GB2052800A - Sterilizer control cycles. - Google Patents

Abstract

A sterilizer user customizes basic sterilizing cycles to his needs by the use of a switch matrix (148). The selected customizing information is transferred by a microprocessor (140) of an electronic controller (36) to a buffer store (146) from where it is transferred by a writer/ reader (152/154) to a magnetic stripe on a card (302). The information is thereby automatically stored in permanent, machine-retrievable form. In operation, the electronic controller (36) combines the information stored on the card with a program for a basic sterilizer cycle stored in a memory (144). The number of customized cycles which can be established by the use is not limited by the memory capacity of the controller and provision can be made for security of customized cycles. <IMAGE>

Description

SPECIFICATION Sterilizer control This invention is concerned with sterilizer control and operation.

Various basic sterilizing methods using either steam or a chemically biocidal gas, such as ETO (ethylene oxide), as the sterilizing medium, have been established and are generally accepted.

Such basic sterilization methods are, as provided on commercial sterilizing units, suitable for many institutional uses, especially hospital usage where standardized sterilizing cycles are generally used regardless of the load size and, within limits based on heat sensitivity of the goods, regardless of the type of load.

Prior art electromechanical controls for multi-cycle sterilizer units utilized a modular approach to control; for example, in a typical combination steam/gas hosptial sterilizer each cycle has essentially its own control, including a separate control panel, for carrying out a standardized sterilization method.

An advance in sterilizer control is described in copending U.K. Patent Application No.

7944336. This prior patent application describes an integrated control approach for control of differing types of sterilizing units each capable of carrying out one or more of a selected number of such basic sterilizing cycles.

Industrial users of sterilizing equipment sterilize bulk loads of diverse products including paper goods, bandages, liquid and solid pharmaceuticals, and hardgoods, many of which have requirements for differing levels of sterility probability. Also of concern are the packaging and product stability in establishing and relieving sterilization conditions. The basic sterilization methods which have developed over the years and have become somewhat standardized for hospital sterilization will meet the most stringent sterility requirements (e.g. 100% kill of indigenous environment organisms and, where required, sterilization indicator organisms).

However, the particular product lines of an industrial sterilizer user can frequently be biocidally treated more efficiently with lower energy usage by modification of such basic sterilization methods.

There are numerous value selections in the individual parameters for the plurality of steps in a basic sterilizing method which can be made while still meeting sterility requirements for a particular product. For example, selections can be made in the vacuum and/or pressure level during conditioning, the sterilizing medium exposure times and temperatures, the exhaust times for removal of the sterilization medium, the load dry times, and other parameters for the steps of a basic sterilization method in order to customize a cycle to a particular product. However, once acceptability of such a customized cycle has been established, good manufacturing practice standards in the sterilizing field require that such cycle be reliably repeatable.The type of adjustability available with the prior art electromechanical systems cannot be relied upon to meet such requirements when cycles with differing parameters are to be carried out at differing times using the same sterilizing apparatus.

Also, because of industry established standards and specifications, modifications of a basic sterilizing method developed by a user to provide an acceptable customized cycle for a particular product are, most frequently, considered to be proprietary by that user and provisions for security of that customized cycle are required and undertaken by the user.

With the variety of product lines and the number of differing industrial users of sterilization equipment; it is not practical to provide the number of differing types of sterilization units individually programmed to provide the large number of customized sterilization cycles that industrial users would require. The problem is not solved by the miniaturization contributions and other advantages of microprocessing equipment. While reliable repetition would be available the number of customized cycles available would still be limited.

Further, assuming availability of higher cost-larger storage capacity computer equipment, it is not generally economically practical for most individual industrial users to acquire programming equipment or develop programming skills in their otherwise specialized staffs as would be necessary to maintain confidentiality within the user's establishment. Where such equipment and skills were available to large users, the number of different cycles would still be limited.

An object of the present invention is the provision of methods and apparatus which enable a user to customize sterilizing cycles to his products without concern for program capacity limits of a sterilizer controller and, without requiring separate programming personnel, expensive programming equipment, or development of programming skills in operators.

