METHOD FOR DECONTAMINATING LOW-TEMPERATURE ARTICLE AND A PASS BOX USED IN SAME

Abstract

A method for decontaminating a low-temperature article to accomplish decontaminating a surface of the such article, and to reduce duration of operations to increase efficiency of decontamination, and a pass box used in such method.

The method includes an applying step of applying a decontamination agent to external surfaces of the article, and a drying step of irradiating the article with agent thereon with ultrasonic waves and drying the surface. In the applying step, a gas, fog or mist of the decontamination agent is supplied to a target surface to form a condensed film of the agent on the target surface. In the drying step, dry air is supplied to the target surface.

Claims

1. A method for decontaminating a low-temperature article, the method comprising: an applying step including applying a decontamination agent to external surfaces of a low-temperature article; and a drying step including irradiating with ultrasonic waves the low-temperature article with the decontamination agent applied thereto and drying an external surface thereof.

2. The method for decontaminating a low-temperature article according to claim 1, wherein the drying step includes supplying dry air to said external surface.

3. The method for decontaminating a low-temperature article according to claim 2, wherein wherein the applying step includes supplying a mist of decontamination agent to an external surface of said low-temperature article to form a condensed film of the decontamination agent on said external surface.

4. The method for decontaminating a low-temperature article according to claim 3, wherein the drying step includes ultrasonically vibrating vibration boards disposed on the periphery of the low-temperature article to generate sound flows from board surfaces by an ultrasound in a vertical direction; and subjecting the external surface of the low-temperature article to ultrasonic vibration and acoustic radiation pressure.

5. A pass box for use in the method according to claim 4, the pass box comprising: a working chamber configured for decontaminating a low-temperature article, a decontamination agent supply means, a dry air supply means, and an ultrasound vibration means, wherein: the decontamination agent supply means is configured to supply the decontamination agent, in a state of a decontamination agent mist, to an inside of the working chamber that accommodates the low-temperature article to form a condensed film of the decontamination agent on an external surface of said, the dry air supply means is configured to supply dry air to the external surface of the low-temperature article, the ultrasound vibration means includes vibration boards disposed adjacent to internal wall surfaces of the working chamber, the vibration boards being configured to be ultrasonically vibrated to generate sound flows from board surfaces by an ultrasound in a vertical direction, and the pass box configured such that the dry air and the sound flows on the low-temperature article in the working chamber are directed to dry the condensed film of the decontamination agent formed on the external surface of the low-temperature article.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1A shows the state in an applying step and FIG. 1B shows the state in a drying step, each outlining the inside of a pass box used in a method for decontaminating a low-temperature article according to this embodiment; and

[0033] FIG. 2 is a schematic perspective view showing a plurality of ultrasonic speakers arranged in a speaker base in a vibration board included in the pass box in FIG. 1.

DETAILED DESCRIPTION

[0034] The method for decontaminating a low-temperature article according to the present invention and a pass box used therein will be described with reference to an embodiment. The present invention is not restricted to the following embodiment.

[0035] In this embodiment, the method for decontaminating a low-temperature article is performed by an applying step for applying a decontamination agent to external surfaces of a low-temperature article to be decontaminated, and a drying step for irradiating with ultrasonic waves the low-temperature article applied with the decontamination agent and drying the surface. FIG. 1(A) shows the state in an applying step and FIG. 1(B) shows the state in a drying step, each outlining the inside of the pass box used in the method for decontaminating a low-temperature article according to this embodiment.

[0036] <Applying Step>

[0037] First, an applying step will be described. In FIG. 1(A), a pass box 10 is a stainless housing that is linked to an isolator (not shown) through an opening/closing door (inner door) on a wall surface thereof, the isolator including an opening/closing door (outer door) on other wall surface, leading to the external environment. The linking state between the pass box 10 and the isolator and the structure of opening/closing doors are not particularly restricted, and the pass box is the same as conventional pass boxes in structure. The position of the pass box relative to the isolator is not restricted to that on a side wall surface, and the pass box may be linked to a top wall surface or a bottom wall surface. FIG. 1 shows no inner door, outer door, air supply and exhaust device, or the like.

