US3791424A

US3791424A - Apparatus for sterilizing gas containers and filling same with a sterile gas

Info

Publication number: US3791424A
Application number: US00147211A
Authority: US
Inventors: G Strople; J Mills
Original assignee: LIF O GEN Inc
Current assignee: Aqua Lung America Inc
Priority date: 1970-07-09
Filing date: 1971-05-26
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12

Abstract

One or more gas containers connected by a conduit means to a feed source are sterilized and sterilely filled by the evacuation of the containers and conduit means to a low pressure, the introduction of a sterilizing agent into the containers and conduit means for a suitable holding period, the removal of the sterilizing agent by a further evacuation of the containers and conduit means, and the introduction of a gaseous feed stock to the containers through a sterilizing unit in the conduit means.

Description

United States Patent Strople et a].

APPARATUS FOR STERILIZING GAS CONTAINERS AND FILLING SAME WITH A STERILE GA S Inventors: Gordon N. Strople, Cherry Hill;

Junstin W. Mills, Jr., Cinnaminson, both of NJ.

Assignee: Lif-O-Gen, Inc., Cambridge, Md.

Filed: May 26, 1971 Appl. No.: 147,211

Related US. Application Data Division of Ser. No. 53,394, July 9, 1970, Pat. No.

3,620,265, which is a continuation-in-part of Ser. No. 765,044, Oct. 4, 1968, abandoned.

US. Cl 141/92, 2 1/58, 21/78, 21/DIG. 4, 53/88 Int. Cl B65b 55/10 Field of Search... 21/58, 78, DIG. 4; 53/11, 12, 53/79, 88; 99/211, 214, 249, 251, 252;

References Cited UNITED STATES PATENTS 10/1958 Geisler 53/11 X 1 Feb. 12, 1974 2,874,523 2/1959 Ryan, Jr 53/88 X 1,659,384 2/1928 Thomas. 141/4 3,372,980 3/1968 Satas.... 21/58 3,069,734 12/1962 Leuthner 21/58 X 3,088,179 5/1963 Leuthner 21/58 X Primary Examiner-Houston S. Bell, Jr.

Assistant Examiner-Frederick R. Schmidt Attorney, Agent, or Firm-Howson & Howson; Richard D. Weber 5 7] ABSTRACT One or more gas containers connected by a conduit means to a feed source are sterilized and sterilely filled by the evacuation of the containers and conduit means to a low pressure, the introduction of a sterilizing agent into the containers and conduit means for a suitable holding period, the removal of the sterilizing agent by a further evacuation of the containers and APPARATUS FOR STERILIZING GAS CONTAINERS AND FILLING SAME WITH A STERILE GAS This application is a division of co-pending application Ser. No. 53,394, filed July 9, 1970, entitled Method and Apparatus for Sterilizing Gas Containers and Filling Same with a Sterile Gas now US. Pat. No. 3,620,265, issued Nov. 16, 1971. Application Ser. No. 53,394 was a continuation-in-part of application Ser. No. 765,044, filed Oct. 4, 1968, entitled Method and Apparatus 'for Sterilizing Gas Containers and Filling Same with a Sterile Gas, which application is now abandoned.

There are many situations in which a gaseous product is desirably provided in a sterile condition. An obvious example is the field of medicine wherein respiratory gases should be in a sterile state prior to administration to a patient. Similarly, compressed gases used to power surgical devices and gases used as propellants in drug aerosol packaging should be free from contaminants. There are in addition many laboratory and industrial situations such as space simulation chambers, and industrial clean rooms in which the sterility of a gaseous stock is desirable.

Gaseous products are readily available at purities exceeding 99.999 percent and methods are also available to analyze gases to such a high degree of accuracy. However, the methods conventionally employed for gas analysis, including mass spectrometry, spectrophotometry, gas chromatography and wet chemistry, will not detect bacteria or viruses even if present in a gas in large quantities. It is commonly thought that the cryogenic processes normally utilized to produce atmospheric gases and/or the high pressures at which they are stored and packaged serve to sterilize the gases. However, the extremely low temperatures may only cause bacteria to become dormant and high pressures per se do not have a sterilizing effect.