The present invention comprises a method of operating a sterilizing apparatus including a sealable sterilization chamber with access door means, piping for delivering fluids to and exhausting of fluids from the chamber, sensing means for measuring a chamber condition responsive to the delivery of fluids, remotely controllable valve means for controlling the delivery and exhausting of fluids, and an electronic controller for signalling operation of a plurality of steps of at least one basic sterilization cycle, said controller including memory means for storing a program of said basic sterilization cycle steps; in which cycle customizing information representative of a desired parameter for at least one step of a basic sterilization cycle is established and is electrically transferred into the sterilizer electronic controller by storing such information in permanent reusable form externally of such basic sterilization cycle program to be machine retrievable for delivery as an electrical signal input for the sterilizer electronic controller, and in which the sterilizing chamber is loaded with goods to be sterilized and the sterilizing chamber access door means is closed, and furthermore in which a sterilization cycle is performed by automatically combining such externally stored customizing information with such basic sterilizer cycle program to controllably carry out a customized sterilizing cycle with at least one of the plurality of steps of the basic sterilization program being in accordance with the cycle customizing information selectively established and stored externally of such basic sterilization cycle program, such storing of cycle customizing information eliminating any furthrer requirement or establishing such customizing information in order to repeat such customized cycle and providing for automatic tamper-proof repetition of such customized cycle utilizing such externally stored information.

The invention includes sterilizing apparatus comprising a sealable chamber; means for controlling addition of fluids to and withdrawal of fluids from the chamber including piping connected to the chamber with remotely controllable automatically operable valve means controlling flow of fluids in such piping; means for sensing at least one chamber condition responsive to such flow of fluids; an electronic controller containing a stored program for directing a plurality of steps of at least one basic sterilizing cycle, such steps including control of said automatically operable valve means responsively at least in part to said sensing means; selection means for selectively establishing a value for a parameter of at least one of said plurality of steps of a basic sterilizing cycle, and means for storing the selected value in permanent, reusable form externally of the basic sterilization cycle stored program, the selected value being stored so as to be automatically machine-retrievable, said electronic controller including means for combining said externally stored selected value and the basic sterilization cycle stored program to carry out a customized sterilizing cycle and enabling automatic repetition of such customized sterilizing cycle as desired free of any further requirement for selectively establishing cycle customizing information.

The numerous modifications to basic sterilizing cycles required in order to accommodate diverse products from a wide spectrum of industrial users are thus made available by adapting the present invention notwithstanding use of economic, relatively low-storage capacity microprocessor controls and the number of customized cycles available is virtually without limit.

Also, the permanent storing of the customizing information in machine-retrievable form enables the user to maintain security of customized cycles while at the same time providing for tamper-proof and reliable repeatability of customized cycles by operators without requiring special skills or training of such operators.

Security of a user's customized cycles can thus be maintained along with foolproof repeatability of customized cycles and these advantages are provided economically without limiting the customized cycles available and without requiring programming equipment or development of computer programming skills by the user.

The integrated control as described in the copending Patent Application identified above, provides for operating a plurality of differing types of sterilizing units each capable of carrying out one or more basic sterilizing cycles. For example, a sterilizing unit can be provided with one or more of such basic sterilizing cycles as a high vacuum steam cycle, gravity steam cycle, liquid sterilization steam cycle, static conditioning gas cycle (e.g. U.S. Patent No. 3,068,064), dynamic conditioning gas cycle (e.g. U.S. Patent No. 3,598,516), or balanced pressure gas sterilization (e.g. U.S. Patent No. 3,589,861). Additional basic cycles, such as a pulse conditioning cycle, can also be included, as described in U.S.A. Patent No. 4164538.

For practical purposes, the various combinations of the basic sterilizing cycles required by most industrial users can be met with about ten differing types of sterilization units. Such commercially desirable combinations of basic cycles are readily provided in the differing types of sterilizer units by utilizing integrated control based on a plurality of circuit boards in a manner described in the above-identified copending Patent Application No. 7944336.

In addition, however, the present invention facilitates selection, in terms familiar in the sterilization art, and establishment of values for the parameters of one or more of the plurality of steps in one or more of each of the basic sterilization cycles provided. This enables the user to customize his sterilising cycles to his products without having to understand the computer language.

