The validation andperiodic testing ofbenchtop vacuumsteam sterilizers

BULLETINMDA DB 9804

JUNE 1998

The Medical Devices Agency helps safeguard public health by working with users, manufacturers andlawmakers to ensure that medical devices meet appropriate standards of safety, quality and performanceand that they comply with the relevant Directives of the European Union.

Our primary responsibility is to ensure that medical devices achieve their fullest potential to helphealthcare professionals give patients and other users the high standard of care they have a right toexpect.

The Medical Devices Agency is an Executive Agency of the Department of Health

WHO THIS DOCUMENT IS FOR

This bulletin does not specify requirements but is intended to provideguidance to owners, managers and Users of vacuum benchtop steamsterilizers, and to those responsible for installation, validation and routinetesting of these devices.

For Owners and Managers: this document draws attention to obligationsunder Consumer Protection, and Health and Safety legislation, in order tominimise risk to patients and operators.This includes ensuring that:

l the equipment complies with safety requirements and it isinstalled and maintained appropriately;

l it is operated in accordance with the manufacturersinstructions;

l operators are trained;

l it is validated and routinely tested;

l records of validation, performance qualification, periodictesting, and sterilization cycles are made, and retained underappropriate conditions.

For Users: this document provides information to ensure the sterilizer isfunctioning safely and correctly through:

l daily testing;

l weekly safety checks and

l weekly testing.

For medical physicists and Test Persons (sterilizers): this documentprovides test protocols. Methods of test are provided in Annex A.

This bulletin complements the Medical Devices Agency’s (MDA)'sDevice Bulletin DB96052, ‘The purchase, operation and maintenance ofbenchtop steam sterilizers’.

SUMMARY

Saturated steam under pressure at the highest temperature compatible withthe product is the preferred method for the sterilization of medical devices.

Steam sterilization requires direct contact between dry saturated steam andall surfaces of the load at a specified temperature and pressure, and for aspecified time. Direct contact is prevented by blood, mucus and tissuedeposits on the load items, and by air present in the chamber and load. Toenable sterilizing conditions to be achieved, load items must, therefore, becleaned thoroughly and air removed effectively from the chamber andload. Guidance on cleaning and decontamination of medical devices isprovided in MDA’s publication ‘Sterilization, disinfection and cleaning ofmedical equipment’3

.

Sterilization is a process whose effectiveness cannot be verified byinspection and testing of the product. For this reason, successfulsterilization depends on the consistent reproducibility of sterilizingconditions. Sterilizers have therefore to be validated before use, theirperformance monitored routinely (by periodic testing) and the equipmentproperly maintained.

Whenever practicable, sterile items should be obtained from a centralSterile Services Department which has the equipment and expertise todecontaminate and sterilize re-usable medical devices; they also offerconsistent quality and economy of scale. In the absence of centralsterilization services a suitable, properly operated, benchtop steamsterilizer may be used provided it has been validated for the intended load.

This Bulletin provides guidance on the validation and periodic testing ofvacuum benchtop steam sterilizers whose chamber volume is less than 54litres. These sterilizers are equipped with a pre-sterilization active airremoval (vacuum) stage and are not connected permanently to mainservices. They may also be referred to as benchtop porous loadsterilizers. For sterilizers which are permanently connected to mainservices, reference should be made to Health Technical Memorandum2010 (HTM 2010) - Sterilization, Part 3: Validation and verification’.

Steam sterilizers have to be validated to demonstrate that the physicalconditions required for sterilization (temperature, pressure and time) areachieved. This includes commissioning checks and tests (to ensure that theequipment, as delivered, functions safely and will produce sterilizingconditions consistently), and routine periodic testing to ensure that theequipment continues to perform correctly.

It is the responsibility of the manager of the sterilizer to ensure that thesterilizer is functioning correctly, is safe to use and will produce sterileproduct consistently. The manager is therefore ultimately responsible foragreeing the necessary validation and periodic testing and may wish toseek independent advice from a person who is knowledgeable andexperienced in all aspects of sterilization, such as an Authorised Person(sterilizers).

The test methods for steam sterilizers are provided in HTM 2010 : Part 31

and wherever possible we specify test methods by reference to HTM 2010.

Daily tests have to be performed by the User and because Users may nothave access to HTM 20101, the test methods for these are provided in full.

For some of the periodic tests which are performed by a Test Person(sterilizers) [TP(s)], the HTM 2010 method is not directly applicable. Inthese cases methods are either provided by the sterilizer manufacturer, orin this bulletin. The User may wish to have any manufacturer’srecommendations or test methods verified during commissioning.

The validation and periodic testing ofbenchtop vacuum steam sterilizers

CONTENTS

1. GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.1 Personnel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2 Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3. PRESSURE SYSTEMS AND TRANSPORTABLE GASCONTAINERS REGULATIONS 1989. . . . . . . . . . . . . . . .

4. ASSURING THE PERFORMANCE OF STERILIZERS . . .

4.14.24.34.44.54.64.6.14.6.24.6.34.6.44.6.54.6.64.6.74.6.84.7

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Test equipment . . . . . . . . . . . . . . . . . . . . . . . . . . .Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Procedure on failure of a test . . . . . . . . . . . . . . . . . . . . .THE VALIDATION PROCESS . . . . . . . . . . . . . . . . .COMMISSIONING. . . . . . . . . . . . . . . . . . . . . . . . . .

Installation checks and tests . . . . . . . . . . . . . . . . . . .Installation tests . . . . . . . . . . . . . . . . . . . . . . . . . .Preliminary checks . . . . . . . . . . . . . . . . . . . . . . . . .Electrical checks. . . . . . . . . . . . . . . . . . . . . . . . . .Functional checks. . . . . . . . . . . . . . . . . . . . . . . . .Response to faults . . . . . . . . . . . . . . . . . . . . . . . . .Installation tests . . . . . . . . . . . . . . . . . . . . . . . . . .Commissioning tests. . . . . . . . . . . . . . . . . . . . . . .

PERFORMANCE QUALIFICATION. . . . . . . . . . . . . . . .

5. PERIODICTESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.2 Weekly and quarterly safety checks . . . . . . . . . . . . . . .5.3 Yearly safety checks . . . . . . . . . . . . . . . . . . . . . . . . . . .5.4 Yearly tests and revalidation . . . . . . . . . . . . . . . . . . . .

6. USE OF CHEMICAL INDICATORS. . . . . . . . . . . . . . . . .

ANNEX A - Test methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A.1 Steam penetration test. . . . . . . . . . . . . . . . . . . . . . . . . .

A.2

A.3A.3.1A.3.2

Automatic control test. . . . . . . . . . . . . . . . . . . . . . . . .

Air leakage test. . . . . . . . . . . . . . . . . . . . . . . . . . . . .Automatic test - User. . . . . . . . . . . . . . . . . . . . . . . .Manual test - Test Person. . . . . . . . . . . . . . . . . . . . .

A.4 Chamber wall temperature test . . . . . . . . . . . . . . . . . . .

A.5 Thermometric tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . .A.5.1 Small load test. . . . . . . . . . . . . . . . . . . . . . . . . . . . .A.5.2 Full load test . . . . . . . . . . . . . . . . . . . . . . . . . . . .A.5.3 Solid load test. . . . . . . . . . . . . . . . . . . . . . . . . . . .

8

8

89

10111111121212121314141517

17

17182121

23

24

24

25

272828

28

29303030

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A.6 Load dryness tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31A.6.1 Porous load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31A.6.2 Solidload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31A.7 Microbiological test for Performance Qualification . . . . 32A.8 Standard test pack . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32ANNEX B - European directive . . . . . . . . . . . . . . . . . . . . . . . . . 33

ANNEX C - Pressure systems and transportable gas containersregulations 1989 . . . . . . . . . . . . . . . . . . . . . . . . . . 35

ANNEX D - Sources of further information . . . . . . . . . . . . . . . . 36ANNEX E - MDA publications relevant to sterilization . . . . . . . . 37

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

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1

1.1

GLOSSARY

Personnel

Further information, including qualifications and areas of responsibility,can be found in HTM 2010 : Part 14.

Is a person designated by management to provide independent auditing andadvice on sterilizers and sterilization and to review and witness validationdocumentation. A list of suitably qualified Authorised Persons (Sterilizers)is maintained by the Institution of Healthcare Engineering and EstatesManagement (see Annex D).