There are a number of well known methods for sterilizing gases and also for sterilizing gas containers. Until I the present invention, however, there has not been a satisfactory apparatus for charging one or more gas containers with a gaseous feed stock which effectively insures the sterilization of both the containers and their contents. Since Federal regulations prohibit the shipment of conventional pressurized containers unless safety relief valves are provided which are sensitive to temperature (212F.) and pressure (2265 p ig), the containers cannot during sterilization and filling be subjected to conditions of temperature and pressure which exceed these limits.

The present process in brief involves the connection of a plurality of empty gas containers to a conduit means connecting the containers with a gaseous feed stock. The containers and the conduit means are then evacuated to a low pressure following which the containers and conduit means are filled with a sterilizing agent for a predetermined holding period to effect a sterilization of both the containers and the conduit means. The sterilizing agent is then evacuated from the containers and conduit means, and the gaseous feed stock is introduced to the containers through a suitable filtering means in the conduit means which may for example comprise a submicron filter. The container valves are then closed, and the filled containers are disconnected from the conduit means. All of the above steps are carried out with the containers sealed against the entrance of ambient air and at a temperature below 212F.

It is accordingly a primary object of the present invention to provide an apparatus for the sterile packaging of gases and gaseous mixtures.

A further object of the invention is to provide an apparatus as described which can be utilized for the simultaneous sterile filling of a large number of gas containers.

A still further object of the invention is to provide an apparatus as described which is adapted for the sterile filling of a plurality of containers at a relatively rapid rate and with low initial and operating costs.

Additional objects and advantages of the invention will be more readily apparent from the following detailed description of an embodiment thereof when taken together with the accompanying drawing which is a schematic illustration of apparatus in accordance with the present invention for providing a sterilized filling of a plurality of containers with a gaseous feed stock.

Referring to the drawing, an apparatus is illustrated for sterilizing a plurality of gas containers l0 and filling said containers with a sterile gaseous feed stock which is supplied from a storage tank 12 and suitably sterilized. The gas containers 10 may for example be made of steel in a cylindrical shape and include a valve 14 at the upper end thereof which is connected to the neck of the container in a gas tight seal. Conventional temperature and pressure relief valves (not shown) are provided on each container as required by Department of Transportation regulations for pressurized vessels. The containers 10 are connected to a charging mani fold 16 by tubes 18 extending between the container valves 14 and spaced outlets 20 of the manifold. The manifold at its left hand end 24 opens into a humidity and temperature control unit 26 through which it connects by means of conduit 28 with the vertical conduit 30.

The feed stock tank 12, which includes a valve 32 at its upper end, is connected to a conduit 34 by tube 36. The conduit 34 leads into a compressor 38 driven by motor 40. The outlet of the compressor 38 opens into a sterilizer 42 which is in turn connected with the lower end of the conduit 30. A valve 44 is provided between the compressor 38 and the sterilizer 42. An additional gas tank 46 filled with a diluent gas such as carbon dioxide is connected with the conduit 34 by means of tube 50. A valve 52 on the tank 46 permits control of the diluent gas flow.

A conduit 54 which opens into the conduit 30 at'56 is coupled to tanks 58 containing a sterilizing agent by connecting tubes 60. Valves 62 on the tanks 58 permit control of the flow of sterilizing agent from the tanks.

The upper end of conduit 30 leads into a sterilizer 64 to the opposite side of which is connected a vacuum pump 66 driven by a motor 68. A vacuum gauge 70 is provided between the vacuum pump and sterilizer, and a valve 72 is included in the conduit 30 between the sterilizer and the juncture S6 with the conduit 54. A pressure gauge 74 is located in the conduit 30 between the

valves

44 and 72 to indicate the pressure and hence the amount of gas in the containers 10.

The sterilizer units 42 and 64 in a typical embodiment of the invention, for example, may comprise submicron filter media having a screen opening size of about 0.4 microns. A commercially available filter suitable'for this purpose is manufactured by the Cox instrument Corporation, Model 430 Filter Element CBAA.45. It is also desirable to include in each filter unit a primary filter which is preferably a 10 micron filter to remove larger particles of contamination.

Sterilization as defined by the American Medical Association is an absolute term meaning complete destruction or removal of all forms of life, i.e., the absence or destruction of all micro-organisms, and the term sterilizing agent as used in this specification means an agent which will accomplish sterilization in accordance with this definition. Thus the sterilizing agent in a typical embodiment of the invention may be ethylene oxide which is most effectively employed in the flammable range (3-100 percent by volume in air). Concentrations approaching 100 percent are preferred but must be diluted prior to evacuation to atmosphere to eliminate the danger of explosion or fire.

