US3861872A - Steam sterilizer - Google Patents

Steam sterilizer Download PDF

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Publication number
US3861872A
US3861872A US347329A US34732973A US3861872A US 3861872 A US3861872 A US 3861872A US 347329 A US347329 A US 347329A US 34732973 A US34732973 A US 34732973A US 3861872 A US3861872 A US 3861872A
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US
United States
Prior art keywords
vessel
load
upper area
roughness
sterilizing
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
US347329A
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English (en)
Inventor
Roderick T Macfarlane
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 US347329A priority Critical patent/US3861872A/en
Priority to CA189,347A priority patent/CA1000929A/en
Priority to AU64790/74A priority patent/AU474036B2/en
Priority to DE2403525A priority patent/DE2403525C3/de
Priority to GB1310674A priority patent/GB1457304A/en
Priority to JP49034782A priority patent/JPS49128594A/ja
Application granted granted Critical
Publication of US3861872A publication Critical patent/US3861872A/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 MDT CORPORATION, A DE CORP., SANTA BARBARA RESEARCH CENTER, GOLETA, CA., A CA CORP. reassignment MDT CORPORATION, A DE CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CASTLE COMPANY
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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 (as by sandblasting) 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.
  • 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.
  • 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. l-3 show a preferred construction of a steam sterilizer incorporating the present invention
  • FIG. 4 shows the formation of water droplets as occurs in prior art sterilizers.
  • FIGS. 1-3 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 hea srilsqsuastadua wa ag QO W/1 W) strip heater] is located adjacent the bottom of the vessel 12.
  • a fan 24 operated by a motor 26 (for example a l/ HP. 3000 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 I6.
  • 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 250F 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 a sterilizer vessel32 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 flashoff of the surface 30.
  • water droplets tend to form from condensate at irregularities, such as openings and areas of nonuniform thicknesses, on the interior surface 30 ,of an upper area 42.
  • this problem is solved, according to the present invention by providing an interior surface 40 of at least the upper area 42 of the vessel 12 (overlying the loadcontaining area of the sterilizer), with a roughened finish.
  • 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 surface 40. The roughness obtained depends, of course, on the grit used and can be conveniently expressed in microinches.
  • the 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 microincheswill allow droplets 34 to form.
  • 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.
  • the formation of droplets on irregularities is prevented by eliminating irregularities (such as openings and areas of non-uniform thickness) from the interior surface 40 of the upper area 42.
  • the formation of droplets at irregularities is caused by a heat sink effect wherein the area immediately adjacent to the irregularity is cooler than the surrounding area.
  • 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 cross-section at a mid-point is smaller than that at the largest part of the droplet.
  • 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.
  • 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 vessel being cylindrical with a horizontal axis
  • said providing step comprises providing said roughness in the range of about 250-300 microinches.

Landscapes

  • 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)
US347329A 1973-04-02 1973-04-02 Steam sterilizer Expired - Lifetime US3861872A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US347329A US3861872A (en) 1973-04-02 1973-04-02 Steam sterilizer
CA189,347A CA1000929A (en) 1973-04-02 1974-01-02 Steam sterilizer
AU64790/74A AU474036B2 (en) 1973-04-02 1974-01-23 Steam sterilizer
DE2403525A DE2403525C3 (de) 1973-04-02 1974-01-25 Dampfsterilisator
GB1310674A GB1457304A (en) 1973-04-02 1974-03-25 Steam sterilizers
JP49034782A JPS49128594A (OSRAM) 1973-04-02 1974-03-29

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US347329A US3861872A (en) 1973-04-02 1973-04-02 Steam sterilizer

Publications (1)

Publication Number Publication Date
US3861872A true US3861872A (en) 1975-01-21

Family

ID=23363260

Family Applications (1)

Application Number Title Priority Date Filing Date
US347329A Expired - Lifetime US3861872A (en) 1973-04-02 1973-04-02 Steam sterilizer

Country Status (6)

Country Link
US (1) US3861872A (OSRAM)
JP (1) JPS49128594A (OSRAM)
AU (1) AU474036B2 (OSRAM)
CA (1) CA1000929A (OSRAM)
DE (1) DE2403525C3 (OSRAM)
GB (1) GB1457304A (OSRAM)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4192845A (en) * 1977-04-01 1980-03-11 Firma Vereinigte Edelstahlwerke Aktiengesellschaft Sterilization process and apparatus for infusion solutions and the like filled in containers
US4195061A (en) * 1977-05-17 1980-03-25 Firma Vereinigte Edelstahlwerke Aktiengesellschaft Sterilization apparatus for infusion solutions or the like, filled in containers
US4497773A (en) * 1981-03-03 1985-02-05 Vernitron Corporation Process and apparatus for shortening the drying stage of a steam sterilization cycle
WO1989002753A1 (en) * 1987-10-02 1989-04-06 Sven Karl Lennart Goof Apparatus for sterilizing objects, in particular dental and medical utensils

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5745937U (OSRAM) * 1980-08-29 1982-03-13
DE3516495A1 (de) * 1985-05-08 1986-11-13 Aesculap-Werke Ag Vormals Jetter & Scheerer, 7200 Tuttlingen Heizkoerper fuer einen sterilisierkessel
AU620049B2 (en) * 1987-10-30 1992-02-13 Douglas Colin Bean Autoclave container

Citations (8)

* 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
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

Patent Citations (8)

* 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
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 (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4192845A (en) * 1977-04-01 1980-03-11 Firma Vereinigte Edelstahlwerke Aktiengesellschaft Sterilization process and apparatus for infusion solutions and the like filled in containers
US4195061A (en) * 1977-05-17 1980-03-25 Firma Vereinigte Edelstahlwerke Aktiengesellschaft Sterilization apparatus for infusion solutions or the like, filled in containers
US4497773A (en) * 1981-03-03 1985-02-05 Vernitron Corporation Process and apparatus for shortening the drying stage of a steam sterilization cycle
WO1989002753A1 (en) * 1987-10-02 1989-04-06 Sven Karl Lennart Goof Apparatus for sterilizing objects, in particular dental and medical utensils
US5252303A (en) * 1987-10-02 1993-10-12 Goof Sven Karl Lennart Apparatus for sterilizing objects having chamber wall as heater

Also Published As

Publication number Publication date
AU474036B2 (en) 1976-07-08
GB1457304A (en) 1976-12-01
DE2403525A1 (de) 1974-10-10
DE2403525B2 (de) 1979-02-08
CA1000929A (en) 1976-12-07
JPS49128594A (OSRAM) 1974-12-09
DE2403525C3 (de) 1979-10-04
AU6479074A (en) 1975-07-24

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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)

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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

Owner name: MDT CORPORATION, A DE CORP.

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

Effective date: 19890221