Title:
ARTICLE TREATING APPARATUS
United States Patent 3650038


Abstract:
Apparatus for sterilizing articles including means to release gaseous sterilant from cartridge held within the sterilizing chamber, said means actuated by pressure sensing means so as to release the sterilant only after a required degree of vacuum has been attained. May also include time-limit alarm means for the vacuum pulling stage and the sterilant releasing stage.



Inventors:
Alessi, Patrick A. (Needham, MA)
Jansky, Joel W. (Jamaica Plain, MA)
Application Number:
04/867008
Publication Date:
03/21/1972
Filing Date:
10/16/1969
Assignee:
ADVANCED INSTRUMENTS INC.
Primary Class:
Other Classes:
422/33, 422/34, 422/108, 422/112, 422/119
International Classes:
A61L2/20; (IPC1-7): A61L3/00
Field of Search:
21/58,91,DIG.4 222
View Patent Images:
US Patent References:



Foreign References:
AU236071A
Primary Examiner:
Wolk, Morris O.
Assistant Examiner:
Millman D. G.
Claims:
What we claim is

1. Apparatus for treating articles deposited in an enclosed vessel by releasing thereto the contents of a closed container comprising:

2. The apparatus of claim 1 in which means are provided for varying the pressure within said vessel, and wherein said first sensing means comprises a pressure sensor arranged to detect the pressure within said vessel, said pressure sensor being coupled to said relative movement effecting means to automatically cause said relative opening movement in response to a predetermined monitored level of pressure in said vessel.

3. The apparatus of claim 2 which further comprises means for automatically deactuating said pressure varying means when said predetermined opening pressure has not been achieved within a preset time after actuation thereof.

4. The apparatus of claim 3 in which said pressure varying means produces a vacuum in said vessel, in which said container opening means comprises a puncturing element adapted to puncture said container, and in which said container contents comprises volatile material, said apparatus further including means for maintaining said puncturing element and said container in their puncturing position for a period of time to control the exit rate of said cartridge contents.

5. The apparatus of claim 1 in which said container contents change a condition within said vessel when released and which further comprises a second means for sensing said changed condition after said container has been opened, and alarm means coupled to said second sensing means to indicate when a predetermined quantity of change of the sensed condition has not occurred within a preset time after said container has been opened.

6. The apparatus of claim 5 in which said two sensing means comprise pressure sensors arranged to sense the pressure within said vessel, and said container contents increase the pressure within said vessel when released, said apparatus further comprising means for evacuating said vessel, said first sensor being adapted to automatically actuate said relative opening movement effecting means to open said container in response to a predetermined high vacuum within said vessel, and said second sensor being adapted to energize said alarm means when a predetermined low vacuum condition has not been achieved within a preset time after said container has been opened.

7. The apparatus of claim 1 which further comprises means for returning said container opening means and said container holding means to their initial relative positions.

8. The apparatus of claim 7 wherein said relative opening movement effecting means comprises a pneumatic piston shiftable between retracted and advanced container opening positions, and wherein said returning means comprises spring means adapted to be strained by the shifting of said piston.

9. The apparatus of claim 1 wherein said relative opening movement effecting means comprises an assembly adapted to respond to a differential pressure force, said apparatus further comprising means for coupling said relative movement opening effecting means to a source of differential pressure.

10. The apparatus of claim 9 in which said coupling means comprises an electrically operable valve having three ports, said valve having a deactuated position in which a first valve port is in pneumatic communication with a second valve port;

Description:
BACKGROUND OF THE INVENTION

This invention relates to article treating apparatus and more particularly to an automatically controlled means for opening an enclosed container to release its contents to an enclosing vessel, whereby to treat articles placed within said vessel.

It is common practice in one aspect of such article treating within a closed vessel, to sterilize medical instruments in an autoclave using pressurized super-heated steam. However, many instruments, such as those made of plastic, or those incorporating electronics, cannot be sterilized in this manner, because of their susceptibility to deformation or damage at the high steam-sterilization pressures and temperatures. A frequently used sterilizing treatment of such instruments, then, is again within completely closed, evacuated chamber, but by exposing them to a gas sterilization medium, such as ethylene oxide.

Heretofore known devices for introducing the highly toxic gas into the sterilizing chamber have introduced that gas from a container which is positioned and opened externally of the chamber. In one prior art opening means a piercing lance is disposed within a cylinder and arranged to pierce a cartridge of liquid sterilant when a cap to the cylinder is manually screwed down on the cartridge forcing it against the lance. The sterilizing chamber is evacuated, and the cylinder so arranged that, when the cartridge has been pierced, the thereby released gas may be drawn to the evacuated chamber through an appropriate, external valved conduit. In another such prior art means, a valve is opened on a re-usable container.