Further, provision is made for readily storing such selected values for customized cycle operation in a permanent reusable form so that the identical cycle can be easily, automatically, and reliably repeated for a particular product, at any time, with machine-readable features of the invention eliminating possibility of operator error.

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of sterilizing apparatus in accordance with the invention; Figure 2 is a graphical presentation of a sterilization cycle which can be carried out by the method of the present invention; Figure 3 is a schematic illustration of selector apparatus forming part of the apparatus; Figure 4 is a schematic illustration of a control and display panel forming part of the apparatus; Figure 5 is a box diagram of control apparatus; Figure 6 is a flow chart of the cycle customizing portion of the method; Figure 7 is a flow chart for operation of a portion of the cycle of Fig. 2; and Figure 8 is a schematic perspective view, with portions cut away, of a magnetic card readerwriter apparatus forming part of the control apparatus.

A single chamber 10 is shown in Fig. 1 along with a composite of the various conduits and other elements representative of apparatus used in carrying out steam or gas cycles. As will be readily understood, a gas source and gas conduits would not be part of sterilizing apparatus offering only steam cycles. Also, other chamber wall heating means, such as heat insulation covering electrical strip heaters, could readily be substituted for a chamber jacket.

A sterilizing chamber 10 is defined by a shell 1 2 and the closure 14. A jacket 1 5 surrounds a major portion of the chamber walls and can be supplied with a temperature control fluid, such as steam, through a conduit 1 6 with a valve 1 7 being controlled by a solenoid 18. The jacket 1 5 is drained through a valve 1 9 under the control of a solenoid 20.

A check valve 22 is provided in a supply conduit 70 to the chamber and a check valve 23 in an exhaust conduit 26. The chamber 10 can be exhausted to a vacuum source 28 or to a drain 29 at valve 30 so that either high vacuum or gravity type cycles can be carried out.

Chamber conditions can be sensed by pressure sensing means 31 or other sensing means 32 representative of the various other condition sensing means usable in the differing available cycles. Sensing means 32 can, for example, include a jacket temperature sensor and/or a drain line temperature sensor; or any other sensor functional in carrying out or terminating a cycle or step. Pressure sensing means 31, which can comprise a plurality of pressure transducers, is connected through electrical signal line 34 and sensing means 32 is connected through line 35, to a controller 36.

The various valves for controlling flow in the piping are remotely controllable automatically.

Solenoid 37 for exhaust valve 30 is connected to controller 36 by line 38. Similarly, the solenoid control valves on the chamber supply lines are connected to controller 36; line 44 is connected to a solenoid 46 for a steam valve 48 which controls flow from source 50 in conduit 52. When a gas cycle is provided, a line 60 to a solenoid 62 for a valve 64 in a gas conduit 68 controls flow of biocidal gas from a source 66. The steam conduit 52 and the gas conduit 68 are schematically illustrated as being directed through the common supply conduit 70 into the chamber 10.

To provide for selection of and storage of cycle customizing information, cycle customizing means 72 communicates through conductors 74 and 75 with controller 36. Monitored cycle information is transmitted from controller 36 to display panel 76.

While combinations of various steam and gas cycles can be provided on the sterilizing apparatus of Fig. 1, a steam sterilizing cycle with pulsed conditioning as shown in Fig. 2 will be described in a sterilizing unit which also includes gravity displacement steam cycles.

In the steam pulse conditioning sterilizing cycle of Fig. 2, after loading of the chamber and closure of its access door, the cycle is initiated at point 78 by injecting steam, with chamber drain valve 30 open for a fixed period of time to flush air from the chamber. At the end of the air flush phase, steam injection is interrupted at point 79 and evacuation takes place along line 80 to a subatmospheric level at point 81. Evacuation is then interrupted and steam injection takes place raising the chamber pressure level to point 82, a level below the pressure corresponding to the desired sterilization temperature.

