US2289890A - Cleaning and sterilizing instruments and other articles - Google Patents

Description

Juli;` 14, 1942.

c. WALTER V CLEANING AND STERILIZING INSTRUMENTS AND OTHER ARTICLES Filed Feb. 2, 1939 5 Sheets-Sheet l July 14, 1942. c. w. WALTER 2,289,890

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CLEANING AND STERILIZING INSTRUMENTS AND,OTHER ARTICIJEISI Filed Feb. 2, 19:59 l 5 sheets-sheet 4 July-14, 1942. i' Q W WALTER 2,289,890

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Patented July 14, 1942 I JNITEDL STATES PATENT OFFICE CLEANING AND STERILIZING INSTRUMENTS AND OTHER ARTICLES 28 Claims.

The method and apparatus of my present invention relate to and are appropriate for the washing'and sterilizing of any articles and goods adapted ,for immersion in water, including such things as glassware, food receptacles and utensils, especially those used in hospitals, hotels and restaurants, in fact any immersible articles as to which cleanness and sterility are important or desirable. One of the most important applications of the invention is inconnection with surgical practice, for post-operative cleaning Vand sterilizing of instruments and other surgical equipment. In its .broad aspects, however, amain object .of ,the invention is to provide a new method and meansfor rapidly, safely and certainly cleaning .and'sterilizing any articles for which such treatment is in order andas to which a brief immersion in superheated water is not objectionable.

In the drawings illustrating by way of example certain embodiments ofthe invention and means for practicing the method thereof,

Fig. 1 is a View `mainly in vertical section of one form of Washing sterilizer;

Fig. 2 is an enlarged horizontal section through the sterilizer, just below the cover;

Fig. 3 is a .detail `section on the line v3 3 of Fig. 2;

Fig. 4 isa View corresponding to Fig. l illustrating a further embodiment;

Fig. 5 is a View corresponding to Fig. 1 illustrating a further embodiment, particularly suitable for the treatment of larger or more numerous articles;

Figs. 6, 7 and 8 respectively are a section, an elevation and top plan of a flash tank comprised in the apparatus; and

Fig. 9 is a chart explanatory of the cleaning and sterilizing cycle, in a surgical operating room.

The common practice in sterilizing surgical instruments for the operating table does not insure absolute sterility. Bacteriologists have repeatedly pointed out that boiling water does not kill spores even after prolonged exposure. Abbreviated boiling periods, the use of oil on instruments, the formation of scale in hard water areas, and depressed boiling temperature caused by altitude are additional factors causing inadequate sterilization. The safety of a technique based upon `boiling depends upon the care with which spore-bearing organisms and spores have been excluded by mechanical means. Inevitable disaster results whenever dangerous spores are not removed from instruments prior to sterilization by boiling. In short, there have heretofore been no absolutely reliable methods for the post-operative sterilization of instruments contaminated with oil, feces, blood, or pus known to contain virulent bacteria or spores.

Nevertheless, the disinfection of instruments from septic cases or instruments soiled by pus or feces Where spore bearers are likely tobe encountered, has received much attention. The danger of spore-bearing organisms in the operating room hasbeen recognized and special techniques for the routine sterilization of such instruments have been devised. The number of techniques in use and the wide range of minimum standards for sterilization of these instruments are indications of the inefciency of the existing methods of caring for dirty instruments. The only safe bacteriologic technique of those in current use is that of immersing the soiled instruments in a 10 percent soap solution and autoclaving them at 250 degrees F. for 30 minutes. This practice has the disadvantage of using equipment primarily designed for another purpose. The interior of the autoclave is usually fouled with soap and denatured proteins which are spattered on the chamber wall when the steam is vented. The danger of scalding the attendants who remove the instruments from the sterilizer is great. Soaking dirty instruments in a germicide, prolonged boiling after thorough scouring and scrubbing, or combining these in various ways is not only time-consuming but also removes the instruments from circulation. What is of greater importance to safety, dangerous spores may be spread throughout the operating room during the cleansing process, or sterilizers may be contaminated with spores which survive hours of boiling.

My present invention provides a safe, rapid technique for the cleansing and sterilization of such instruments and other articles, by exposing them to heated water, carrying the oil and other insoluble matter to the surface of the water, and removing the oil and scum from the Water surface, leaving thereon at the most a monomolecular nlm of oil, which can be sterilized.

Referring now to the drawings, in Figs. 1 to 3 I have illustrated one embodiment of apparatus for the practice of my method. As there shown,

\ the shell or main receptacle 6 of the autoclave or washing sterilizer is set in upright position on a stand or base l. The mainchamber 8 is thus vertically disposed, that is, arranged for opening at the top, where a pressure-tight closure or cover 9 is provided. The latter may be of any preferred form, that'I shown being carried on a diametral cross arm Ill having one end pivoted on the top ring or casting II and its other end arranged to interlock with a hold-down at an opposite point on said ring. A pivot post I2 rising centrally from the cover is threaded through the cross arm IIJ and provided with a turning bar or handle I3 for clamping the cover securely in closed position. The autoclave as a whole includng the parts described is constructed to withstand an operating pressure of 27 pounds per square inch (gauge pressure) with adequate safety factor.

