EP0429960A2
Expired / Lapsed
EP
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Method and apparatus for steam sterilization of articles
Assignee: Sci Can Ltd
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Filing: 1990-11-14
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Granted: —
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Expires: 2010-11-14
Abstract
Abstract A process, system and pressure chamber for the automated sterilization of articles, particularly medical or dental instruments is disclosed, which is simple to use and economically efficient by comparison with conventional autoclaves and steam sterilizing system. Steam is generated by the pulsed injection of a controlled quantity of water into a heated boiler (20) whenever it runs dry. The boiler (20) is coupled in a closed-loop system to a relatively small pressure chamber in the form of a cassette (10) that is readily inserted and removed from a holder comprising means for connecting the chamber to a steam inlet conduit (18) and a venting conduit (16), the latter being closed off during pressurization of the chamber. By automated monitoring of the boiler and chamber temperatures, conditions in the chamber (10) are measured and the boiler and valves in the system controlled to effect a sterilization cycle.
Inventors
- 👤 Duncan Newman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 17:37
CPC Classifications
A; A61; A61L; A61L2/00; A61L2/24; A61L2/02; A61L2/04; A61L2/06; A61L2/07
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
272 words
A process for the steam sterilization of articles by controlled delivery of steam from an electrically heated boiler in communication with a pressure chamber through a steam delivery conduit, said pressure chamber having a venting conduit closable by a valve, characterized in that the process comprises the steps of: (a) generating a flow of steam throughout said steam delivery conduit by the pulsed injection of a controlled quantity of water into the hot boiler, whenever dryness of the boiler is detected, said boiler and said pressure chamber being jointly sealed from the atmosphere when said first valve is in the closed position; (b) permitting steam from the boiler to pass into the chamber with said valve open to expel the air initially therein through said venting conduit; then (c) closing the venting conduit so that steam generated in the boiler raises the pressure and the temperature in the chamber and monitoring the temperature in the chamber until a desired sterilization temperature is attained; then (d) controlling the temperature in the chamber to remain substantially constant at said sterilization temperature for a desired sterilization period by modulating the electric power supply to the boiler; and (e) at predetermined intervals during pressurization of the chamber in step (c) and during maintenance of the sterilization temperature within the chamber in step (d), opening said venting conduit to cause condensed liquid water from the chamber to be purged therethrough, then closing the venting conduit; and (f) upon completion of sterilization exposure of the articles in the chamber, turning off the boiler and opening the venting conduit to exhaust the chamber and return it to atmospheric pressure.
Claim 2
Dependent Claim
272 words
A process for the steam sterilization of articles by controlled delivery of steam from an electrically heated boiler in communication with a pressure chamber through a steam delivery conduit, said pressure chamber having a venting conduit closable by a valve, characterized in that the process comprises the steps of: (a) generating a flow of steam throughout said steam delivery conduit by the pulsed injection of a controlled quantity of water into the hot boiler, whenever dryness of the boiler is detected, said boiler and said pressure chamber being jointly sealed from the atmosphere when said first valve is in the closed position; (b) permitting steam from the boiler to pass into the chamber with said valve open to expel the air initially therein through said venting conduit; then (c) closing the venting conduit so that steam generated in the boiler raises the pressure and the temperature in the chamber and monitoring the temperature in the chamber until a desired sterilization temperature is attained; then (d) controlling the temperature in the chamber to remain substantially constant at said sterilization temperature for a desired sterilization period by modulating the electric power supply to the boiler; and (e) at predetermined intervals during pressurization of the chamber in step (c) and during maintenance of the sterilization temperature within the chamber in step (d), opening said venting conduit to cause condensed liquid water from the chamber to be purged therethrough, then closing the venting conduit; and (f) upon completion of sterilization exposure of the articles in the chamber, turning off the boiler and opening the venting conduit to exhaust the chamber and return it to atmospheric pressure.
Claim 3
Dependent Claim
74 words
The process of claim 1, further characterized in that the substantially complete expulsion of air from the chamber in step (b) is effected by monitoring the temperature of the effluent stream vented from the pressure chamber and, when the temperature of the effluent steam has risen to about 100°C indicating substantially complete expulsion of chamber air, allowing steam to continue to pass through the chamber until a selected air expulsion conditioning period has elapsed.
