US3861873A - Steam sterilizer - Google Patents

Steam sterilizer Download PDF

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Publication number
US3861873A
US3861873A US347330A US34733073A US3861873A US 3861873 A US3861873 A US 3861873A US 347330 A US347330 A US 347330A US 34733073 A US34733073 A US 34733073A US 3861873 A US3861873 A US 3861873A
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US
United States
Prior art keywords
vessel
upper area
microinches
interior surface
roughness
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US347330A
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English (en)
Inventor
Roderick T Macfarlane
Alfred C Lawson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MDT Corp
Raytheon Co
Original Assignee
Sybron Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sybron Corp filed Critical Sybron Corp
Priority to US347330A priority Critical patent/US3861873A/en
Priority to CA189,285A priority patent/CA1013116A/en
Priority to DE2403526A priority patent/DE2403526C3/de
Priority to AU65124/74A priority patent/AU479015B2/en
Priority to GB1310574A priority patent/GB1468396A/en
Priority to JP49034783A priority patent/JPS49128595A/ja
Application granted granted Critical
Publication of US3861873A publication Critical patent/US3861873A/en
Assigned to SC ACQUISITION CORP., NO. 1, A NEVADA CORP. reassignment SC ACQUISITION CORP., NO. 1, A NEVADA CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SYBRON CORPORATION
Assigned to CASTLE COMPANY reassignment CASTLE COMPANY CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFETIVE JULY 28, 1986 Assignors: SC ACQUISITION CORP. NO. 1
Assigned to SANTA BARBARA RESEARCH CENTER, GOLETA, CA., A CA CORP., MDT CORPORATION, A DE CORP. reassignment SANTA BARBARA RESEARCH CENTER, GOLETA, CA., A CA CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CASTLE COMPANY
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/02—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using physical phenomena
    • A61L2/04—Heat
    • A61L2/06—Hot gas
    • A61L2/07—Steam