Heating means is provided in the chamber 8, adjacent its bottom, in this instance in the form of a steam coil I5. One end of the coil communicates through the sterilizer shell 6 with a steam supply pipe I6 and the other end is connected with a steam outlet conduit I1 leading through a trap I8 to the steam return line I9. The steam coil is of large capacity, for quickheating effects, and is so designed and positioned as to concentrate the greatest heat at the side of the sterilizer opposite the overflow to be referred to. Thus in Fig. 1, the overflow being at the rear, said heat concentration is at the front, at which location the inlet end of the coil is installed.

The steam coil I is enclosed by a baille 20 herein including a supporting base 2|, a perforate plate 22 overlying the coil and an upwardly extending ange 23 adapted to support the article receptacle or bucket 25 and to force the Water in the sterilizer to circulate upwardly through the perforate article-receiving shelf 26, herein at the bottom of the bucket.

The dirty instruments or other articles A to be washed and sterilized are collected on the perforate floor of the bucket 25, directly from the operating table or other point of contaminating use. The bucket preferably is of stainless steel, Monel metal or other non-corrosive material, and is of a size to be easily receivable in the sterilizer, in spaced relation to the side walls, and to extend well up toward the top of the chamber 8. A depending peripheral flange 21 at the bottom of the bucket serves to position the latter on the top ange 23 of the baille. After the bucket 25 containing the articles A is set into the sterilizer the latter is filled with water until it overflows at the knife-edge overflow to be described. The water is admitted, and subsequently drained, at the bottom of the sterilizer shell through a relatively large port 28, for quick filling and emptying, the port desirably being screened as at 29. Communicating with the chamber port 28 is a 3-way valve 30.

One port of this valve 30 is connected with a conduit 3| leading to the water supply, at any convenient point adjacent the sterilizer, above it in the illustrated example. Interposing said conduit 3| and the water supply line is a water supply valve 32 and an air break device 33. The latter insures that the liquid in the sterilizer can never return into the water supply system under a siphoning or other action, such as might otherwise occur for example in the event of a drop in the pressure of the water supply. Another port of the 3-way valve 30 is connected with an emptying pipe 35 leading to a ash tank mounted at the rear of the sterilizer or other convenient point, adjacent or remote, for example, in the basement of the building.

The ash tank referred to is a device whereby the heated water under pressure can be suddenly released to atmospheric pressure, in a safe, quieted manner. Such device, as adapted to be mounted on or adjacent the sterilizer or otherwise incorporated in the apparatus as a whole, is illustrated by way of example in Figs. 6 to 8. As there shown, upon a somewhat smaller scale than Fig. l, it comprises a closed tank 43 having a capacity at least one-third that of the sterilizer chamber. The pipe 35 from the sterilizer enters the tank 43 at a relatively low point and discharges into the tank, preferably adjacent a side wall, as seen in plan in Fig. 8. The wall of the tank opposite the pipe 35 desirably is shaped to have a delecting, and hence silencing, action on the incoming stream of Water, as seen in said Fig. 8. The energy stored in the water is dissipated by vaporizing a portion of it, which is carried from the tank by means of a vent 44 of relatively large size, desirably at least twice the diameter of the inlet pipe 35. The residual water accumulates at the lower portion of the tank and is drained to waste through a deep sealed trap 45 having its mouth near the bottom of the tank and communicating outwardly and through an air break 46 to the waste drain. A series of baiiles or varies 41 may be installed in the tank to assist in silencing the action and cooperating in distributing the water around the specially shaped tank as described.

Referring again to Fig. 1, the filling, closing and draining valve 38 of the sterilizer may be of the plug type or other suitable form constructed and arranged to afford the desired three positions. In one position of the valve, water is admitted to the sterilizer chamber 8 at its port 28 through the conduit 3| leading from the water supply, the emptying port of the valve being closed in this position. In a second position the chamber port 28 is completely closed off, both from the water supply and from the emptying line. In the third position of the valve the water port is closed and the sterilizer chamber is placed in communication through the outlet 28 with the emptying line 35. The valve operating stern 35 is extended to a conveniently accessible point, herein at the front of the sterilizer, where it is provided with an operating handle 31 desirably having a pointer 38 movable over a dial 39 marked with suitable indicia such as Fill, Sterilize, Drain, corresponding to the valve settings as above described.

The water may be admitted to the chamber S either before or after closing the latter. Preferably the cover 3 is closed and secured before turning on the water, the filling of the chamber up to the desired level, that of the overflow 55, being indicated by water owing from the ejector 53, as is visible and audible at the air break 51 (these elements to be described shortly). Thereupon the water is shut off and the valve 33 turned to the sterilizing position.