The steam can be pulsed between the levels established by point 81 and point 82 a selected number of times, after which, steam is injected from point 84 along line 85 to a pressure corresponding to the desired sterilization temperature at point 86. The exposure period is represented by line 87. After exposure to the sterilizing medium, the chamber is exhausted along line 88 to point 89. Evacuation can be used and the chamber held for a dry time represented by line 90. The chamber is then brought up to atmospheric pressure along line 91 and can be opened for removal of the goods at point 92.

Selections to customize a basic cycle to a particular product could include the number of conditioning pulses, pressure/vacuum levels of such pulses, sterilization temperature, exposure time, the parameters for drying the load, and others. Selection of the subatmospheric evacuating level 81 and the repressurization level 82 will be described later as representative of a user's selection and establishment of values for parameters of particular steps of a basic cycle.

After being established, the selected parameter values are stored in a permanent, machinereadable storage medium to provide for reliable repetition of the identical cycle. A plurality of such customized cycles, each for sterilization of a specific product or type of product, may be established and stored with identification so that, upon selection and use of the appropriate stored data, any selected customized cycle may be reliably reproduced. In some cases, the customizing information may include total step changes, e.g. elimination of a step, in place of establishment of a value for a particular step.

The customizing data are selected and recorded in the storage medium when the sterilization apparatus is in the "Customize" mode; in effect, this permits the user to do "custom programming". But, the user does not have to make any machine entry or program code. Cycle steps used for selection of customizing values are in terms familiar in the sterilizing art and familiar to the sterilizer user. In brief, no encoding is required and no special programming skills are required for the user to "program" his own cycle.

The customized cycle can be carried out when the apparatus is in the "Operate" mode. The status of the apparatus is controlled by positioning a mode selector switch 100 which is located on a selection panel 102 (Fig. 3). Mode selector switch 100 is, preferably, key operated so that only authorized personnel can customize a cycle. Panel 102 is preferably located on the sterilization apparatus but could be arranged for remote selection through electrical communication with the sterilizer controller. Placement of the mode selector switch 100 in "Operate" mode prevents any change in selected values by an operator. After selection of customizing data and placement of selector switch 100 in operate position, the panel 102 can also be secured behind a key-operated door.

As shown in Fig. 3, selector switches 104 to 111 for customized information are preferably thumbwheel switches which are rotatable to a selected value for a sterilizing cycle phase familiar in the sterilizing art. While other sterilization cycle parameters or combination of parameters for the differing cycles of the sterilizing unit than those shown could be provided, for purposes of this explanation, the panel in Fig. 3 depicts only a combination of frequently used selector switches for the cycle graphically represented in Fig. 2.These include exposure and dry time selected through switches 104 and 105 respectively; exposure and jacket temperatures selected through switches 106 and 107 respectively; the number of conditioning pulses selected through switch 108; the vacuum and pressure levels of the conditioning pulses selected through switches 109 and 110 respectively, and, the drying vacuum selected through switch 111. On a multi-cycle sterilizing unit, the basic sterilization cycle which is customized by such parameter selections is selected by number or name through cycle switch 11 2.

The procedure for selecting and recording customized data is to place the apparatus in cycle customizing mode at switch 100 and select the customization parameters with selector switches 104 to 111. The selected data is automatically established on a machine-readable storage medium; selections can be made as long as switch 100 is in "Customize" mode; selections are automatically stored when a storage medium is present.

In the preferred embodiment, the storage medium comprises plastic cards with hard magnetic material portions for permanent magnetic encoding.

To store customizing data, such a card is placed in card slot 304 of panel 11 6 (Fig. 4). A card inserted into card slot 304, while selector switch 100 is in cycle customizing mode, is automatically fed to a magnetic head which automatically writes, i.e. encodes the card, and returns the card. When selector switch 100 is in "Operate" position and a card is inserted, the magnetic head automatically reads the encoded card for transfer of stored information to controller 36 and the card is returned. Thus, after the customization data is magnetically written or encoded on the card, the customized sterilization cycle may be performed by placing selector switch 100 in operate mode, placing the encoded card in card slot 304, and pressing start switch 118 on panel 116.

The apparatus may be provided with a printer arranged to print out the parameter values read from the card by the magnetic reader so that the user may check the parameters before proceeding. Panel 11 6 includes print-out slot 1 20 for this purpose.

