US3503703A

US3503703A - Apparatus for sterilizing

Info

Publication number: US3503703A
Application number: US417974A
Authority: US
Inventors: Robert L Mcdonald; Alvin F Bernreuther
Original assignee: Sybron Corp
Current assignee: MDT Corp; Raytheon Co
Priority date: 1964-12-14
Filing date: 1964-12-14
Publication date: 1970-03-31
Anticipated expiration: 1987-03-31

Description

March 31, 1970 MCDONALD ETAL 3,503,703

APPARATUS FOR STERLIZING 3 Sheets-Sheet 1 Filed Dec. 14, 1964 FIG. 2

FIG. 3

INVENTORS ROBERT L. MCDONALD BY ALVIN E BERNREUTHER ATTORNEYS March 31, 1970 c o ETAL 3,503,703

APPARATUS FOR STERLIZING Filed Dec. 14, 1964 3 Sheets-Sheet 2 FIG. 4

I NVENTORS ROBERT L. MCDONALD 6 BY ALVIN E BERNREUTHER ATTOR NEYS March 31, 1970 Filed Dec. 14, 1964 IT) 5 r 3 FIG. 8

R. L. M DONALD ETAL APPARATUS FOR STERLIZING MANUALLY START OFF 56 on H8 78 OPEN 5| OPEN 56 OPEN 3 Sheets-Sheet 3 1N VENTORS ROBERT L. MCDONALD ALVIN F. BERNREUTHER ATTORNEYS United States Patent 3,503,703 APPARATUS FOR STERILIZING Robert L. McDonald, Rochester, and Alvin F. Bernrenther, Macedon, N.Y., assignors, by mesne assignments, to Sybron Corporation, a corporation of New York Filed Dec. 14, 1964, Ser. No. 417,974 Int. Cl. A61l 3/ 00, 5/00, 7/00 US. Cl. 21-91 5 Claims ABSTRACT OF THE DISCLOSURE A sterilizing apparatus having a gas impermeable barrier, a completely flexible and collapsible gas impermeable bag having an aperture for receiving articles to be sterilized and adapted to be mounted in gastight connection with the barrier. Suitable means for connecting the bag onto the barrier in gastight relationship and exhaust means for reducing the internal pressure in the bag and for circulating air in the bag and valving and controls for carrying out a sterilizing cycle in the bag.

This invention relates to improved method and apparatus for sterilizing with a gaseous sterilant. In the past, it has been common practice in the sterilizing art to utilize a rigid structure as the sterilizing chamber in which effective sterilization is carried out. This invention provides improved method and apparatus for sterilizing with a flexible, collapsible sterilizing chambersuitable for use with gaseous sterilants such as ethylene oxide or betapropiolactone.

It is an important object of our invention to provide method and apparatus utilizing a flexible, collapsible sterilizing chamber.

It is a furtherimportant object of our invention to provide improved method and apparatus for introducing, circulating and exhausting the gas sterilant from the sterilizing chamber which is particularly well suited for sterilization with a flexible, collapsible sterilizing chamber.

According to this method and apparatus, it has been discovered that it is particularly suitable to sterilize at less than atmospheric pressure with a flexible bag; this guarantees n0 leakage of agent to the area surrounding the flexible sterilizer chamber in case of damage to the bag itself.

It is a further object of our invention to provide novel i (2) This invention permits portability of large capacity 7 units, sterilization of rigidly mounted frames, machines and the like, at location. This portability eliminates the hazard of moving contaminated materials through noncontaminated areas. g (3) The separable gas impermeable barrier which provides a mechanical and control section for the flexible bag permits servicing an unlimited number and variety of sterilizing chambers by a single mechanical and control section.

(4) The arrangement of the gas impermeable barrier "ice or mechanical and control section automatically and safely controls and disposes of the sterilant if a leak should develop in the sterilizing chamber.

(5) As the sterilizing chamber is operated at less than barometric pressure, the flexible sterilizing chamber will collapse to the size of the load resulting in a minimum requirement for sterilant.

(6) Forced circulation of the sterilant atmosphere through and around the load insures that the sterilizer load has a maximum exposure to the sterilant in a minimum time, permitting shorter cycles than existing gas sterilizers.