Definitions

  • ABSTRACT In a steam sterilizer of the self-contained, single shell, steam generating type, the interior surface of the chamber is roughened to prevent the formation of water droplets, during cool-down, on all interior surfaces located above the load, to prevent water from dripping onto the load and thus to minimize the amount of moisture absorbed by the load during the sterilization process.
  • a layer of insulation is located on the exterior surface of the upper area of the vessel so that, during cool-down, by forced air cooling of the vessel, the temperature of the upper area of the vessel remains sufficiently high to flash off condensate from the interior surface thereof.
  • the formation of water droplets on, and the consequent dropping of water droplets from, the interior surface of the upper area of a self-contained, single shell, steam sterilizer, are prevented according to the present invention as follows.
  • the interior surface of at least the upper area of the sterilizing vessel is treated (for example, by sandblasting) to provide a surface on which the formation and development of droplets is prevented or reduced.
  • the sandblasted surface preferably has a roughness of about 250-300 microinches. The roughness causes the condensate to form over a large area with a low profile configuration.
  • a layer of insulation is placed over only the upper area of the vessel, so that during cool-down, by forcing air across the outer surface of the vessel, the temperature of the upper area of the vessel remains high enough to flash off or rapidly evaporate condensate that develops thereon.
  • Other means than insulation can be used to insure such flash off.
  • FIG. 1 is a schematic longitudinal cross-sectional view through a steam sterilizer made according to the present invention
  • FIG. 2 is a schematic transverse cross-sectional view through the sterilizer of FIG. 1;
  • FIG. 3 is an enlarged fragmentary view through the upper area 42 of FIG. 2;
  • FIG. 4 is an enlarged fragmentary view through an upper area of a prior art sterilizer vessel.
  • FIGS. l3 show a preferred construction of a steam sterilizer incorpo-
  • FIG. 4 shows the formation of water droplets as occurs in prior art sterilizers.
  • FIGS. l-3 show a steam sterilizer 10 designed for operating automatic cycles to process such items, for example, as wrapped instruments, unwrapped instruments for immediate use, cotton dressings and bandages, disassembled syringes, liquids, and solutions.
  • the system employed for the sterilization process is the admission of a controlled amount of distilled water into the chamber which is heated to provide steam. The steam rapidly and effectively penetrates the load.
  • a fan cooling system rapidly cools the vessel 12 after the sterilizing phase, condensing the chamber steam and moisture in the load.
  • the sterilizer 10 includes a cylindrical pressure vessel 12 (preferably of stainless steel) having a door 14 and enclosing a sterilizing chamber 16.
  • the sterilizer 10 also includes a water supply tank 18 for filling a water reservoir 20 inside the chamber 16.
  • a ter 2.21 29 1 ss. d atwattae 0 1 s p heater is located adjacent the bottom of the vessel 12.
  • a fan 24 operated by a motor 26 (for example, a 1/100 H.P. 3,000 RPM motor) accelerates the condensation process during cool-down.
  • the goods to be sterilized are placed in a plurality of trays 28 in the chamber 16.
  • the preferred sterilizer 10 is a table top model that heats to about 280 F in about 24 minutes.
  • a temperature of about 270 F is maintained for a minimum of about 3 minutes, and above 250 F for a minimum of about 8% minutes.
  • the vessel 12 is cooled by the fan 24 to about F in about 17 minutes.
  • the cycle time from a cold start is about 42 minutes.
  • FIG. 4 shows the prior art wherein an interior surface 30 of the upper area of a sterilizer vessel 32 has a highly polished smooth surface on which condensate forms with very low surface tension between the condensate and the interior surface 30, into droplets 34 with a very low contact area 36 between the droplet and the surface 30.
  • the latent heat that remains in the upper portion of the vessel 12 during cool-down is not sufficient to cause the droplet 34 to flash off of the surface 30.
  • water droplets tend to form from condensate at irregularities, such as openings and areas of non-uniform thicknesses, on the interior surface 30 of an upper area 42.
  • this problem is solved, according to the present invention by: (1) providing an interior surface 40 of at least an upper area 42 of the vessel 12 (overlying the load-containing area of the sterilizer), with a roughened finish, and (2) insulating the exterior surface of the upper area 42 of the vessel 12.
  • the surface 40 is roughened such that condensate 44 will not bead or form droplets that can drop onto the load, but rather the condensate will form over a large area of the surface 40 with a low profile configuration (in sharp contrast to the formation of the droplets 34).
  • the roughness can be provided, for example, by sandblasting the metal surface 40.
  • the roughness obtained depends, of course, on the grit used and can be conveniently expressed in microinches.
  • a roughness of 250-300 microinches has been found to give superior results in preventing development of moisture droplets 34, while it has been found that a matte finish of 45 microinches will allow droplets 34 to from.
  • the useful range of roughness is above 50 microinches and the preferred range is 250-300 microinches.
  • Other methods of treating the interior surface 40 than sandblasting can, of course, be used to provide the rough surface. While the roughness is necessary only in the upper area 42, it can be employed over the entire inner surface of the chamber 16, if desired. For example, it may be easier to sandblast the entire inner surface than to restrict it to just one area thereof.
  • a layer 46 of fiberglass insulation with a thin aluminum backing, three-quarter inches thick is attached to the upper half of the vessel 12 by straps.
  • the layer 46 of insulation extends over only the sides of the upper half of the cylindrical vessel 12 and does not cover the front or the backhead 52.
  • the layer 46 of insulation provides a means for preventing rapid temperature decrease in the upper area 42 of the vessel 12, such as occurs in the remaining, uninsulated areas of the vessel 12.
  • the use of the layer 46 of insulation on only the upper area 42 of the vessel 12 causes a temperature differential between the upper area 42 and the lower or remaining areas of the vessel 12, causing a more rapid heat loss (and therefore a more rapid temperature decrease) on the lower or remaining areas of the vessel 12 and greater maintainence of heat on the upper area 42 of the vessel 12 during cool-down.
  • the upper area 42 is thus kept warmer and condensation forms and remains only on the remaining areas (i.e., the lower sides 50 and the backhead 52).
  • the point is to provide a means for insuring that the temperature of the interior surface 40 of the upper area 42 of the vessel 12 is maintained sufficiently high to flash off the condensate that forms or develops thereon.
  • the layer 46 of insulation maintains the temperature of the upper area 42, during cool-off.
  • This aspect of the invention thus provides a flash zone at the top of'the chamber, and a condensing zone (not positioned over the load, thereby to return condensate to the water reservoir 20 without any dripping on the load).
  • the condensing zone is cooled by exterior cooling means (such as air cooling, water cooling, or other means).
  • flash off is hereby defined for use in the present specification and claims to mean the instantaneous, nearly instantaneous, and very rapid evaporation or change of condensate from the liquid to the gas or vapor state.
  • droplet is hereby defined for use in the present specification and claims as meaning condensate such as shown in FIG. 4 wherein the area of a horizontal crosssection at a mid-point is smaller than that at the largest part of the droplet.
  • Other means for preventing or reducing the formation of droplets 34 can be used such as other means for roughening a smooth surface, or even by forming the surface with a rough finish when it is initially made.
  • the rough surface can be the inside surface of the vessel 12 as shown and described above or a liner with a rough surface can be inserted into the vessel.
  • the interior surface can be coated with a material with a high affinity for water that will reduce the formation of droplets 34.
  • other means for maintaining the temperature of the upper area 42 can be used in place of the layer 46 of insulation, such as other types of insulation and/or a heater, and/or means for shielding the upper area 42 from the cooling effect of the forced air.
  • Other means for cooling the vessel 12 can be used in place of the fan 24, such as, for example, water cooling.
  • a self-contained, single shell, steam generating sterilizer including a sterilizing vessel having a sterilizing chamber therein, and a fan adjacent the vessel for cooling the outside surface of the vessel, the improvement comprising:
  • said preventing means comprises a layer of insulation on the outside surface of only said upper area of said vessel.
  • said providing step comprises providing said roughness in the range of about 250-300 microinches.
  • said providing step comprises providing said roughness in the range of about 250-300 microinches.
  • a self-contained, single shell, steam generating sterilizer comprising a sterilizing vessel having a sterilizing chamber therein, including means for maintaining, during cool-down, the interior surface of only an upper area of said vessel, overlying substantially all load-containing areas of said chamber, at a temperature sufficiently high to flash off condensate therefrom.