Panel 11 6 can also include the display means 76 of Fig. 1 for cycle monitored data. For example, chamber temperature can be shown at window 122, chamber pressure at window 124, and cycle time remaining at window 1 26. Instantaneous display of other chamber values can be made during operation of the sterilizer. Conventional light emitting diode or liquid crystal displays may be employed.

Panel 11 6 is further provided with manual abort switch 1 28 so that, if an automatic abort feature is not provided, the cycle can be aborted manually before damage to a load.

Magnetically encodable plastic cards are preferred because they are compact, they may be kept and handled easily, they store the customizing data in visually imperceptible form which is advantageous for security purposes, they allow storage of customized cycle data for differing products or cycles on physically separate entities, and they provide for product or cycle identification information to be written directly on such separate entities. While other media may not be as advantageous, storage media including but not limited to disks, magnetic tape, optically encoded media, and various types of memory devices may be used.

Fig. 5 presents a block diagram of control apparatus for accomplishing the sterilization cycle customization and operation described above. The sterilizing apparatus is controlled by the electronic controller 36 which includes a processor and a memory which contains a stored program or series of instructions for directing a sterilization cycle. In the preferred embodiment, the processor is a microprocessor 140 and the memory is a read-only memory 144, although it is to be understood that other types of processors and memories may be utilized.

Various condition sensors such as pressure sensors and temperature sensors are disposed in the sterilization chamber, jacket, or drain line. Data from these sensors are fed to the input ports of the processing system. In general, the processor includes a central processing unit which operates under the direction of a control and timing unit to process the input data and control the solenoid valves shown in Fig. 1 in accordance with the program information which is stored in a read-only memory 146. A data or buffer memory 146 for temporary storage and processing can also be utilized and appropriate read-out displays provided. For a more detailed discussion of micro-computer control of sterilizing apparatus, reference may be made to the above identified copending Patent Application No. 7944336.

The stored program or instructions for a basic sterilization method in the read-only memory 144, or other type of memory if a microcomputer is not utilized, are arranged to be supplemented or modified by the customizing data established with selector switches such as 104 to 111 of Fig. 3. As described above, during the cycle customizing mode, the customizing data is recorded on a permanent, machine-readable storage medium such as magnetically encodable cards. Before the cycle begins, the selected card is automatically read and, during operation, the customizing data is utilized when called for by the steps of the stored program.

Referring further to Fig. 5, the controller 36 comprises the microprocessor 140 (with working registers), the read-only memory 144, and the read-write memory unit 146; the read-only memory and read-write memory may be part of or separate from the microprocessor. During the cycle customizing mode, the controller is arranged to scan a switch matrix 148 and enter matrix signals at the read-write memory 146.

The switch matrix 148 is automatically encoded by selection at the thumbwheel switches 104 to 112, shown in Fig. 3. The thumbwheels are conventional. Each thumbwheel controls four switch elements. The thumbwheel is rotated to select a value, for instance from 0 to 9, and the rotating element is mechanically linked to a group of four switch elements which set, in digital code, the value selected with the thumbwheel. This provides a convenient input to the computer, since this same digital code is used for storing and processing digits in the computer system.

The microprocessor 140 scans the switch matrix 148 and transfers the information entered through the thumbwheels to read-write memory 146. This data transfer is made through the working registers of microprocessor 140 which facilitate routing of information.

The addresses in read-write memory 146 are correlated with the thumbwheel switches 104 to 11 2 of panel 102. Thus, for example, the coded values for exposure time will always be stored at the same addresses of the read-write memory, and so on for each of the other parameters or cycles selected. When a card 302 is inserted in slot 114, with selector switch 100 set in the cycle customizing mode, the information in read-write memory 146 which was selected at thumbwheels 104 to 11 2 is transferred to a magnetic writer 1 52 and is encoded on the card.

The information as encoded may be in the same code format as in the switch matrix 1 48.