(7) Disposal of the sterilant gas and odors by means of chemical conversion, absorption, or adsorption within the mechanical and control section eliminates the requirement for an external vent permitting portability and minimum setup time.

(8) The purging phase of the cycle and aeration with heated sterile air eliminates or greatly reduces odors contained in a sterilizer load. In this regard, provision can be made to introduce and circulate through the load an aromatic masking or odor destroying material.

It is a general object of this invention to provide method and apparatus which fulfills the above enumerated advantages.

It is a further object of our invention to provide an improved method and apparatus for sterilization which is portable.

It is a further object of our invention to provide a flexible, collapsible sterilizing chamber having an opening adapted to receive goods to be sterilized which is releasably or separably connected to the bag.

This invention contemplates a gas impermeable barrier to which is connected a completely flexible, collapsible gas-impermeable bag having an aperture permitting insertion therein of articles to be sterilized and preferably mounted horizontally to the barrier.

Other objects and advantages of this invention will be particularly set forth in the claims and will be apparent from the following description, when taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a first embodiment of this invention;

FIG. 2 is a top view with parts broken away of the FIG. 1 embodiment of this invention;

FIG. 3 is a bottom elevational view of the FIG. 1 embodiment of this invention;

FIG. 4 is a schematic view of the FIG. 1 embodiment of this invention;

FIG. 5 is a schematic view of a second embodiment of this invention;

FIG. 6 is a cross-sectional view of a third embodiment of this invention;

FIG. 7 is a perspective view of a fourth embodiment of this invention with parts broken away;

FIG. 7A is an enlarged partial cross-sectional view of of the circled portion of FIG. 7; p FIG. 7B is a reduced left-end view of the FIG. 7 embodiment illustrating the following tray 20C;

FIG. 8 is a schematic wiring diagram of the control circuit suitable for use with all embodiments of thisine vention; and

FIG. 9 is a timed sequence chart of the automatic cycle controlled by the circuitry of FIGS.

With reference to the drawings, basically this invention comprises a gas impermeable barrier generally indicated by the numeral 10, which includes a mechanical and control section described more in detail hereinafter, a gas impermeable, completely flexible and collapsible bag 12 releasably or separately connected to the barrier 10. The barrier 10 includes control means for introducing suit- 3 able sterilant adapted to assume a gaseous state through the barrier into, through and out of the bag 12 thereby to satisfactorily sterilize articles contained in the bag 12.

BAG AND CONNECTION TO BARRIER The bag may'be re-usable or disposable, single use type of any thin, flexible membrane, film, or laminant such as polyethylene, nylon-vinyl or clear polystyrene, Buna N and Buna S rubbers, hycar and nylon fabric of neoprene coated fabric forming a completely flexible, collapsible gas-impermeable sterilizing chamber in lieu of the conventional rigid type pressure vessel. The sterilant is adapted to assume the form of vapor, gas, aerosol, or other finely divided particulate matter and it will be understood that as herein used, the term gaseous, gas or gaseousstate will be construed to broadly define such forms of matter.

The flexible bag or sterilizing chamber 10 is releasably secured or connected in air-tight relationship to the barrier, as for example, by adhesive tapes, clamping devices, airtight, pressure sealing zippers, screw hold-down plates, or any other suitable means. The FIG. 1 embodiment illustrates one type releasable connection between the flexible bag or sterilizing chamber 12 and the barrier 10 which comprises a set of screw hold-

down plates

16, 17 and 18 defining various rectangular shapes (see FIG. 2) outlining corresponding but smaller holes provided in the lower surface of the bag 12 which are designed to surround certain inlets, outlets and control apparatus in the barrier 10. A clear plastic cover 93 overlies certain control apparatus to seal it from the sterilizing chamber when the center hold-down plate 17 is secured to tray 20.

The three hold-down plates 1618 overlie the edges of the corresponding holes in the flexible bag and are secured by a plurality of hold-down screws 21 to a wooden tray or bag support 20 to which the barrier 10 is connected. These hold-down plates 1618 are releasable to enable repair of the barrier 10 and controls included therein. It is also a desirable feature of this invention to provide means for releasably connecting the bag to the barrier to enable the barrier to be used with a variety of flexible bags.

