JPH0576869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ethylene oxide vaporizer for sterilization for supplying ethylene oxide gas to a sterilizer for sterilizing medical instruments and the like with ethylene oxide gas.

[Conventional technology]

Conventionally, this type of vaporizer includes a block heating element 10, a heater 5', a power source 6', and a power source 6', as shown in FIG.
The switch 7' stores the amount of heat required to vaporize the ethylene oxide required for one sterilization operation, and supplies the liquefied gas from the liquefied ethylene oxide gas cylinder 1 through the solenoid valve 2 and capillary reach tube 3 to the block heating element 10. The liquid is vaporized in a spiral tube 4 and injected into a sterilizer 9.

In addition, in this type of vaporizer, for example,
As disclosed in Publication No. 60-63054, when the temperature inside the vaporizer is below a predetermined temperature required for vaporizing ethylene oxide, the vaporizer is configured so that liquefied ethylene oxide gas is not supplied to the vaporizer. Things are also known.

[Problem to be solved by the invention]

According to the conventional vaporizer shown in FIG. 4, in the initial stage of ethylene oxide injection, heat exchange between the block heating element 10 and the liquefied gas is successful, and completely vaporized gas at a desired temperature is injected into the sterilizer 9. However, the stored heat is gradually taken away by the liquefied gas, the temperature of the block heating element decreases, the temperature of the vaporized gas decreases and becomes uneven, and eventually some or all of the liquefied gas becomes vaporized. There is a problem that the liquid is injected into the sterilizer 9 without being filled.

As a solution to this problem, a block heating element 10
It is possible to increase the size of the block heating element or increase the output of the heater 5', but increasing the size of the block heating element will make the entire vaporizer larger and heavier, increasing manufacturing costs and increasing the temperature. On the other hand, if the heater output is increased, the production cost increases accordingly and the power consumption increases.

In addition to the above solution, there is also a method of attaching the gas reservoir container 8 in front of the inlet of the sterilizer 9,
Another possible method is to make the capillary reach tube 3 longer so as to reduce the flow rate so that heat exchange can be performed smoothly, thereby allowing vaporized gas to be injected into the sterilizer 9 even without the gas reservoir 8. However, the former method requires the provision of a gas reservoir container 8, which increases cost and requires additional space for installing the container. In addition, in the latter method, the vaporization time becomes longer, and the diameter of the capillary reach tube is usually 1 mm, and if liquid ethylene oxide remains stagnant in the tube for a long time, polymers will be generated.
It will clog the tube.

In this regard, according to the carburetor disclosed in Japanese Patent Application Laid-Open No. 60-63054, the above-mentioned problems in the conventional carburetor shown in FIG. 4 are somewhat solved. However, the vaporizer taught in Japanese Patent Application Laid-Open No. 60-63054 still has the following problems.

That is, in the vaporizer according to the publication, the temperature is measured by a temperature measuring means such as a thermistor,
The measured temperature is compared with a predetermined temperature to determine whether or not to supply liquefied ethylene oxide gas to the vaporizer, but the responsiveness of the temperature measuring means to changes in vaporizer temperature is not good. However, even if the vaporizer temperature falls below the boiling point of ethylene oxide, there is a risk that liquefied ethylene oxide gas may still be supplied to the vaporizer.

This fear becomes greater as the predetermined temperature serving as the predetermined criterion is closer to the boiling point of ethylene oxide. Therefore, it is conceivable to set the predetermined temperature sufficiently higher than the boiling point, but in this case, the supply of liquefied ethylene oxide gas may be stopped even when the vaporizer temperature is still sufficient to vaporize the liquefied ethylene oxide gas. There is a risk of it being stored away.

Therefore, an object of the present invention is to provide an ethylene oxide vaporizer for sterilization in which various problems in the conventional vaporizers are largely solved compared to the conventional vaporizers described above.