[0038] In FIGS. 1A, 1B, an article 50 that is conveyed from the external environment to the inside of the isolator is conveyed to a center inside the pass box 10. In FIG. 1 A, a glass cover 50 covers the low-temperature article 40 from an upper portion to a side lower portion thereof. The cover 50 is provided such that a decontamination agent mist supplied from a decontamination agent supply means (later-described) concentrates around external surfaces of the low-temperature article 40. The cover 50 may be provided in the applying step as needed.

[0039] In this embodiment, the low-temperature article 40 is to be decontaminated, and a freeze-dried vial. The low-temperature article 40 is conveyed to the inside of an isolator after decontamination inside the pass box 10. In FIG. 1A, 2 vibration boards 21, 22 are disposed inside the pass box 10 as an ultrasound vibration means. These vibration boards 21, 22 are not operated in the applying step, and mentioned in a later-described drying step.

[0040] Then, a decontamination agent supply means will be described. In this embodiment, the decontamination agent supply means used is a two-fluid spray nozzle 30, which is placed on a bottom wall surface 13 of the pass box 10 (see FIG. 1A). In this embodiment, the decontamination agent used is a hydrogen peroxide solution (H.sub.2O.sub.2 solution). The decontamination agent is not restricted to a hydrogen peroxide solution, and any decontamination agent may be used so long as it is liquid.

[0041] The two-fluid spray nozzle 30 converts a hydrogen peroxide solution into a hydrogen peroxide solution mist 31 by compressed air from a compressor (not shown) to supply the same to the inside of the pass box 10. In the present invention, the mist supply device is not restricted to a two-fluid spray nozzle, and a mist generation mechanism and output are not particularly restricted. In FIG. 1 A, the hydrogen peroxide solution mist 31 generated from the two-fluid spray nozzle 30 is supplied to the inside of the cover 50 to concentrate on the periphery of the low-temperature article 40. Herein, the hydrogen peroxide solution mist 31 is cooled at a low surface temperature of the low-temperature article 40, and condensed on the surface of the low-temperature article 40 to form a condensed film.

[0042] In this embodiment, a decontamination agent mist is employed in the applying step. However, the method for applying a decontamination agent to external surfaces of a low-temperature article in the present invention is not restricted to the supply of a decontamination agent mist using a two-fluid spray nozzle or the like. For example, a low-temperature article with a condensed film formed on the surface may be conveyed to the inside of a pass box after a decontamination agent is applied using a hand spray or the like beforehand. The low-temperature article may be immersed in a decontamination agent aqueous solution adjusted to have a predetermined concentration, and the low-temperature article with a condensed film formed on the surface may be conveyed to the inside of the pass box.

[0043] The term “a decontamination agent mist employed in this embodiment” is broadly interpreted and defined as the state of a liquid droplet of a decontamination agent miniaturized or reduced in size and floating in the air, the state of a gas and a liquid agent of a decontamination agent in mixture, and the state of the decontamination agent to repeat the change in phase between condensation and evaporation of a gas and a droplet, and the like. In terms of particle size as well, the mist is also broadly interpreted to include mists, fogs, and liquid droplets, which can be subclassified.

[0044] Accordingly, the mist according to the present invention is categorized into a “mist” (the size may be defined as 10 μm or less) or a “fog” (the size may be defined as 5 μm or less), and a mist having a larger particle size. In the present invention, condensation for a mist is time-consuming, and such a mist contains a decontamination agent gas as well.

[0045] <Drying Step>

[0046] Then, a drying step will be described. In FIG. 1B, a low-temperature article 40 with a condensed film of a hydrogen peroxide solution formed on the surface in the applying step is accommodated inside the pass box 10. A cover 50 covering the low-temperature article 40 is removed. Also, 2 vibration boards 21, 22 are disposed so as to sandwich the low-temperature article 40 on right and left sides. The 2 vibration boards 21, 22 are disposed inside 4 side walls of the pass box 10 against side wall surfaces 11, 12 that are opposite such that vibration surfaces 21a, 22a face horizontally inside the pass box 10. These 2 vibration boards 21, 22 are arranged by allowing board surfaces (vibration surfaces 21a, 22a) thereof to be opposite each other, and the low-temperature article 40 is disposed at the central portion.

