may be further depressurized. In FIG. 2, the pressure reduction target pressure is the same as the target pressure of the pressure reduction operation S12 immediately after the purge operation S11, but may be different. Further, when the ascending / depressurizing operation S15 is performed a plurality of times, the depressurization target pressure at each time may be the same or different.

  In the subsequent steam supply step S2, steam is supplied into the sterilization tank 2 by the steam supply means 5, and the pressure in the sterilization tank 2 is increased to the sterilization pressure. Specifically, with the vacuum valve 15, the air supply valve 20, and the exhaust valve 32 closed, the steam supply valve 23 is opened to supply steam into the sterilization tank 2 up to the sterilization pressure. During the supply of steam into the sterilization tank 2, the pressure sensor 9 monitors the pressure in the sterilization tank 2 and the temperature sensor 10 to monitor the temperature in the sterilization tank 2. When the temperature reaches the sterilization temperature, the process proceeds to the next step. .

  In the sterilization step S3, the temperature sensor 10 monitors the temperature in the sterilization tank 2, and the opening / closing of the steam supply valve 23 is controlled so that the temperature maintains the sterilization temperature for a predetermined sterilization holding time. As a result, the article to be sterilized in the sterilization tank 2 is maintained at the sterilization temperature for the sterilization holding time and sterilized. Thereafter, the steam supply valve 23 is closed and the process proceeds to the next step.

  In the exhaust process S4, the exhaust valve 32 is opened, the steam is discharged out of the sterilization tank 2, and then the exhaust valve 32 is closed. In the subsequent drying step S5, the object to be sterilized in the sterilization tank 2 is dried for a set time. In the present embodiment, the inside of the sterilization tank 2 is depressurized to a predetermined pressure (this predetermined pressure is referred to as a third predetermined pressure) and maintained under the reduced pressure, so that the object to be sterilized in the sterilization tank 2 is dried. Specifically, drying is performed by opening the vacuum valve 15 and the sealing water supply valve 17 and operating the vacuum pump 16 to maintain the inside of the sterilization tank 2 under a predetermined reduced pressure. However, in the drying step S5, the pressure reduction to the predetermined pressure (third predetermined pressure) and the return pressure to the atmospheric pressure may be repeated until the set time is reached.

  FIG. 3 is a diagram showing another example of the operation method of the steam sterilizer 1 of the present embodiment, and shows the relationship between the pressure in the sterilization tank 2 and the elapsed time. 3 is basically the same as the operation method of FIG. 2, the following description will focus on the differences between the two, and corresponding portions will be described with the same reference numerals. .

In the operation method of FIG. 3, the purge operation S11 is not performed. Instead, in the first decompression operation S12, steam is supplied into the sterilization tank 2 by the steam supply means 5 to the extent that the inside of the sterilization tank 2 is not decompressed in the middle of the decompression in the sterilization tank 2 by the decompression means 3. Specifically, with the air supply valve 20 and the exhaust valve 32 closed, the vacuum valve 15 and the sealed water supply valve 17 are opened and the operation of the vacuum pump 16 is continued, while the steam supply valve 23 is temporarily opened. Close it. As a result, in the first decompression operation S12, decompression S12a without steam supply, decompression S12b with steam supply, and decompression S12c without steam supply are sequentially performed.

  The timing for starting the supply of steam (starting point of S12b) is appropriately set. Preferably, the saturated steam temperature in the sterilization tank 2 is close to the temperature of the object to be sterilized, and the vacuum in the sterilization tank 2 is set. As the degree increases, the pressure reduction speed of the vacuum pump 16 starts to decrease. As the inside of the sterilization tank 2 is depressurized, the saturated steam temperature in the sterilization tank 2 decreases and eventually approaches the temperature of the object to be sterilized, but at that time (for example, the saturated steam temperature in the sterilization tank 2 and the temperature of the object to be sterilized). This is because if the steam is supplied into the sterilization tank 2 from the time when the difference between the sterilization point and the difference is within a predetermined range, the object to be sterilized need not be wetted more than necessary. In addition, the vacuum pump 16 suddenly decreases the exhaust speed at a pressure close to the performance limit. However, if the steam is temporarily introduced during the decompression, the steam and the steam once condensed but then re-evaporated This is because, when sucked into the water-sealed vacuum pump 16, the volume is rapidly reduced by recondensing, so that the exhaust speed from the inside of the sterilization tank 2 can be increased.

  On the other hand, the time for ending the supply of steam during the decompression in the sterilization tank 2 (the end point of S12b) is set as appropriate, for example, until the temperature of the object to be sterilized reaches 60 ° C. Thereby, it can prevent that condensed water arises excessively. Others are the same as in FIG.

  FIG. 4 is a diagram showing still another example of the operation method of the steam sterilizer 1 of the present embodiment, and shows the relationship between the pressure in the sterilization tank 2 and the elapsed time. The driving method of FIG. 4 is basically the same as the driving method of FIG. 2, so the following description will focus on the differences between the two, and corresponding portions will be described with the same reference numerals. .