[Means to solve the problem]

In order to solve the above problems, the present invention is an ethylene oxide vaporizer for sterilization for supplying ethylene oxide gas to a sterilizer, and includes a heat exchanger equipped with an ethylene oxide passage and an electric heater, and a heat exchanger equipped with an ethylene oxide passage and an electric heater. an automatic opening/closing valve connected to the inlet, a means for measuring the temperature of the heat exchanger, a means for measuring the atmospheric pressure in the sterilizer, and a heat measured by the temperature measuring means after the electric heater starts being energized. When the exchanger temperature reaches a predetermined first temperature higher than the boiling point of ethylene oxide, the automatic opening/closing valve is opened, and ethylene oxide gas is introduced by opening the automatic opening/closing valve, and the atmospheric pressure measuring means measures the sterilizer. a valve control unit that closes the automatic on-off valve when the internal pressure rises by a predetermined value; Ethylene oxide vaporization for sterilization, characterized in that the temperature is set approximately equal to the pressure increase in the sterilizer during the temperature drop to a predetermined second temperature that is lower than the first temperature but still higher than the boiling point of ethylene oxide. Provide utensils.

In this case, the control unit may be configured to close the automatic opening/closing valve when the pressure measured by the atmospheric pressure measuring means in the sterilizer exceeds a predetermined sterilization pressure.

[Effect]

In the vaporizer of the present invention, a liquefied ethylene oxide gas cylinder is connected to the inlet of the automatic opening/closing valve, and the ethylene oxide passage outlet of the heat exchanger is connected to the sterilizer. Operate.

Initially, the automatic opening/closing valve is closed, and when the electric heater of the heat exchanger is energized to inject ethylene oxide gas into the sterilizer, the temperature begins to rise, and the heat exchanger temperature measured by the temperature measuring means increases. When the temperature reaches a predetermined first temperature or higher, the valve controller opens the automatic opening/closing valve, and the liquefied ethylene oxide gas flows from the cylinder to the heat exchanger passage, where it is vaporized and flows into the sterilizer.

Thus, when the internal pressure of the sterilizer increases by a predetermined value due to gas introduction, the automatic opening/closing valve is closed by the valve control section while the electric heater remains energized. As a result, the temperature of the heat exchanger rises again, and when the temperature reaches the first temperature or higher, the automatic opening/closing valve is opened again, and the liquefied gas is introduced, vaporized, and injected into the sterilizer.

The above operations are repeated to supply a predetermined amount of ethylene oxide gas into the sterilizer.

According to another example of the control unit, as a result of the repeated operation, if the internal pressure of the sterilizer measured by the pressure measuring means becomes equal to or higher than a predetermined sterilization pressure, the automatic opening/closing valve is closed and the supply of ethylene oxide gas is closed. The operation ends.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The illustrated vaporizer is equipped with a heat exchanger 11 . This heat exchanger 11 has a main body 110 with an ethylene oxide passage consisting of a flexible tube 14 and an electric heater 5 attached thereto.

The main body 110 of the heat exchanger 11 is desirably made of a material with good heat transfer properties, and in this example is made of a thin aluminum plate.

An electromagnetic on-off valve 2 is connected to the inlet of the flexible pipe 14, and a liquefied ethylene oxide gas cylinder 1 is connected to the inlet of this valve. The outlet of the flexible pipe 14 is connected to the inlet of the sterilizer 9 via a solenoid valve 91 attached to the sterilizer 9.

A power supply circuit 60 is connected to the electric heater 5, and the circuit is provided with a power source 6 and a switch section 7 for opening and closing the circuit.

The electromagnetic on-off valves 2 and 91 and the switch section 7 are all operated based on instructions from a control section 15 including a microcomputer.

The control unit 15 receives a temperature signal from a temperature sensor 12 attached to the heat exchanger 11 (more precisely, a coiled pipe 14
temperature signal) is input and the sterilizer 9
A measured pressure signal from a pressure sensor 13 provided inside is input.

According to this carburetor, the solenoid valve 2 is initially closed, and the operator first operates the start switch (not shown) on the control section 15 to turn on the control section 1.
The switch part 7 is closed based on the instruction from 5.
As a result, the heater 5 of the heat exchanger 11 is energized, and the temperature of the entire heat exchanger 11 starts to rise. Note that the solenoid valve 91 attached to the sterilizer is also turned on and opened.

Heat exchanger 1 measured by temperature sensor 12
When the temperature T 1 reaches a predetermined first temperature T ₁ (70° C. in this example) which is higher than the boiling point of ethylene oxide that can quickly and sufficiently vaporize the liquefied ethylene oxide gas, the control unit 15 opens the solenoid valve 2. . Note that this temperature _T1 is set sufficiently higher than the boiling point in consideration of the case where the responsiveness of the temperature sensor 12 is low.

