Combined ultrasonic cleaning and biocidal treatment in a single pressure vessel

• US 4,193,818 A
• Filed: 05/05/1978
• Issued: 03/18/1980
• Est. Priority Date: 05/05/1978
• Status: Expired due to Term

• Current Assignee: American Sterilizer Company (Steris Corporation)
• Original Assignee: American Sterilizer Company (Steris Corporation)
• Inventors: Halleck, Frank E., Karle, David A., Young, Jack H.
• Primary Examiner(s): Fisher, Richard V.
• Application Number:
  US05/903,249
• Time in Patent Office: 683 Days
• Field of Search: 134/1, 134/18, 134/21, 134/29, 134/30, 134/184, 134/56 R, 134/57 R, 134/95, 134/98, 134/99, 134/102, 21/102 A, 21/96, 366/114, 366/139, 55/15, 422/20, 422/26, 422/33, 422/128, 422/295
• US Class Current: 134/1
• CPC Class Codes: B08B 2203/002 the liquid being a degassed liquid
• CPC Class Codes: B08B 3/12 by sonic or ultrasonic vibrations washing or rinsing machines for crockery or tableware using sonic or ultrasonic waves A47L15/13; of natural teeth, of prostheses using ultrasonic techniques similar to those used for natural teeth A61C17/20; application of ultrasonic vibrations to chemical, physical or physico-chemical processes in general B01J19/10

Abstract

Method and apparatus are provided for ultrasonic cleaning and decontaminating, disinfecting, or sterilizing articles, such as surgical instruments, in a single piece of equipment. Energy transmission through a unitized shell wall coupled with deep vacuum conditions in the chamber enables rapid degasification, enhanced cavitation providing effective and efficient ultrasonic cleaning in a sealed vessel capable of carrying out high pressure sterilization.

Sonic energy transducers are rigidly mounted externally of the unitized shell to achieve desired cavitation substantially uniformly throughout the volume of the chamber established for placement of articles to be ultrasonically washed and biocidally treated.

Claims

1. Method for combined ultrasonic washing and biocidal treatment of articles, such as surgical instruments, comprising

providing a sealable chamber capable of operating at pressures other than atmospheric including both positive pressures and vacuum levels in excess of 15" Hg. and defined by a unitized shell main body portion,

placing an article to be ultrasonically cleaned and biocidally treated in such chamber and sealing the chamber,

admitting an ultrasonic washing liquid into the shell chamber,

controlling such washing liquid admission to cover the article to be cleaned,

evacuating the chamber to expose the washing liquid to a deep vacuum in excess of about 15" Hg.,

transmitting ultrasonic energy through such unitized shell while maintaining such deep vacuum during at least a portion of the time that ultrasonic energy is transmitted into the washing liquid,

such ultrasonic energy being transmitted by energizing a plurality of transducers secured to such unitized shell externally of such chamber to achieve desired degassing of and cavitation in such washing liquid to ultrasonically clean the article,

releasing the vacuum in the chamber,

draining the washing liquid from the chamber, and

admitting a biocidal fluid into the chamber to provide desired biocidal treatment of such article.

2. The method of claim 1 wherein the step of evacuating the chamber comprises evacuating to a vacuum level in the range of about 20" Hg. to about 30" Hg.

3. The method of claim 1 in which such transmitting of ultrasonic energy is initiated after establishing substantially the desired deep vacuum.

4. The method of claim 1 in which evacuation is initiated as washing liquid is being added.

5. The method of claim 1 including continuing evacuating during at least a portion of the time that ultrasonic energy is being transmitted.

6. The method of claim 1 including maintaining the biocidal fluid in the chamber for a time sufficient to sterilize the article in the chamber.

7. The method of claim 1 in which the step of admitting a biocidal fluid comprises admitting a biocidal gas.

8. The method of claim 7 further comprising the step, after drainage of washing liquid, of

removing any redeposited material from the article before biocidal treatment.

9. The method of claim 7 in which the step of admitting a biocidal gas comprises admitting steam.

10. The method of claim 9 including the step of,

evacuating the chamber after biocidal treatment to remove steam and dry such article before opening such sealed chamber.

11. The method of claim 9 further comprising the step of,

heating the washing liquid to a temperature in the range of about 80°

F. to about 120°

F. by injecting live steam into the washing liquid in the chamber.

12. The method of claim 1 including the step of injecting a detergent into the washing liquid prior to injecting the live steam to heat the washing liquid.

13. The method of claim 1 wherein the step of admitting biocidal fluid into the chamber comprises pressurizing the chamber with live steam to a pressure in the range of about 15 to 45 psig and maintaining substantially such steam pressure for a desired exposure time to effect sterilization.

14. The method of claim 1 comprising evacuating the chamber to a vacuum level of approximately 25" Hg. before commencing the application of the ultrasonic energy and maintaining substantially that vacuum level while applying ultrasonic energy to the washing liquid to substantially complete such degassing, cavitation and ultrasonic cleaning in a predetermined time not substantially in excess of about fifteen (15) minutes in which the total ultrasonic washing and treating cycle includes washing liquid admission, detergent injection, heating of the washing liquid, vacuum draw-down to about 25" Hg., transmitting ultrasonic energy into the washing liquid, releasing vacuum in the chamber, draining washing liquid, rinsing any redeposited soil materials, purging the chamber with steam, sterilizing the article with steam at a pressure in the range of about 15 to about 45 psig., exhausting the steam and applying a vacuum to remove steam from the chamber and dry the sterilized article, and in which such total cycle is carried out in about thirty (30) minutes.