The sterilizer thus closed and its chamber 8 filled with water to the indicated level is in readiness or the washing and sterilizing of the articles in the submerged container or bucket 25. Heat is then supplied in the chamber, herein below said bucket 25, in this instance by the admission of steam to the large-capacity coil I5, effected by opening a valve 46 placed in the steam supply line at a convenient point adjacent the sterilizer. This valve 45 may be manually operable, both as to opening and closing but desirably and as shown in Fig. l it is constructed and arranged for manual opening, and automatic closing upon attainment of the desired pressure over a limitless surface of water, which effort is maintained until but a monomolecular expanded film remains. The non-obstructing knife-edge overflow provides, in effect, a limitless surface at the overflow level of the water chamber, and permits this expanding property of the oily material to be availed of in the functioning of the apparatus. The final remaining monomolecular film, if any, is itself readily sterilized and is too slight to dirty the instruments as the water is subsequently drained from the sterilizer.

From the foregoing description in connection with the drawings, it is evident that any body of air in the closed chamber, after admission of the water, whether the latter is admitted before or after closing of the chamber, is in the space above the water level; where the water is let in after closing, a volume of air equal to that previously in the water-occupied portion of the chamber passes out through the fluid overflow and discharge port 5d. During a first part of the heating operation, any air till then remaining in the space above the water, and which is relatively cool, passes off and down to and through the ejector 55 with the liquid and ahead of the steam forming in the closed chamber, it being noted that the port 50 is at the liquid level, the lowest point above the liquid in the chamber.

The addition of a detergent, to peptonize the proteins and saponify and peptize the greases, removes all the dirt, eliminating the necessity for mechanical cleansing of the instruments. The use of sodium hexametaphosphate or similar material, such as that known commercially as Calgonite, in the detergent softens the water and prevents the precipitation of a film of alkaline earth, soaps and salts on the instruments.

The described heating and discharging action is rapidly carried on through a cleaning period which may be considered as lasting until the water has been heated to approximately 250 degrees F. From that point the action is continued uninterruptedly for a period affording a large factor of safety and assured sterilizing effect upon the articles in the bucket, until a temperature of 270 to 273 degrees F. is attained, with the corresponding gauge pressure of 27 plus to 29 plus pounds per square inch. Under the automatic operation described in connection with the pressure-closing valve 4l! of Fig. 1, the steam supply is thereupon automatically shut off. Desirably also a signal is given to the attendant, automatically, to notify that the steam supply has been shut olf, or indicating that it is proper to do so in the case of a manually operated steam control valve, such as shown for example in Fig. 4.

Such signal may be visual or audible. In Fig. 1, I have shown for the purpose a signal light 65 located at some readily observable point, as adjacent the dial 39 previously referred to, at the front of the sterilizer. Power for the signal light may be provided by a plug-in connection 66 with the supply main, the light being connected in series, through a conductor 61, with a thermostatic switch 68 subject to the temperature conditions in the sterilizer, for example, in the discharge reservoir 55, as illustrated. This switch is regulated for actuation at the selected temperature adequate to insure sterility, including the killing even of resistant spores, for which purpose I prefer to use 273 degrees F.

On receipt of the signal the attendant manipulates the valve handle 31 to turn the 3-way valve 30 to drain position. The heated water rapidly drains off from the chamber 8 through the pipe 35 and into the flash tank 43 as previously described. Following this emptying of the water contents the instruments or other articles in the bucket become subject to the remaining saturated steam in the sterilizer while the pressure is being relieved. After the steam passes off and the sterilizer is opened, the residual heat in the instruments is suicient to flash any adherent moisture.

Thereupon the clean, dry, sterile instruments or other articles are ready for immediate use upon removal from the sterilizer. The action of this sterilizer is so rapid and satisfactory that it may be used for the routine sterilization of surgical instruments, thereby supplanting less eicient methods. Various other uses for this cleaning and sterilizing apparatus, in hospitals and other institutions, hotels and elsewhere, will be evident.

The described operation of the pressure washer-sterilizer apparatus of my invention will readily be understood and visualized from an inspection of the chart, Fig. 9. This chart shows graphically the actual operation and results obtained in a surgical operating room with a typical sterilizer embodying the invention, such as that of Figs. 1 to 3. The time-temperature curve is plotted in units of operating time against degrees of temperature Fahrenheit. A key explanatory of the marked areas of the chart is found at the lower right corner portion of said Fig. 9. As there seen, a black area of the width indicated represents a l-second unit of the nurses or attendants time. Like time units of heat required to kill resistant spores, and factor of safety time units are indicated respectively by the slanting lined area and the dotted areas.