When the solenoid valve 2 opens, liquefied gas flows from the cylinder 1 into the flexible pipe 14 of the heat exchanger 11. The liquefied gas flowing into the flexible pipe 14 quickly vaporizes while passing through the pipe, becomes ethylene oxide gas, and flows into the sterilizer 9.

As time passes while the liquefied gas is vaporized in the corrugated pipe 14, the amount of heat stored in the heat exchanger 11 is gradually taken away, and the temperature of the heat exchanger decreases. When the pressure within the sterilizer 9, which is measured with relative accuracy by the pressure sensor 13, rises by a predetermined value h, the control unit 15 closes the solenoid valve 2 while continuing to energize the heater 5. Closed to stop the flow of liquefied gas into the heat exchanger 11.

The temperature of the heat exchanger 11 thus begins to rise again and the temperature of the heat exchanger 1 measured by the temperature sensor 12 increases.
When the temperature of the liquefied gas becomes equal to or higher than the first temperature T ₁ , the control unit 15 opens the solenoid valve 2 again to flow the liquefied gas into the heat exchanger 11 , where it is vaporized and sent to the sterilizer 9 .

From then on, the internal pressure of the sterilizer 9 becomes the predetermined sterilization pressure P.
Similar operations are repeated until reaching . The changes in the gas flow rate Q, heat exchanger temperature T, gas temperature, and internal pressure from this repeated operation until the sterilization pressure P is reached are as shown in the graph of FIG. 2.

As shown in FIG. 2, the pressure increase h is caused by the time when the solenoid valve 2 is opened and the ethylene oxide gas begins to be introduced into the sterilizer 9, and the heat exchanger temperature T increases to a temperature _T1. The temperature is set to be approximately equal to the pressure rise value inside the sterilizer while falling to a predetermined second temperature T ₂ (30°C in this example), which is lower but higher than the boiling point of ethylene oxide and still allows sufficient vaporization of the liquefied gas. be determined in advance through experiments. In this example
Assuming T ₁ = 70°C and T ₂ = 30°C, h = 50 mmHg.

In this way, the opening/closing timing of the solenoid valve 2 as the temperature of the heat exchanger decreases is not determined by measuring the second temperature _T2 with the temperature sensor 12, but by measuring the timing with the pressure sensor 13, which has good response. Since the determination is made based on the increase in pressure inside the sterilizer based on the above, the liquefied gas can be vaporized smoothly and safely even if the responsiveness of the temperature sensor 12 is low.

When the above operations are repeated and the pressure inside the sterilizer 9 increases due to the supply of ethylene oxide gas, and the pressure measured by the pressure sensor 13 exceeds the predetermined sterilization pressure P, the control unit 15 receives this and The solenoid valve 2 is closed, the power to the heater 5 is cut off, the solenoid valve 91 is closed, and the supply of ethylene oxide gas to the sterilizer 9 is stopped.

In this way, predetermined sterilization of medical instruments etc. stored in the sterilizer 9 in advance can be performed.

The opening/closing control of the electromagnetic valves 2, 91 and the opening/closing control of the switch section 7 by the control section 15 are as shown in the flowchart of FIG.

That is, in step S1, the heater 5 is turned on,
In step S2, the solenoid valve 91 is turned on and opened, and in step S3, when the heat exchanger temperature T reaches the first temperature T1 _or higher, in step S4, the solenoid valve 2 is turned on and opened, and in step S5, the sterilizer internal pressure is set to h. Determine whether it has increased. When the pressure rise exceeds h, the solenoid valve 2 is turned off and closed in step S6, and the solenoid valve 2 is closed in step S7.
Determine whether the internal pressure of the sterilizer is greater than or equal to the sterilization pressure P,
If the pressure is above P, the heater 5 is turned off in steps S10 and S11, and the solenoid valve 91 is turned off and closed.
If the pressure rise is lower than h in step S5, it is determined in step S8 whether the sterilizer internal pressure is greater than or equal to P, and P
If it is lower, the process returns to step S5, but if it is higher than P, the solenoid valve 2 is turned off and closed in step S9.

〔Effect of the invention〕

The ethylene oxide vaporizer for sterilization of the present invention described above has the following advantages.

Ethylene oxide is prevented from flowing into the sterilizer in a liquid state.

