US3450487A - Method of and apparatus for sterilizing articles - Google Patents

Description

K. A. o. WALLDEN 3,456,487

June 17, 1969 7 METHOD OF AND APPARATUS FOR STERQILIZING ARTICLES Original Filed Nov. -18, 1963 Sheet June-17, 1969 K. A. WALLDEN METHOD OF AND APPARATUS FOR STERILIZING ARTICLES o'rigihal Filed Nov. 18, 1963 Sheet 2 0:2

Ill .1

lllll lllllllll .llllllllllllll United States Patent US. CI. 21-56 8 Claims ABSTRACT OF THE DISCLOSURE An autoclave having a housing provided with a top compartment overlying a chamber for sterilizing articles and a bottom compartment disposed about the chamber for holding a body of water heated to generate saturated steam passing into the top compartment, flowing the saturated steam in the top compartment through an elongated hollow member which is electrically heated to dry the steam, discharging the dry steam from an apertured diffuser tube in the upper part of the sterilizing chamber, controlling the flow of the dry steam from the elongated member to the diffuser tube b a valve which is in the top compartment and has a control member accessible outside the housing, heating the dry steam in the diffuser tube by saturated steam flowing from the bottom compartment to the top compartment through a conduit which extends through the diffuser tube, producing a first pressure less than atmospheric pressure in the steam spaces of the top and bottom compartments of the housing by a first evacuator, and withdrawing air and steam from the bottom part of the sterilizing chamber by a second evacuator to produce a second pressure therein which is less than the first pressure.

This application is a continuation of application Ser. No. 325,807, filed Nov. 18, 1963, now abandoned.

As known it is necessary in hospitals to disinfect bedding and the clothes of certain patients. This can be performed in formalin chambers and also in autoclaves operated by saturated steam. Formalin chambers do not give an absolutely trustworthy result. Further, it is very time-wasting to get rid of the objectionable odor of the disinfected objects. The autoclaves operated by saturated steam have a steam temperature varying between 103 C. and 120 C. Due to the fact that wet steam is used, it has turned out to be very diflicult and sometimes impossible to dry bulky objects like mattresses, for example. It is the humidity that spoils textile fabrics and not the rather high temperature produced during disinfection. Shoes and other leather products are completely destroyed at a temperature above 100 C. and hence in the disinfection of such products the temperature should not exceed 80 C. They will then keep their form and softness.

The purpose of the present invention is to overcome these drawbacks. The main feature of the invention is that saturated steam is produced in the lower compartment of a two-compartment container, housing a disinfection chamber, at a pressure lower than atmospheric pressure, and the steam is dried in the upper compartment ofthe container by being fed through tubes which are heated, and thereupon is distributed through a heated diffuser tube in the upper portion of the disinfection chamber and finally is withdrawn or sucked out from the lower portion of the disinfection chamber. By means of this method it is possible to produce a stream of dried steam with a temperature of about -80 C. through the disinfection chamber. At this rather low temperature, which nevertheless is sufiiciently high to disinfect the objects in question, leather products are not influenced in such a way that they are distorted and shoes which are disinfected in this manner retain their form. The steam fed to the disinfection chamber does not humidify the objects more than it will be possible to dry them completely by a subsequent evacuation.

The invention also relates to an autoclave for carrying out the method according to the invention. The autoclave comprises a disinfection chamber housed in the lower compartment of a two-compartment container and in provided with a diffuser tube for the steam. The autoclave is characterized by heating means for producing saturated steam in the lower compartment of the container at a pressure below the atmospheric pressure, by heating means for drying the steam before it reaches the diffuser tube, and by pump means for producing the lower pressure than the pressure of the steam in the disinfection chamber. In such an autoclave the heat losses will be very small and the condensation in the conduits to the disinfection chamber are practically completely avoided.

The invention will now be described with reference to the accompanying, partly diagrammatical drawings. In the drawings:

FIG. 1 is a vertical sectional view of an autoclave embodying the invention,

FIG. 2 shows a horizontal section through the upper poiltion of the autoclave on the line IIII in FIG. 1, an

FIG. 3 shows a horizontal section on the line III-III in FIG. 1.

