Container Filling Apparatus

Abstract

A rotary filling machine which comprises a tunnel disposed substantially from before the filling station to the sealing station of the machine along the direction of travel of a container, and means for introducing an inert gas into the tunnel under a slight positive pressure. The inert gas excludes air from the tunnel and provides an inert gas atmosphere within the tunnel which effectively maintains at a reduced level the oxygen content of the void space of containers being filled. The tunnel has orifices permitting the passage of reciprocating filling spouts for introducing inert gas into the containers being filled and, in a separate step, for filling the containers.

Parent Case Text

This application is a continuation-in-part of application Ser. No. 716,521 filed Mar. 27, 1968, now abandoned.

Description

The disclosure is directed to apparatus for the lowering of oxygen concentration in the void space of containers filled with oxidizable materials. More particularly, the invention is directed to apparatus for providing an inert gas environment about containers from the time they are filled with oxidizable drugs until they are sealed, for instance, on a rotary filling machine.

The term "containers" is used to describe the receptacles usually employed to package oxidizable pharmaceuticals and other chemical materials, compounds and compositions, such as bottles, vials, ampoules and disposable cartridges, particularly those having a small capacity-to-void space ratio. For convenience, the container contents will be referred to as "drugs."

It is a practice in the pharmaceutical industry to fill containers with a single dose of a drug for convenience in dispensing it. The drug usually does not fill the container and a "void space" of gas-filled volume exists above the drug after the containers are sealed.

Many of the drugs are sensitive to oxidative decomposition. That is, they decompose, or otherwise lose potency, in the presence of oxygen. When a void space of a container contains oxygen, the potency of a contained oxidizable drug is reduced to the extent that reaction takes place between the oxygen and the drug.

It is a common practice in the pharmaceutical packaging art to flush the containers with an inert gas, typically nitrogen, immediately prior to filling. However, the nitrogen flushing procedure is not entirely satisfactory, and it has been found that the concentration of oxygen increases in the void space where even a few seconds pass between filling and sealing. Such a time lapse typically occurs in a rotary filling machine where, due to design considerations, a sealing station is relatively remote in time from a filling station. Without wishing to be bound by a theory of operation it is believed that this is due to a rapid dispersion of the nitrogen flushing gas out of the void space into the surrounding air, and the concurrent in-flow of the surrounding air into the void space.

It has long been known that oxidizable drugs may be protected by the exclusion of oxygen from contact with them by replacement of oxygen with an inert gas. However, the practical solution to the problem as applied to small containers while they are filled on rotating filling machines has not been obvious.

It is an object of the present invention to improve the shelf like and maintain the potency of oxidizable drugs.

It is another object of the present invention to provide an apparatus for maintaining an inert gas atmosphere substantially free of oxygen in the void space of small containers as they are filled on a filling machine.

It is a particular object of the present invention to provide an arcuate inert gas tunnel along the path of travel of a container between the filling and sealing stations of a rotary machine.

It is a further object of this invention to provide an economical apparatus for providing an inert gas atmosphere about containers being filled on commercially available filling machines.

Other objects and advantages of the invention will be apparent to those skilled in the art from a reading of the following description taken in conjunction with the drawings in which:

FIG. 1 is a perspective view, partly schematic, of a rotary filling machine to which the inert gas tunnel of the invention has been applied;

FIG. 2 is a plan view of an inert gas tunnel of this invention showing the relationship of the functional stations of a typical rotary filling machine;

FIG. 3 is a sectional view taken generally along lines 3--3 of FIG. 2 and showing the relationship of an inert gas conduit and an orifice to the inert gas tunnel;

FIG. 4 is a sectional view taken generally along the line 4--4 of FIG. 2 and showing the relationship of an inert gas flushing station to the inert gas tunnel; and

FIG. 5 is a sectional view taken generally along line 5--5 of FIG. 2 and showing the relationship of a filling station to the inert gas tunnel.

It has been found that the objects of this invention may be achieved by providing filling machine 10 with an inert gas tunnel 12 extending along the path of travel of a container 14 from shortly before a filling station C to shortly before a sealing station E.

In a preferred embodiment, the inert gas tunnel 12 comprises an arcuate, substantially planar, gas impermeable cover 18 which is supported from the frame 16 of the rotary filling machine 10. A first, or inner, wall 20 is supported from the cover, extends downwardly from it to a machine turret top 22 and is substantially linearly coextensive with the cover 18. At its lower extreme the inner wall is in close juxtaposition with, but does not contact, the upper surface 24 of the machine turret top 22. A second wall 26 is similarly supported from the cover 18, extends downwardly from the cover 18 to a position near the machine turret top 22, and is substantially linearly coextensive with the cover 18. Preferably both the inner wall 20 and the outer wall 26 are arcuate with the center of rotation about the center of rotation of the machine turret top 22.