The FIG. 1 embodiment also includes a pressure sealable zipper 22 which extends substantially entirely around the periphery of the bag 12 in a horizontal plane; thereby to substantially release the upper part 21 of the bag from substantiallythe entire bottom part 23 and the barrier 10 This zipper provides an aperture in the bag adapted to receive the goods to be sterilized which are illustrated in broken line (five mattresses 24 with spacers 25 interposed therebetween to facilitate sterilization thereof). The upper part 21 only remains attached to the barrier by reason of an unzippered portion extending partially along the left-hand side of the bag 12 as viewed in FIGS. 1 and 2 so that the upper part of the bag 12 opens back somewhat in the manner of a clam shell. It will be understood that the substantially releasable connection such as the zipper 22 could be extended around the entire periphery so that it may be completely releasable or detachable from the barner.

In the second embodiment illustrated in FIG. 5, there is schematically shown another manner in which the flexible bag 12A may be releasably or detachably connected to the barrier 10A by a pair of

releasable clamps

26 and 27 respectively mounted at the upper end of an inlet flexible hose 28 and outlet flexible hose 29 communicating with the flexible bag sterilizing chamber 12A. This would be in lieu of the screw type hold-down plates 16-18 inclusive of FIGS. 1-4. As is shown and illustrated in this drawing, the bag 12A would have an openingZZA as is provided by the air-tight zipper 22 of the FIG. 1 embodiment adapted for introducing and withdrawing goods to be sterilized.

In FIG. 6, is illustrated a flexible bag 12B and a gas impermeable barrier. It will be understood that a conven- 4 ventional stainless steel door frame 30 and a conventional annular or rectangular sterilizer door 31 with radial locking arms 32. The door 31 in the conventional manner is hinged (not shown) to the door frame 30. A conventional peripheral sealing gasket 33 is provided intermediate the door frame 30 and door 31 to provide a gas impermeable barrier. It will be understood that a conventional mechanical and control section well known in the art for controlling the introduction and exhaustion of gas and moisture is incorporated with the FIG. 6 embodiment to complete the gas impermeable barrier with controls.

The upper right-hand corner of the flexible bag 12B ripherally spaced screws 40 transversing the frame 30, the and a spring 36 attached to a supporting structure (not shown) for supporting the bag upright. The flexible bag 12B is releasably connected to the barrier 10B and the frame 30 is likewise releasably connected to a peripheral supporting base 38 of channel iron by a plurality of peripherally spaced screws 40 transversing the frame 30, the bag 12B and base 38, thereby to releasably connect the flexible bag 12B to the gas impermeable barrier 10B. The base 38 is rigidly mounted to an upper supporting structure or wall 39 and to a lower supporting structure or floor 41. At the right, there is provided a channel iron base 43 rigidly mounted to the floor 41. There is a laterally extending tray or support 38A rigidly mounted to the bases 38 and '43 for supporting the bag 12B and goods to be sterilized therein. The aperture through which the goods are received may or may not be the same aperture which is releasably connected in gas-tight relationship with the gas impermeable barrier.

In the FIG. 7 embodiments, parts corresponding to the FIG. 1 embodiment are identified by the same numeral followed by the suflix C. There is a completely flexible collapsible bag 12C of plastic or rubberized fabric having an opening or aperture 100 adapted to receive the goods to be sterilized such as matteresses 24C. Also the aperture 100 is adapted to receive the periphery of a horizontally disposed lateral tray or support 20C rigidly mounted on a base generally indicated by the numeral 38C which extends under the tray 20C. Base 38C includes four conventional casters 42C, only the front two of which are illustrated, thereby providing a portable structure as shown in FIG. 1. However, as shown in FIGS. 7 and 7B, the tray 20C is divided into three sections d, e, and f. Sections d and f are hinged to center section e and fold upwardly as illustrated in broken line in FIG. 7B to pass through doorways.

