RKI Sterilization in the Autoclave
RKI 1: Legal Requirements & Overview 
RKI 2: Correct Pre-Cleaning 
RKI 3: Cleaning & Disinfection 
RKI 4: Instrument Care 
RKI 5: Instrument Packaging 
RKI 6: Sterilization in the Autoclave 
RKI 7: Release & Documentation 
RKI 8: Storage of Sterile Instruments 
RKI 9: Labelling After Sterilization 
RKI 10: Documentation After Patient Use 
RKI 11: Hygiene Room per KRINKO 
RKI 12: Initial Validation of Klasse B Autoclave
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Sterilization in a Klasse B Autoclave
Sterilization in an autoclave is the critical step that converts the reprocessed, packaged medical device to a sterile state, achieving a Sterility Assurance Level (SAL) of 10-6 – provided that the preceding cleaning, disinfection, drying and packaging steps have been carried out correctly. For packaged and hollow-body (critical) instruments, the Klasse B steam sterilizer compliant with DIN EN 13060 is the reliable standard.
1Why Klasse B?
A Klasse B sterilizer operates with fractionated vacuum: before sterilization, air is evacuated from the chamber in multiple cycles so that saturated steam fully penetrates even narrow lumens, hollow bodies and packaged instruments. Klasse B therefore covers the entire range of steam-sterilizable medical devices (solid, porous, hollow, packaged – including critical B). Non-heat-/steam-resistant (thermolabile) products are excluded; the reprocessing instructions provided by the respective instrument manufacturer (in accordance with DIN EN ISO 17664) are authoritative. Klasse S devices are approved only for a limited range of loads defined by the manufacturer.
Sources: KRINKO/BfArM 2012, Section 2.2.5; DIN EN 13060 (small steam sterilizers, classes B/S/N).2Preparing the load
· Place instruments on trays or in sterilization containers.
· Wrapped instruments go into clear-view sterilization pouches, sterilization paper or containers.
· Unwrapped, solid and heavy instruments should be placed separately.
· Separation: wrapped items on top, unwrapped/heavy instruments on the bottom.
· Use inserts for vertical arrangement to make optimal use of the available space.
Loading rules
· Film side facing up: for paper-film pouches, the film (clear) side faces upward (condensate drainage).
· Do not stack paper directly on plastic; pouches may overlap by no more than two-thirds.
· Ensure clearance: steam must be able to circulate around every instrument completely – do not overload.
Document a reference load: Define typical loading patterns and document them (photo + item list). This keeps every cycle reproducible – a prerequisite for validation.
3Water quality
The feed water must meet the limits for steam-generator feed water specified in DIN EN 13060 (based on DIN EN 285), including low conductivity and low hardness. Distilled or fully demineralized (deionized) water is suitable; tap water is unsuitable and causes staining, corrosion and error messages. A water treatment system (e.g. AQUAdem) provides consistently suitable quality.
4Sterilization programmes
| Programme | Application |
|---|---|
| 134 °C, wrapped (Universal) | Standard programme for wrapped instruments and mixed loads; holding time (plateau time) at least 5 min per KRINKO/BfArM, otherwise according to the validated process and manufacturer specifications. |
| 134 °C, unwrapped (Solid) | For unwrapped, solid instruments. |
| 121 °C | For heat-sensitive products (with manufacturer approval). |
| Prion programme 134 °C | In case of prion/TSE risk: holding time 18 min following a suitable (partially prion-inactivating) cleaning procedure; steam sterilization has limited efficacy here and forms part of a coordinated package of measures. |
5After sterilization
The documented release of critical instruments is carried out by a person authorized in writing based on: conformity of the load/process parameters with the configuration specified during validation, evaluation of the batch-related indicators (Class 1 process indicator; for critical B additionally a PCD, e.g. Helix test, Class 2), visual inspection of the packaging (dryness, integrity, intact seal seams) and verification of complete labelling. Batch, date and release of the sterile goods are recorded in the batch documentation and archived (see Step 7: Release & Documentation). This release documentation can be completed in just a few clicks with the free ClavioSoft – including tamper-proof filing.
