GB2327613A

GB2327613A - Method and apparatus for automatically testing an autoclave

Info

Publication number: GB2327613A
Application number: GB9814347A
Authority: GB
Inventors: Keith Hannant
Original assignee: Smiths Group PLC
Current assignee: Smiths Group PLC
Priority date: 1997-07-26
Filing date: 1998-07-03
Publication date: 1999-02-03
Anticipated expiration: 2018-07-03
Also published as: GB9715716D0; GB9814347D0; GB2327613B

Abstract

An autoclave has a chamber 1, a control unit 4 and a timer means 20 wherein the control unit is arranged automatically to run a test procedure for the autoclave in response to a signal from the timer means. A method of running the procedure comprises closing the autoclave door 2 and leaving the autoclave automatically to perform the test procedure at a pre-programmed time. The tests include running a leak test, testing whether an air detector 23 functions properly and testing for sufficient steam penetration into a porous load test pack 40.

Description

AUTOCLAVE APPARATUS This invention relates to autoclave apparatus and methods of testing.

Autoclaves, such as for sterilization, subject articles within the autoclave chamber to elevated pressure and temperature in the presence of a vapour, which is usually steam. The autoclave may have a vacuum pump for pumping out air before the sterilization or other treatment is started. In order to ensure that the autoclave is functioning correctly, it must be tested regularly, and in some cases, daily. This testing can be time consuming. Also, with more complex autoclaves, such as those used to sterilize porous loads, there is a further problem in that the test procedures can be quite complicated to perform correctly.

It is an object of the present invention to provide an improved autoclave and methods of testing.

According to one aspect of the present invention there is provided an autoclave having a chamber arranged to receive articles to be treated, a control unit and timer means, the control unit being arranged automatically to run a test procedure for the autoclave, and the test procedure being initiated automatically in response to a signal from the timer means to the control unit.

The test procedure preferably includes a step of operating the purnp to reduce pressure in the chamber.

According to another aspect of the present invention there is provided a method of running a test procedure in an autoclave, comprising the steps of closing a door of a chamber of the autoclave, leaving the autoclave without further manual intervention to perform a test procedure automatically at a pre-set time, and subsequently checking the autoclave for the test results.

The test procedure preferably includes a leak test, which may include the step of reducing pressure in the chamber and monitoring rise in pressure over time. The leak test may be arranged to detect if a leak increases over subsequent test procedures. The test procedure may include an air detector function test, which may include the steps of reducing pressure in the chamber, introducing a controlled leak into the chamber and monitoring whether an air detector responds to the leak. The test procedure may include placing a porous test pack in the chamber, automatically initiating a cycle of the autoclave at a pre-set time and subsequently removing and inspecting the test pack some time after completion of the cycle.

According to a further aspect of the present invention there is provided an autoclave for use in the method of the above other aspect of the invention.

An autoclave sterilizer and a method of testing a sterilizer, according to the present invention, will now be described, by way of example, with reference to the accompanying drawing, which shows the sterilizer schematically.

The sterilizer has a chamber 1 with a door 2 through which articles to be sterilized are placed in the chamber. An electrical heating coil 3 at the bottom of the chamber 1 is energized by a control unit 4 to raise the temperature of water 5 and produce steam. When the chamber 1 is sealed, the steam raises the pressure and temperature in the chamber sufficiently for the articles to be sterilized.

The sterilizer also has a vacuum pump 10 connected via a pipe 12 and a filter 11 to the upper end of the chamber 1. Operation of the vacuum pump 10 is controlled by the control unit 4. When the pump 10 is off, it prevents passage of air through it. A solenoid-controlled fine valve 13 is also connected to the pipe 12, between the pump 10 and the filter 11, the valve also being connected to the control unit 4.

The control unit 4 includes a timer 20 and receives outputs from various sensors, such as a pressure sensor 21, a temperature sensor 22 and an air detector system 23. The air detector system 23 monitors variations in pressure and temperature with time. In an effective air removal cycle, these values will have a particular process profile. If the parameters are outside particular ranges, this can indicate that air removal has not been effective, so the cycle is aborted. In particular, a minimum vacuum level has to be achieved within a particular time.

If this is achieved, the chamber 1 is sealed and pressure is monitored to detect leakage into the chamber. Then water 5 is heated under vacuum and a second vacuum phase is performed and pressure is monitored to ensure that a particular vacuum level is achieved in a particular time. Then, pressure is monitored at a set temperature to determine if there is good correlation with steam table values. Outputs from the control unit 4 are connected to a display panel 30 and a printer 31.