As shown in FIGS. 7 and 7A, there is a releasable band or clamp 102 which defines a U in cross-section and extends around the entire periphery of the tray 20C. Releasable band 102 may include any type of conventional releasable latch (not shown) to draw the band 102 tight about the bag 12C which it overlies in order to seal the bag at the periphery of the tray 20C in gas-tight relationship With a gas-impermeable flexible covering 101 overlying the tray 20C. 7

A gas impermeable barrier 10C rigidly mounted to the base 38C includes controls section 104 for housing the controls illustrated in FIGS. 1-4 and described more in detail hereinafter, communicating with the flexible sterilizing bag 12C through the tray 20C and covering 101 in the same manner as illustrated in FIGS. 1-4. Thus, covering 101 Would comprise part of the gas impermeable barrier 10C. It will be understood that the controls could be of any conventional known type which fulfill suitable functions for sterilizing within the flexible chamber. In the alternative, the controls mounted in control section 1'04 may communicate with the flexible sterilizing chamber directed through openings. provided in the bag with a releasable connection therebetween. The ampule C mounted on the outside of the controls section 104 supplies the gaseous sterilant. Y

A significant aspect of this invention is to preferably mount the

flexible bag

12, 12A, 12B or 12C horizontally, that is, so that its greatest length lies in a horizontal plane rather than in a vertical plane. It will be understood as contrasted between, for example, the FIG. 1 and FIG. 6 embodiments, that the gas impermeable barriers 10 and 10B respectively, to which the horizontally mounted bag is connected, may lie in either a vertical or horizontal plane depending upon the desired use of the sterilizer and the type of releasable connection, or for any other reason. The desirability of mounting the bag horizontally in length versus vertically in length is obviously to prevent vertical distribution of weight and bulk of the goods which could, among other disadvantages, result in the bag being tipped when hit and inadvertently dislodged from the barr1er.

DETAILS OF BARRIER 10 This invention includes a novel method and apparatus for introducing, circulating and exhausting air and sterilant through the apparatus above described which is particularly suitable for a flexible bag sterilizer. In FIG. 4, we have schematically illustrated our novel circulation system. As heretofore already mentioned, the control system included in the gas impermeable barrier 10 for controlling the introduction, circulation and exhaustion of gases within the sterilizing chamber 12 is incorporated by reference in the FIG. 7 embodiment as well as the FIGS. 1-5 embodiments of our invention. Moreover, it will be understood that this control system may be utilized with the FIG. 6 embodiment in lieu of conventional sterilizer controls. In the FIG. 1 embodiment, such control apparatus is mounted on the underside of the tray 20 as illustrated in FIGS. 1, 3 and 4 and is spaced from the floor over which the portable unit is transported by four conventional casters 42 mounted on the lower surface of the supporting tray 20. Rigidly mounted on tray 20 at the left-hand end thereof as viewed in FIGS. l3 inclusive there is provided a handle 19 by which the operator may push the portable sterilizer to any desired location.

With reference to FIGS. 1-3 inclusive, we have shown a control box or base 44 to which the gas impermeable barrier 10 is connected. Control base 44 houses the electrical controls for the motor and solenoid valves and any other control mechanism for operating the hereinafter described circulation system. The details of the electric circuitry will be described hereinafter under the heading Electrical Circuitry which terminates in a suitable electrical cord 45 and plug. It will be understood that any number of variations in such electrical circuitry could be provided all within the spirit of the present invention and not depart from the spirit of this invention which may be manually controlled as well as automatically controlled.

The control system, as illustrated in FIGS. 1 to 4 includes an air inlet housing 46 and an air outlet housing 48. Attached to the air inlet housing 46 is a suitable inlet 49 communicating with a dust filter 50, valve 51, deodorizer 52, heater 53, and bacteria filter 55 all in series as shown schematically in FIG. 4. Also attached to housing 46 is a second valve 56 communicating with an ampule containing an aromatic or masking or odor destroying material 58 supplying the deodorizer 52. Outlet housing 48 has three

compartments

60, 62 and 70. A motorized fan 58 is rigidly mounted substantially in the center of the center compartment 60 as shown in FIG. 2 with the fan blade being received in a corresponding opening provided in a horizontal partition 59. The left-hand compartment 62 as viewed in FIG. 4 is the sterilant disposal compartment in which is mounted a micron-partical size filter 64. For preventing bacteria from contaminated mattresses (typical goods to be sterilized) from being exhausted from the system into the atmosphere, a gas sorbing agent 65 such as activated charcoal fills the remainder of chamber 62. There is a check valve 66 disposed in the partition be tween the fan compartment 60 and sterilant disposal compartment 62. There is an outlet 67 through which purged air is exhausted. The right-hand compartment 70 has three sections, the left-hand one of which houses a second heater 68. The right-hand compartment 70 also includes a center humidifier section adapted to receive water 72; a partition 71 separates the humidifier section from a right-hand sterilant injection section receiving liquid sterilant 73 adapted to assume a gaseous state. There are a pair of conduits or