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  • Health & Medical Sciences (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Apparatus For Disinfection Or Sterilisation (AREA)
US347330A 1973-04-02 1973-04-02 Steam sterilizer Expired - Lifetime US3861873A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US347330A US3861873A (en) 1973-04-02 1973-04-02 Steam sterilizer
CA189,285A CA1013116A (en) 1973-04-02 1974-01-02 Steam sterilizer
DE2403526A DE2403526C3 (de) 1973-04-02 1974-01-25 Dampfsterilisator
AU65124/74A AU479015B2 (en) 1973-04-02 1974-02-01 Steam sterilizer
GB1310574A GB1468396A (en) 1973-04-02 1974-03-25 Steam sterilizers
JP49034783A JPS49128595A (ja) 1973-04-02 1974-03-29

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US347330A US3861873A (en) 1973-04-02 1973-04-02 Steam sterilizer

Publications (1)

Publication Number Publication Date
US3861873A true US3861873A (en) 1975-01-21

Family

ID=23363263

Family Applications (1)

Application Number Title Priority Date Filing Date
US347330A Expired - Lifetime US3861873A (en) 1973-04-02 1973-04-02 Steam sterilizer

Country Status (5)

Country Link
US (1) US3861873A (ja)
JP (1) JPS49128595A (ja)
CA (1) CA1013116A (ja)
DE (1) DE2403526C3 (ja)
GB (1) GB1468396A (ja)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4166096A (en) * 1978-03-23 1979-08-28 American Sterilizer Company Biohazard steam sterilizer
WO1999058165A1 (en) * 1998-05-12 1999-11-18 Steris Corporation Sterilizer with elliptical pressure vessel
WO2005004931A1 (en) * 2003-06-11 2005-01-20 Midmark Corporation Sterilizing apparatus
EP2763704A1 (en) * 2011-10-04 2014-08-13 American Sterilizer Company Steam sterilizer
US11575281B2 (en) 2017-09-26 2023-02-07 Stryker Corporation System and method for wirelessly charging a medical device battery

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5262996U (ja) * 1975-11-05 1977-05-10
JP2520542B2 (ja) * 1992-06-24 1996-07-31 泰治 西山 蒸気滅菌装置の運転方法
GB2309387B (en) * 1996-01-27 1999-08-04 El Sokkary Mohamed Adel A dual function automatic autoclave