Claim 4
Dependent Claim
43 words
The process of claim 2, further characterized in that detection of dryness in the boiler is effected by monitoring the temperature of the boiler and observing a sudden rise in boiler temperature indicative of the evaporation of water in the boiler to dryness.
Claim 5
Dependent Claim
39 words
The process of claim 3, further characterized in that completion of said purging of condensed liquid water through said vent opening is detected by an abrupt decrease in the temperature of the effluent stream vented from the pressure chamber.
Claim 6
Dependent Claim
34 words
The process of claim 3, further characterized in that modulation of the electric power supply to the boiler during step (e) comprises turning the electric power on and off according to a duty cyc!e.
Claim 7
Dependent Claim
38 words
The process of claim 3, further characterized in that it comprises the further step, following step (g), of introducing a stream of dry, clean compressed air through the chamber to cool and to dry the sterilized articles therein.
Claim 8
Dependent Claim
61 words
The process of claim 3, further characterized in that it includes a deviation correction, comprising the further step of comparing the temperature of the boiler to the temperature in the chamber and opening said venting conduit for a brief period, if the difference between the two temperatures exceeds a predetermined limit indicative of the presence of residual air in the chamber.
Claim 9
Dependent Claim
25 words
The process of claim 7, further characterized in that said deviation correction is carried out following attainment of the desired sterilization temperature in step (d).
Claim 10
Independent Claim
395 words
A system of steam sterilizing articles, characterized in that it comprises: (a) a pressure chamber (10) for holding the articles to be sterilized, having an inlet conduit (18) for steam and an outlet conduit (16); (b) means for venting the interior of said chamber, comprising a first valve (V) in said outlet conduit (16) having an open position and a closed position, and valve control means for switching the first valve between its open and closed positions; (c) means for injecting steam into said chamber, comprising: (i) an electrically heated boiler (20) in communication with said pressure chamber (10) through said steam inlet conduit (18), and boiler control means for the electrical power supplied to said boiler, and (ii) pump means (26) for injecting a pulse of water of a predetermined quantity from a water container into said boiler (20) to produce steam, and pump control means to actuate said pump means, (d) first temperature sensor means (34a) for monitoring the temperature at said outlet conduit (16) when venting the pressure chamber (10) and the temperature of steam in said chamber (10) when pressurized by steam, (e) sensor means for detecting dryness of the boiler; and (f) sequencing means responsive to said first temperature sensor means (34a) and to said sensor means for detecting dryness of the boiler (20) for controlling the operation of said valve control means, said boiler control means and said pump control means, said sequencing means being configured to perform the following steps: (i) actuating said pump control means when the boiler is dry, to cause a pulse of water to be injected into the boiler, (ii) in an initial air purging phase, actuating said valve control means to close said first valve means a predetermined period of time following attainment of a predetermined chamber outlet threshold temperature indicating the venting of saturated steam from the chamber, (iii) when a predetermined desired sterilization temperature has been attained in the pressurized chamber, actuating said boiler control means to modulate the electrical power supplied to the boiler, so as to maintain said sterilization temperature substantially constant within the chamber over a selected sterilization period, and (iv) upon completion of sterilization at the end of said sterilization period, actuating said valve control means to open said first valve means to depressurize the chamber and actuating said boiler control means to turn the boiler off.