Is a person or organisation designated by management to exercise certainlegal responsibilities under the Pressure Systems and Transportable GasContainers Regulations 1989 (see HTM2010 : Part14).

Is a person or organisation designated by management to be responsible forthe supply and installation of the sterilizer, and for the conduct of theinstallation checks and tests. The contractor is commonly the manufacturerof the sterilizer.

Is the person who is ultimately accountable for the operation of thepremises. Depending on the nature of the organisation, this may be theowner, occupier, employer, general manager, chief executive, or otherperson of similar authority. In small, autonomous installations the Usermay take on this function.

Is a person or organisation responsible for the manufacture of a sterilizeror other equipment.

Is any person with the authority to operate a sterilizer, including the notingof sterilizer instrument readings and simple housekeeping duties.

Is a person designated by management to carry out validation and periodictesting of sterilizers.

Is a person designated by management to carry out maintenance duties onsterilizers.

Is the person designated by management to be responsible for themanagement of the sterilizer. In a hospital the User could be a SterileServices Department manager or Theatre manager or, in primary care, ageneral practitioner, dentist, or other healthcare professional.

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1.2 Testing:

is the removal of air from the chamber using mechanical means eg vacuum

pump.

are the physical characters, such as time, temperature, pressure, thatinfluence the efficacy of the sterilization process.

is the period which elapses between attainment of the sterilizationtemperature in the chamber and the attainment of the sterilizationtemperature at all points within the load. It begins when the temperature inthe coolest part of the chamber (normally the active chamber discharge)first attains the sterilization temperature. It ends when the holding timebegins.

begins when the part of the load that is the slowest to heat up first attainsthe sterilization temperature. It ends when the temperature in the coolestpart of chamber falls below the sterilization temperature.

a device which is open at one end, is hollow if the ratio of cavity length todiameter is greater than one. If the device is double open-ended, it ishollow if the ratio of cavity length to diameter is greater than two.

is that shown by a visual display fitted permanently to the sterilizer,

is that shown on a test instrument, such as a thermometric recorder or a testpressure gauge, attached to the sterilizer for test purposes.

air and other gas which will not condense under the conditions of steamsterilization.

is that written down by the operator, usually as the result of observing anindicated. recorded or measured value.

is the process of obtaining and documenting evidence that the equipmentas commissioned will produce acceptable product when operated inaccordance with the process specification.

is the equilibration time plus the holding time.

material or configuration that can hold or trap air that will interfere withsteam penetration.

4

is that shown on the output of a recording instrument fittedthe sterilizer.

permanently to

are the ranges of the cycle variables which may prevailchamber and load during the holding time.

throughout the

is the minimum acceptable temperature of the sterilization band.

is the range of temperatures which may prevail throughout the load duringthe holding time. These temperatures are expressed as a minimumacceptable temperature (the sterilization temperature) and a maximumallowable temperature, and are stated to the nearest degree Celsius.

2 INTRODUCTION

Minor surgical procedures are increasingly being performed in healthcarepremises and General Practitioners’ (GPs’) surgeries; they are performedregularly in dental practices.

Whenever practicable the sterile items required for these procedures shouldbe obtained from a central Sterile Services Department (SSD). These havethe equipment and expertise to decontaminate and sterilize re-usablemedical devices; they also offer consistent quality and economy of scale.In the absence of central sterilization services a suitable validated, andproperly operated, benchtop steam sterilizer may be used.

Benchtop steam sterilizers in which air is passively displaced by steam aresuitable only for processing instruments and utensils that are not wrapped,and are not hollow. Instruments or utensils enclosed in any form ofwrapping, hollow items or devices with lumens, and porous materialsshould be processed only in a benchtop sterilizer equipped with an activeair removal system which has been validated for the intended loads.

Steam sterilization requires direct contact between dry saturated steam andall surfaces of the load at a specified temperature and pressure, and for aspecified time. Direct contact is prevented by blood, mucus and tissuedeposits on the load items, and by air present in the chamber and load. Toenable sterilizing conditions to be achieved, load items must, therefore, becleaned thoroughly and air removed effectively from the chamber and load.Effective air removal is essential to enable steam to penetrate packs andlumens, and this can only be achieved if the sterilizer is equipped with anactive air removal system. Such sterilizers are known as vacuum benchtopsterilizers or benchtop porous load sterilizers.

5

Vacuum benchtop sterilizers are available from a number of manufacturersand are essential when the load includes:

l hollow instruments and utensils, either wrapped orunwrapped;

l wrapped solid instruments and utensils;

l porous loads.

They have the following features:

l an active air removal stage prior to the sterilizing stage;

l a post-sterilization drying stage;

l electrical heating;

l sterilizing chamber volume less than 54 litres;

l no connections to main services (except for electricity).(Note : Benchtop steam sterilizers which are connected tomain services should meet in ful l the test ingrequirements of HTM 2010: Part 31.)

The active air removal (vacuum) stage is essential if sterilizing conditionsare to be established and maintained throughout the load for one of thetemperature/time combinations specified in Table 7 (p.27).

The drying stage is intended to reduce the moisture content of packagesand porous materials to a level which will not permit bacterialrecontamination.

Sterilization is a process whose effectiveness cannot be verified byinspection and testing of the product. For this reason, successfulsterilization depends on the consistent reproducibility of sterilizingconditions. Sterilizers have therefore to be validated before use, theirperformance monitored routinely (by periodic testing) and the equipmentproperly maintained.

Validation is intended to demonstrate that the physical conditions requiredfor sterilization (temperature, pressure and time) are achieved. It includescommissioning checks and tests (to ensure that the equipment, asdelivered, functions safely and will produce sterilizing conditionsconsistently), and routine periodic testing to ensure that the equipmentcontinues to perform correctly.

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Guidance on the management, installation, validation, periodic testing,operation and maintenance of a variety of types of sterilizer is provided inHealth Technical Memorandum (HTM) 2010. This is published in six Partsand Part 31 is the standard work on the validation and periodic testing ofsterilizers, but it only partly covers vacuum benchtop sterilizers.

The Medical Devices Agency (MDA) Device Bulletin DB96052, publishedin June 1996, provides information specific to benchtop steam sterilizersfor unwrapped solid instruments and utensils but is not directly applicableto vacuum benchtop steam sterilizers.

This bulletin provides guidance to Users, Test Persons (sterilizers)[TP(s)] and Authorised Persons (sterilizers) [AP(s)] on the validationand periodic testing of vacuum benchtop steam sterilizers which arenot fully covered in other publications.

These terms are explained in the Glossary.

A list of suitably qualified AP(s) is maintained by the Institute ofHealthcare Engineering and Estate Management (see Annex D). The AP(s)will provide advice regarding the services of a TP(s), where necessary.

Users are reminded of their obligations under the Consumer Protection andHealth and Safety legislation.

Amongst other things, Users must ensure that the equipment complies withsafety requirements, it is installed and maintained appropriately and that itis validated and routinely tested. The equipment should be operated only inaccordance with the manufacturer’s instructions. Operators who arefamiliar with other types of steam sterilizer are not necessarily qualified tooperate vacuum benchtop steam sterilizers unless they have receivedspecific training in the use of this equipment.

Because vacuum benchtop steam sterilizers are more complicated than thetraditional (non vacuum) benchtop steam sterilizers, they require morerigorous testing to demonstrate that they function correctly.

It is MDA’s opinion that this type of sterilizer should be equipped onlywith cycles for porous loads in order to minimise the possibility of anincorrect cycle being selected and consequentfailure to sterilize the load.

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3 PRESSURE SYSTEMS ANDTRANSPORTABLE GASCONTAINERS REGULATIONS 1989

Benchtop steam sterilizers contain pressure vessels and must comply withthe Pressure Systems and Transportable Gas Containers Regulations 1989(SI 1989/2169)5. These regulations are intended to minimise the risk of apressure system, or part of it, failing and causing injury. They require allpersons using these machines to be adequately trained in their operationand in the procedures to be used in an emergency.

Owners are primarily responsible for ensuring compliance.

All pressure vessels must be inspected periodically by a Competent Person(Pressure Vessels), according to a written scheme. Further information isprovided in Annex C.

4 ASSURING THE PERFORMANCE OFSTERILIZERS

4.1 Introduction

The effectiveness of sterilization cannot be verified retrospectively byinspecting or testing the product. Tests and checks carried out duringmanufacture, during validation and during periodic testing of the sterilizerprovide assurance that the process will consistently produce a sterile product.