The charted operation commences at the Zero point with the collecting of the dirty instruments from the operating table, represented as occupying about 15 seconds of the nurses time. Within the next 2 minutes the loaded bucket 25 is placed in the sterilizing chamber, the cover closed and secured and the sterilizer filled with water. At a time point shortly beyond the 2-minute line of the chart the steam supply is turned on and the heating commences. The temperature rises rapidly following a regular curve closely approaching a straight line, continuously to the 273 degrees F. point, reached in this case in approximately 3 minutes from the time when the steam is admitted. The cleaning period, with substantial safety factor, is indicated by the bracket, being completed in this instance at the end of 5 minutes from the Zero time point at which the collecting of the instruments was started. The time of absolute sterilizing temperature at 273 degrees F. arrives about one-half minute later, is indicated by the signal, and the steam is shut off, automatically or otherwise. The nurse or attendant, noting the signal, turns the valve 3S to emptying position. The temperature and pressure are maintained in the sterilizer for approximately 1 minute while the water is drained into the ash tank. An abrupt temperature drop occurs following the draining of the sterilizer and complete relief of pressure. After the indicated drying period of approximately 10 seconds the contents of the bucket are completely sterile and dried and in full readiness for use for their intended operating or other purposes, the entire cycle occupying substantially under l0 minutes and in this case actually less than 8 minutes, in-

cluding a total of but about 3 minutes of the attendant nurses time.

In Fig. 4 I have illustrated another washersterilizer embodying my invention and by which the method thereof may be practiced. In this example similar reference numerals indicate corresponding parts as in the previous gures. Parts not otherwise referredl to may be assumed to be the same as in said earlier gures. The ap-paratus of Fig. 4 is more particularly intended for installations Where the available budget necessitates a relatively inexpensive structure for the sterilizer as a whole and where such features las automatic control or extremely rapid operation are less important.

Referring to Fig. 4, the steam supply line l5, controlled by a manual valve 45a, leads directly into the main chamber d of the steriliaer, as at Ita. Within the outer or main shell there is installed an inner container l of general bucket form, having a closed bottom 'il and a circumferentially continuous side wall 'l2 the top `edge 'F3 of which is spaced below the cover of the sterilizer.

This container 'lil in this example provides the water chamber in the sterilizer, whereas in the case of Figs. 1 to 3 the Water is admitted directly to the main or outer chamber B as the water chamber. The discharging overflow of the water, in Fig. 4, takes place across the top edge of said inner container or water chamber l5.

`Said edge accordingly is formed in such manner as to provide a knife-edge or free-overiiow formation within the definition of those terms as given in connection with Figs. 1 to 3, said formation extending through a substantial arc, desirably at least about one fourth to one third of the circumference. As illustrated said overow formation extends completely around the top of the chamber 10.

This water container or chamber lil is supported within and in spaced relation to the main outer shell E. The space between them, at the sides and below the chamber 'Hl together with the discharge conduit 'H provides a discharge reservoir corresponding functionally to the element 55 of Figs. 1 to 3. A water inlet-outlet port 14 in the bottom wall 1l of the chamber lil is connected with the 3way valve 3!! by a short pipe 'l5 extending through the base of the outer shell 6. As in the previous example, one port of the 3-way valve 30 is connected by a conduit 3l and through an air break 33 to the Water supply line, controlled by a water supply valve 32.

The principle of operation is essentially the same as fully explained in connection with Figs. 1 to 3 and the chart of Fig. 9. The instruments or other articles to be cleaned and sterilized are collected in a bucket or basket having not only a perforate bottom 26 but also perforate side Walls 26a. This bucket is adapted to be received in the Water chamber le, in spaced relation to the latter, with its top edge ending distinctly below the overflow knife-edge 'i3 of said chamber.

Similarly as in the previous example, the instrument bucket and the container or water chamber 70 are lled with water, by turning the 3-way valve 30 to the appropriate position, until the level of the Water reaches the knife-edge overflow 1S. The water supply is then shut oif and the S-Way Valve 30 turned to operating position, closing off the inlet-outlet port i4 completely. 'I'he sterilizer being closed and secured, the steam is admitted by manipulation of the steam Valve 40a.

for a horizontal autoclave The steam thus admitted throughout the main chamber 8 acts to heat the water in the chamber 'I6 and bucket 25, setting up convection currents and also causing the constant overiiow of the water at the knife-edge 13 due to its expansion as it becomes heated. The expansively spreading and overowing dirty oily material and water passes down outside the Water chamber 10, be.- tween the latter and the main shell 6, to a discharge port 'I5 at the bottom of the latter. A discharge conduit Tl leads from this port to an ejector 56 discharging through an air break 51 to a drain connection 58 similarly as in the previcus example. As previously stated, said olisu charge conduit 'I1 and the space at the sides and bottom of the main sterilizer chamber 8, between the walls of the latter and the water chamber 'lil constitute a discharge reservoir within which the fluid is cooled sufliciently to operate the ejector 56. The thermostatic switch E8 for Ycontrolling the signal 65 may be located at any appropriate point subject to the sterilizing temperature conditions, as in the discharge conduit Tls ahead of the ejector 56. A pressure gauge A6l! and safety valve El may be provided, in communication with the main sterilizer chamber 8 through a passage 60a in the top ring or casting Il. A bleeder connection and carry-off line for the water supply valve 32, mentioned in connection with the previous figures, is illustrated at 18.