Claim 11
Independent Claim
395 words
A system of steam sterilizing articles, characterized in that it comprises: (a) a pressure chamber (10) for holding the articles to be sterilized, having an inlet conduit (18) for steam and an outlet conduit (16); (b) means for venting the interior of said chamber, comprising a first valve (V) in said outlet conduit (16) having an open position and a closed position, and valve control means for switching the first valve between its open and closed positions; (c) means for injecting steam into said chamber, comprising: (i) an electrically heated boiler (20) in communication with said pressure chamber (10) through said steam inlet conduit (18), and boiler control means for the electrical power supplied to said boiler, and (ii) pump means (26) for injecting a pulse of water of a predetermined quantity from a water container into said boiler (20) to produce steam, and pump control means to actuate said pump means, (d) first temperature sensor means (34a) for monitoring the temperature at said outlet conduit (16) when venting the pressure chamber (10) and the temperature of steam in said chamber (10) when pressurized by steam, (e) sensor means for detecting dryness of the boiler; and (f) sequencing means responsive to said first temperature sensor means (34a) and to said sensor means for detecting dryness of the boiler (20) for controlling the operation of said valve control means, said boiler control means and said pump control means, said sequencing means being configured to perform the following steps: (i) actuating said pump control means when the boiler is dry, to cause a pulse of water to be injected into the boiler, (ii) in an initial air purging phase, actuating said valve control means to close said first valve means a predetermined period of time following attainment of a predetermined chamber outlet threshold temperature indicating the venting of saturated steam from the chamber, (iii) when a predetermined desired sterilization temperature has been attained in the pressurized chamber, actuating said boiler control means to modulate the electrical power supplied to the boiler, so as to maintain said sterilization temperature substantially constant within the chamber over a selected sterilization period, and (iv) upon completion of sterilization at the end of said sterilization period, actuating said valve control means to open said first valve means to depressurize the chamber and actuating said boiler control means to turn the boiler off.
Claim 12
Dependent Claim
74 words
A system according to claim 9, further characterized in that said sensor means for detecting dryness of the boiler (20) comprises second temperature sensor means (34b) for monitoring the temperature of said boiler (20) and wherein said sequencing means is responsive to the onset of a sensed increase in the temperature of the boiler (20) relative to the temperature of the chamber (10) indicative of the complete evaporation of water from the boiler (20).
Claim 13
Dependent Claim
28 words
A system according to claim 10, further characterized in that said second temperature sensor means (34b) is operable to monitor the temperature of steam in the boiler (20).
Claim 14
Dependent Claim
21 words
A system according to claim 10, further characterized in that said first and second temperature sensor means each comprises a thermocouple.
Claim 15
Dependent Claim
29 words
A system according to claim 9, further characterized in that said pump means (26) is a reciprocating plunger pump, and said pump control means comprises an electrically powered solenoid.
Claim 16
Dependent Claim
78 words
A system according to claim 9, further characterized in that said sequencing means is configured to perform the further step of actuating said valve control means to open said first valve means (V) at suitable intervals when the chamber (10 ) is being pressurized and during sterilization to vent condensate from the chamber (10), and to close said first valve means (V) when expulsion of the condensate is detected by an abrupt drop in the chamber outlet temperature.
Claim 17
Dependent Claim
99 words
A system according to claim 11, further characterized in that said sequencing means is configured to perform the additional step, when a predetermined desired sterilization temperature has been attained in the pressurized chamber (10), of comparing the temperature of steam in the boiler (20) and the temperature of steam in the chamber (10) and, if the difference between the two temperatures exceeds a predetermined limit indicative of the presence of residual unpurged air in the chamber, opening said vent valve (V) for a brief period to permit purging of said residual air and then closing the vent valve (V).
Claim 18
Dependent Claim
82 words
A system according to claim 9, further comprising: (a) a source of clean, dry compressed air connected by a branch conduit (36) to said pressure chamber steam inlet conduit (18); (b) means in said branch conduit for controlling the flow of compressed air into said chamber steam inlet conduit (18), so that said source may be closed off from the system during sterilization and a stream of drying air may be passed through said chamber (10) following completion of a sterilizing cycle.
Claim 19
Dependent Claim
211 words
Apparatus for holding articles to be sterilized by steam, characterized in that it comprises: (a) a pressure chamber (10) in the form of a cassette, comprising (i) a bottom tray (10b) for receiving said articles, (ii) a lid (10a) for placement over said bottom tray (10b), and (iii) perimetrical compressible sealing means (68) disposed between said tray (10b) and said lid (10a), said pressure chamber (10) being provided with a steam inlet port (12) and with a venting port (14) near the lowermost point thereof to allow the passage from the chamber (10) of condensate formed during sterilization; and b) a holder for maintaining said tray and said lid in pressure tight relationship, comprising (i) a spaced pair of upper (11a) and lower (11b) rigid plates having thermally insulating opposed interior lateral surfaces presenting therebetween a space to closely receive said pressure chamber (10) and to hold said pressure chamber (10) firmly in place when pressurized by steam, and (ii) means for sealingly connecting a steam inlet conduit (18) to communicate with the inlet port (12) of said chamber (10) and a venting conduit (16) to communicate with the venting port (14) of said chamber (10) when said chamber (10) is slid between said insulating surfaces to a limiting operating position.