Standards and RegulationsUnder the Medical Devices Directive (93/42/EEC)6, sterilizers which areintended to re-process medical devices will have to be manufactured to meetacceptable standards of safety and performance. All such sterilizers placedon the market after 13 June 1998 will have to bear the CE marking,signifying conformity with this Directive. [See Annex B for moreinformation]. Until 14 June 1998, in the absence of CE marking, sterilizersshould be manufactured under a recognised quality management system egBS EN ISO 9001 (1994)7 or BS EN ISO 9002 (1994)8 and should complywith BS3970 : Part 1 : 19909, BS EN 61010 : Parts 110 and 2-04111 and theElectro Magnetic Compatibility (Amendment) Regulations 1994 (SI 1994No 3080)12. Most steam sterilizers will have to conform with the PressureEquipment Directive when it comes into force (see Annex B).

At present there are no standards which apply specifically to vacuumbenchtop sterilizers, but European Standards are being prepared (1998)13,14,15

under a mandate from the European Commission.

8

Steam sterilizers have to be validated to demonstrate that the physicalconditions required for sterilization (temperature, pressure and time) areachieved. This includes commissioning checks and tests (to ensure that theequipment, as delivered, functions safely and will produce sterilizingconditions consistently), and routine periodic testing to ensure that theequipment continues to perform correctly.

ValidationSpecified checks and tests should be carried out following delivery andinstallation of the sterilizer (and at regular intervals thereafter) to provideassurance that a sterilizer is safe to use and will consistently achievesterilizing conditions throughout a load.

Periodic TestingThe User is required to perform routine daily tests. After suitable training,and with the agreement of the AP(s), the User may also carry out weeklytesting. These tests, and the reference to the test procedure, are presentedin tables 1 to 4. Details of the test methods are in Annex A. Some of themore complicated tests undertaken by the TP(s) are specific to vacuumbenchtop steam sterilizers and test methods for these are also provided inAnnex A. Other tests performed by the TP(s) are identical to those in HTM2010 : Part 31 and are identified in the Tables by reference to the relevantparagraphs in the HTM.

MaintenanceAppropriate maintenance is essential to ensure the continuing safety andperformance of the sterilizer. The User may perform minor, routinemaintenance tasks specified by the manufacturer but other maintenance orrepair should be performed only by trained specialists. Before a sterilizeris returned to service after modification or repair it should be tested andchecked to provide assurance of the effectiveness of the sterilizationprocess and the safety of the equipment.

Where repairs or modifications have involved any part of the pressuresystem (eg the pipework, the chamber, and its fitting) the advice of aCompetent Person (pressure vessels)5 should be sought before the sterilizeris returned to service.

4.2 Test Equipment

Information about the type of test equipment required for the validationand routine testing of steam sterilizers, its calibration and sources of erroris available in HTM 2010 : Part 3, Chapter 61.

Tests performed by the User should not require specialised test equipment.

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4.3 Documentation

Guidance on the documentation that should be kept is provided in HTM2010 : Part 416.

Records of maintenance, testing and operating cycles provide evidence thatthe process will deliver sterile product consistently. All checks, tests andmaintenance performed on sterilizers must be documented and the recordskept securely as specified in BS EN ISO 9001 (1994)7 or BS EN ISO 9002(1994)8,and the Pressure Systems and Transportable Gas ContainersRegulations 19895

A record should be made of the values and permitted tolerances of thecycle variables for each correctly functioning operating cycle available tothe operator, and for each load type that is to be processed. This forms theMaster Process Record (MPR) against which:

l the User should compare production cycle records to verifythat sterilizing conditions have been achieved for each load;

l the results of the weekly User tests should be compared toestablish whether the sterilizer is functioning correctly andachieving sterilizing conditions.

The MPR also provides the means to determine whether the results ofperiodic tests and performance re-qualification tests carried out by theTP(s) are satisfactory. Information about the preparation of an MPR isprovided in HTM2010: part 31, 8.58 et seq.

The results of the daily tests should be recorded in the sterilizer log book,dated and signed by the User. Steam penetration indicator test sheets,marked with the result of the test, dated and signed by the operator, shouldbe retained for at least three months and stored under the conditionsrecommended by the manufacturer of the test sheet.

Every production cycle must be fully documented and the record keptsecurely for the time specified by the management [guidance is provided inHealth Circular HC(89)2017]. The information recorded should include:

l whether the cycle was a pass or a fail;

l the date and cycle number;

l the chart record for the cycle;

l the identity of the operator;

l the type of load (eg whether porous materials, solidinstruments, hollow instruments or a mixture etc);

10

l the sterilization cycle selected.Recording and retention of temperature, pressure and time data generatedduring testing and normal use of the sterilizer is simplified if the sterilizeris fitted with a recorder.

[It is MDA’s opinion that this type of sterilizer should always be equippedwith a pressure and temperature recorder.]

4.4 PROCEDURE ON FAILURE OF A TEST

The AP(s) and the User should agree in advance the procedure for handlingtest failures.

A failure of a test implies that the sterilizer is not working to specificationand it should be withdrawn from service, the failure investigated, and thecause rectified.

It should be emphasised that the User has the ultimate responsibilityfor certifying that the sterilizer is fit for use.

4.5 THE VALIDATION PROCESS

Validation is the documented procedure for obtaining, recording andinterpreting the results needed to show that a process will consistently yielda product complying with pre-determined specifications. It is considered asa total process which comprises commissioning followed by performancequalification (Figure 1).

Commissioning

VALIDATIONThermometric tests

Performance qualification (PQ)Microbiological tests

Figure 1. The validation process(if necessary)

4.6 COMMISSIONING

Commissioning is the process of obtaining and documenting evidence thatthe equipment has been supplied and installed in accordance with itsspecifications, that it is safe to operate and that it functions within pre-determined limits when operated in accordance with the manufacturer’soperating instruction. It consists of installation checks, installation testsand commissioning tests which should be carried out after installation ofthe sterilizer in the place of use.

During commissioning, the AP(s) may wish to verify anyrecommendations from the manufacturer relating to test procedures.

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4.6.1 Installation checks and tests

The purchasing contract should specify who is responsible for carrying outinstallation checks and tests.

4.6.2 Installation checks - the Contractor

These are set out below and are carried out by the contractor (who may alsobe the manufacturer), after the sterilizer has been delivered and installed.

4.6.3 Preliminary checks

Check that:

l the sterilizer has been supplied and installed in accordancewith the contract;

l no defects are apparent from a visual inspection of thesterilizer;

l security and settings of door safety switches and door-locking components comply with data provided by themanufacturer and with HSE Guidance Note PM7318;

l load supports, trays and other aids are effective and safe inuse;

l keys, codes or tools required to operate locked cycle-selectcontrols are supplied and operate satisfactorily and that eachkey, code or tool unlocks only the cycle-select control forwhich it is intended;

[To prevent an inappropriate cycle being selected by theoperator, controls which enable non-standard cycles tobe selected should be available only to MaintenancePersons (sterilizers), TP(s) and AP(s).]

l the manufacturer has supplied all the documents specified inthe contract, including calibration verification certificates forthe temperature and pressure instruments and controllers.

4.6.4 Electrical checks

After 13 June 1998 benchtop steam sterilizers intended to reprocess medicaldevices will have to bear the CE marking, signifying that the equipmentmeets relevant standards of safety and performance (including electricalsafety) of the Medical Devices Directive 93/42 EEC6. Until then, the

12

sterilizer should conform with the requirements of BS EN 61010 : Part 110,and Part 2 - 04111 and a certificate of conformity should be provided. Theelectrical installation in the building should conform with BS 767119. Nofurther electrical tests are necessary provided that a visual inspectionconfirms that the equipment and electrical installation is undamaged.

4.6.5 Functional checks

Several cycles may be necessary to complete all the functional checks.

During an operating cycle with an empty chamber, the following shall bechecked:

l the selection of automatic or manual control is by key, codeor tool. [Manual control should be available only toMaintenance Persons (sterilizers), TP(s) and AP(s) fortesting];

l the operating cycle cannot start until the door is closed andlocked;

l throughout the cycle, indicated and recorded steam pressuresand temperatures are within the limits specified by themanufacturer, and the sterilization temperature and holdtime are within the appropriate band specified in Table 7,p27;

l there are no leaks of steam or water;

l the operation and readings of all instruments appearsatisfactory;

l where the air vent and/or the chamber drain discharges intothe water reservoir, that the water in the reservoir does notboil.