In Fig. 5 I have illustrated a further embodiment of the invention. The sterilizer in this nstance is horizontally disposed, being particularly adapted for the cleansing and sterilization of bulky objects loads of dishes, and other loads more readily presented and removed horizontally. These may be inserted into the sterilizer on a small truck or rack, or other open support on which they may be immersed in and subject to the action of the water, as in a perforate receptacle or basket as in the previous figures. The horizontal form of sterilizer of Fig. 5 may equally be used for any of the purposes of those of Figs. 1 and 4.

Like reference numerals indicate similar elements in Fig. 5 as in the preceding iigures, and parts not otherwise mentioned may be assumed to be the same. The main enclosure 8l) may be of any usual or preferred general construction or sterilizer, including a closure 8| the whole adapted to withstand pressures of 27 pounds with adequate safety factor. The article support 32, illustrated as a perforate or open-mesh shelf or tray is inserted and positioned at the lower portion of the sterilizer chamber 83, front closure, as shown).

This article-receiving portion of the main chamber 83 is adapted to be closed oiT at the front, to constitute the Water chamber or compartment 84, by means of a displaceable partition or bulkhead 85. This partition is constructed and arranged so that it may be moved out 4of the path of the articles and their support, in `in-serting and removing them, but may be fastened in place to form a watertight dam across the lower front portion of the sterilizer chamber 83 and dening the front wall of the water chamber 84. For this purpose the partition maybe pivotally mounted in the sterilizer as indicated at 85a, or otherwise movably positioned ther'eimfor disposed for bodily removal from positioning guides on the chamber wall. The upper edge of this dam or partition 85 is formed to provide the knife-edge and spaced inwardly from the upon tracks or vways (not or free-overflow formation 8S as previously described.

The steam coil l is located in this case at the rear of the water chamber 85.1, opposite the overflow 38 and beneath a perforate baffle 20 inclining upwardly and rearwardly, to aid in directing the water currents, indicated by the arrows, in the same general manner as in Fig. 1. The steam supply pipe and control valve are indicated at I6 and 40a respectively, the water inlet-outlet at 23, the 3-way valve at 3Q, the water supply line at 3l and the drain line at 35 leading to the flash tank 43, all generally similar as in the previous figures.

The overflow across the knife-edge 86 runs into the compartment 8l at the front of the sterilizer and through the discharge port 88 and discharge conduit ll to the ejector 53, from which it is ejected past the air brake 5l to the drain conduit 58. It will be seen that said compartment 87 and the discharge conduit 11 provide a reservoir for the overflow, for cooling it to afford the ejecting action, similarly as in the previous examples. An automatic signal of the arrival of sterilizing temperature, and automatic cut-off of the steam supply may be provided if desired, as in the other embodiments. In the example of Fig. 5 the water compartment within which the articles are supported in immersed position is provided in part by the wall of the sterilizer chamber and in part by the movable bulkhead 85, while in Fig. 1 the overflow is in eiect built into a wall of the sterilizer chamber which itself is also the water compartment, and in Fig. 4 the water compartment is in a container spaced from the main chamber walls. In other instances the water compartment may be a unit which is bodily removable relative to the main enclosure of the sterilizer.

From the foregoing it will be apparent that the method of my invention includes some or all of the following steps or operations: subjecting dirty articles and instruments to be cleaned and sterilized to immersion in water in a pressuretight main chamber, applying heat to and raising the temperature of the water to a heated state; carrying off from the articles any dirty oily matter thereon, raising it to the surface of the water and causing said matter to be continuously discharged from the water chamber and from the sterilizer until substantially but a monomolecular oil lm remains on the water surface, sterilizing said film, continuing the heating action until a selected temperature preferably of at least 270 degrees 1*". and a corresponding steam pressure are reached, signaling the arrival of said temperature, cutting ofrr the heat supply manually or automatically, draining the water chamber and relieving the pressure in the sterilizer, and effecting the complete sterilization and drying of the treated articles in the sterilizer, in full readiness for use.y

My invention is not limited to the particular means or steps as herein illustrated or described, and I point out its scope in my following claims.

I claim:

1. Washing and sterilizing apparatus comprising, in combination, a V pressure-tight main enclosure having a water-receiving chamber therein, perforate means for supporting articles at an intermediate level in the chamber so as to subject them to vertical currents in the water therein, means to heat the water, overiiow lip means on a wall of the chamber above the supported articles, said overflow means having a crest defining the maximum water level and there providing uninterruptedly over a substantial horizontal extent a free escape for heated water expansively rising above said level, a reservoir for the iiuid from such overflow means, and pressure-retaining means to discharge the fluid from the reservoir while maintaining the temperature and pressure in the main enclosure and its water chamber.