Several shortcomings have become apparent of these prior art means requiring external (to the sterilizer) positioning of the container opening, or more particularly cartridge puncturing device. The most serious of these is that the highly toxic ethylene oxide frequently escapes past the cap while the cartridge is being pierced and before the cap is fully sealed. Moreover, leaks frequently occur in the external conduit and valving. These leaks create a serious safety hazard to the operators of the device and also result in the dispersion of the sterilizing gas into the chamber being incomplete.

The described, screwcap lanced, prior art puncturing devices require more particularly smooth and speedy hand threading of the cap into the cartridge in the effort to assure that the cartridge is properly pierced and that the cartridge is sealed with the least amount of escape of the toxic gas. However, the torque necessary to carry out this procedure is frequently greater than most nurses can apply, and as a result these prior devices are subject, in effect, to faulty manual manipulation.

It is, therefore, highly desirable to provide an opening device capable of opening the sterilizing gas container both with the container located wholly within the enclosed vessel, and as actuated by an automatic control means.

SUMMARY OF THE INVENTION

In accordance with the invention, an opening device herein disclosed as a pressure-responsive pneumatic cylinder and piston assembly, is associated with a closed vessel and is in operative juxtaposition to a container, herein a gas cartridge, to be opened wholly within, and to release its contents to, said enclosing vessel. As disclosed, an air or other fluid conduit opens into the cylinder assembly on the opposite side of the piston from the piston shaft.

The invention further comprises a control means for automatically controlling actuation of the opening device in response to a sensed condition, be it the pressure level, or other physical or chemical condition within the evacuated chamber. The preferred control means includes an electrically operable three-way valve such as a solenoid actuated valve. One port of that valve is in fluid communication with the opening device inlet, another port is in fluid communication with a vacuum pump and the third port is open to an environment of higher pressure than the chamber, such as the atmosphere when the vessel is evacuated. A sensor of the pressure within the evacuated chamber insures that opening does not take place unless a predetermined vacuum is established within that chamber. A second sensor of the pressure also senses the pressure within the enclosed chamber, and insures that sterilization does not proceed further if the container opened was empty or only partially filled so that the environment within the chamber is not sufficiently toxic to insure proper sterilization.

In the operation of the preferred embodiment, the enclosed vessel is sealed, and a vacuum pump is automatically actuated to evacuate the chamber. When the chamber has reached the proper vacuum for opening, the three-way valve is automatically actuated to introduce atmospheric pressure on one side of the piston, thereby creating a pressure differential acting on two sides of the piston to cause the piston to move from its rest position to an extended position to open the container. The control means preferably controls the opening of the container for a predetermined time to insure that the gas escapes entirely in a gaseous form. At the end of this predetermined time, the three-way valve is automatically switched to equalize the pressure on both sides of the piston, and a return means such as a helical spring retracts the opening mechanism from the container to allow complete dispersion of the container contents within the vessel.

It should thus be apparent that as applied to ethylene oxide gas sterilization, this invention significantly reduces the hazards to operating personnel from gas leakage while at the same time insuring complete dispersion of the gas within the vessel. By utilizing the pneumatic pressure differential between the vessel and the atmosphere to actuate or trigger the opening device through a valved conduit system which is automatically controlled by the pressure within the chamber, the apparatus operates automatically, and also controls the flow rate from the container to protect items placed within the vessel.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The objects, features and advantages of the invention will become apparent as the following detailed description of the preferred embodiment thereof proceeds with continued reference to the attached drawings wherein.

FIG. 1 is a side elevation of the preferred opening device and container holder of the invention mounted within a sealed chamber; and

FIG. 2 is a schematic representation of the control system employed with the opening device shown in FIG. 1.

Referring initially to FIG. 1, an enclosed vessel such as a reinforced sterilization tank 10 is provided with a hinged upper cover 12 and is sealed from the ambient environment by a circumferential gasket 14 to define an air tight chamber 16. Positioned within the chamber 16 is an opening or puncturing device 18 which is secured in operative juxtaposition to an article securing means such as a container holder 20.

The preferred puncturing device 18 includes a cup 22 which is secured to a frame plate 24 opposite, and herein below the container holder 20. The cup 22 has a cylindrical bore 26 within which a piston 28 having shaft 30 is slidably mounted for reciprocating towards and away from the container holder 20. The shaft 30 extends from the piston 28 through a guiding aperture provided in a cap 32 which closes the open end of the cup 22. The outer end of the shaft 30 mounts a puncturing lance 34, and a helical spring 36 is disposed around the piston shaft 30, between the cap 32 and the piston 28. The cap also has a ventilation hole 37 formed therein to subject the upper side of the piston 28 to the same pressure as the chamber. A pneumatic inlet 38 opens through the bottom wall of the cup 22, to the opposite or lower side of the piston 28.