At the end of a cycle check that:

l the door opening system cannot be operated until thechamber pressure has returned to atmospheric pressure;

l the door interlock system is fitted with at least twoindependent interlocks and failure of one interlock does notallow the door to be opened when conditions within thechamber would cause a hazard;

l the automatic controller has operated in accordance with thespecification.

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4.6.6 Response to faults

The sterilizer should not create a safety risk and should not give a falseindication of “cycle complete” when it is subjected to the followingsimulated faults :

l interruption of power supply (including power failure,operation of emergency stop button - where fitted, switchingoff, etc);

l insufficient water to complete a cycle;

l the required vacuum level, before or after the sterilizationstage, is not achieved;

l the required combination of sterilizing temperature and holdtime is not achieved;

l excessive pressure and/or temperature in the chamber for thecycle selected.

When excessive pressure has been generated in the chamber it is advisable,before the sterilizer is re-pressurised, for a Competent Person (pressurevessels) to check that the pressure integrity of the chamber has not beenimpaired and that the over-pressure protection devices function correctly.

If the sterilizer fails any check, the condition causing the failure must berectified and the complete programme of checks repeated sequentially.

After successful completion of all checks, the contractor shall carry out theinstallation tests to demonstrate that the sterilizer is working satisfactorilyand that it complies with its specifications.

4.6.7 Installation tests - the Contractor

These tests should be carried out by the contractor, after successfulcompletion of the safety checks, using the method prescribed in thisdocument. They should be carried out with the sterilizer at normal workingtemperature (except for the air leakage test) and completed in the ordershown in Table 1.

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TABLE 1

INSTALLATION TESTS

These tests should be performed by the contractor after successfulcompletion of the safety checks.

1 Air leakage test* (manual) A.3.2†

2 Automatic control test for each cycle available to the User A.2

3 Verification of calibration of sterilizer instruments (can bedone at the same time as the previous test).

HTM 2010:3, 6.32et seq and 12.2

* HTM 2010 refers to this test as Vacuum Leak Test. See annex A, p24.

The Contractor shall provide:

l a list identifying the checks and tests that have beenperformed during installation;

l data showing the control settings (including time,temperature, pressure and air detection system settings,where applicable) for each cycle available. For micro-processor controlled sterilizers, it should be possible to printout these settings;

l written confirmation that control settings have been set up asrecommended by the manufacturer.

4.6.8 Commissioning tests - the Test Person

Commissioning tests evaluate basic performance and safety. The tests setout in Table 2 should be performed by the TP(s) after successfulcompletion of the installation checks and tests; all cycles available to theUser should be tested. The sterilizer should be accepted only aftersuccessful completion of all tests to demonstrate that it is workingsatisfactorily and that it conforms with its specifications.

Because the design of these sterilizers may differ considerably betweenmanufacturers, some of the specified tests may require test procedureswhich are unique to particular models of sterilizers. Such cases areidentified in the Tables by the symbol u and for these the manufacturer ofthe sterilizer will have to provide the test method.

The manufacturer shall also provide :

l evidence that the water recommended for use in the sterilizerwill consistently produce steam with a non-condensable gaslevel below 0.5% when tested by the method described inprEN 13060 - Part 415;

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l evidence of the effectiveness of the air detection system;

l evidence of the effectiveness of the sterilizer in processingthe porous loads intended by the manufacturer.

If commissioning follows within 10 working days of the installation teststhere is no need to repeat any commissioning tests which have already beenperformed successfully as installation tests.

TABLE 2

COMMISSIONING TESTS

These tests are performed by the TP(s)

Air leakage test (automatic) A.3.1

2 Air leakage test (manual) (temperature and pressure A.3.2sensors connected)

3 Automatic control test A.2

4 Verification of calibration of sterilizer instruments.* HTM 2010:3, 6.32et seq and 12.2

5 Chamber wall temperature test** A.4

6 Steam generator overheat cutout test HTM 2010:3, 15.3

7 Air detection system performance test for a small load. u

8 Air detection system performance test for a full load u

9 Thermometric test for a full load A.5.2

10 Load dryness test* A.6.1

11 Thermometric test for a small load A.5.1

12 Thermometric test for a solid load A.5.3

13 Solid load dryness test* A.6.2

14 Thermometric tests for PQ as required by the User HTM 2010:3, 8.13

15 Microbiological tests for PQ A.7

16 Air leakage test (automatic) (sensors removed) A.3.1

17 Air detection system function test (automatic)

18 Steam penetration test

u

A.1

* Can be done at the same time as the previous test.u Test method as specified by the manufacturer.** This test is required only when the chamber wall is heated eg for the

drying cycle.

NOTE : only cycles available to the User need be tested.

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4.7 PERFORMANCE QUALIFICATION (PQ) - the TestPerson

Data from the thermometric commissioning tests provide assurance thatsterilizing conditions are attained throughout most loads. PQ testing isneeded to show that sterilizing conditions are attained throughout any otherloading condition which the User judges to be particularly difficult tosterilize.

PQ comprises tests 14, 15, 16, 17, 18 and 10 from Table 2, which areperformed either on the load which the User judges to be particularlydifficult to sterilize or on a test load that represents it.

For some loads, eg lengths of polymeric (including rubber) tubing or otherdevices with lumens, thermometric monitoring of the adequacy of airremoval may not be appropriate as residual static air in the tubing may beheated by conduction. For this type of load, the advice of an AP(s) and asuitably qualified microbiologist should be sought.

Performance qualification should not be attempted on any sterilizerthat fails to meet the requirements of the commissioning tests.

5 PERIODIC TESTS

5.1 Introduction

The responsibility for performing the Periodic Tests is shared by the Userand the TP(s); the tests are carried out at daily, weekly, quarterly and yearlyintervals to demonstrate that the performance of the sterilizer continues tobe satisfactory. All periodic tests should be carried out with the sterilizer atnormal working temperature (except for the air leakage test) and completedin the order shown in Tables 3 to 6.

The User should perform the daily tests and, after suitable training, withthe agreement of the AP(s) the User may also perform the weekly tests. TheTP(s) should perform the quarterly and annual tests listed in Tables 5 and6, for each cycle available to the User.

Air DetectorsEffective removal of air and other non-condensable gas (referred tocollectively as ncg) is essential to the achievement of sterilizing conditions.Porous load sterilizers must therefore be fitted with a means to detect ncgpresent in sufficient quantity to prevent the attainment of sterilizingconditions within the load. These devices are commonly called airdetectors. They are fitted to large porous load sterilizers. Vacuum Benchtopsteam sterilizers must also be equipped with either an air detector oranother system for detecting the presence of ncg which is capable of beingvalidated.

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Air detector testingThe continued correct functioning of the air detection system must betested weekly, quarterly and annually. If the sterilizer is fitted with an airdetector, the method specified for the air detector function test in HTM2010: Part 3 11.62 et seq1 should be followed. (Note: it may not be possibleto place the pack at the height specified in 11.62). The test should beperformed by a TP(s) but, if the sterilizer is equipped with an automatic testcycle, the User may perform the weekly test with the agreement of theAP(s).

As there is unlikely to be a standard air detection system, each sterilizermanufacturer must specify the test method to demonstrate that theautomatic air detection system is functioning correctly. Although the testmethods may differ, in all cases the test result shall demonstrate that the airdetection system will detect ncg present in sufficient quantity to depressthe temperature at the centre of a test pack by more than 2°C below thetemperature in the active chamber discharge. The test pack shall representthe maximum density of porous load material that the sterilizer is capableof processing.

Air detector system performance tests and function tests must also beperformed quarterly and annually by the TP(s) using independent,calibrated instruments. The results of these tests shall demonstrate thecorrect functioning of any automatic air detection system fitted to thesterilizer.

TABLE 3

DAILY TESTS

These tests may be performed by the User

1 Steam penetration test A.1

2 Automatic control test* A.2

*May be done at same time as the preceding test. This test is not requiredif the sterilizer is equipped with a recorder which provides a permanentrecord of the temperature, pressure and elapsed time during all sterilizingcycles.

NOTE : the manufacturer should advise whether these daily tests maybe done without pre-heating the sterilizer chamber.