To operate the sterilizer with the selector switch 100 in the operate position, a card is inserted into slot 304. The card is automatically read by a magnetic reader 1 54 and the coded information read is transferred to read-write memory 146 through the working registers of microprocessor 140. After the start switch 118 is turned on, the sterilizer is operated following the program stored in read-only memory 144. Information from the vacuum, pressure, and temperature sensors, represented by block 1 56 in Fig. 5, is fed to the controller 36 which processes the data in accordance with the stored program and automatically controls operation of the flow valves of Fig. 1 to effect the desired pressure and temperature conditions in the sterilization chamber at the proper time to define the customized cycle.Such control is represented by valve controls 1 58 in Fig. 5. Appropriate chamber conditions can be monitored and shown on display means 76 and/or a separate print-out record can be provided at printer 159.

The program in read-only memory 144 is arranged to instruct the processor 140 to fetch customization data from read-write memory 146 at the times in the sterilization cycle when such data is called for; e.g., to fetch selected values at points 81 or 82 of the cycle graphically represented in Fig. 2. Flow control valves such as steam valve 48 or vacuum valve 30 are operated to attain the customized cycle value. For instance, the customized pressure value which is read out of read-write memory 1 46 is fed into microprocessor 140 while actual chamber pressure is also fed into the microprocessor 140 from the appropriate pressure sensor.The selected parameter value is subtracted from the actual value with the result tested for zero or a negative number when going from a higher to a lower pressure; or, for zero or a positive number when going from a lower to a higher pressure. When controlling temperature or time, similar appropriate techniques are utilized.

The operation and interrelation of the elements of Fig. 5 will be better understood by referring to the flow charts of Figs. 6 and 7. Fig. 6 is a flow chart of that part of the program stored in read-only memory 144 which controls the encoding of the customization data on the magnetically encodable card, while Fig. 7 is a flow chart of a part of the stored program which controls operation of the customized sterilization cycle.

Referring to Fig. 6, starting at decision block 200, the controller first checks to see if the mode selector switch is in the customize mode. If it is not, then no further steps leading toward the encoding of data on the card are performed; if the switch is in the customize mode then switch matrix 148 is scanned in line-by-line fashion as represented at block 202 of Fig. 6. The coded data in the switch matrix is transferred line-by-line to read-write memory 146 through the working registers of the microprocessor as represented at block 204. The process of scanning the switch matrix and storing in the read-write memory line-by-line continues until the entire switch matrix has been scanned, as shown at block 206.

After all of the data in the switch matrix has been transferred to the read-write memory, the controlled checks to see whether or not a card has been inserted in magnetic writer 1 52 es shown at block 208. If no card is in the writer, then the entire process described above is repeated, as represented by the arrow in Fig. 6 returning to the topmost block, until a card is present in writer 1 52.

After a card is detected, the magnetic writer is controlled to write a leader on the card, as depicted at block 210. As known to those skilled in the art, the leader is a synchronization code which is written at the beginning of a stream of serially entered data bits so that, when read, the beginning of the data may be located. After this, magnetic writer 1 52 is controlled to write the data stored in the read-write memory onto the magnetically encodable card. This process continues until all of the data in the read-write memory is written on the card, as shown at block 214. When encoding is completed, the controller may cause a printer to print out a record of the recorded parameters, for visual checking by the operator, as shown at block 216.After this printing, if it is desired to encode further magnetic cards with the same customizing data, then the steps described above are repeated as depicted by the arrow returning from block 216 to block 200 in Fig. 6.

Fig. 7 is a flow chart covering a portion of the stored program for controlling operation of the sterilizer. The portion illustrated and described is representative of how externally stored customizing data is utilized to control sterilization cycle parameters. Specifically, the flow chart shown in Fig. 7 is for that portion of the sterilization cycle shown in Fig. 2 from the beginning of the cycle until point 82 in the cycle is reached; other externally stored values can be introduced in a similar way to control later portions of the cycle.

Referring to Fig. 7, the controller first checks selector switch 100 to see whether it is in the "Operate" mode, as represented at block 240 in the Figure. If it is, then a series of steps is taken to ensure that the jacket of the sterilization chamber is maintained at the selected value, as depicted at block 242. The magnetic reader 1 54 is then checked to see whether or not a card is present, and if a card has not yet been inserted, maintenance of the jacket at the selected temperature is continued.