Claim 20
Dependent Claim
211 words
Apparatus for holding articles to be sterilized by steam, characterized in that it comprises: (a) a pressure chamber (10) in the form of a cassette, comprising (i) a bottom tray (10b) for receiving said articles, (ii) a lid (10a) for placement over said bottom tray (10b), and (iii) perimetrical compressible sealing means (68) disposed between said tray (10b) and said lid (10a), said pressure chamber (10) being provided with a steam inlet port (12) and with a venting port (14) near the lowermost point thereof to allow the passage from the chamber (10) of condensate formed during sterilization; and b) a holder for maintaining said tray and said lid in pressure tight relationship, comprising (i) a spaced pair of upper (11a) and lower (11b) rigid plates having thermally insulating opposed interior lateral surfaces presenting therebetween a space to closely receive said pressure chamber (10) and to hold said pressure chamber (10) firmly in place when pressurized by steam, and (ii) means for sealingly connecting a steam inlet conduit (18) to communicate with the inlet port (12) of said chamber (10) and a venting conduit (16) to communicate with the venting port (14) of said chamber (10) when said chamber (10) is slid between said insulating surfaces to a limiting operating position.
Claim 21
Dependent Claim
67 words
A pressure chamber according to claim 17, further characterized in that said pressure chamber (10) is rectangular in shape and said venting port (16) is located near the bottom at one corner thereof, said holder being in a fixed spatial orientation such that said chamber (10), when inserted therein in use, is tilted to position said corner vertically below the three other corners of said chamber (10).
Claim 22
Dependent Claim
182 words
Apparatus according to claim 17, further characterized in that: said perimetrical sealing means (68) is so configured to define a channel which is closed between the wall of said bottom tray (10b) and the wall of said lid (10a) in the region of a first end of the chamber (10) and which partly opens into the interior of the pressure chamber at a second end of the chamber remote from said first end; said steam inlet port (12) is located at said first end of the chamber (10), and communicates with the interior of said channel; and said venting port (14) is located near said steam inlet port (12) and communicates with the interior of said chamber near the bottommost point thereof, such that steam introduced into said inlet port (12) at said first end of the chamber (10) proceeds along the closed portion of the channel and is distributed into the chamber (10) through the open portion of the channel remote from said inlet port (12), passing about the articles to be sterilized, and is vented through said venting port (14).
Claim 23
Dependent Claim
135 words
Apparatus according to claim 19, further characterized in that the lower portion of said lid (10a) is stepped outwardly to form a perimetrical recess, and said sealing means (68) is an elongate resilient member of generally J-shaped cross-section seated within said perimetrical recess of the lid and has upper (68a) and lower (68b) transverse sealing edges projecting slightly outwardly from said perimetrical recess, both of said sealing edges being in sealing contact with the outer wall surface of said bottom tray (10b) in the region of said first end of the chamber (10), to form said closed channel, and only the lower sealing edge (68b) being in sealing contact with the outer wall surface of said bottom tray (10b) in the region of said second end of the chamber, to form said partly open channel.
Claim 24
Dependent Claim
90 words
Apparatus according to Claim 20, further characterized in that said perimetrical recess is tilted downwardly with respect to the upper edge of said bottom tray (10b) from said second end of the chamber (10) to the first end thereof, whereby said sealing member (68) lies entirely below the top edge of said bottom tray (10b) in the region of said first end of the pressure chamber (10) and partly above the top edge of the bottom tray (10b) in the region of said second end of the pressure chamber (10).
References Cited (Backward Citations)
No citation records indexed.
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