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Important additional points per RKI & standards
These points are frequently overlooked in practice but are essential for correct and legally compliant implementation:
- Validation as a prerequisite for routine operation (MPBetreibV § 8): A validated sterilization process is a prerequisite for any routine operation: the reprocessing of critical medical devices must be carried out using suitable, validated procedures (MPBetreibV § 8). This includes the initial validation (installation, operational and performance qualification) at the point of use, periodic re-qualification of performance, and re-validation after significant changes; each batch is checked against the configuration specified during validation.Source: MPBetreibV § 8; KRINKO/BfArM 2012 Section 1.3 / Annex 1; DIN EN ISO 17665
- Daily routine checks before the first sterilization run: Before the first sterilization run of the day, daily checks must be performed and documented: including a function test, inspection of the recording device, where applicable a vacuum test (leak test) and, where applicable, a steam penetration test using a suitable process challenge device (PCD; e.g. Bowie-Dick/Helix test). Sterile goods may only be produced after all checks have been passed.Source: KRINKO/BfArM 2012 Annex 7 (Daily routine checks); DIN EN ISO 17665-1
- Batch-related monitoring and PCD/Helix test for critical B: Each batch must be monitored and documented on a per-batch basis: conformity of the load with the validated configuration, evaluation of the process indicator (Class 1), review of the physical process parameters (time, temperature, pressure via the recording device) and, for critical-B loads, an additional Process Challenge Device (PCD), e.g. Helix test (Class 2 indicator).Source: KRINKO/BfArM 2012 Annex 7 (Batch-related checks: critical B with PCD)
- Drying as an integral part of the process; cooling before handling: The sterilization cycle includes a drying phase that is an integral part of the process and must not be deactivated. Remove and handle sterile goods only after sufficient cooling to prevent condensation and recontamination of the still warm, moist packaging. Residual moisture prevents release.Source: DIN EN 13060 (drying as part of the process); KRINKO/BfArM 2012 Annex 7 (visual inspection: dryness of packaging)
- Labelling, shelf life and traceability of sterile goods: Each released packaging unit must be labelled, including sterilization date, batch identification and, where applicable, sterile-goods shelf life. The shelf life depends on the type of packaging and storage conditions (DIN 58953). The batch documentation must ensure traceability back to the person who released the goods; this seamless batch documentation can be conveniently managed digitally with the free ClavioSoft.Source: KRINKO/BfArM 2012 Annex 7 (labelling, batch documentation, release); DIN 58953 (sterile goods storage)
- Competence of operating and releasing personnel: Sterilization and release may only be performed by demonstrably qualified personnel; persons authorized to release goods must be designated in writing (authorization list). The competence requirements are described in KRINKO/BfArM Annex 6; tasks and responsibilities should be defined in standard operating procedures (SOPs).Source: KRINKO/BfArM 2012 Annex 6 (personnel competence) and Annex 7 (authorization list/release)
- Packaging and seal seam inspection (standard): Sterile barrier systems must comply with DIN EN ISO 11607-1 (packaging) and the sealing process with DIN EN ISO 11607-2; seal seams must be inspected for completeness and integrity. Do not overfill clear-view pouches (rule of thumb: fill no more than approximately three-quarters) to ensure intact seams and reliable steam penetration.Source: DIN EN ISO 11607-1/-2 (packaging/sealing process); DIN 58953
Required equipment, consumables & accessories
Checklist for this process step – items you should have ready (shopping list):
Equipment
- Steam sterilizer (Klasse B autoclave per DIN EN 13060) with fractionated pre-vacuum, integrated drying and process data recording Order in our shop
- Recording/logging device (integrated printer) or digital documentation software for seamless batch documentation Order in our shop Create digitally with ClavioSoft
- Water treatment system for supplying demineralized/deionized feed water (alternatively a water distiller) Order in our shop
- Conductivity meter for monitoring feed water quality
- Sealing device for standard-compliant sealing of clear-view sterilization pouches (preceding step for wrapped instruments) Order in our shop
Consumables
- Distilled or demineralized/deionized feed water of suitable quality (low conductivity, not tap/utility water) Order in our shop
- Clear-view sterilization packaging (paper-film pouches/rolls) and/or sterilization paper per DIN EN ISO 11607-1 Order in our shop
- Class 1 process indicators (one per package/batch) Order in our shop
- Process Challenge Device (PCD) or Class 2 Helix test indicators for batch-related monitoring of critical B loads Order in our shop
- Steam penetration / Bowie-Dick test pack or indicators for daily routine testing Order in our shop
- Biological indicators (supplementary only; not a substitute for validation or physical/chemical routine testing)
- Labels/marking materials for sterilization date, batch identification and shelf life Order in our shop
- Wear parts: replacement door gasket and water treatment filters/cartridges Order in our shop
Accessories
- Trays, perforated trays and sterilization baskets (chamber inserts) matching the device Order in our shop
- Holders/inserts for vertical arrangement of wrapped instruments (condensate drainage) Order in our shop
- Sterilization containers (if used) Order in our shop
- Validation report and reference load documentation (loading pattern with photo and item list) kept at the device Commission validation
- Standard operating procedures (SOPs), batch/release records and authorization list of persons approved to release goods Create digitally with ClavioSoft
- Heat-protection gloves and a surface for cooling sterile goods before handling
Templates & sources
Autoclave loading patternReference load for reproducible cycles.