5.2 Weekly and quarterly safety checks

These checks should be made by the User before starting the sequence ofweekly tests, and by the TP(s) before starting the sequence of quarterlytests:

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l examine the door seal [performed weekly by the User,quarterly by the TP(s)];

l check the security and performance of door safety devices[quarterly by the TP(s)];

l make any other checks required by the Competent Person(Pressure Vessels) (see Annex C) in connection with thewritten scheme of examination for the pressure vessel.

TABLE 4

WEEKLY TESTS

These tests should be performed by the test person - after successfulcompletion of the weekly safety checks .

1 Air leakage test (automatic) A.3.1

2 Automatic air detection system function test u

3 Automatic control test A.2

4 Steam penetration test* A.1

* May be done at the same time as the previous test.u Test method specified by the manufacturer.

NOTE : these tests may be performed by the User with the agreementof the AP(s).

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TABLE 5

QUARTERLY TESTS

These tests should be performed by the TP(s) - after successfulcompletion of the weekly safety checks.

1 Air leakage test - automatic A.3.1

2 Air leakage test - manual - (temperature and A.3.2pressure sensors connected)

3 Automatic control test A.2

4 Verification of calibration of sterilizer instruments* HTM 2010:3, 6.32 etseq and 12.2

5 Thermometric test for a small load* A.5.1

6 Air leakage test (automatic) (sensors removed) A.3.1

7 Air detection system function test (Manual) HTM2010:3,11.601†

8 Air detection system function test (Automatic) u

9 Steam penetration test A.1

* Can be done at the same time as the previous testu Test method specified by the manufacturer† (Note : it may not be possible to place the pack at the height

specified in 11.62).

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5.3 Yearly safety checks

These are performed by the TP(s), to ensure the safe functioning of thesterilizer. The checks should be selected from the list of commissioningchecks, identifying those which affect safety and also those which mayhave changed over the course of time. The AP(s) will advise which checksneed to be included.

If the sterilizer fails any check, the fault should be rectified and all checksshould be completed satisfactorily before starting the yearly or revalidationtests.

5.4 Yearly tests and revalidation

The yearly and revalidation test programmes are identical and areperformed by the TP(s).

The yearly tests are intended to confirm that the data generated duringvalidation remain consistent and valid.

Revalidation comprises recommissioning and performance requalification.It is required:

l when modification or engineering work has been carried outwhich could affect the performance of the sterilizer*;

l after planned maintenance, repair or any work requiring theremoval of components that could affect the performance ofthe sterilizer*;

l when the preset values of cycle variables have been changed;

l when the software used for the control of the process hasbeen modified;

l when the batch record is outside the limits specified on theMPR;

l when the sterilizer is returned to service after investigationand correction of unacceptable deviations from the MasterProcess Record (MPR);

l when required by the User or the AP(s).

* In these cases it may be necessary for a Competent Person (pressurevessels)5 to examine the sterilizer before it is tested.

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TABLE 6YEARLY AND REVALIDATION TESTS

These tests are performed by the TP(s) - after the successful completionof the yearly safety checks.

1 Air leakage test (automatic) A.3.1

2 Air leakage test (manual) (temperature and pressure A.3.2sensors connected)

3 Automatic control test A.2

4 Verification of calibration of sterilizer instruments* HTM 2010:3, 6.32et seq and 12.2

5 Chamber wall temperature test** A.4

6 Steam generator overheat cutout test HTM 2010:3, 15.3

7 Air detection system performance test for a small load u

8 Air detection system performance test for a full load u

9 Thermometric test for a full load A.5.2

10 Porous load dryness test* A.6.1

11 Thermometric test for a small load A.5.1

12 Thermometric test for a solid load* A.5.3

13 Solid load dryness test A.6.2

14 Tests for performance requalification as required HTM 2010:3, 8.64by the User

15 Air leakage test (automatic) (sensors removed) A.3.1

16 Air detector system function test (automatic)

17 Steam penetration test

u

A.1

* May be done at the same time as the previous test.u Test method as specified by the manufacturer.** This test is required only when the chamber wall is heated eg for the

drying cycle.

RevalidationThe revalidation tests are identical to those in the yearly tests schedule setout above. Any performance qualification tests which were performedduring the original validation will need to be repeated. Note: this isnecessary only for loads that will continue to be processed.

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6 USE OF CHEMICAL INDICATORS

BS EN 867 : 199720 provides specifications for chemical indicators forsterilization processes.

Chemical indicators should be used only for the process specified bythe manufacturer, as the use of an inappropriate indicator may givedangerously misleading results.

Chemical indicators are designed to show a defined colour change whenspecified conditions have been attained but they should only be used tosupplement definitive thermometric results. A failed operating cyclemust always be regarded as unsatisfactory, irrespective of the resultsobtained from any chemical indicators.

The performance of indicators may be adversely affected by the storageconditions before use, the methods of use, and storage conditions after use.It is important, therefore, to select the correct indicator and to follow themanufacturer’s recommended instructions precisely. Indicators should notbe used beyond the expiry date stated by the manufacturer.

There are two types of chemical indicator which are commonly used insteam sterilizers:

a)

b)

process indicators (eg autoclave tape), known as Class A indicators,which serve only to distinguish processed items from unprocesseditems. These indicators should not be used for any other purpose;

indicators for use in specific tests, known as Class B indicators.These include indicators for use in standard test packs to indicate theeffectiveness of steam penetration (the Bowie and Dick test), and indisposable/reusable alternative Bowie and Dick type test packs.

The indicators to which this bulletin refers are Class B indicators.

Class D (integrating) indicators are available for monitoring this type ofsterilizer but they do not indicate sterility of the product.

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ANNEX A

TEST METHODS

The AP(s) may wish to verify, during commissioning, anyrecommendations from the manufacturer relating to test procedures.

A.1 Steam penetration test

This test is analogous to the Bowie and Dick test performed on largeporous load sterilizers and is part of the commissioning, daily, weekly,quarterly and annual test programmes. The daily and weekly test isperformed by the User or a TP(s); the quarterly and annual test isperformed by a TP(s). The test should be performed according to theinstructions of the sterilizer manufacturer or, if a proprietory test pack isused, the manufacturer of the test pack.

A successful test confirms that steam penetration into a test pack is rapidand even and, by implication, that air and other non condensable gas (ncg)has been effectively removed. It does not confirm that the sterilizingconditions have been achieved within the load.

The test pack may be either a standard test pack described in A.8 or analternative test pack specified by the sterilizer manufacturer (A.8 Note 4).It contains a Class B chemical indicator which is designed to show adefined colour change when exposed to a specific combination of time,temperature and steam. When there is no ncg in the chamber, steam willpenetrate the pack rapidly and completely and the indicator will show auniform colour change. When ncg is present, it will collect towards thecentre of the pack as a bubble which will impair contact between the steamand the indicator. The temperature or moisture level (or both) will be lowerin the region of the bubble and will result in a non-uniform colour changeof the indicator.

When used in conjunction with a standard test pack, Class B indicatorsare designed to show a failure if, at the start of the holding time, either thetemperature at the centre of the test pack is 2°C or more below thetemperature at the coldest point in the chamber, or the indicator is exposedto insufficient moisture. Both conditions are usually caused by the presenceof ncg.

When used in conjunction with an alternative test pack, Class Bindicators shall show an uneven colour change when there is sufficient ncgpresent in the chamber to cause a 2°C temperature depression at the centreof a standard test pack.

Note: in order to detect a temperature difference of 2°C, the indicatormay show signs of failure with a smaller temperature difference.

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Daily and weekly tests - the User.

Test procedure

Use only the test pack specified by the manufacturer.

If a standard test pack is specified it should be as described in A.8 with aClass B chemical indicator conforming with EN86720 inserted between thesheets nearest to the centre of the pack.

Place the test pack in the position which the sterilizer manufactureridentifies as being the most difficult from which to remove air from theload.

Select a standard cycle or the cycle specified by the sterilizer manufacturer.(The test should be performed always using the same cycle).

At the end of the test, examine the test sheet. The test is satisfactory if theindicator shows a uniform colour change.

A successful test does not confirm that sterilizing conditions in the loadhave been achieved. If the test result is unsatisfactory, the reasonshould be investigated [this might require thermometric testing by aTP(s)] and the machine must not be used until the fault has beenrectified.

The result of the test should be recorded in the sterilizer log book and theindicator paper should be marked with the result and kept for reference forat least three months. It should be stored according to the manufacturer’sinstructions.