The cover 18, inner wall 20, and outer wall 26 define the tunnel 12 through which the containers 14 travel during filling and before sealing. The tunnel 12 is preferably open at both ends for free ingress and egress of the containers 14. A flexible end wall or curtain, not shown, may be provided at each end of the tunnel, if desired. The clearances between the machine turret top 22 and each of the inner wall 20, and the outer wall 26 is preferably as small as possible to reduce to a minimum the flow of inert gas between them. A seal may be provided between the top 22 and each of the walls 20,26, if desired, but seals have been found to be unnecessary in a well-made tunnel.

Orifices 28,30 are provided in the cover 18 between the two walls 20,26 through which inert gas may be introduced by means of a conduit 32 connected to a source of inert gas under a low pressure. The preferred inert gas is nitrogen, particularly high purity nitrogen, such as Seaford grade nitrogen, although other gases inert or non-reactant with the drug may be substituted. Preferably the inert gas pressure is slightly greater than atmospheric pressure, typically, about 1 to 3 inches of water. In an embodiment such as is shown in the drawings, the inert gas consumption is typically about 1 cubic foot per minute.

The cover, inner and outer walls of the tunnel may be made of any gas-impermeable material. However, it has been found especially advantageous that they be made of a transparent material so that the containers may be observed while in the tunnel. Methyl methacrylate has been found to be especially advantageous as a material for construction of the inert gas tunnel.

As is best seen in FIGS. 1 and 3, the conduit 32 is connected at one end to a source of an inert gas, not shown, and serves to conduct the inert gas to orifices 28 and 30 where the inert gas enters the interior 38 of the tunnel. The inert gas flows through the tunnel 12 and exits at tunnel entrance 36 and tunnel exit 40.

In operation, the empty containers 14 are loaded into a hopper 34, flow downwardly and are individually inserted into a rotary machine turret top 22 at station A. The empty containers 14 rotate in step-wise, or indexing, manner with the machine turret top 22 into the inert gas tunnel 12 at tunnel entrance 36.

As may be seen in FIGS. 1 and 4, at flushing station B, the empty containers 14 are flushed with an inert gas by means of a hollow needle 42 which reciprocates vertically through an orifice 44 to permit passage of the containers 14. The needle 42 is connected at one end to a conduit 46 which is in turn connected to a source of inert gas, not shown. The needle may be made to reciprocate in any well known fashion, for instance, by a gear, cam and cam follower arrangement synchronized with the rotation of the turret top. The needle 42 introduces the inert gas to the bottom of each container, displacing any air present upwardly and out of the container into the tunnel interior 38 where it is exhausted with the current of environmental inert gas.

At filling station C, each container 14 is filled by a reciprocating needle 48 which is connected through a conduit 50 to a source of a desired drug. The needle 48 may be made to reciprocate vertically in well known fashion, and the exact amount of contents may be measured into the container in well known fashion.

In the embodiment shown, as is frequent in the industry, the sealing station E is remote from the filling station C due to the requirements of economy, design, and the like. There is, therefore, a time lag between the filling and the sealing operations. During the travel of the filled container 14 from the filling station C to shortly before the closure applying station D, an inert gas atmosphere surrounds each container 14, so that, any equilibration of the materials in the void space with the environment merely exchanges one moiety of an inert gas for another while in the tunnel. That is, no oxygen is introduced into the void space while the containers are in the tunnel. After sealing, the filled, sealed containers are removed from the machine turret top at the unloading station F and pass to further inspection and packaging operations in well known fashion.

As is shown in the drawings, it is frequently impossible to extend the tunnel past the sealing station, and frequently impossible to extend it to a point immediately adjacent to the sealing station. This is due, frequently, to the positioning of the sealing apparatus directly about the rotating filled containers. As is shown in the drawings, the inert gas tunnel terminates at exit 40, shortly before the closure applying station D.

In order more clearly to disclose the nature of the present invention, specific examples of the practice of the invention are hereinafter given. It should be understood, however, that this is done solely by way of example and is intended neither to delineate the scope of the invention nor limit the ambit of the appended claims.

EXAMPLE I

The following example illustrates the effect of an inert gas environment on the air concentration in the void space of a container.

A. a nitrogen flushing needle is positioned in one of a series of empty disposable cartridges and connected to a source of nitrogen under pressure. A polyethylene bag containing air is positioned around the filling area and sealed into position. The cartridge is flushed with high purity nitrogen for five seconds, then immediately filled halfway with nitrogen purged water, and sealed immediately while within the bag.

The concentration of air in the void space above the liquid is determined by polarographic analysis carried out on a Leeds and Northrup Polarograph 62200 Electro-Chemograph, type E. The contents of the void space are injected into an oxygen-free polarographic cell after the diffusion current is measured. A fixed potential is applied to the electrode and the diffusion current is recorded. The difference between the current readings before and after the substitution of the contents of the void space is compared with a standard curve of diffusion currents of known oxygen contents to determine the oxygen content of the void space.