2. A pressure washer-sterilizer comprising in combination, a main pressure-tight receptacle having a closure affording access for objects to be washed and sterilized, a water chamber in said receptacle having a vertical wall thereof provided with an upright free overow formation of an uninterrupted horizontal extent defining the highest water level and in effect there providing for the water a limitless surface area for the expansion of water-carried matter rising to said surface, means whereby the objects to be treated are positioned in the water chamber below said overflow formation and in the path of upward currents in the water therein, heating means for the water in said chamber, and discharge means to carry off the overflowing liquid while maintaining the chamber temperature and pressure.

3. A pressure washer-sterilizer comprising, in combination, a main pressure-tight enclosure having provision for loading, a load-receiving water chamber therein, means to heat the water in said chamber to steam-producing condition, said enclosure serving to confine the evolving steam, a pressure-maintaining discharge outlet from the enclosure, horizontally extensive overflow means for the water chamber presenting a knife-edge formation dening the water level and over which the surface water and matter carried by it may flow freely from the chamber to the discharge outlet, and means in the Water chamber below the knife-edge formation whereby the load to be washed and sterilized is held in immersed suspension in the heated water in said chamber.

4. Sterilizing apparatus comprising, in combination, a pressure-tight enclosing chamber including a water-receiving portion, an inner opentop container for a load to be treated, means positioning the container in said water-receiving portion of the chamber, an overflow edge formation of substantial horizontal extent disposed at a lateral boundary of the water-receiving chamber portion and defining the upper water level therefor, means to heat the water to temperatures above the normal atmospheric boiling point and under pressure developing in the chamber while permitting it to overflow at said edge formation, and means to receive and periodically discharge the overflow.

5. Sterilizing apparatus comprising, in combination, a pressure-tight enclosing chamber including a water-receiving portion, upwardly open means in the water-receiving chamber portion to position the load to be sterilized, an upstanding edge formation at a lateral wall of the waterreceiving chamber portiony said formation spaced below the chamber top wall and above the load position to define the upper level of the water, heating means to heat the water to temperatures above the normal atmospheric boiling point and under pressure developing in the chamber, and thermally responsive receiving and discharging means for the overflow from said edge formation.

6. Sterilizing apparatus comprising, in combination, a sterilizing chamber adapted for pressure-tight closure, an inner open-top container for the load to be sterilized, means positioning the container in spaced relation to the bottom wall of the chamber, said chamber with the container therein adapted to receive water to a determined level above the container and below the chamber top wall, a horizontal overflow formation of substantial extent disposed on a wall laterally of the container, above the top of the load therein and determining the upper level of the water, means for producing a steampressure-subject heated condition of the water under which it overflows said formation, and receiving and pressure-retaining discharge means for the fluid in communication with said overflow formation.

7. Sterilizing apparatus comprising, in combination, a water and steam receiving chamber adapted for pressure-tight closure, an inner open-top container for a load to be sterilized, means positioning the container to support the load above the bottom wall of the chamber and below a determined water-level therein, said container having a lower wall providing for upward passage of water through it, a fluid-escape wall formation on a wall in the chamber having a horizontal upper edge above the top of the container and defining the water level in the chamber, heating means for the water, and means to receive and to discharge from the chamber the fluid which overpasses said edge of the wall formation.

8. Sterilizing apparatus comprising, in combination, a closure-equipped sterilizing chamber constructed and arranged to receive a load for sterilizing and to enclose a body of water submerging the load, said chamber provided with a substantially vertical wall confining the water laterally, said wall having an upstanding horizontally extending edge formation in spaced relation to the chamber top wall and adapted to define the water level above the submerged load, heating means for the water, and thermally responsive pressure-retaining means associated with the chamber to receive and discharge water overflowing said edge formation.

9. The method of washing and sterilizing contaminated loads which comprises pressure-tightly conning a body of water while providing a limited enclosed space above the water level, submergently positioning the load in the water, heating the water and inducing convection currents therein aiding to carry oily matter from the load to the water surface, affording free lateral egressicn for the rising heated water ntially at its surface level and thereby enabling the surface-carried oily matter to expand as over a limitless area so that any such matter iinally remaining is reduced to substantially a mcncmolecular expanded and ready sterilizable nlm at the water surface, and passing off the fiuid so egressing while maintaining a heated condition of and pressure upon the water retained.

l0. The method according to claim 9 including the steps of subsequently releasing and carrying off the residual water and relieving the pressure within the remaining load-enclosing space.

ll. The method according to claim 9 including the steps of discontinuing the application of heat following arrival of a selected above-normalboiling temperature, subsequently releasing and carrying off the residual water, exposing the load to saturated steam and relieving the pressure within the enclosed load-containing space.