The frame plate 24 extends upwardly along the side wall of the tank 10, being secured thereto by a screw 42 passed through an oversized hole 44 receiving also a sleeve 46 confined between the screw head and a wall mounted block 48 into which the screw 42 is threaded as shown FIG. 1.

A U-shaped container holding shield 50, (FIG. 1), is secured at both ends to the frame member as by screws 52. A horizontal apertured platform 54 is secured within the holding shield 50 to form a floor upon which a container or cylinder 56 may be supported, and a vertical spacer plate 58 is secured at its ends to the opposite shield sides, as by screws 60, at a spacing from the frame member to hold the cylinder 56 against the round of the shield. A spring loaded captivating stop 62 is secured to the upper end of the spacer plate 58 to form a retaining cap for the cylinder 56.

To allow the puncturing device 18 and container 56 to remain aligned for various deformations of the chamber in response to various pressure conditions within the chamber, a horizontal space indicated at 64 is normally left between the frame plate 24 and the mounting block 48, which space, together with the oversized hole 44, allow for both vertical and horizontal displacement of the unit in response to deformation of the chamber walls without disrupting the alignment between the container and the puncturing device 18.

A gas deflecting shield or baffle may be placed around the container holder 20 to aid diffusion of gas released into the remainder of the chamber 16, said baffle being conventional and therefore not shown.

Turning now to FIG. 2, the system or means for automatically controlling actuation of the preferred form of opening device 18 includes a pneumatic inlet conduit 66 opening at one end to the opening device inlet 38 and which conduit 66 at the other end opens into one port indicated (but not shown) at 68, of a solenoid actuated three-way valve 70. A second port 72 of the three-way valve 70 is open to the atmosphere, while a third port 74 of that valve is fluid connected through conduit 76 to a pressure varying means such as a vacuum pump 78. The conduit 76 is also provided with an electrically energized, normally closed line valve 79 to regulate the flow therethrough, and a bypass conduit 80 establishes fluid communication between the conduit 76 and the chamber 16.

To provide electrical control signals for the described system, two pressure sensors 82 and 84 are provided adjacent the vessel. The first sensor 82 shall be hereinafter called the "high vacuum" sensor, and the second sensor 84 shall be called the "low vacuum" sensor. Said sensors 82, 84 are incorporated in an electrical circuit generally indicated at 86 and which includes an interlocking switch 88 disposed beneath the door 12, which switch 88 is closed when the door 12 is closed to seal the chamber 16, whereupon operation of the sterilizing apparatus may only then commence.

Once the door 12 has been shut, a start or master switch 90 may be depressed either manually or otherwise to commence the puncturing cycle of the device. When the start switch 90 has been depressed, the vacuum pump 78 is energized and the line valve 79 is opened by energization of a master line 92, while at the same time the solenoid valve 70 remains deenergized, or in the position shown, whereby to interconnect the vacuum pump 78 with the opening device 18 and chamber 16. The vacuum pump 79 thus operates to progressively evacuate the chamber 16 while maintaining both sides of the piston 28 of the puncturing device in equilibrium.

The circuit 86 also includes a control line 94 which is connected to two conventional timers 96 and 98, preferably of the multiple-cam preset clock-motor type, which timers are energized simultaneously with the vacuum pump 78. The first timer 96 is called the "high vacuum" timer and is set to yield an output signal set a predetermined time after evacuation of the chamber 16 has commenced, say 5 minutes, which predetermined time is that in which a properly sealed chamber 16 should reach a predetermined vacuum. Concomitantly, the high vacuum sensor 82 is set to produce an output signal when the predetermined puncturing vacuum (say 20 inches of mercury) has been achieved. The selected high vacuum is the optimum dispersion vacuum for the particular gas to be dispersed within the chamber.

The outputs of the high vacuum sensor 82 and timer 96 are coupled to comparator 100, that preferably includes an opening AND-gate 102 to which the two high vacuum signals are coupled to produce an opening signal on line 104 only if the proper puncturing vacuum has been achieved, that is only if the high vacuum sensor 82 emits an output before the high vacuum timer 96 does. Assuming proper opening conditions exist and line 104 is energized, the solenoid valve 70 is energized to interconnect the second port or air inlet 72 with the pneumatic inlet 66 to raise the pressure on the lower side of the pneumatic piston 28 to atmospheric pressure. With reference to FIG. 1, it should be apparent that the presence differential on the two sides of the piston 28 produces a net upward force on the piston thereby producing relative opening movement between the container 56 and lance 34 by urging the piston shaft 30 and lance 34 against the spring 36 and into the container 56, whereby to puncture the said container 56 while at the same time straining the spring 36.