B. The same procedure is repeated three times except that the nitrogen flushing time is 10 seconds, 20 seconds, and 60 seconds, respectively.

C. The same procedure is repeated except that the bag is filled with nitrogen and the flushing time is 5 seconds. The results are shown in Table I below.

TABLE I

Oxygen percent Relative oxygen N.sub.2 flush by volume in concentration Environment Time void space in percent (seconds) __________________________________________________________________________ air 5 2.65 100.0 air 10 1.58 59.5 air 20 1.38 52.5 air 60 1.42 54.0 nitrogen 5 0.17 6.4 __________________________________________________________________________

As may be seen from Table I, the provision of a nitrogen environment surrounding the filling area greatly reduces the air concentration in the void space. Extended nitrogen flushing time in an air environment decreases the oxygen (O.sub.2) content in the void space somewhat, but extended flushing after about 20 seconds does not further reduce the oxygen concentration. Flushing in a nitrogen atmosphere greatly lowers the oxygen content. As may be seen from the table, the oxygen concentration in the void space with the 5 second flush in nitrogen environment is less than 7 percent of the oxygen concentration of the 5 second nitrogen flush in an air environment.

EXAMPLE II

The following example illustrates the effect of a nitrogen environment on the oxygen content of the void space of a container when flushing is carried out under production conditions.

A rigid enclosure, substantially the same as the inert gas tunnel 12 shown in FIGS. 1-5 is installed on a Shields Ampoule Machine Co. rotary filling machine. Various sizes of disposable cartridges are filled to various solution capacities in the filling machine following a nitrogen flush performed by a flushing needle reciprocably inserted within the container. The solutions are purged with nitrogen before filling. The oxygen concentration in the void space is determined as described in Example I. The test is run first with an air environment within the tunnel and is repeated with a Seaford grade nitrogen environment. Typical results are shown below in Table II.

TABLE II

Oxygen Concentration in Void Space

percent Relative Container A. N.sub.2 flushed B. N.sub.2 flushed concentration contents within N.sub.2 without N.sub.2 in B based & size environment Environment on A __________________________________________________________________________ Sparine; 0.27 0.74 269% full: 1 cc. capacity Phenergan; 0.17 0.63 375% full 1 cc. capacity Largon; 1/2 0.27 2.10 770% filled: 2 cc. capacity __________________________________________________________________________

Sparine is promazine hydrochloride. Phenergan is promethazine hydrochloride. Largon is propiomazine hydrochloride.

As may be seen in Table II, the use of a nitrogen environment greatly reduces the amount of air present. The relative concentration of oxygen in the containers when filled in an air environment as compared to that when filled in a nitrogen environment ranges from 269 to 770 percent as much. The greatest improvement is found when the void space is largest.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

Claims

What is claimed is:

1. In a rotary filling machine for filling containers with oxidizable drugs and including a rotating, indexing machine turret having means to support open-topped containers, the improvement comprising:

A. a substantially planar, gas-impermeable cover supported from a frame for the filling machine and being coextensive with and overlapping the periphery of the top of the machine turret top from shortly before an inert gas flushing station to shortly before a sealing station;

B. a first wall supported from said cover and extending downwardly from said cover to the top of said machine turret top, said first wall being disposed between the center of rotation of said machine turret top and the containers, and being substantially arcuate in shape having a center of rotation substantially at the center of rotation of said machine turret top;

C. a second wall supported from said cover and extending downwardly therefrom to a position adjacent the machine turret top, said second wall being disposed on the opposite side of said containers from said center of rotation of said machine turret top and being substantially arcuate having a center of rotation substantially centered at said center of rotation of said machine turret top;

D. a plurality of orifices disposed in said cover and further comprising:

1. A first orifice located so as to permit passage of an inert gas-flushing apparatus;

2. A second orifice disposed so as to permit passage of a filling apparatus; and

3. A third orifice for the introduction of an inert gas;

E. an inert gas-flushing apparatus mounted on said filling machine frame for reciprocation through said first orifice into each container indexed beneath said first orifice;

F. a filling apparatus mounted on said filling machine frame for reciprocation through said second orifice into each container indexed beneath said second orifice;

G. at least one conduit connected to said third orifice and to a source of inert gas,

Whereby said cover and first and second walls define a tunnel maintaining an inert gas atmosphere through which said containers pass during a major portion of the time between flushing and sealing.

2. The apparatus as defined in claim 1 wherein said inert gas is nitrogen.

3. The apparatus as defined in claim 1 where said cover and first and second walls are fabricated from transparent material.

4. The apparatus as defined in claim 1 where said cover and first and second walls are fabricated from methyl methacrylate.