A.2 Automatic control test

The automatic control test is the main test for ensuring that the sterilizercontinues to function correctly as shown by values of the cycle variables.These may be indicated by the gauges fitted to the sterilizer, or obtainedfrom the recorder. This test is part of the commissioning, weekly, quarterlyand annual test programmes.

The test is performed daily by the User if the sterilizer is not equipped witha recorder but, if it is fitted with a recorder, the test may be performedweekly by the User, with the agreement of the TP(s). It must be performedquarterly and annually by the TP(s).

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Test procedure

Place a standard test pack as described in A.8 (or an alternative test packdefined by the sterilizer manufacturer - A.8, Note 4) in the chamber, in theposition specified by the sterilizer manufacturer.

Select the sterilization temperature for the operating cycle to be tested - thisshould be the highest temperature compatible with the load. Start the cycle.

Ensure that a batch process record is made:

A.2.1 Daily test - without a recorder.

Observe and note the elapsed time, and indicated chambertemperatures and pressures at all significant points of the operatingcycle, eg the beginning and end of each stage or substage, and themaximum values during the holding time. At the approximate mid-point of the plateau period note the elapsed time and indicatedchamber temperature and pressure.

A.2.2 Weekly test - with a recorder.

Ensure that a batch process record is made by the recorder. At theapproximate mid-point of the plateau period note the elapsed timeand indicated chamber temperature and pressure. (Indicated valuesare also required in addition to the recorder chart in order to satisfyclause A.2.6, below.)

Note: It is the MDA’s opinion that this type of sterilizer should beequipped with pressure and temperature recorders.

The test can be considered satisfactory if:

A.2.3 a visual display of “cycle complete” is indicated;

A.2.4 during the whole of the cycle the values of the cycle variables, asshown on the batch process record, are within the limitsestablished by the manufacturer as giving satisfactory results, orwithin the limits previously established on the MPR;

A.2.5 the indicated and recorded chamber temperature are within theappropriate sterilization temperature band specified in Table 7,p.27;

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A.2.6 during the plateau period determined from the recorded chambertemperature:

(i) the difference between the indicated and recorded chambertemperature does not exceed 2°C;

(ii) the difference between the indicated and recorded chamberpressure does not exceed 0.1 bar;

A.2.8 the door cannot be opened until the cycle is complete;

A.2.9 no mechanical or other anomaly is observed.

TABLE 7

STERILIZATION TEMPERATURE BANDS WITH HOLDING TIMES

Sterilization temperature [°C]* 121 126 134

Maximum allowable temperature [°C] 124 129 137

Minimum holding time [min] 15 10 3

*The temperature setting on the automatic controller will generally be ahigher temperature within the sterilization temperature band.

A.3 Air leakage tests - User and Test Person

Note: HTM 2010 refers to this test as the vacuum leak test.

This test forms part of the commissioning, weekly, quarterly and annualtest requirements.

Leakage of air into the chamber at a rate greater than that specified by thesterilizer manufacturer is unacceptable because:

l the presence of air may inhibit the penetration of steam intothe load and prevent sterilization;

l air leaking into the chamber during the drying stages will nothave passed through the bacterial retentive filter and there isa risk of recontaminating the load.

During the test, the rate of change of vacuum in the chamber is measuredafter all valves leading to it have been closed and the vacuum sourceisolated.

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The test may be performed weekly either by the User, using an automatictest cycle incorporated into the sterilizer, or by a TP(s) using the manualtest.

The quarterly and annual air leakage test must be performed by a TP(s)using both the automatic method and the manual method. Conditionswhich cause a failure to be indicated during manual testing shall alsocause a failure to be indicated by the automatic testing system.

A machine which fails to meet the requirements of this test should notbe used until the fault has been rectified and the test satisfactorilycompleted.

Test procedure

A.3.1 Automatic test - User

This is a weekly test that may be performed by the User, using automatictest cycles incorporated into the sterilizer. The test should be performedaccording to the sterilizer manufacturer’s instructions.

The sterilizer shall indicate clearly whether the test result is a pass or failand shall indicate a pass only if the absolute pressure at the end of thevacuum stage is within the limits specified by the manufacturer, and therate of pressure rise during the test is not greater than 1.3 mbar per minute.

A.3.2 Manual test - Test Person

This test method is described in HTM2010 : Part 3 paragraphs 11.1 to11.18.

The test should be considered satisfactory if the absolute pressure at thestart of the 10 minute period is within the limits specified by themanufacturer and the rate of pressure rise during the test is not greater than1.3 mbar per minute.

A.4 Chamber wall temperature test

This test is intended to prevent superheating by demonstrating that thechamber wall temperature is below the sterilizing temperature at thebeginning of the cycle.

Temperatures and pressures should be recorded by independent measuringequipment.

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Test procedure

Place one thermocouple in each of the following positions:

l on the chamber wall at the hottest point as defined by themanufacturer

l in the active chamber discharge or usable space as defined bythe manufacturer

The test is performed with the chamber empty. Select and start the cyclewhich has the highest operating temperature and drying stage. When thecycle is complete, immediately start a second cycle. The test result shouldbe considered acceptable if the temperatures and pressures recorded duringthe holding time of each cycle are within the limits specified in Table 7 andthe chamber wall temperature at the beginning of the second cycle is belowthe sterilizing temperature.

A.5 Thermometric tests (small and full porous loadsand solid load)

Thermometric tests for small, full and solid loads form part of thecommissioning and annual test programmes; the small load test isperformed additionally, as part of the quarterly test programme. These testsare intended to demonstrate that after the air removal stage of the operatingcycle, at the levels at which the cycle variables are set, steam penetratesrapidly and evenly throughout a specified test load and that the sterilizingconditions are achieved.

The test should be performed:

l at each of the sterilization temperatures available on thesterilizer, and a standard drying time;

l after a warm-up cycle, with drying (in order to achieveconsistent results);

l with the test pack placed in the usable space according to themanufacturer’s operating instructions.

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A.5.1 Small load test

Test procedure

The method is described in HTM 2010 : Part 3l, 13.7 to 13.14 but with 13.9and 13.10 replaced by the following:

Use a standard test pack conforming with A.8, or an alternative test pack(A.8, Note 4). Place one temperature sensor at each of the three followingpositions:

l the approximate centre of the test pack, carefully arrangingthe wire so that steam does not track along it and place theassembly in the position identified by the sterilizermanufacturer as the most difficult to sterilize;

l the coldest point in the chamber as identified by themanufacturer (this may be the active chamber discharge);

l the free space above the approximate geometrical centre ofthe pack.

The acceptance criteria are as stated in HTM 2010 : Part 31, 13.24.

A.5.2 Full load test

Test procedure

This test forms part of the commissioning and annual test programmes.The test method described in HTM 2010 : Part 31, 13.15 to 13.24 but with13.19 and 13.20 replaced by the following:

Use the test pack specified by the sterilizer manufacturer. This may beeither a standard test pack conforming with A.8, or an alternative test pack(A.8, Note 4). Place one temperature sensor at each of the three positionsspecified in A.5.1.

Load the rest of the usable space with porous material according to theinstructions of the sterilizer manufacturer.

The acceptance criteria are specified in HTM 2010 : Part 31, 13.24.

A.5.3 Solid load test

The solid load is designed to represent the maximum mass of metal instrumentswhich the sterilizer manufacturer specifies can be processed in the sterilizer. It isused to demonstrate that, at the levels at which the cycle variables are set, rapid andeven penetration of steam throughout the load occurs and the sterilizing conditionis achieved.

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The solid load consists of M12x100 hexagon head screws to ISO 401721,made from austenitic stainless steel to EN 10088-122, wrapped in multi-layer packaging conforming with EN86823.

Test procedure

Place one temperature sensor at each of the following positions:

l attached to one of the screws using a single layer ofautoclave tape with a width less than 25mm;

l at the coldest point in the chamber as identified by themanufacturer (this may be the active chamber discharge);

l in the free space above the approximate centre of the pack.

Place the screw with the temperature sensor at the approximate centre ofthe test pack and place the pack centrally in the usable space. Immediatelystart the sterilization cycle. At the end of the cycle, the test is satisfactoryif, throughout the holding time, the temperatures in the load and the usablespace:

l are not lower than the sterilization temperature;

l are not more than 3°C above the sterilization temperature;

l do not fluctuate by more than +/- 1.5°C;

l do not differ from each other by more than 2°C.