tubes

75 and 76 having in-

line valves

77 and 78 respectively. Conduit or tube 75 communicates between an ampule or other source of water at 79 and the humidifier section. Likewise, the conduit 76 communicates between a pierceable ampule or other suitable supply of sterilant 80 adapted to assume a gaseous state. For a portable construction such as is illustrated in FIGS. 14 inclusive, it is desirable to mount the Water ampule 79 and sterilant ampule 80 in the control base 44 so that periodically they may be conveniently replaced or replenished after lifting the lid of the control box 44.

Although not an essential element of my invention, with a portable construction such as this, we have found it particularly desirable to provide a sterilant in liquid form pressurized or unpressurized in a container adapted to be pierced by a pin or other means well-known in the art, to open the container thereby to provide liquid sterilant readily adapted to assume a gaseous state. A conduit or connecting pipe 82 communicates between the two

housings

48 and 46 with a connector valve 83 in line.

We provide a selected length of perforated exhaust hose 85 shown in broken line in FIG. 1, in solid line but broken away in FIG. 2, and only a terminal portion thereof in solid line in FIG. 4. The multiple perforations extending throughout the entire length of the hose 85 receives gaseous sterilant and/or air being withdrawn from the flexible chamber by the fan 58, after which the air passes through a pair of conduits 87 communicating between the perforated hose 85 and the top of center fan compartment 60. Gaseous mediums pass through a dust filter 90 mounted in the top of the center fan compartment 60. The hold-down plate 1 8 has a pair of spaced openings adapted to receive terminal ends of the perforated hose 85 so that the hose 85 is removably mounted to the holddown plate 18. The perforated hose 85 as seen in FIGS. 1 and 2, extends around the mattresses 24.

As seen in FIGS. 2 and 4, clear plastic cover 93 which overlies and seals the outlet housing 48 from the sterilizing chamber provides an easy access for repair of the fan 58 and access to the three compartments comprising the housing 48.

The gas impermeable barrier 10A of the FIG. 5 embodiment is identical to the FIG. 1 embodiment except that communication with the flexible bag 12A is through

flexible couplings

28 and 29 rigidly connected respectively to the two

housings

46A and 48A. As described above, there are releasable clamps or

bands

26 and 27 interconnecting the bag 12A with the

hoses

28 and 29 respectively. In all illustrated embodiments the gas impermeable barrier 10 is sealed in gas-tight relationship with the gas impermeable bag 12.

OPERATION For the purposes of illustration, the bag 12 is illustrated in FIGS. 1, 2 and 3 in an inflated position in order that the goods to be sterilized, i.e., the mattresses 24, could be more easily distinguishable from the bag 12. While the foregoing described structure could operate under positive pressure, it is preferable to operate at sub-atmospheric pressure in order to guarantee no hazards of leakage in the event of damage to the bag itself. Under sub-atmospheric conditions, the flexible bag 12 will conform to the shape of the goods to be sterilized.

The mattresses 24 are placed on the bottom part 23 of bag 12 with alternate layers of spacers 25 to facilitate penetration of the goods by the sterilant. The upper part 21 of bag 12 is then placed over the mattresses and the operator zips the pressure sealing zipper 22 so that the bag is gas impermeable. Evacuation of the flexible chamber and goods (if permeable) is effected by closing all valves above describedair inlet valve 51, valve 56, water inlet valve 77, sterilant inlet valve 78 and housing connector valve 83. These valves all being closed, the fan 58 sucks air out of the flexible chamber 12 and goods (if permeable) as indicated by the arrows 95 to exhaust contaminated air from the flexible sterilizing chamber through the dust filter 90. The air is discharged through the check valve 66 and bacteria filter 64 through charcoal filter 65 and through outlet 67 to atmosphere. It will be understood that the check valve opens when positive pressure is produced at the exhaust side of fan 58 to permit expulsion of air. After a preselected evacuation period, a sub-atmospheric condition is established in the flexible chamber 12. Thereafter, the

