EP0015328A1
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EP
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Method and apparatus for steam sterilization
Assignee: American Sterilizer Co
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Filing: 1979-02-08
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Granted: —
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Expires: 1999-02-08
Abstract
Abstract In methods and apparatus for steam sterilization, goods are conditioned in a sterilizing chamber (16) by removing air and heating to a desired temperature. Pressure change in the chamber is monitored and employed to control conditioning. The goods are subjected to a plurality of controlled cyclic pressure pulses below a predetermined super-atmospheric pressure level by alternate evacuation and steam pressurization of the chamber. The cyclic pressure pulsing is made responsive to load characteristics which are determined by monitoring pressure change in the chamber (16) by means of a pressure sensing assembly (66). In a specific embodiment, air is flushed from the chamber (16) initially by the injection of steam via a valve (45) from a jacket (22) simultaneously with evacuation of the chamber (16) by means of a water ejection (48). The evacuation phase of each pulse continues until both a predetermined time has lapsed and a predetermined vacuum level has been attained; and the steam pressurization phase of each pulse is continued until a fixed pressure related to sterilization temperature is reached. Thereafter steam is admitted to the chamber (16) and steam pressure is maintained therein until the sterilization has been completed.
Inventors
- 👤 Jack H. Young
- 👤 Frank E. Halleck
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 22:51
CPC Classifications
A; A61; A61L; A61L2/00; A61L2/24
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
158 words
A method of steam sterilizing materials within a sealed sterilizing chamber in which a random load of such materials is loaded into the chamber and the load is conditioned prior to steam sterilization in that air is removed from the load and the load is heated to a desired temperature related to the sterilizing temperature by subjecting the chamber to a plurality of cyclic pressure pulses in each of which pressure is reduced during an evacuating phase and pressure is subsequently increased by introducing a vapour into the chamber during a vapour injecting phase, characterized in that the change of chamber pressure in relation to time lapse is measured during at least a portion of the evacuating phase, the measured change serving as an indication of chamber evacuation rate during the evacuating phase, and in that the indicated chamber evacuation rate automatically controls the termination of that evacuation phase and initiates the succeeding cyclic pressure pulse pressurization phase.
Claim 2
Independent Claim
158 words
A method of steam sterilizing materials within a sealed sterilizing chamber in which a random load of such materials is loaded into the chamber and the load is conditioned prior to steam sterilization in that air is removed from the load and the load is heated to a desired temperature related to the sterilizing temperature by subjecting the chamber to a plurality of cyclic pressure pulses in each of which pressure is reduced during an evacuating phase and pressure is subsequently increased by introducing a vapour into the chamber during a vapour injecting phase, characterized in that the change of chamber pressure in relation to time lapse is measured during at least a portion of the evacuating phase, the measured change serving as an indication of chamber evacuation rate during the evacuating phase, and in that the indicated chamber evacuation rate automatically controls the termination of that evacuation phase and initiates the succeeding cyclic pressure pulse pressurization phase.
Claim 3
Dependent Claim
26 words
A method according to claim 1 characterised in that at each of the evacuation phases is automatically terminated by automatically controlling the chamber evacuation pressure level.
Claim 4
Dependent Claim
24 words
A method according to claim 1 characterised in that each of the evacuation phases is automatically terminated by automatically controlling the chamber evacuation time.
Claim 5
Dependent Claim
27 words
A method according to claim 1, 2 or 3 characterised in that the range of pressure of the cyclic pressure pulses extends above and below atmospheric pressure.
Claim 6
Dependent Claim
31 words
A method according to claim 4 characterised in that the evacuation phase of each cyclic pressure pulse is continued until both a minimum vacuum level and minimum time duration are reached.
Claim 7
Independent Claim
23 words
A method according to any preceding claim further characterised by selecting the number of cyclic pulses to control the conditioning of the load.
Claim 8
Independent Claim
22 words
A method according to any preceding claim characterised in that the vapour introduced into the sterilizing chamber during the conditioning comprises steam.
Claim 9
Independent Claim
44 words
A method according to any preceding claim characterised in that the load conditioning is initiated prior to the cyclic pressure pulses by purging air from the chamber by introducing the vapour into the chamber while simultaneously evacuating such vapour and air from the chamber.
Claim 10
Independent Claim
43 words
A method as claimed in claims 7 and 8 characterised in that the air is purged from the chamber by introducing steam into the chamber at a rate to initially produce a substantial pressure increase in the chamber while simultaneously evacuating the chamber.