To carry out the present process utilizing the above described apparatus, the empty gas containers 10 to be filled with the feed stock are connected to the charging manifold by tubes 18 to seal the container against the entrance of ambient air and the valves 14 thereof are opened. With the

valves

32, 44, 52 and 62 being closed, the valve 72 is opened and a high vacuum is drawn on the entire system by means of the pump 66. By evacuating the gas containers l and the various conduits of the system, virtually all airborne contaminents are removed from the containers and the system. The valve 72 is then closed, the pump 66 shut off and valves 62 are opened to permit the sterilizing agent to pass into the containers as well as the conduit system. The sterilizing agent is allowed to remain in the system for a suitable holding period, and the concentration, humidity and temperature are accurately controlled in a well known manner to insure an effective sterilization of the containers as well as the system conduits.

The period required for the effective sterilization of the containers and the conduit system will depend not only on the sterilizing agent used, the concentration of the agent, and the temperature, pressure and humidity conditions within the system, but also on such variables asthe condition of the containers, and the size of the system. A typical example of effective sterilization is as follows: an 88 percent concentration of ethylene oxide at 78F. with a humidity of 40 percent and a holding period of one hour at about one atmosphere.

Following closure of the valves 62 and after the sterilizing agent has remained in the system for the required holding time, the valve 72 is opened and the pump 66 again employed to evacuate the sterilizing agent from the system. Since the sterilizing agent may be utilized in a flammable concentration, it may first be necessary before evacuation to inject an inert diluent gas such as carbon dioxide into the system from the container 46 by opening

valves

44 and 52. When the gas mixture in the system reaches a safe concentration, the valve 52 is closed and the valve 72 is opened to permit a safe evacuation of the gas mixture. To insure a complete removal of the sterilizing agent, a high vacuum is preferably drawn on the containers and conduit system by the pump 66.

When the sterilizing agent and diluent gas have been removed from the container 10 and the conduit system, the valve 72 :is closed and the

valves

32 and 44 are opened to permit passage of the feed stock through the conduit 34 into the sterilizer 42, thence through conduits 30 and-28 into manifold 16 and into the several containers 10. When the containers 10 have been filled to the desired pressure as indicated by the gauge 74, the container valves 14 are closed, the valve 32 on the feed stock tank 12 is closed and the containers 10 may be disconnected from the tubes 18 and are ready for packaging and shipment. A sample may be taken from one of the containers 10 and tested to insure the sterile condition of the gas.

During the entire sterilizing and filling process, the containers are maintained at a temperature below 212F. and at a pressure below 2,265 psig to prevent the opening of the temperature and pressure sensitive relief valves built into the containers.

The compressor 38 is available for use in transferring gas products from the tanks 12 and 46 into the conduit system and containers 10 to the desired pressure.

The sterilizer 64 may be of the same type and construction as the sterilizer 42 and is provided to prevent recontamination of the system by the entrance or reentrance of contaminants into the system, for example, in the event of failure of the vacuum pump 66 which would permit a feed back into the charging system.

In the process described above, it is not essential that a complete evacuation of the system be effected prior to the addition of the sterilizing agent since the sterilizing agent would act on air-borne contaminants as well as those on the surfaces of the system and containers. However, in the preferred process a high vacuum is initially drawnto eliminate all air-borne matter.

Although submicron filters have been described as one form of a suitable sterilizing means, other methods of sterilizing the feed stock can be employed.

The term gas as used with reference to the feed stock, sterilizing agent and diluent for the sterilizing agent refers to fluids which at atmospheric pressure are normally in the gaseous state. It should be understood, however, that at elevated pressures, these fluids may be in the liquid stage and that the invention is not in any way affected by the stage or change of stage of these fluids.

From the foregoing the invention can be understood to provide an apparatus for effecting the sterilization of one or more containers and the filling of the sterilized container with a sterile gas without contaminating the container. The filled container is placed in a sealed enclosure containing a sterilizing agent to effect and maintain a sterilization of the exterior of the container until ready for use.

Manifestly, changes in details of construction can be effected by those skilled in the art without departing from the spirit and the scope of the invention as defined in and limited solely by the appended claims.