A.6 Load dryness test

This test is used to check that a normal operating cycle, incorporating adrying stage, will produce a product that is sufficiently dry. It forms part ofthe commissioning and annual test programmes.

A.6.1 Porous load

The test procedure described in HTM 2010 : Part 31, paragraphs 13.25 to13.35, should be used in conjunction with a standard test pack as describedin A.8, or an alternative test pack (A.8, Note 4).

A.6.2 Solid load

The test load is the solid load test pack. The test should be conducted foreach available cycle which has a drying stage. The test is successful if atthe end of the test there is no visible condensate present and the weightgain is less than 1%.

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A.7 Microbiological test for Performance Qualification

For some loads, eg lengths of polymeric (including rubber) tubing or otherdevices with lumens, thermometric monitoring of the adequacy of airremoval may not be appropriate as residual static air in the tubing may beheated by conduction. For this type of load, the advice of an AP(s) and asuitably qualified microbiologist should be sought.

A.8 Standard test pack

This is intended for use in small porous load sterilizers with chambervolumes between 10 and 54 litres and with an internal diameter (or, forrectangular vessels, an inscribed circle) greater than 180 mm.

1.

2.

3.

4.

5.

6.

The pack shall be constructed from plain cotton sheets complyingwith BS 581524, bleached to a good white, and each having anapproximate size of 450mm x 300mm. Edges other than selvedgesshall be oversewn, not hemmed.

The mass per unit area of the sheets shall be approximately 180g m-2.

The sheets shall be washed when new and when soiled. During thewashing process the sheets shall not be subjected to any fabricconditioning agent.

After washing, the sheets shall be dried and aired but not ironed orcalendered.

Before use, the sheets shall be stored unfolded and well separated,for at least 1 hour at a temperature between 15°C and 25°C and at arelative humidity (RH) of 45% to 55%.

The sheets shall be folded to approximately 110mm x 150mm andstacked to a height of approximately 120mm after compressing byhand. The pack shall be wrapped in a single sheet of the same fabricand secured with a tape not exceeding 18mm in width. The total massof the pack shall be 900g±100g.

Note 1: When forming the pack, consecutive sheets should be stackedwith the folded side alternating to ensure an even stack.

Note 2: Packs which are not used within one hour of preparation may bestored until required, providing the environmental conditions aremaintained within the limits specified above.

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Note 3: With repeated use the sheets will become compressed. When themass of sheets used to form a stack 120mm high exceeds 1000g,the sheets should be discarded.

Note 4: The standard test pack should not be used if its volume is morethan one fifth of the usable chamber space; in such cases asmaller version of the pack may be used. This should be ofcuboid form and its volume should be about one fifth of theusable chamber volume. It may be made from a differentmaterial, and be of different size and weight, from the standardtest pack, provided its performance can be demonstrated to beequivalent to that of the standard test pack in each test for whichit is to be used.

Note 5: The cotton test sheets should be stored at a relative humidity(RH) of between 45% and 55% as sheets which have been storedoutside these limits (but within the limits 30% to 70% RHspecified in HTM2010) have been found to give variable andmisleading results in thermometric testing. Paper test packs,however, appear to give results which are less dependent on theRH of the storage conditions.

Cotton sheets having the recommended RH may be obtained bystoring the sheets above a saturated solution of magnesiumnitrate in a sealed container for at least 12 hours before use.Sheets that have been conditioned may be stored in ahermetically sealed container (eg for transportation to site)where they will retain the correct humidity for 24 hours.

Further information and details should be sought from an AP(s).

ANNEX B

European Directive

The purpose of the Medical Devices Directive (93/42/EEC)6 is to removebarriers to trade in medical devices throughout the European Union, and toprovide assurance that the devices perform their intended function as safelyas possible. The Directive has been transposed into UK law by the MedicalDevice Regulations (SI 1994 no. 3017)25 which come fully into force on 14June 1998, after the present transition period expires. After that datemanufacturers will not be able to place medical devices on the EuropeanCommunity (EC) market legally, unless the devices comply with theDirective. Medical devices that comply with the Directive will carry the CEmarking and can be freely sold throughout the EC without further control.The CE marking may only be affixed to a product which the manufacturer

33

claims to satisfy the Directive’s Essential Requirements of safety andfitness for its intended purpose. Products which are manufactured toconform with mandated harmonised European standards are presumed alsoto conform with the relevant Essential Requirements.

If the manufacturer of a benchtop sterilizer intends it to be used to re-process medical devices, the Regulations consider the sterilizer to be anaccessory to the devices. The Regulations treat accessories as medicaldevices and regulate them to the same extent as their related devices.

The following standard is relevant to the validation of steam sterilizers:

European Standard BS EN 554: 1994: Sterilization of medical devices -validation and routine control of sterilization by moist heat26.

European Pressure Equipment Directive

After the Pressure Equipment Directive comes into force, all steamsterilizers will have to conform if the product of their chamber volume (inlitres) multiplied by the normal operating pressure (in bar) is greater than50 bar litres. The AP(s) or the Competent Person (Pressure Vessels) willadvise whether, and in which ways, a sterilizer is affected by this Directive.

Medical Device Directives: MDA Guidance Documents

Information Bulletins

2. The CE Marking3. The Vigilance System4. Conformity Assessment Procedures5. Pre-Clinical Assessment Routes6. The Notified Body7. The Competent Authority8. Information about the EC Medical Devices Directives9. The Citizens Charter and a Code for Enforcement10. The Classification Rules11. CE and EFTA member states (EEA Agreement)12. Sale and Supply of In Vitro Diagnostic Medical Devices13. Standards14. Compliance Cost Assessments15. The Medical Devices, Electromagnetic Compatibility and Low

Voltage Directives16. Information about the Packaging and packaging Waste Directive17. Medical Devices and Medicinal Products18a. The Medical Devices Regulations : Implications on Healthcare and

34

other Related Establishments.19. Own Brand Labelling and Rented Products

Please note that Bulletin Number 8 has been updated and now supersedesBulletin 1 which has been withdrawn from circulation.

Further information on the Medical Devices Regulations and guidance onthe Medical Devices Directives may be obtained from MDA.

ANNEX C

Pressure Systems and Transportable Gas Containers Regulations 1989

In addition to the requirements of the Medical Devices Regulations,transportable sterilizers must comply with the Pressure Systems andTransportable Gas Containers Regulations 1989 (SI 1989/2169)5. Theoverall intention of these Regulations is to prevent risk of injury fromstored energy as a result of failure of a pressure system or part of it.

Under these regulations all sterilizers containing pressure vessels aresubject to periodic inspection by a Competent Person (Pressure Vessels),according to a written scheme of inspection. Where repairs ormodifications have involved any part of the pressure system (eg thepipework, the chamber, and its fittings) the advice of a Competent Person(pressure vessels) should be sought before the sterilizer is returned toservice.

Responsibility for compliance with the regulations is placed primarilyupon the person responsible for the management of the sterilizer.

The management’s responsibilities may be summarised as follows:

l to define the scope of the written scheme of examination (awritten scheme may be supplied by the manufacturer);

l to ensure that the parts of the pressure system defined in thewritten scheme are examined by a Competent Person(Pressure Vessels);

l the management must not allow the sterilizer to be operatedunless a written scheme has been drawn up and certified assuitable by a Competent Person (Pressure Vessels);

l the management shall also ensure that the system is properlymaintained in good repair, so as to prevent danger.

The Competent Person (Pressure Vessels) has three principal duties underthe Regulations:

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l advising on the scope of the written scheme of examination;

l drawing up the written scheme of examination or certifyingthe scheme as being suitable;

l carrying out examination in accordance with the writtenscheme, assessing the results and reviewing the writtenscheme for its suitability.

An Authorised Person (Sterilizers) will be able to advise on theapplication of these regulations to any particular system.

ANNEX D

Sources of further information

NHS Estates1 Trevelyan SquareBoar LaneLeeds LS1 6AE

Tel : 0113 254 7000

The Institute of Healthcare Engineering and Estate Management,2 Abingdon House,Cumberland Business Park,Northumberland Road,Portsmouth P05 1DS

Tel: 01705 823186

National Accreditation of Inspection BodiesUnited Kingdom Accreditation ServiceQueens RoadTeddingtonMiddlesex TW11 0NA

Tel: 0181 943 6657

The Association of Sterilizer and Disinfector ManufacturersSt Georges House195-203 Waterloo RoadLondon SE1 8WD

Tel : 0171 787 3060Fax : 0171 787 3061

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The Health and Safety ExecutiveField Operations Division14 Cardiff RoadLutonBedfordshire LU1 1PP

Tel : 01582 444200Fax : 01582 444320

ANNEX E

MDA Publications relevant to sterilization

1.