Claim 11
Dependent Claim
74 words
A method as claimed in claim 9 characterised in that steam is introduced into the chamber and the chamber is evacuated at rates to produce initially a rapid increase in chamber pressure followed by a substantial reduction in the rate of chamber pressurization and in that the change in the rate of chamber pressurization is sensed and the introduction of steam is terminated in response to the sensed reduction in rate of chamber pressurization.
Claim 12
Dependent Claim
64 words
A method as claimed in claim 9 characterised in that steam is introduced into the chamber and the chamber is evacuated at rates to produce initially a substantial increase in chamber pressure followed by a gradual reduction in chamber pressure, and in that the reduction in chamber pressure is sensed and the introduction of steam is terminated in response to the sensed pressure reduction.
Claim 13
Independent Claim
32 words
A method according to any preceding claim characterised in that the pressure in the chamber is reduced during the evactuating phase by applying to the sterilizing chamber a vacuum by ejector means.
Claim 14
Independent Claim
20 words
A method according to any preceding claim characterised in that the load conditioning comprises at least four cyclic pressure pulses.
Claim 15
Dependent Claim
215 words
Sterilizing apparatus for steam sterilizing a random load of materials, the apparatus having a sealable sterilizing chamber capable of operation at pressure above atmospheric and being provided with evacuation means operable to evacuate the sterilizing chamber, vapour injection means operable to introduce a vapour into the sterilizing chamber, and a control device for controlling operation of the evacuation means and the vapour injection means during conditioning of the load prior to sterilization to provide a plurality of cyclic pulses of chamber pressure below an upper pressure level related to desired temperature for sterilization, each cyclic pulse including an evacuating phase during which pressure in the chamber is decreasing during operation of the evacuation means and a vapour injecting phase during which pressure within the chamber is increasing during operation of the vapour injecting means, characterised in that the control device is connected to a pressure sensing device (66) for monitoring chamber pressure change and includes a timing device (82) for measuring the time of the evacuation phase of the cyclic pulses, and in that the control device (70) is responsive to such indication of chamber pressure and evacuation time for determining the rate of evacuation of the chamber and for controlling such cyclic pulsing to control load conditioning in response to the chamber evacuation rate.
Claim 16
Dependent Claim
215 words
Sterilizing apparatus for steam sterilizing a random load of materials, the apparatus having a sealable sterilizing chamber capable of operation at pressure above atmospheric and being provided with evacuation means operable to evacuate the sterilizing chamber, vapour injection means operable to introduce a vapour into the sterilizing chamber, and a control device for controlling operation of the evacuation means and the vapour injection means during conditioning of the load prior to sterilization to provide a plurality of cyclic pulses of chamber pressure below an upper pressure level related to desired temperature for sterilization, each cyclic pulse including an evacuating phase during which pressure in the chamber is decreasing during operation of the evacuation means and a vapour injecting phase during which pressure within the chamber is increasing during operation of the vapour injecting means, characterised in that the control device is connected to a pressure sensing device (66) for monitoring chamber pressure change and includes a timing device (82) for measuring the time of the evacuation phase of the cyclic pulses, and in that the control device (70) is responsive to such indication of chamber pressure and evacuation time for determining the rate of evacuation of the chamber and for controlling such cyclic pulsing to control load conditioning in response to the chamber evacuation rate.
Claim 17
Dependent Claim
57 words
Apparatus according to claim 14 characterised in that the control device (70) includes pulse cycle control means (84,38,90) for controlling such cyclic pulsing responsive to such indication of chamber pressure and evacuation time, whereby to continue each evacuation phase until both a predetermined time has lapsed and a predetermined vacuum level is reached in the sterilizing chamber.
Claim 18
Dependent Claim
38 words
Apparatus according to claim 14 or 15 characterised in that the control device (70) includes means (80) for initiating load conditioning by introducing steam into the chamber while simultaneously evacuating the chamber to flush air from the chamber.
Claim 19
Dependent Claim
79 words
Apparatus according to any of claims 14 to 16 characterised in that the vapour injector means (44) has a first electrically operated valve (45) to respectively pressurize the chamber (16) and stop the flow of steam into the chamber, and in that the evacuating means includes a suction device (48) and a second electrically operated valve (54) to respectively connect the chamber (16) to the suction device to evacuate the chamber and disconnect the chamber to stop the evacuation.
Claim 20
Dependent Claim
33 words
Apparatus according to any of claims 14 to 17 characterised in that the control device (70) includes counting means (72) operable to terminate the cyclic pressure pulsing after a predetermined'number of such pulses.
References Cited (Backward Citations)
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