The autoclave shown in the drawings is adapted to produce the steam required for the disinfection. The autoclave comprises a container 3 within which is provided a disinfection chamber 2, having a door 1. The chamber 2 in partly surrounded by a body of water 4. The water level is indicated by a gauge glass 5. A horizontal partition 6 divides the container 3 into a lower compartment 7, in which the body of water 4 is held and an upper compartment 8 which functions as a steam chamber, The upper compartment 8 communicates with the lower compartment 7 through a plurality of ports 9. A number of heating elements 11 in the lower compartment 7 are controlled by thermostats 10, the heating elements 11 being connected to a source of electric current (not shown). In the steam chamber 8 a number of tubes 12, 13, 14 are connected in series. The tube 12 at one end 15 is in communication with the steam chamber or compartment 8 and one end of the tube 14 is connected by a conduit 14a to a main valve 16 having its lower end connected to a diffuser tube 17 provided in the upper part of the disinfection chamber 2. In each of the tubes 12, 13 and 14 is axially arranged an electric heating element 18. The electric current fed to the heating elements is controlled by a suitable automatic device (not shown). Such automatic device controls the whole disinfection process. The diffuser tube 17 may be provided with a plurality of openings 19 or diffuser jets 20 or both. A conduit 21 extends axially through the diffuser tube to one end of which is connected a vertical tube 22 in communication with the upper .compartment or steam chamber 8 and the opposite end 23 of which is in communication with the lower compartment 7 above the Water surface level therein.

A tube 25 extends downward from the bottom 24 of the disinfection chamber 2 and has its lower end connected to a valve 26 which in turn is connected to a vacuum pump 27. To the steam chamber or upper compartment 8 is connected one end of a tube 28, the opposite end of which is connected to a valve 29 which in turn is connected to a vacuum pump 30.

The method of disinfection is as follows: Electric current is supplied to the heating elements 11. The vacuum pump 30 is started. When the pressure in the steam chamber or upper compartment 8 has been reduced to about 410 mm. Hg, the pump 30 is stopped. At this pressure the steam temperature in the upper compartment 8 is about 80 C. The objects to be disinfected are now placed in the chamber 2. The door 1 is closed and the vacuum pump 27 is started. The pressure in chamber 2 is reduced to a value somewhat lower than the pressure established in the steam chamber or upper compartment 8.

When the steam in the upper compartment 8 is at the desired temperature, the valve 16 is opened and the electric current is supplied to the heating elements 18. The vacuum pump 27 continues to operate with the valve 26 completely open until the temperature in the lower portion of the chamber 2 is at the same temperature as the steam. This will require about 7 to 8 minutes. The opening in the valve 26 is now reduced to such an extent that a uniform temperature will be maintained at the bottom portion of the chamber 2. When the disinfection is terminated, the time depending on the kind of goods to be treated, the main valve 16 is closed and the supply of electric current to the elements 18 is terminated. The valve 26 is now opened to render the vacuum pump 27 operable to produce a strong negative pressure in the disinfection chamber 2 to promote drying of the goods therein. As a rule, the length of time required for such drying of the goods will not exceed 15 minutes.

The consumption of steam for disinfecting goods in accordance with the invention is rather low. The pressure and also the temperature in the disinfection chamber 2 is kept fairly constant. The heating elements 18 are so dimensioned and constructed that at normal load when electrical energy is supplied thereto the body of steam maintained in the upper compartment 8 will remain in the form of saturated steam and excessive heating effective to change the saturated steam to super heated steam will be avoided.

When the saturated steam is introduced into the disinfection chamber 2 in the manner explained above, it

will require some minutes before the steam reaches the vacuum pump 27 and the temperature in the chamber has reached the desired value. Only then is the valve 26 adjusted in such a way that there passes through the disinfection chamber exactly the required quantity of steam for maintaining the temperature in the disinfecting chamber 2 at a constant value. It is to be noted in this connection that a certain amount of steam must always pass through the disinfection chamber 2 for otherwise the temperature in the chamber will drop rapidly.

It is also to be noted that the pressures in the autoclave are adjusted in such a way that the pressure in the disinfection chamber 2 during the disinfection operation is always kept below the pressure in the upper compartmentor steam chamber 8.

The shown and described embodiment is to be regarded only as an example and the different details of the autoclave may be constructively changed in many ways within the scope of the invention.

What is claimed is:

1. Apparatus comprising (a) structure defining a chamber for disinfecting articles therein and a housing having first and second compartments in communication with one another, said first compartment being at one level and said second compartment being at a higher level,

('b) said first compartment being adapted to hold a body of water, means for heating the body of water in said first compartment to generate saturated steam which passes into said second compartment and forms a body of said saturated steam therein,

(c) an elongated hollow member in said second compartment having an inlet and an outlet and through which said saturated steam generated in said first compartment is adapted to flow out of physical contact with and enveloped by the body of said saturated steam in said second compartment, said elongated hollow member comprising a plurality of spaced elongated piping sections disposed alongside one another and connecting ends,

(d) heating means extending lengthwise of said elongated member for heating said saturated steam flowing therethrough to dry the steam, said heating means comprising a plurality of electrical heating elements, said heating elements extending axially of said piping sections and disposed in heat exchange relation with said saturated steam adapted to flow therethrough,

(e) an apertured diffuser disposed in the upper part of said chamber,

(f) means for conducting the dry steam from the outlet of said elongated member to said apertured diffuser for discharging steam therefrom into said chamber,

(g) means in heat exchange relation with said diffuser for heating the steam introduced therein,

(h) a first evacuating means in communication with said housing above the liquid surface level of the body of water in said first compartment for producing a first pressure less than atmospheric pressure in said second compartment, and

(i) a second evacuating means in communication with the bottom part of said chamber for withdrawing vaporous fluid therefrom by producing a pressure therein which is less than the first pressure in said second compartment.