2.

3.

4.

5.

6.

7.

8.

9.

MDA DB 9501 January 1995. The Reuse of Medical DevicesSupplied for Single use only.

MDA DB 9605 June 1996. The purchase, operation and maintenanceof benchtop steam sterilizers.

MDA DB 9607 November 1996. Decontamination of Endoscopes.

FPN 654 / SAB(94)22 Instruments and Appliances Used in theVagina and Cervix.

Sterilization, Disinfection and Cleaning of Medical Equipment :guidance on Decontamination from the Microbiology AdvisoryCommittee to the Department of Health Medical Devices Agency.

Hazard HN 9503 Handpieces used in Phaco Microsurgical Proceduresand Their Re-usable Accessories.

Safety Notice SN 9618 Mediclave or Medical Clave Steam Sterilizers- Inadequate Safety Locks.

Safety Notice SN 9619 Compatibility of Medical Devices and theiraccessories and Reprocessing Units with Cleaning, Disinfecting andSterilizing Agents.

Safety Notice SN 9635 SES Matron Steam Sterilizers (Autoclaves),Eschmann Equipment, Risk of Overheating or Fire.

37

REFERENCES

1. Health Technical Memorandum 2010 Part 3: Validation andverification. HMSO.

2. MDA DB9605. June 1996. The purchase, operation and maintenanceof benchtop steam sterilizers.

3. Sterilization, disinfection and cleaning of medical equipment:guidance on decontamination from the Microbiology AdvisoryCommittee to Department of Health Medical Devices Agency.

4. Health Technical Memorandum 2010 Part 1: Management Policy.HMSO.

5. SI No 2169. The Pressure Systems and Transportable Gas ContainersRegulations HMSO 1989.

6. Council Directive 93/42/EEC 14 June 1993 concerning medicaldevices. Official Journal of the European Communities, L169,vol.36,12.7.93.

7. BS EN ISO 9001 (1994). Model for Quality Assurance indesign/development, production, installation and servicing.

8. BS EN ISO 9002 (1994). Model for Quality Assurance in productionand installation.

9. BS 3970 : Part 1 : Sterilizing and disinfecting equipment for medicalproducts. Part 1. Specification for general requirements.

10. BS EN 61010-l Safety requirements for electrical equipment formeasurement, control, and laboratory use. Part 1: 1993 : Generalrequirements

11. BS EN 61010-2-041 Safety requirements for electrical equipment formeasurement, control, and laboratory use. Part 2-041 : 1997 :Particular requirements for autoclaves using steam for the treatment ofmedical materials, and for laboratory processes.

12. The Electromagnetic Compatibility Regulations (Amendment)Regulations 1994 (SI 1994 No. 3080).

13. Draft BS EN 13060 Small steam sterilizers - Part 1: Generalrequirements for all types of small steam sterilizers.

14. Draft BS EN 13060 - Part 2: Particular requirements and test methods

38

for type B sterilizers, intended for the sterilization of wrapped solid,hollow and porous products.

15. Draft BS EN 13060 - Part 4: Particular requirements and test methodsfor type S sterilizers, intended for the sterilization of productsspecified by the manufacturer of the sterilizer.

16. Health Technical Memorandum 2010 Part 4: Operationalmanagement. HMSO.

17. HC(89)20 Preservation, retention and destruction of records. (InScotland :MEL (1993) 152 “Guidance for retention and destruction ofHealth Records”, and in Wales : WHC(89)60 and WHC(94)59).

18. Guidance Note PM 73 from the Health and Safety Executive - Safetyat Autoclaves.

19. BS 7671: 1992 Requirements for Electrical Installations.

20. BS EN 867 : 1997 Non-biological systems for use in sterilizers - Part3 Specification for Class B indicators for use in the Bowie and Dicktest. Draft BS EN 867 Part 5 : Specification for indicator systems andprocess challenge devices for use in performance testing for smallsterilizers type B and type S.

21. ISO 4017 BS EN 24017 : 1992 Hexagon head screws. Product gradesA and B

22. BS EN 10088-l : 1995 Stainless steels, Part 1 : List of stainless steels

23. EN 868 Packaging materials and systems for medical devices whichare to be sterilized

24. BS 5815 : Part 1: 1989. Specification for sheeting, sheets andpillowslips.

25. Medical Device Regulations 1994 (SI 1994 No 3017)

26. BS EN 554: 1994. Sterilization of Medical Devices-Validation andRoutine Control of Sterilization by Moist Heat.

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RECENT DEVICE BULLETINS

MRI Static Magnetic Field Safety Considerations - The projectile effect caused by theinfluence of the static magnetic field of magnetic resonance imaging systemsMDA DB 9803 (February 1998)

Adverse Incident Reports 1997 MDA DB 9802 (February 1998)

Medical Device and Equipment Management for Hospital and Community-basedOrganisations MDA DB 9801 (January 1998)

Medical Devices and the Year 2000 MDA DB 9704 (November 1997)

Selection and Use of Infusion Devices for Ambulatory ApplicationsMDA DB 9703 (April 1997)

Electromagnetic Compatibility of Medical Devices with Mobile CommunicationsMDA DB 9702 (March 1997)

Adverse Incidents Reports 1996 MDA DB 9701 (February 1997)

Decontamination of Endoscopes MDA DB 9607 (November 1996)

Wheelchair & Vehicle Passenger Lifts: Safe Working PracticesMDA DB 9606 (September 1996)

The Purchase, Operation and Maintenance of Benchtop Steam SterilizersMDA DB 9605 (June 1996)

Withdrawal of MLQ Forms - England MDA DB 9604 (June 1996)

Adverse Incidents Reports 1995 MDA DB 9603 (April 1996)

Guidance of the Safe Use of Lasers in Medical and Dental PracticeMDA DB 9602 (April 1996)

Latex Sensitisation in the Health Care Setting (Use of Latex Gloves)MDA DB 9601 (April 1996)

REPORTING ADVERSE INCIDENTS

Incidents relating to medical devices must be reported to the MedicalDevices Agency as soon as possible.

To report an incident, for more information or printed incident reportforms contact:

MDA Adverse Incident CentreMedical Devices Agency, Hannibal House, Elephant & Castle, LondonSE1 6TQ

Telephone 0171 972 8080 or Fax 0171 972 8109(An answer-phone service operates outside normal office hours)

Further information and incident report forms are also available on theMDA’s Internet site http://www.medical-devices.gov.uk

DISTRIBUTION

This Device Bulletin should be brought to the attention of managers and staff in all hospitals, liaisonofficers and others who report adverse incidents.

This Device Bulletin should also be brought to the attention of all hospital and community healthcarestaff who are involved in the purchase, installation, validation and routine testing of benchtop vacuumsteam sterilizers. This will include: Sterile Services Managers, Estates Managers, Chairs of InfectionControl Committees, Infection Control Doctors, Infection Control Nurses and ConsultantMicrobiologists. It will also be of interest to staff who use benchtop vacuum steam sterilizers in: GPsurgeries, dental practices, operating theatres, Intensive Care Units, Accident and EmergencyDepartments and Outstations.

TECHNICAL ENQUIRIES

Enquiries concerning the content of this Device Bulletin should be addressed to :

Mr R Havard Mr M GlasspoolMedical Devices Agency Medical Devices AgencyHannibal House Hannibal HouseElephant and Castle Elephant and CastleLondon SE1 6TQ London SE1 6TQTel : 0171 972 8163 Tel : 0171 972 8174Fax : 0171 972 8106 Fax : 0171 972 8106

HOW TO OBTAIN COPIES

Copies of this Device Bulletin are free to the NHS and may be obtained on written request from :

quoting reference MDA DB9804

Department of HealthPO Box 410WetherbyLS23 7LNFax : 0990 210266

Otherwise, copies of the bulletin at a charge of £25.00 per copy, may be obtained from:

Medical Devices AgencyMDA/DTS OrdersLevel 9Hannibal HouseElephant and CastleLondon SE1 6TQ

© CROWN COPYRIGHT 1998Medical Devices AgencyAn Executive Agency of the Department of Health

13387 MDA 8K JUL 98 SA (ABB)