  In the operation method of FIG. 2, the ascending / depressurizing operation S15 is performed only once. However, in the operating method of FIG. 4, the ascending / depressurizing operation S15 is performed twice. In addition, the pressure increase in the second pressure increase / decrease operation S15 is set to a pressure equal to or higher than atmospheric pressure. At this time, the pressure is preferably increased to 0.5 to 1 times the sterilization pressure. In the subsequent depressurization operation S14, the pressure in the sterilization tank 2 is simply lowered to the atmospheric pressure simply by opening the exhaust valve 32. However, in some cases, the inside of the sterilization tank 2 may be further depressurized and the inside of the sterilization tank 2 may be in a vacuum state.

  According to the operation method of FIG. 4, steam is supplied into the sterilization tank 2 at the final stage of the air evacuation step S <b> 1 so that the pressure is 0.5 to 1 times the holding pressure in the sterilization step S <b> 3. And the inside of the sterilization tank 2 is decompressed. By evacuating after raising the pressure to 0.5 to 1 times the holding pressure in the sterilization step S3, a sufficient pressure difference can be secured during this time, and the residual air in the sterilization tank 2 can be expelled. Others are the same as in FIG.

  FIG. 5 is a diagram showing still another example of the operation method of the steam sterilizer 1 of this embodiment, and shows the relationship between the pressure in the sterilization tank 2 and the elapsed time. The driving method of FIG. 5 is also basically the same as the driving method of FIG. 2, so the following description will focus on the differences between the two, and the corresponding parts will be described with the same reference numerals. .

  In the operation method of FIG. 2, the pressure increase target pressure of the ascending / depressurizing operation S15 is set to the atmospheric pressure. However, in the operation method of FIG. The reason is the same as that described in the operation method of FIG. 4, and it is preferable to increase the pressure to 0.5 to 1 times the sterilization pressure. Others are the same as in FIG.

  The steam sterilizer and the air evacuation method of the present invention are not limited to the configuration of the above embodiment, and can be changed as appropriate. For example, as described above, the presence / absence or number of the ascending / depressurizing operation S15 in the air exclusion step S1, or the pressure increase target pressure or pressure reduction target pressure can be changed as appropriate. Moreover, in the said Example, although the vapor | steam supplied into the sterilization tank 2 was saturated vapor | steam in any location, you may use superheated vapor | steam in air exclusion process S1. In this case, the amount of vapor condensation can be further reduced.

  In the above embodiment, the jacket 11 is provided with a pressure sensor (outer can pressure sensor 38) and controlled to maintain a predetermined pressure in the jacket 11. However, the jacket 11 has a temperature sensor (outer can temperature sensor). May be provided to control the inside of the jacket 11 to be maintained at a predetermined temperature. This temperature sensor may be provided at the outlet from the outer can 13 in the outer can drain discharge line 31, or may be provided at the top of the outer can 13 or the like.

  Further, in the operation methods of FIGS. 2, 4 and 5, the purge operation S11 in the sterilization tank 2 by steam is performed for a predetermined time, but the temperature detected by the temperature sensor 10 is monitored and the temperature is set to a desired temperature (for example, The purge operation S11 may be performed until the temperature reaches 100 ° C.

DESCRIPTION OF SYMBOLS 1 Steam sterilizer 2 Sterilization tank 3 Pressure reduction means 4 Pressure reduction means 5 Steam supply means 6 Exhaust means 8 Drain discharge means S1 Air exclusion process S2 Steam supply process S3 Sterilization process S4 Exhaust process S5 Drying process S11 Purge operation S12 Pressure reduction operation S13 Pressure increase Operation S14 Depressurization operation S15 Ascending / depressurizing operation S12a Depressurization without steam supply S12b Depressurization with steam supply S12c Depressurization without steam supply

Claims (2)

A sterilization tank in which objects to be sterilized are stored;
A vacuum means for sucking and discharging the gas in the sterilization tank to the outside, and reducing the pressure in the sterilization tank;
A return pressure means for introducing outside air into the sterilized tank that has been depressurized and returning the pressure in the sterilization tank;
Steaming means for supplying saturated steam into the sterilization tank;
Exhaust means for deriving the gas in the sterilization tank to the outside by a differential pressure from the atmospheric pressure;
As the air evacuation step prior to the sterilization step, the sterilization tank can be evacuated from the sterilization tank by the exhaust means so that the inside of the sterilization tank is not pressurized as the steam temperature exceeds 105 ° C. A control means for performing a decompression operation in the sterilization tank by the decompression means in a state where the exhaust by the exhaust means and the steam supply by the steam supply means are stopped after a purge operation for performing steam supply into the interior,
The control means, as the air exclusion step, performs an ascending / decreasing operation including a pressure increase in the sterilization tank by the steam supply means and a pressure decrease in the sterilization tank by the pressure reduction means or the exhaust means after the pressure reduction operation. More than once,
The last pressurization of the ascending / depressurizing operation is performed by supplying steam into the sterilization tank by the steam supply means to a pressure that is 0.5 to 1 times the holding pressure in the subsequent sterilization step. Sterilizer. Instead of the purge operation, in the decompression operation, steam is supplied into the sterilization tank by the steaming means to the extent that the sterilization tank is not decompressed in the middle of the decompression by the decompression means. Perform temporarily, and then further reduce the pressure in the sterilization tank by the pressure reducing means in a state where the steam supply is stopped,
The steam sterilizer according to claim 1, wherein the pressure in the sterilization tank is decreased by continuing the operation of the decompression unit even during the temporary steam supply.

Images