heaters

68 and 53 are turned on and

valves

77 and 83 are opened. Housing connector valve 83 when opened, releases the pressure on check valve 66 permitting it to close, thereby to maintain the sub-atmospheric pressure of approximately 15 to 25 inches, water column, within the closed system and the air being drawn through the motorized fan compartment then passes through heater 68 to be warmed, through the humidifying section where the Warm air is moisturized by the water 72. Water 72 is drawn from the source 79 by the negative pressure system; while it is preferable that the source 79 of water he in pressure sealed relationship with conduit 75, it will be understood that the fan 58 which is a conventional vacuum cleaner type fan, will maintain a sub-atmospheric pressure in the system even if slight leaks develop in the system. The sub-atmospheric pressure guarantees that both the barrier and bag 12 are maintained as gas-impermeable, preventing leaking of sterilizing gas out of the system.

The warm, humidified air is circulated through the flexible bag 12 and the goods to be sterilized in order to prop erly condition the goods for the desired moisture conditions in accordance with the teachings of the Robert L. McDonald Patent 3,068,064. When a selected moisture condition has been established in the goods to be sterilized in the sterilizing chamber, valve 78 is then opened and liquid sterilant 73 from ampule 80 or other source is drawn by the negative pressure into the sterilant injection section. Preferably, the ampule 80 is sealed in gastight connection with the conduit 76. The sterilant, preferably ethylene oxide or beta-propiolactone is adapted to readily assume a gaseous state and pass through the housing connector valve 83 and housing 46 to the chamber 12 where sterilization is effected for a selected period of time.

The fan 58 continues to recirculate and moisturize the gaseous sterilant from the chamber 12 from the perforated hose 85 back through housing 48, housing connector valve 83, and housing 46 in an endless, continuous cycle until sterilization has been effected during a selected sterilizing period. Filters 55 and 90 are sterilized with each cycle as the sterilant is circulated through the endless cycle just described.

At the end of the sterilizing period,

heaters

53 and 68 are turned off and all of the valves including 51, 56, 83, 77 and 78 are closed so the chamber is again evacuated in the same manner as heretofore described, thereby to evacuate and substantially purge the flexible chamber of gaseous sterilant. The filter 64 sorbs the noxious and toxicsterilant and releases purged gas at outlet 67. The valve 51 is then opened thereby to draw air from outside of the chamber through the inlet 49, bacteria retentive dust filter 50, through the deodorizer 52 past the heater 53 through the sterile bacteria filter 55 into and through the flexible sterilizing bag 12 and mattresses 24, out through the perforated hose 85, conduit 87, bacteria retentive dust filter 90, past fan 58 and out check valve 66 at 67 to atmosphere, thereby aerating the goods and chamber with pure air for a selected aerating period. During the aearation period, the valve 56, may, if desired, be opened, thereby supplying deodorant from the ampule 58 to the deodorizer 52 to deodorize the chamber and goods during the terminal portion of the aeration period. Thereafter, the heater 53 and fan 58 are turned off and atmospheric pressure is established throughout the system by holding valve 51 open.

It will be understood from the above description that the valve 83 functions to permit pressure increase or decrease at exhaust side of the fan thereby causing releasably controlled check valve 66 to open or close respectively, thereby to releasably prevent sterilant from passing through the check valve 66 and outlet 67 during the sterilizing cycle, and only when valve 83 is closed will the sterilant be evacuated through the one-way check valve 66 and outlet 67. Valve 51 cooperates with valve 83 during aeration to release the remainder of the sterilant not purged during evacuation.

The above sequential operation may be carried out manually or automatically. FIG. 9 is a sequential time chart or bar graph illustrating a typical timed cycle in accordance with the sequence above described. The elongated bars in the FIG. 9 graph illustrate the. respective portions of time during which the fan and heaters are activated and valves are open as listed according to FIG. 1 parts numerals in vertical column A whether the cycle is manual or automatic; whereas vertical column B lists the respective periods during which electrical switches are closed which control the structural elements listed in column A if the cycle is automated according to the circuit of FIG. 8.

ELECTRICAL CIRCUITRY FIG. 8 schematically represents the electrical controls mounted in the control box or base 44 for automating the cycle described in the preceding section. In parallel across a volt AC line, is the following circuit, the switches of which are controlled by a timer motor 110 driving a shaft 112 shown in broken line in turn sequentially controlling a plurality of switches. The operator manually closes a switch 114 which energizes the timer motor 110 and turns on an indicator light 116.