[0047] Herein, the vibration board 21 will be described (also applied to the vibration board 22). FIG. 2 is a schematic perspective view showing a plurality of ultrasonic speakers arranged in a speaker base in a vibration board included in the pass box in FIG. 1. In FIG. 2, the vibration board 21 includes a base and a plurality of transmitters. In this embodiment, the base used is a speaker base 25, and the transmitter used is an ultrasonic speaker 26. In this embodiment, 25 ultrasonic speakers 26 are arranged on a planar surface 25a of the speaker base 25 so as to be uniform in transmission direction of a vibration surface 26a (leftward as seen from the front shown). The number of ultrasonic speakers is not particularly restricted.

[0048] In this embodiment, the ultrasonic speaker 26 used is an ultradirectional ultrasonic speaker. Specifically, an ultrasonic speaker (DC12V, 50 mA) of frequency modulation system for transmitting an ultrasound whose frequency is around 40 KHz is used. The type, size, structure and output of the ultrasonic speaker are not particularly restricted. In the present invention, the vibration board included in the mist control device is not restricted to an ultrasonic speaker, and the ultrasonic generation mechanism, frequency range and output are not particularly restricted.

[0049] In this embodiment, a plurality of (25) ultrasonic speakers 26 are arranged so as to be uniform in transmission direction of the vibration surface 46a, and the transmitters are operated in the same phase to mutually amplify ultrasounds from the plurality of ultrasonic speakers 46 in the front direction and mutually cancel out ultrasounds from the plurality of ultrasonic speakers 46 in the lateral direction. Consequently, the ultrasonic speakers 26 arranged on the speaker base 25 are ultrasonically vibrated to generate a significantly directional sound flow traveling in the air from each of the vibration surfaces 26a in the vertical direction. The frequency and output of the ultrasonic speakers 26 are controlled by an ultrasonic controller (not shown) to achieve efficient decontamination operations.

[0050] In FIG. 1B, an intake pipe 60 and an exhaust device 70 are provided. The intake pipe 60 is provided on the bottom wall surface 13 of the pass box 10 to supply dry air to the inside of the pass box 10. Other dry gas such as nitrogen gas may be supplied in place of dry air. The exhaust device 70 is provided on the side wall surface 12 of the pass box 10 to discharge wet air generated by drying inside the pass box 10 and an evaporated decontamination agent gas to the outside. In FIG. 1B, the two-fluid spray nozzle 30 is not operated, and it is not described.

[0051] The supply of dry air from the intake pipe 60 in this state and ultrasonic vibration of the ultrasonic speaker 26 of each vibration board generate significantly directional sound flows traveling in the vertical direction from 2 vibration surfaces 21a, 22a. These sound flows generate pressing forces by ultrasonic vibration and acoustic radiation pressure on the surface of the low-temperature article 40. Accordingly, a condensed film of a hydrogen peroxide solution condensed on the low-temperature article 40 is vibrated, and the condensed film is dried by the action of dry air and condensation of the hydrogen peroxide solution is promoted, resulting in higher decontamination effects by oxidation.

[0052] Subsequently, using the pass box 10 according to this embodiment by reference to an example, the method for decontaminating a low-temperature article according to the present invention will specifically be described. The present invention is not restricted to the following example.

Example

[0053] In this example, an operation of decontaminating external surfaces of a freeze-dried vial (surface temperature: 0° C., contents: 5 ml of distilled water) in a pass box and conveying it to the inside of an isolator was performed. The vial used is made of polyethylene with the dimensions of 7 cm in height, 2 cm in diameter and 15 ml in volume.

[0054] Decontamination effects on external surfaces of the freeze-dried vial were confirmed by an enzyme indicator (EI). EI is an apparatus for fluorescence assay of residual enzymatic activity after a test to confirm decontamination effects, and this approach is advantageous in removing culture operations in conventional biological indicator (BI) and reducing the duration of operations. EI's comparative equality with BI was recently confirmed and the EI technique has proactively been used. The log spore reduction (LRD) value was calculated by the logarithmic decrement of fungi from the EI's fluorescence intensity after decontamination, and the LRD of 4 to 6 or more was judged as a sufficiently acceptable decontamination standard effect inside the pass box.

[0055] In this example, a pass box 10 of FIGS. 1A,1B was used. A pass box 10 disposed is 0.0022 m.sup.3 in volume (15 cm in length, 12 cm in width, 12 cm in thickness; and internal wall surfaces are stainless plates), including 2 vibration boards 21, 22. There are 4 applying methods in the step for applying hydrogen peroxide: (1) dipping method; (2) hand spray method; (3) mist method (using two-fluid spray nozzle); and (4) fog method (using ultrasonic humidifier: nebulizer). In the (3) mist method and (4) fog method, a hydrogen peroxide solution (35 W/V %) was used for spraying. On the other hand, in the (1) dipping method and (2) hand spray method, a 6 W/V %-diluted hydrogen peroxide solution was used.