The force characteristically required to puncture a gas container is 15 pounds, which force may be produced by a relatively small piston at a puncturing pressure differential of about 20 inches of mercury. It will be understood the size of the piston may be reduced as the pressure differential increases and it is desired to produce a larger puncturing force, or to reduce the size of the cylinder assembly 22, various conventional mechanical linkages and opening means may be operatively associated with, for actuation in response to movement of the piston shaft 30 to increase the mechanical advantage achieved by the puncturing device.

The above described opening cycle is to take place only if the chamber 16 is properly sealed. To stop the device and indicate a malfunction if the proper opening condition is not achieved, the comparator 100 preferably also has a second or alarm AND-gate 106 to which the high vacuum timer 96 and high vacuum sensor 82 are coupled, with the high vacuum sensor signal being inverted by invertor 108. The alarm AND-gate 106 produces an alarm signal only if the high vacuum timer 96 produces a signal before the high vacuum sensor 82 does. In the event an alarm signal is transmitted over alarm line 110 to both energize an alarm means 112, such as a signal light or buzzer, and to open a normally closed master relay 114 to open the circuit 86 and hance stop the device.

One of the pecularities of ethylene oxide, aside from its high volatility, is that in liquid form it is highly destructive to the items to be sterilized, while in gaseous form it effectively sterilized the items without injuring them. Therefore, means are preferably provided for insuring that the sterilizing medium emanates from the cartridge 56 solely in gaseous form. This function is accomplished by a puncture timing control switch 116, typically a bistable flip-flop switch, which switch 116 is placed in the opening line 104 and remains closed for a period of time after the opening line 104 is energized, preferably until the predetermined low vacuum has been achieved, so that initially gas can escape only around the lance. Thereafter the opening control switch 116 is opened when the low vacuum sensor emits a signal over line 115, thereby deenergizing the solenoid valve 70 and allowing the repositioning to connect the bypass conduit 80 and the inlet conduit 66 so as to equalize the pressure on both sides of the piston. The theretofore strained or compressed spring 36 is thereby released to return the lance 34 to its retracted position and more particularly to fully open the container, and for complete dispersion of the contents of the container 56. Of course the opening time delay can be varied with the particular container contents, with the only requirement being that the puncture time delay be such as to insure the escape in gaseous form of the particular contents being dispersed. It will be appreciated also that the described return actuation of the container opening means may be used to reclose a re-usable container.

The control circuit 86 also insures that the container 56 being opened has been properly filled and opened, or conversely, stops the device and energizes the alarm 112 if these conditions do not exist. This function is performed by the low vacuum sensor 84 which is set to emit a signal when the chamber pressure has risen to a predetermined low vacuum, which vacuum indicates that the container was sufficiently charged to release an amount of gas to raise the pressure within the chamber to the predetermined level, and by the low vacuum timer 98 which is set to emit a signal at a predetermined time after opening, say 5 minutes, during which time a properly filled container would have raised the chamber 16 pressure to the selected low vacuum. The outputs of the low vacuum elements 84 and 98 are coupled to a second comparator 117 that preferably includes an invertor 118 for inverting the low vacuum sensor signal and a second alarm AND-gate 120. The output of low vacuum comparator 117 is coupled to the alarm line 110 and energizes that line to energize the alarm 112 and open the master relay 114 if the low vacuum timer 98 emits a signal before the low vacuum sensor 84 does. On the other hand, if the container 56 is properly filled and opened so that the low vacuum sensor 84 emits a signal before the low vacuum timer 98 does, the comparator 117 emits no alarm signal.

In considering this description of the preferred embodiment of the invention, it should be appreciated that other activating means and other opening devices, such as magnetic-, hydraulic-, bellows-, solenoid-, or other electro-mechanical-actuated means, could be employed to open the cartridge 56 within the chamber 16 in association with appropriate control systems. Also, other opening devices such as cover lifters, cover twisters, cover sliders, valve turners, valve lifters, and valve pressers could be employed. From among these devices the pneumatic piston and cylinder assembly hereof is preferred for its compact size and ease of control.

It should thus be understood that numerous modifications and equivalents of the invention will become apparent to those skilled in the art which do not depart from the spirit and scope of the appended claims.