1 2. `The method according to claim 9 including the steps of discontinuing the application of heat following arrival of a selected above-normalboiling temperature, subsequently releasing and carrying off the residual water, exposing the load to saturated steam, relieving the pressure within the enclosed load-containing space and utilizing in the practice of said method temperatures such that the residual heat in the load when including articles such as surgical instruments, following said relieving of the pressure, is suflicient to flash adherent moisture, whereby the clean, dry1 sterile instruments are ready for immediate use.

13. In a sterilizer, `in combination, a pressuretight enclosure, a water compartment in said enclosure, means to heat the water therein, said compartment having laterally thereof a free overflow formation below the top wall of the enclosure and determining the maximum water level for the compartment, said formation comprising an upright wall having a thin knife-like upper edge and of such contour and extent peripherally of the water compartment as to present the minimum obstruction of surface-carried matter at said formation and pressure-retaining outlet means for releasing said overflow from the enclosure.

lll. In a sterilizer, in combination, a pressuretight enclosure, a water compartment in said enclosure, and means to heat the water therein, said compartment having laterally thereof a free overflow formation of substantial horizontal extent, said formation disposed below the top wall of the enclosure and determining the maximum water level for the compartment, a reservoir in communication with and adapted to receive the liquid overiiow from said formation, and thermally responsive pressure-retaining discharge means associated with the reservoir, the latter and the water compartment being of such relative volume and arrangement as to provide for a collecting of the received fluid and resulting intermittent actuation of the discharge means whereby a continuous overflow and carrying off of the fluid is afforded under avoidance of any return backing-up of fluid to the enclosure.

15. A washer-sterilizer comprising in combination a vertically disposed outer shell having a top closure, a like-disposed water chamber in the shell, valve-controlled means to admit water to and ydrain it from said chamber, a free-overflow fc-rmation at an upper portion of the chamber, a valve-controlled steam coil at the lower portion of the chamber to heat the water therein, supporting means for the articles to be treated, said means disposed below the overflow formation and arranged to position the articles in the water above the steam coil and in the path of water currents set up by the heat therefrom, a reservoir to receive the rising heated fluid passing said free-overflow formation, and ejector means to discharge said iiuid from the reservoir.

16. A washer-sterilizer comprising in combination an outer shell having a closure for admission and removal of articles to be treated, a container in said shell, spaced from its walls and providing a water chamber, means to admit water to and to drain it from said chamber, heating and vertical current producing means for the water, supporting means for articles in the water chamber to hold them in immersed position subject to upward currents in the water, valve-controlled means to supply steam in the shell to heat the water in said chamber, a horizontally extensive free-overiiow formation upon a wall of the water chamber above the supported articles, and a conduit and ejector means communicating with a lower portion of the interior of the shell for receiving and discharging the fluid coming from said overiiow formation.

17. Washer-sterilizer apparatus comprising in combination a horizontally disposed autoclave having a pressure-tight door at its front end, article supporting means at an intermediate level in the autoclave and spaced rearwardly from the door, a vertical watertight partition extending laterally in the autoclave at a location between the door and the supported articles, upwardly to a level above the latter and providing the front wall of a water chamber surrounding the articles, said partition being movable to facilitate insertion and removal of the articles, a free-overflow formation at the upper edge of said partition, water inlet and outlet means for said water chamber, means to heat the water in the chamber so as to induce upward and forward currents therein, and collecting and discharging means for the iiuid coming from the overflow formation.

18. Washer-sterilizer apparatus comprising in combination an autoclave having a charging door, a water chamber in the autoclave for immersing articles to be washed and sterilized, said chamber having at an upper level a horizontally extensive free-overflow formation, means to heat the water suiciently to evolve steam under pressure in the autoclave and to cause the water with surface-carried matter from the articles to overflow the said formation, collecting and discharging means for said overflowing fluid, and a flash tank communicating with the water chamber and into which the residual heated water under pressure may be released from said chamber to atmospheric pressure.

19. In a sterilizer apparatus having a compartment in which water is adapted to be heated under pressure of steam therefrom and at temperatures above that of normal atmospheric boiling, a valve-controlled drain conduit in communication with said compartment through a lower wall portion thereof, a closed tank into which said conduit opens, the tank having a vent for vapor forming therein, and a sealed trap drain leading out from near the bottom of the tank to carry off the residual water, the tank being shaped and arranged relative to the water inlet to deect and distribute the incoming stream of water throughout the tank.

20. The method of washing and sterilizing contaminated articles which comprises confining a body of water together with an overlying enclosed space, immersng the articles in the water so conned, heating the water to a steam-evolving state and causing it to overflow from said body expansively at its surface level while simultaneously causing the contaminating matter on the articles to be carried to the surface of the water and there to spread and pass off with the overflow until but substantially a monomolecular film remains at the water surface, discharging the overflow, continuing the heating action to produce a positive sterilizing temperature, determining the arrival of said condition and discontinuing the heating action, and draining off the water and relieving the associated steam pressure, thereby presenting the articles in sterile condition for use.