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1995361A (en) * 1933-12-11 1935-03-26 Wesley M Nagle Surface condenser
US2159571A (en) * 1935-08-13 1939-05-23 Elmer S Stack Water heater
US2532655A (en) * 1949-09-27 1950-12-05 Backer Stanley Method of sandblasting
US2648108A (en) * 1948-06-28 1953-08-11 James B Pentz Sterilizer
US3203404A (en) * 1961-02-17 1965-08-31 Avy L Miller Water heater with heat insulating coating on tubes
US3206381A (en) * 1960-04-07 1965-09-14 Gen Electric Dropwise condensation distillation apparatus
US3361517A (en) * 1966-02-28 1968-01-02 Skaller Hans George Sterilizing apparatus and method
US3393628A (en) * 1966-09-29 1968-07-23 William Vischer Pressure cooker
US3739710A (en) * 1971-12-30 1973-06-19 Hubbert B & Son Inc Processing kettle

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1288247B (de) * 1962-04-25 1969-01-30 Storz Walter Dampfsterilisier-Autoklav
DE1642124C3 (de) * 1966-02-25 1975-03-27 Hans George Flushing New York N.Y. Skaller (V.St.A.) Sterilisationsapparat

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1995361A (en) * 1933-12-11 1935-03-26 Wesley M Nagle Surface condenser
US2159571A (en) * 1935-08-13 1939-05-23 Elmer S Stack Water heater
US2648108A (en) * 1948-06-28 1953-08-11 James B Pentz Sterilizer
US2532655A (en) * 1949-09-27 1950-12-05 Backer Stanley Method of sandblasting
US3206381A (en) * 1960-04-07 1965-09-14 Gen Electric Dropwise condensation distillation apparatus
US3203404A (en) * 1961-02-17 1965-08-31 Avy L Miller Water heater with heat insulating coating on tubes
US3361517A (en) * 1966-02-28 1968-01-02 Skaller Hans George Sterilizing apparatus and method
US3393628A (en) * 1966-09-29 1968-07-23 William Vischer Pressure cooker
US3739710A (en) * 1971-12-30 1973-06-19 Hubbert B & Son Inc Processing kettle

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4166096A (en) * 1978-03-23 1979-08-28 American Sterilizer Company Biohazard steam sterilizer
WO1999058165A1 (en) * 1998-05-12 1999-11-18 Steris Corporation Sterilizer with elliptical pressure vessel
WO2005004931A1 (en) * 2003-06-11 2005-01-20 Midmark Corporation Sterilizing apparatus
US7951342B2 (en) 2003-06-11 2011-05-31 Midmark Corporation Sterilizing apparatus
EP2763704A1 (en) * 2011-10-04 2014-08-13 American Sterilizer Company Steam sterilizer
US8865087B2 (en) 2011-10-04 2014-10-21 American Sterilizer Company Steam sterilizer
EP2763704A4 (en) * 2011-10-04 2015-04-15 American Sterilizer Co steam sterilizer
EP2763704B1 (en) 2011-10-04 2016-08-17 American Sterilizer Company Steam sterilizer
US11575281B2 (en) 2017-09-26 2023-02-07 Stryker Corporation System and method for wirelessly charging a medical device battery
US12034315B2 (en) 2017-09-26 2024-07-09 Stryker Corporation System and method for wirelessly charging a medical device battery

Also Published As

Publication number Publication date
JPS49128595A (ja) 1974-12-09
AU6512474A (en) 1975-08-07
DE2403526B2 (de) 1980-07-03
DE2403526C3 (de) 1981-05-21
DE2403526A1 (de) 1974-10-10
CA1013116A (en) 1977-07-05
GB1468396A (en) 1977-03-23

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AS Assignment

Owner name: SC ACQUISITION CORP., NO. 1, A NEVADA CORP.

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SYBRON CORPORATION;REEL/FRAME:004607/0079

Effective date: 19860711

Owner name: SC ACQUISITION CORP., NO. 1, A NEVADA CORP., STATE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SYBRON CORPORATION;REEL/FRAME:004607/0079

Effective date: 19860711

AS Assignment

Owner name: CASTLE COMPANY

Free format text: CHANGE OF NAME;ASSIGNOR:SC ACQUISITION CORP. NO. 1;REEL/FRAME:004741/0707

Effective date: 19860725

STCF Information on status: patent grant

Free format text: PATENTED FILE - (OLD CASE ADDED FOR FILE TRACKING PURPOSES)

AS Assignment

Owner name: MDT CORPORATION, A DE CORP.

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CASTLE COMPANY;REEL/FRAME:005036/0117

Effective date: 19890221

Owner name: SANTA BARBARA RESEARCH CENTER, GOLETA, CA., A CA C

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CASTLE COMPANY;REEL/FRAME:005036/0117

Effective date: 19890221