In the sequential relationship described in the preceding section, and for the periods of time illustrated in FIG. 9, the following switches are sequentially closed to control elements heretofore described: switch 118 is closed by the shaft 112 to energize the fan 58 which remains on during substantially the entire cycle; after the pre-evacuation period, switch 119 is closed, thereby opening the

valves

77 and 83 and turning on the

heaters

53 and 68, which switch remains closed throughout the pre-humidification and during the sterilizing period; thereafter, switch 120 is closed to open the sterilize valve 78 which switch remains closed through the selected sterilizing period; thereafter, switches 119 and 120 are opened to de-energize the

heaters

53 and 68 and

close valves

77, 78 and 83, and the post-evacuation period commences, during which period the fan is still running to evacuate the chambers; then switch 112 closes to open valve 51 for the aeration period, and thereafter switch 124 closes to open the valve 56 communicating with the deodorizer; for the terminal portion of the cycle, switch is closed to actuate a buzzer or indicator signal 126; then switches 114, 118, 122 and 124 open to de-energize the fan 58 and

close valves

51 and 56. The switch 125 remains closed because the timer motor switch 114 is open so the buzzer 126 continues to ring until the operator manually moves shaft 112 to the off position.

In the alternative, preferred arrangement, the switch 122 may remain closed to maintain valve 51 open after the fan 58 turns off, thereby to return the system to atmospheric pressure as suggested in the preceding section of this disclosure, as indicated on the FIG. 9 bar-graph by the terminal broken line portion of the switch 122 bar.

While we have shown and described the preferred form of mechanism of our invention, it will be apparent that various modifications and changes may be made therein particularly in the form and relation of parts, without departing from the spirit of our invention as set forth in the appended claims.

We claim:

1. A sterilizing apparatus comprising:

(a) a gas impermeable barrier; I

(b) a completely flexible and collapsible gas impermeable bag having a zippered aperture permitting insertion therein of articles to be sterilized and adapted to be mounted in gas-tight connection to said barrier;

(c) means to connect said bag to said barrier in gastight relationship therewith;

((1) means for introducindg into, said bag through said barrier a sterilant adapted to assume a gaseous state;

(e) outlet means permitting said sterilant to pass from said bag through said barrier to the external atmosphere;

(f) control means for releasably preventing sterilant from passing through said outlet means.

2. A sterilizing apparatus comprising:

(a) a horizontal gas impermeable barrier;

() means to conect said bag to said barrier in gastight relationship therewith; and

(d) control means for introducing into and exhausting from said bag through said barrier a sterilant adapted to assume a gaseous state.

3. A sterilizer apparatus comprising:

(a) a gas impermeable barrier;

(c) means to connect said bag to said barrier in gastight relationship therewith; and

(d) control means for reducing internal pressure of said bag to sub-atmospheric pressure, thereafter introducing sterilant adapted to assume a gaseous state into said bag and then exhausting said sterilant from said bag, all through said barrier.

4. A sterilizing apparatus comprising:

(a) a gas impermeable barrier;

(b) a completely flexible and collapsible gas-impermeable bag having a zippered aperture permitting insertion therein of articles to be sterilized and adapted to be mounted in gas-tight connection to said barrier;

(0) means to connect said bag to said barrier in gastight relationship therewith;

(d) fan means communicating with said bag through said barrier; and

(e) valve means coactive with said fan means when said valve means is in a first position for reducing internal pressure in said bag and when in a second position for circulating fluid through said bag and barrier.

5. A sterilizing apparatus comprising:

(a) a gas impermeable barrier;

(-b) a completely flexible and collapsible gas impermeable bag having a zippered aperture permitting insertion therein of articles to be sterilized and adapted to be mounted in gas-tight connection to said barrier;

(d) fan means communicating with said bag through said barrier; and

(e) valve means coactive with said fan means when said valve means is in a first position for exhausting fluid from said bag and when in a second position for circulating fluid through said bag and barrier.

References Cited UNITED STATES PATENTS 2,027,042 1/1936 Hinds 2158 2,131,134 9/1938 Baer et al 21-58 2,965,936 12/1960 Kaye 2l58 X 3,114,599 12/1963 Fanning 2198 JOSEPH SCOVRONEK, Primary Examiner US. Cl. X.R.