The magnetically encoded data is read from the card and transferred into read-write memory 146 via the working registers of the microprocessor as shown at block 246. The start switch 11 8 is then checked, as shown at block 248, and if it is not yet "on", the jacket is maintained at the selected temperature as depicted at block 242. After the start switch has been turned on, there is a timed air flush of the chamber with steam injection; this is represented at block 250 in Fig. 7 and by the upwardly sloping pressure line between 78 and 79 in Fig. 2. In the particular cycle depicted, pressure level 79 has not been selected for customization but rather results from steam injection being on for a predetermined period of time.After this time elapses, the steam is turned off as represented at block 251 and the stored program instructs the microprocessor to fetch the conditioning vacuum level from the read-write memory (block 252 of Fig. 7) to determine value 81 shown in Fig. 2. The conditioning vacuum level being one of the parameters forming part of the customized cycle, the value of that parameter has been selected earlier with thumbwheel switch 109 shown in Fig. 3.

The actual chamber pressure is then read as shown at block 254, and its value is compared with the selected pressure value 81 to determine which is higher. If the chamber pressure is higher than the selected pressure value then the vacuum pump is operated as shown at block 257 to effect evacuation of the chamber until the actual chamber pressure falls to the value at point 81.

At point 81, the vacuum pump is turned off (block 258) and the stored program instructs the microprocessor to fetch the selected conditioning pressure level value from read-write memory 146 as shown at block 260. The conditioning pressure level is a further customized parameter, the value of which has been selected earlier during the customize mode, such selection being through thumbwheel switch 110 of Fig. 3. Again, the actual chamber pressure is read, as depicted at block 262, and if the chamber pressure is less than selected pressure value 82, as shown at block 264, then steam is injected into the sterilization chamber as shown at block 266, until pressure level 82 is attained. Such pulsing is then continued based on the number of pulses which have been selected through thumbwheel 108.

Fig. 8 illustrates a magnetic reader-writer 300 of the type which may be used in the control apparatus. Reader-writer 300 includes magnetic read-write head 301 which is capable of both writing signals on a magnetically encodable medium and reading such signals. To operate the reader-writer, a card such as card 302 having a magnetically encodable stripe 303 is placed in slot 304 of the reader-writer. A drive mechanism within the reader-writer returns the card to slot 304 for removal after the information is either written or read.

In an actual embodiment, the following commercially available components may be used: Microprocessor Intel 8748 Read Only Memory Intel 8755 Read-Write Memory Intel 8155 Input/Output Ports Intel 8243 Thumbwheel Switches Stanford Applied Engineering Santa Clara, California Catalog &num;4022-7000 Reader/Writer Amp Inc.

Amp Capitron Division Elizabethtown, Pa. 1 7022 Model &num;211 Magnetic Card Conforms to ANSI X4.13.1971 Standard In the light of the above description, other basic cycles and other cycle step parameters than those specifically described can be utilized in carrying out the invention.

Claims (14)

1. A method of operating a sterilizing apparatus including a sealable sterilization chamber with access door means, piping for delivering fluids to and exhausting of fluids from the chamber, sensing means for measuring a chamber condition responsive to the delivery of fluids, remotely controllable valve means for controlling the delivery and exhausting of fluids, and an electronic controller for signalling operation of a plurality of steps of at least one basic sterilization cycle, said controller including memory means for storing a program of said basic sterilization cycle steps; in which cycle customizing information representative of a desired parameter for at least one step of a basic sterilization cycle is established and is electrically transferred into the sterilizer electronic controller by storing such information in permanent reusable form externally of such basic sterilization cycle program to be machine retrievable for delivery as an electrical signal input for the sterilizer electronic controller, and in which the sterilizing chamber is loaded with goods to be sterilized and the sterilizing chamber access door means is closed, and furthermore in which a sterilization cycle is performed by automatically combining such externally stored customizing information with such basic sterilizer cycle program to controllably carry out a customized sterilizing cycle with at least one of the plurality of steps of the basic sterilization program being in accordance with the cycle customizing information selectively established and stored externally of such basic sterilization cycle program, such storing of cycle customizing information eliminating any further requirement of establishing such customizing information in order to repeat such customized cycle and providing for automatic tamper-proof repetition of such customized cycle utilizing such externally stored information.