[0056] Table 1 shows the amount of generation, applying time, and total applying amount in the step for applying hydrogen peroxide, and air flow amount and drying time in the drying step. In the applying step, the total applying amount by the (1) dipping method could not be measured. Also, in the drying step, drying for the (2) hand spray method was performed by increasing the air flow amount. Table 1 shows the LRD values and temperature rise of vials decontaminated under these conditions.

TABLE-US-00001 TABLE 1 H.sub.2O.sub.2 applying step Drying step Results Amount Total Air Tem- of Apply- apply- flow per- Apply- gener- ing ing amount Drying ature ing ation time amount (L/ time LRD rise method (g/min) (sec) (g) min) (min) value (ΔT) (1) — 5 — 150 5 >9.0 — Dipping method (2) — — 2.5 150 5 7.9 +3.0° C. Hand spray (3) Mist 2 60 2.0 150 5 >9.0 +3.0° C. (4) Fog 2 180 6.9 150 5 <2.5 +4.0° C.

[0057] As shown in Table 1, the methods other than the (4) fog method all demonstrate favorable LRD values, and sufficient decontamination effects for a short period of time. In the (4) fog method, it is believed that formation of a condensed film on the surface of vials requires much time. The reason for temperature rise on the surface of vials has not clearly been identified, but this is probably because of vibrational energy applied from sound flows. Another reason seems to be prompt oxidation decomposition of a hydrogen peroxide solution. However, it is believed that such a short-time temperature rise doesn't affect the quality of low-temperature articles to be decontaminated.

[0058] Accordingly, the supply of a hydrogen peroxide mist or the like to a low-temperature article causes its surface to be a wet area (to form a condensed film). It is found that when the wet area is supplied with dry air and irradiated with sound flows of ultrasonic vibration, evaporation effects are promoted for a short period of time (approx. 3 minutes), and the surface concentration of a hydrogen peroxide solution sharply rises to obtain significant decontamination effects.

[0059] The present embodiment can provide a method for decontaminating a low-temperature article capable of accomplishing an effect of decontaminating the surface of a low-temperature article, and reducing the duration of operations to achieve more efficient decontamination works, and a pass box used therein.

[0060] The goal of the present invention is achieved not only with the above-described embodiment, but also with the following various alternatives.

[0061] (1) In the above embodiment, a two-fluid spray nozzle is used to apply a decontamination agent in an applying step. However, the spray nozzle is not restricted thereto, and an ultrasonic humidifier (nebulizer) used in the example, a hand spray, or a dipping technique in a decontamination liquid may be used.

[0062] (2) In the above embodiment, a vibration board used includes a plurality of ultrasonic speakers arranged in a speaker base. However, the vibration board is not restricted thereto, and any type of vibration board may be used so long as it includes a Langevin type transducer fixed to a stainless steel having a constant area or a board surface for ultrasonic vibration.

[0063] (3) In the above embodiment, a decontamination agent used is a hydrogen peroxide solution (H.sub.2O.sub.2 solution). However, the decontamination agent is not restricted thereto, and it may be any type of decontamination agent so long as it is liquid.

[0064] (4) In the above embodiment, 2 vibration boards are arranged on 2 side walls. However, the configuration is not restricted thereto, and 4 vibration boards may be arranged on 4 side walls, or vibration boards may be arranged on 2 to 6 side walls out of 6 side walls including a top wall surface and a bottom wall surface on 4 side walls.

REFERENCE SIGNS LIST

[0065] 10 . . . Pass box, 11, 12, 13 . . . Wall surface, [0066] 21, 22 . . . Vibration board, 21a, 22a . . . Vibration surface, [0067] 25 . . . Speaker base, 25a . . . Planar surface of speaker base, [0068] 26 . . . Ultrasonic speaker, 26a . . . Vibration surface of ultrasonic speaker, [0069] 30 . . . Two-fluid spray nozzle, 31 . . . Hydrogen peroxide solution mist, [0070] 40 . . . Low-temperature article, 50 . . . Cover, 60 . . . Intake pipe, 70 . . . Exhaust device.