2. Apparatus as set forth in claim 1 in which said structure defining said chamber and said first and second compartments of said housing includes means to position said second compartment in heat exchange relation with the top of said chamber and said first compartment in heat exchange relation with other parts of said chamber below the top thereof.

a 3. Apparatus as set forth in claim 2 in which said first compartment of said housing is disposed about said chamber and said second compartment of said housing overlies said chamber.

4. Apparatus as set forth in claim 1 in which said means for heating said saturated steam introduced into said apertured diffuser comprises conduit means for conducting said saturated steam from said first compartment to said second compartment, said last-mentioned conduit means including a portion for flowing said saturated steam in heat exchange relation and out of physical contact with dry steam introduced into said diffuser for discharge therefrom into said chamber.

,5. Apparatus as set forth in claim 1 which includes means for regulating the rate at which dry steam flows from the outlet of said elongated hollow member to said apertured diffuser, said regulating means having a part which is enveloped by the body of said saturated steam in said second compartment and formed with a passage for flowing dry steam therethrough.

6. Apparatus as set forth in claim 5 in which said regulating means includes a manually operable control member accessible outside said housing.

7. A method of disinfecting articles in a space which comprises the steps of (a) maintaining a body of water in a first place, 7

(b) heating the water in the first place to generate saturated steam,

(c) flowing the saturated steam from the first place to a second place to provide a body of the saturated steam in the second place,

((1) flowing the saturated steam through an elongated path of flow which has an inlet and outlet and is out of physical contact with and enveloped by the saturated steam in the second place,

(e) generating heat electrically lengthwise of said elongated path of flow at axially extending regions thereof which are distributed along said path of flow between the inlet and outlet, such heating being eflecti ve to heat the saturated steam while flowing through said elongated path of flow to dry the steam,

(f) flowing the dry steam from the outlet of said elongated path of flow into a dispersing zone at the upper part of the space and dispersing the steam into the space at such zone,

(g) heating said dispersing zone at a region in heat exchange relation with the dry steam introduced therein,

(h) evacuating steam in a first fluid evacuating path of flow from the first and second places at a first region above the liquid surface level of the body of water in the first place when the latter is heated to generate saturated steam so as to reduce the steam pressure in the first and second places to a first pressure less than atmospheric pressure,

(i) evacuating air in a second fluid evacuating path of flow from a second region at the bottom part of the space to reduce the pressure therein to a second pressure which is less than the first pressure of the steam in the first and second places,

(j) heating and flowing saturated steam through said elongated path of flolw and flowing the dry steam therefrom at a first rate to said dispersing zone when the saturated steam in said first and second places is at the first pressure and hence at a first temperature,

(k) evacuating steam in the second fluid evacuating path of flow from the second region at the bottom part of said space until the temperature in the bottom part of said space reaches the temperature of the steam,

(l) adjusting the rate at which steam flows from said elongated path of flow to said dispersing zone and is evacuated in the second fluid evacuating path of flow from the second region at the bottom part of said space to maintain the steam in the bottom part of said space at a substantially uniform temperature to disinfect the articles therein, and, When disinfection of the articles in said space has been completed,

(m) stopping the flow of dry steam from said elongated path of flow to said dispersing zone and terminating the heating of saturated steam in said elongated path of flow, and

(n) evacuating vaporous fluid in the second fluid evacuating path of flow from the second region at the bottom part of said space to promote drying of the disinfected articles therein.

8. The improvement set forth in claim 7 which further comprises the steps of flowing a first portion of the saturated steam from the first place to the second place in one path of flow and flowing a second portion of the saturated steam from the first place to the region of said dispersing zone and from the latter to the second place in another path of flow to heat the last-mentioned region, the saturated steam passing through said region in said other path of flow flowing in heat exchange relation and out of physical contact with dry steam at said dispersing OTHER REFERENCES Peacock et al., J. Pharm. PharmacoL, December 1958,

35 pts. I and II, pp. 47T-59T, Dec. 21, 1956.

JAMES H. TAYMAN, Primary Examiner.

US. Cl. X.R.

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