We claim:

1. A sterilizing and packaging apparatus for providing a container of compressed sterile gas suitable for medical use and food, drug and cosmetic packaging, which comprises a closed conduit system including a container to be filled detachably connected to the conduit system, said conduit system and container being sealed against the entrance thereto of ambient air and contaminants, sterilizing agent supply means, means selectively operable to connect the sterilizing agent supply means to the conduit system and container to introduce said agent into said system and container to sterilize the interior thereof, vacuum means, means selectively operable to connect said vacuum means to the conduit system and container to evacuate the same and remove therefrom all traces of ambient air prior to introducing said sterilizing agent therein and after a predetermined holding period following introduction of said sterilizing agent to again evacuate said system and container to remove therefrom all traces of said sterilizing agent, means in said conduit system intermediate said means selectively operable to connect said vacuum means to the conduit system and said vacuum means for sterilizing gases flowing through said vacuum means to prevent contamination of the conduit system and container by the entrance or reentrance of contaminants, compressed gas supply means, means selectively operable to connect said compressed gas supply means to the conduit system and container to introduce into said container a predetermined quantity of the compressed gas, sterilizing means in said conduit system adjacent said compressed gas supply means for sterilizing the compressed gas flowing into the conduit system and container, and means for sealing the container after introduction of said sterilized compressed gas and prior to detachment thereof from the conduit system to maintain the sterilized compressed gas in the container in a sterile condition.

2. A sterilizing and packaging apparatus as claimed in claim 1 wherein the sterilizing agent is a flammable gas and an inert gas supply means in provided together with means selectively operable to connect the inert gas supply means to the conduit system and container upstream of said compressed gas sterilizing means to introduce said inert gas thereto subsequent to introduction of said sterilizing agent to dilute the latter to a nonflammable concentration prior to evacuation of the conduit system and container.

3. A sterilizing and packaging apparatus as claimed in claim 1 wherein humidity and temperature control means is provided in the conduit system operable automatically to control the humidity and temperature of the sterilizing agent and sterile compressed gas supplied to the container.

4. Apparatus for sterilizing a container and filling the sterilized container with a sterile compressed gas comprising a conduit system having a first conduit portion including a manifold having means for connection thereto of a plurality of containers to be sterilized and filled with a sterile gas, a second conduit portion connected at one end to said manifold and at the other end to a vacuum pump operable to evacuate said manifold and the containers connected thereto, a third conduit portion connected at one end to said manifold and at the other end having means for connection thereto of a supply of sterilizing agent, a fourth conduit portion connected at one end to said manifold and at the other end thereof having means for connection thereto of a supply of a gas with which said containers are to be filled, valve means in said second, third and fourth conduit portions operable selectively to connect said manifold to any one of said vacuum pump, sterilizing agent supply, and sterile gas supply, sterilizing means in said second conduit portion intermediate the vacuum pump and said manifold operable to prevent contamination of the conduit system and containers by the entrance or reentrance of contaminants thereinto inwardly through said second conduit portion, and sterilizing means in said fourth conduit portion intermediate the manifold and the connections to the supply of gas operable to sterilize the latter en route to said manifold.

5. Apparatus as claimed in claim 4 wherein a compressor is provided in the fourth conduit portion and is operable to transfer the gas from the supply thereof into the conduit system and said containers to the desired pressure.

6. A sterilizing and packaging apparatus as claimed in claim 4 wherein humidity and temperature control means is provided in the conduit system operable automatically to control the humidity and temperature of the sterilizing agent and sterile compressed gas supplied to the container.

7. Apparatus as claimed in claim 4 wherein means is provided for introducing into the conduit system and said containers upstream of said fourth conduit sterilizing means a sterilized inert gas to dilute the sterilizing agent to a non-flammable concentration. =l= =i=

Claims

2. A sterilizing and packaging apparatus as claimed in claim 1 wherein the sterilizing agent is a flammable gas and an inert gas supply means in provided together with means selectively operable to connect the inert gas supply means to the conduit system and container upstream of said compressed gas sterilizing means to introduce said inert gas thereto subsequent to introduction of said sterilizing agent to dilute the latter to a non-flammable concentration prior to evacuation of the conduit system and container.

7. Apparatus as claimed in claim 4 wherein means is provided for introducing into the conduit system and said containers upstream of said fourth conduit sterilizing means a sterilized inert gas to dilute the sterilizing agent to a non-flammable concentration.