2. A method as claimed in claim 1, in which operation of such sterilizing apparatus is repeated as desired for similar sterilizer loads by machine reading such cycle customizing information as previously established and stored.

3. A method as claimed in claim 1 or 2, in which a plurality of differing basic sterilization cycles are stored in the electronic controller memory means and in which a basic sterilizing cycle for operation of the sterilizing apparatus is selectively established and an electrical signal representative of the basic sterilizing cycle selected is stored so as to be machine retrievable for transfer to the electronic controller with the selectively established cycle customizing information representative of a desired parameter for at least one step of such selected cycle.

4. A method as claimed in claim 3, in which desired values for individual parameters for a plurality of steps of the basic sterilization cycle to be performed are selectively established.

5. A method as claimed in claim 4, in which such selected cycle customizing information includes sterilizing temperature and time of exposure of the goods to be sterilized to the sterilizing medium.

6. A method as claimed in claim 3, 4 or 5, in which the basic sterilization cycle selected includes a step of evacuating the sealed chamber to a selected subatmospheric level and in which the cycle customizing information includes a level of evacuation for the sealed chamber.

7. A method as claimed in any of claims 1 to 6, in which a value representing a parameter of at least one step of the basic sterilization cycle is selected in sterilization cycle terminology at a value selection means.

8. A method as claimed in any of claims 1 to 6, in which the customizing information is established in sterilization terminology and automatically stored in digital code compatible with the stored program of the electronic controller.

9. A method as claimed in any of claims 1 to 8, in which the cycle customizing information is stored on a magnetic storage means and in which such magnetically stored cycle customizing information is read from the storage means and is automatically combined with the basic sterilization cycle stored in the electronic controller, such magnetically stored information being retained for future repetition of such customized cycle.

1 0. Sterilizing apparatus comprising a sealable chamber; means for controlling addition of fluids to and withdrawal of fluids from the chamber including piping connected to the chamber with remotely controllable automatically operable valve means controlling flow of fluids in such piping; means for sensing at least one chamber condition responsive to such flow of fluids; an electronic controller containing a stored program for directing a plurality of steps of at least one basic sterilizing cycle, such steps including control of said automatically operable valve means responsively at least in part to said sensing means; selection means for selectively establishing a value for a parameter of at least one of said plurality of steps of a basic sterilizing cycle, and means for storing the selected value in permanent, reusable form externally of the basic sterilization cycle stored program, the selected value being stored so as to be automatically machine-retrievable, said electronic controller including means for combining said externally stored selected value and the basic sterilization cycle stored program to carry out a customized sterilizing cycle and enabling automatic repetition of such customized sterilizing cycle as desired free of any further requirement for selectively establishing cycle customizing information.

11. Apparatus as claimed in claim 10, in which said selection means include electrical switch means for automatic digital encoding of selected customizing information.

1 2. Apparatus as claimed in claim 10 or 11, in which said means for storing said selected value includes magnetic recording and storage means.

1 3. Apparatus as claimed in claim 12, in which said magnetic storage means comprises a separate magnetic card for storing each customized cycle selected.

14. Apparatus as claimed in any of claims 10 to 13, in which the electronic controller contains a stored program for a plurality of basic sterilizing cycles and said selection means is adapted for selecting a basic sterilization cycle from the plurality of basic sterilizing cycles for storage so as to be automatically machine retrievable.

1 5. Apparatus as claimed in any of claims 10 to 14, in which the selection means for selecting a value for a parameter of at least one step of the sterilization cycle is adapted for selecting a value of a chamber condition identified in sterilizer cycle terminology and for producing an electrical signal representative of such value for storage, and the means for combining such selected value and the stored basic sterilization cycle program is provided with read/write memory means.

1 6. A method of operating a sterilizing apparatus substantially as herein described with reference to the accompanying drawings.

1 7. Sterilizing apparatus constructed and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.