The first temperature, which is the opening/closing reference for the valve that controls the flow of liquefied ethylene oxide gas into the heat exchanger, is set to an appropriate temperature that is sufficiently higher than the boiling point of ethylene oxide, taking into account the low responsiveness of the temperature sensor. At the same time, by appropriately determining the pressure rise inside the sterilizer that serves as the valve opening/closing standard, liquefied ethylene oxide gas can be transferred to the heat exchanger only while the temperature of the heat exchanger is at a temperature that allows the ethylene oxide to be quickly vaporized. Since the liquefied gas can be passed through the vaporizer, the liquefied gas can be reliably vaporized, and the time for the liquefied gas to pass through the vaporizer can be shortened accordingly. The generation of polymer products is extremely reduced,
Pipe clogging is drastically reduced. Furthermore, since the piping in the vaporizer does not include a cupillary tube unlike conventional vaporizers, clogging due to polymers, foreign matter from the cylinder, etc. is greatly reduced.

Because the liquefied gas is vaporized according to the vaporization capacity of the vaporizer, it is possible to inject ethylene oxide gas at a more uniform temperature into the sterilizer than in the past.

There is no need for costly block heating elements or gas reservoirs, which are required in conventional vaporizers, and the piping is simple, so manufacturing costs can be reduced accordingly, and the heat exchanger can be made smaller and lighter. Since it can be manufactured in a number of steps, the overall space can be saved and the weight can be reduced.

Since the heat exchanger body can be made of a thin aluminum plate with good heat transfer properties, the heat exchanger can be heated up in a short time without having to increase the heater output, and it can also store an exceptional amount of heat. There is no need for this, and the amount of heat needed to vaporize ethylene oxide is sufficient, so the power consumption of the heater can be reduced.

Since the vaporization capacity is determined by the heat exchange capacity of the heat exchanger and the output of the heater, it is possible to accommodate many types of sterilizers by adjusting the heater output, which leads to standardization of design and manufacturing and cost reduction. It is advantageous in the following points.

When the internal pressure of the sterilizer measured by the barometric pressure measurement stage becomes higher than the predetermined sterilization pressure, the automatic on-off valve is configured to close, allowing safe use of the sterilizer and ensuring reliable sterilization under the desired pressure. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, and FIG.
The figure is a graph showing changes in heat exchanger temperature, pressure inside the sterilizer, etc. when ethylene oxide gas is supplied to the sterilizer, FIG. 3 is a flowchart showing the operation of the control section in the embodiment of FIG. FIG. 4 is an explanatory diagram of a conventional example. DESCRIPTION OF SYMBOLS 11... Heat exchanger, 14... Corrugated tube, 5... Electric heater, 60... Power supply circuit, 7... Switch part, 2,91
...Electromagnetic on-off valve, 12...Temperature sensor, 13...Pressure sensor, 15...Control unit, 1...Liquefied ethylene oxide gas cylinder, 9...Sterilizer.

Claims (1)

[Scope of Claims] 1. A sterilizing ethylene oxide vaporizer for supplying ethylene oxide gas to a sterilizer, which comprises a heat exchanger equipped with an ethylene oxide passage and an electric heater, and connected to an inlet of the ethylene oxide passage. a means for measuring the temperature of the heat exchanger; a means for measuring the atmospheric pressure inside the sterilizer; and a heat exchanger temperature measured by the temperature measuring means after the electric heater starts being energized. When the temperature reaches a predetermined first temperature which is higher than the boiling point of ethylene oxide, the automatic opening/closing valve is opened, and the internal pressure measured in the sterilizer by the atmospheric pressure measuring means is predetermined by introducing ethylene oxide gas by opening the automatic opening/closing valve. and a valve control unit that closes the automatic opening/closing valve when the internal pressure of the sterilizer increases by a certain value, and the predetermined increase value of the internal pressure of the sterilizer causes the heat exchanger temperature to reach the first temperature after the automatic opening/closing valve is opened. 1. An ethylene oxide vaporizer for sterilization, characterized in that the temperature is set approximately equal to the pressure rise value within the sterilizer during the temperature drop to a predetermined second temperature, which is lower but still higher than the boiling point of ethylene oxide. 2. The ethylene oxide vaporizer for sterilization according to claim 1, wherein the valve control unit closes the automatic opening/closing valve when the internal pressure of the sterilizer, which is measured by the atmospheric pressure measuring means in the sterilizer, becomes equal to or higher than a predetermined sterilization pressure. .