15. The method of claim 1 in which the steps of admitting an ultrasonic washing liquid, evacuating the chamber to a vacuum level in excess of about 15" Hg., and transmitting ultrasonic energy into the washing liquid while maintaining such vacuum level during at least a portion of the time that ultrasonic energy is being transmitted to degas such liquid and produce desired cavitation to ultrasonically clean the article is completed in about fifteen (15) minutes.

16. Apparatus for combined ultrasonic washing and biocidal treatment of articles such as surgical instruments comprising

a sealable chamber for receiving articles to be ultrasonically cleaned and biocidally treated therein, the chamber being capable of operating at pressures other than atmospheric including vacuum levels in excess of about 15" Hg. and defined by a unitized shell main body portion,

means for sealing the chamber,

means for admitting an ultrasonic washing liquid into such sealed chamber,

means for controlling such washing liquid admission to cover the articles to be cleaned,

means for exposing the washing liquid to a deep vacuum,

a plurality of transducers secured to such unitized shell externally of such chamber to transmit ultrasonic energy into the washing liquid to achieve desired degassing of and cavitation in such washing liquid to ultrasonically clean the articles by exposure to the cavitation,

means for releasing the vacuum in the chamber,

means for draining the washing liquid from the chamber,

means for admitting a biocidal fluid into the chamber to provide desired biocidal treatment of such articles, and

control means for controlling sequence of operation of the evacuating means, the plurality of ultrasonic transducers, and the means for releasing vacuum such that the deep vacuum is maintained during at least a portion of the time that ultrasonic energy is transmitted into the washing liquid.

17. Structure for ultrasonic washing and biocidal treatment of articles such as surgical instruments in a chamber capable of operating at vacuum levels in excess of 15" Hg. comprising,

a unitized shell made from corrosion resistant metal plate of relatively thin gage not substantially in excess of 3/16" to provide for desired transmission of sonic energy,

such unitized shell establishing a main body portion partially defining a chamber for holding articles to be ultrasonically washed and biocidally treated,

such chamber being further defined by end walls for such unitized shell,

such end walls including a chamber access door for placement of articles in the chamber and sealing of the chamber,

the unitized shell presenting a transducer receiving external surface extending between such end walls over a dimension correlated with that established for placement of articles within the chamber,

a plurality of sonic transducers rigidly mounted externally of the chamber on such external surface of the unitized shell,

such plurality of transducers being distributed on such external surface between such end walls to provide substantially uniform sonic energy distribution throughout the sonic cleaning liquid in that portion of the chamber established for placement of articles,

means for introducing sonic cleaning liquid to a selected depth within such chamber,

evacuating means for establishing a vacuum level in excess of 15" Hg. within the chamber,

means for energizing such sonic transducers while maintaining approximately such vacuum within the chamber,

means for draining sonic cleaning liquid from the chamber, and

means for introducing biocidal fluid into the chamber and carrying out biocidal treatment of articles placed in the chamber.

18. Apparatus for ultrasonic cleaning and subsequently biocidally treating articles such as surgical instruments in a sealable chamber capable of operating at pressures other than atmospheric, the apparatus comprising,

a chamber defined by a unitized main body shell and closure means,

the unitized main body shell having a horizontal axis, and including a substantially flat bottom wall, opposed upwardly extending sidewalls and a top wall rigidly welded together at their longitudinal edges, the endwall means closing longitudinal ends of such unitized shell wth at least one door means openable to provide access to the chamber and closable to seal the chamber,

shell strengthening means including a plurality of reinforcing ribs positioned externally of and rigidly integral with the unitized body chamber, such ribs circumscribing such unitized chamber body and being substantially uniformly spaced along such horizontal axis,

evacuating means connected in fluid communication with an upper portion of the chamber and operable to evacuate the chamber to vacuum levels in excess of about 15" Hg.,

fluid inlet means for supplying cleaning liquid to the chamber,

a plurality of ultrasonic transducers rigidly integral with the external surface of at least one wall of the unitized chamber body and distributed to provide substantially uniform sonic energy throughout the cleaning liquid in that portion of the chamber established for placement of articles,

power means connected to the transducers for driving the transducers to apply ultrasonic energy to a cleaning liquid in the chamber directly through at least one wall of the unitized chamber body,

fluid removal means including drain means for removing the cleaning liquid from the chamber,

biocidal fluid inlet means for admitting a sterilizing fluid into the chamber,

valve means connected in the cleaning fluid inlet means, the biocidal fluid inlet means, and the fluid removal means to control fluid flow, and

control means operatively connected with and controlling operation of the valve means and the power means connected to the transducers to:

(a) admit a predetermined amount of cleaning liquid into the chamber;

(b) operate the evacuating means to evacuate the chamber to establish a vacuum in excess of about 15" Hg.;

(c) energize the transducers while the chamber is under such vacuum to transmit ultrasonic energy to the liquid in the chamber through at least one wall of the chamber for a time sufficient to degas and obtain desired cavitation in such cleaning liquid;

(d) drain the cleaning liquid from the chamber;

(e) admit sterilizing fluid into the chamber; and

(f) remove the sterilizing fluid from the chamber.