21. Washer-sterilizer apparatus including in combination with a pressure-tight main shell, a chamber therein to contain water of a depth and volume adequate for immersing articles to be Washed and sterilized, a steam coil at the lower portion of the water chamber and arranged so to concentrate the heat as to induce upward and returning convection currents in the water, baffle means adjacent the steam coil to assist in directing said currents, foraminous supporting means presenting the immersed articles in the path of said currents, a horizontally extensive upright knife-edge formation at an upper wall portion of the chamber and disposed for overflowing by the rising heated water, and pressureretaining means for carrying ofi' the overiiow.

22. Washer-sterilizer apparatus comprising a pressure-tight enclosure having therein an article-receiving water chamber, means to heat the water under pressure of steam therefrom in said enclosure, means on a wall of the chamber at an upper portion thereof, said means defining the maximum water level and permitting water to overflow as it rises under the expanding action of the heat, a collecting reservoir for the overflowing water, and temperature-responsive means for discharging the water from the reservoir at a rate to avoid any blocking of the overflow from the chamber to the reservoir and while maintaining the temperature and pressure in the apparatus as a whole.

23. Washing and sterilizing apparatus for surgical instruments and other articles, comprising a sterilizer having therein a water chamber with an over-lying coni-inable space, heating means to supply heat to the water in said chamber for creating steam under greater than normal atmospheric pressure in the sterilizer, fluid discharging means for air, steam and water automatically effective to afford a definite steampressure and temperature relation in the sterilizer and to relieve air therefrom during creating and maintenance of said pressure and temperature relation, a cut-01T device for the heating means adapted for actuation on arrival of a predetermined pressure-temperature condition in the sterilizer, a common inlet and drain port for the water, and valve means communicating with said port and with water supply and water drain conduits respectively, said valve means adapted selectively for admitting water to the chamber, for complete closure during a washing and sterilizing operation, and for draining the water from the chamber.

24. Washing and sterilizing apparatus for surgical instruments and other articles, comprising a sterilizer having therein a water chamber with an overlying confined space, means to supply heat to the water for creating steam under greater than normal atmospheric pressure in the sterilizer, fluid discharging means for air, steam and water automatically effective to aiord a definite steam-pressure and temperature relation in the sterilizer and to relieve air therefrom during creating and maintenance of said pressure and temperature relation, gage means to indicate arrival of a selected temperature as measured in terms of said definite steam-pressure condition in the sterilizer, and means to cut off said heat supply following such indication.

25. Washing and sterilizing apparatus for surgical instruments and other articles, comprising a sterilizer having therein a water chamber with an overlying confined space, means to supply heat to the water for creating steam under pressure in the sterilizer, said chamber having at an upper portion a horizontally disposed overflow formation defining the upper level of the water and the lower level of the space above the water, said formation providing for the escape 0f rising heated water substantially solely at the surface level thereof, a thermally responsive device subject to temperature conditions of the sterilizer, and means controlled by said device automatically to eiect the cutting oi of the heat supply at a predetermined temperature in the steam-pressure-subject heated interior of the sterilizer.

26. Washing and sterilizing apparatus comprising in combination a sterilizer having in it a closeable Water chamber in which articles may be immersed, heating means for water in said chamber to create in the sterilizer steam under greater than normal atmospheric pressure and a temperature above the normal atmospheric boiling point of water, and iiuid overiiow and discharge means constructed and arranged to provide for an overflowing escape of the Water substantially solely at its surface level While maintaining the temperature and pressure in the sterilizer, thereby to carry off from the latter contaminating matter rising from the articles to the surface of the Water.

27. Washing and sterilizing apparatus comprising in combination a sterilizer including a closure-equipped chamber providing for the reception of a body of Water and for a confined space above the upper water level, said Water body of a volume to submerge a load to be sterilized, a water-confining Wall in the chamber having a horizontal upper terminal portion spaced below the top Wall of said chamber, to dene the Water level and to permit overowing passage thereof substantially solely at the surface level of the Water, means to heat the water in said chamber to temperatures above that of the normal atmospheric boiling point, and heatsupply control means adapted for shutting off the heat supply on the arrival of a denite predetermined pressure-temperature condition in the sterilizer.

28. Washing and sterilizing apparatus comprising a sterilizer having therein a Water chamber with an overlying connable space and having provision for admitting Water to and subsequently draining water from said chamber, heatv ing means for Water in said chamber to create steam under pressure in the sterilizer, fluid discharging means effective to relieve air from and to afford a definite steam-pressure-and-temperature relation in the sterilizer, and control mechanism for the heating means adapted for shutting 01T the latter at a determined pressure-temperature condition in the sterilizer, said fluid discharging means including an overflow formation providing for escape of water substantially solely at its surface level during the building up and maintenance of the determined pressure-temperature condition.

CARL W. WALTER.

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