In normal operation, the user places articles to be sterilized, which may be porous, in the sterilizer chamber 1 and closes the door 2. When the user starts the sterilization cycle, the pump 10 evacuates air in the chamber 1, which is then sealed before the heating coil 3 is energized. The sterilizer completes the sterilization cycle in the usual way.

The control unit 4 is arranged automatically to perform various test procedures. At the end of the day, the user places a conventional porous load test pack 40 in the chamber 1 and closes the door 2. At some pre-programmed time, which may be in the middle of the night or early morning, the control unit 4 automatically carries out the test procedures, without any further manual intervention from the user.

The tests may be of various different kinds. In the present example, the sterilizer performs three different tests, as follows.

The first test is a leak test. The control unit 4 turns on the vacuum pump 10 so that it pulls a vacuum in the chamber 1 of about 1 2kPa absolute. The control unit 4 then monitors the output of the pressure sensor 21 for a pre-set time, between about 2 to 5 minutes, to monitor the rate of leakage into the chamber 1. If the leakage is less than 2kPa/min, the control unit 4 determines that the leak rate is satisfactory and causes the printer 31 to print out a message to indicate a satisfactory result. If the leakage rate is too high, a message is printed indicating this. A warning message may also be displayed on the display panel 30. It can also be arranged that the sterilizer is disabled, preventing further sterilization cycles being started until the leak is corrected.

The control unit 4 maintains a store of the leak test results and detects if leakage is increasing over subsequent cycles. If such an increase is detected, the control unit 4 provides an indication of a potential future failure on a printed or displayed message.

The next test is an air detector function test, to test correct operation of the air detection system 23. In this, the control unit 4 causes the sterilizer to run a standard sterilization cycle and then introduces a small, controlled leak, by opening the valve 13 during a phase when the chamber 1 is at below atmospheric pressure. If the air detection system 23 detects the entry of air into the chamber 1, the control unit 4 determines that the sterilizer is functioning satisfactorily and the printer 31 prints out an appropriate message. If no leak is detected, a fault is indicated on the print-out.

The final test is a steam penetration test. This runs a normal sterilization cycle so that the porous load test pack 40 is sterilized. When the user opens the sterilizer in the morning, he removes the pack 40 and notes whether its colour change indicator has changed to the appropriate colour to indicate that there has been adequate steam penetration of the test pack.

These automatic test procedures are performed when the sterilizer is not needed.

Usually, this will be at night or early morning, but the user can program the control unit to alter the time of test to some more suitable time. Because the tests are performed automatically, without the intervention of the user, they do not require skilled staff, and there is less risk of error.

Some of the tests, such as the steam penetration test, need not be performed daily but, instead, perhaps once a week.

Claims

1. An autoclave having a chamber arranged to receive articles to be treated, a control unit and timer means, wherein the control unit is arranged automatically to run a test procedure for the autoclave, and wherein the test procedure is initiated automatically in response to a signal from the timer means to the control unit.

2. An autoclave according to Claim 1 including a pump and wherein said test procedure includes a step of operating the pump to reduce pressure in said chamber.

3. A method of running a test procedure in an autoclave, comprising the steps of closing a door of a chamber of the autoclave, leaving the autoclave without further manual intervention to perform a test procedure automatically at a pre-set time, and subsequently checking the autoclave for the test results.

4. An autoclave or method according to any one of the preceding claims, wherein said test procedure includes a leak test.

5. An autoclave or method according to Claim 4, wherein said leak test includes the steps of reducing pressure in said chamber and monitoring rise in pressure over time.

6. An autoclave or method according to Claim 4 or 5, wherein said leak test is arranged to detect if a leak increases over subsequent test procedures.

7. An autoclave or method according to any one of the preceding claims, wherein said test procedure includes an air detector function test.

8. An autoclave or method according to Claim 7, wherein said air detector function test includes the steps of reducing pressure in said chamber, introducing a controlled leak into said chamber and monitoring whether an air detector responds to the leak.

9. An autoclave or method according to any one of the preceding claims, wherein said test procedure includes placing a porous test pack in said chamber, automatically initiating a cycle of the autoclave at a pre-set time, and subsequently removing and inspecting the test pack some time after completion of the cycle.

10. A method of running a test in an autoclave substantially as hereinbefore described with reference to the accompanying drawing.

11. An autoclave for use in a method according to any one of Claims 3 to 10.

12. An autoclave substantially as hereinbefore described with reference to the accompanying drawing.

13. Any novel and inventive feature as hereinbefore described.