KRINKO Recommendation (RKI)Basis for sterilization (Section 2.2.5).
- KRINKO/BfArM 2012, Bundesgesundheitsbl. 55:1244–1310 – Section 2.2.5.
- DIN EN 13060 (small steam sterilizers); DIN EN ISO 17665 (steam sterilization).
- MPBetreibV § 8; loading patterns (reference load).
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Frequently Asked Questions
RKI Sterilization in the Autoclave – key questions answered clearly.
What does Klasse B mean for an autoclave?
Klasse B designates fully featured small steam sterilizers compliant with DIN EN 13060 that operate with fractionated vacuum. They can safely sterilize wrapped, hollow (lumen) and porous instruments as well as critical medical devices. In medical practices, a Klasse B device is the required standard.
Why does a Klasse B autoclave use fractionated vacuum?
With fractionated vacuum, air is evacuated from the chamber in multiple cycles before sterilization. This allows the saturated steam to fully penetrate even narrow lumens, hollow bodies and wrapped instruments. Residual air would prevent steam penetration and compromise sterilization.
What is the difference between Klasse B, S and N autoclaves?
Klasse B covers the entire range (solid, porous, hollow, wrapped, including critical B). Klasse N may only sterilize unwrapped, solid instruments and is not approved for critical medical devices. Klasse S is approved only for a limited range of loads defined by the manufacturer.
What does a SAL of 10 to the power of minus 6 mean in sterilization?
The Sterility Assurance Level (SAL) of 10 to the power of minus 6 means that the calculated probability of a surviving micro-organism is at most one in a million. This level is considered the requirement for a sterile condition and is achieved in a Klasse B autoclave with correct process control.
Which instruments must be sterilized in a Klasse B autoclave?
A Klasse B autoclave is primarily used to sterilize critical instruments that come into contact with blood, internal tissue or mucous membranes, as well as wrapped and hollow-body products. The risk classification per KRINKO/BfArM 2012 and the reprocessing instructions of the instrument manufacturer are authoritative.
Which instruments must not be sterilized in the autoclave?
Non-heat- or non-steam-resistant (thermolabile) products must not be steam-sterilized, nor may single-use products not intended for reprocessing. The reprocessing instructions of the respective instrument manufacturer are always decisive; when in doubt, choose another suitable method.
Can a Klasse B autoclave sterilize hollow bodies such as handpieces and turbines?
Yes, thanks to the fractionated vacuum the steam penetrates even narrow lumens, so hollow bodies such as handpieces, turbines and tips can be sterilized safely. The only exception is instruments that the manufacturer explicitly marks as non-autoclavable.
What prerequisites must be met before sterilization?
Before sterilization, cleaning, disinfection, drying and packaging must have been carried out correctly. Only a clean, dry and properly packaged instrument can be sterilized safely. Residual soiling or moisture compromises the process and the target SAL of 10 to the power of minus 6.
How do I load a Klasse B autoclave correctly?
Place instruments on trays or in sterilization containers, with wrapped items on top and unwrapped, heavy instruments on the bottom. Ensure sufficient clearance so that steam can circulate around every instrument completely, and do not overload the chamber.
May instruments touch each other inside the autoclave?
Instruments should ideally not touch or slide together so that steam can reach all surfaces. Distribute the load evenly and preferably package instruments individually. An excessively dense or overloaded chamber can lead to non-sterile areas.
Which way up do I place clear-view sterilization pouches in the autoclave?
For paper-film pouches the film (clear) side faces upward so that condensate can drain away. Avoid stacking paper directly on plastic; pouches may overlap by no more than two-thirds so that steam can circulate.
Why must the autoclave not be overloaded?
When overloaded, steam cannot circulate around every instrument completely, leading to non-sterile areas or residual moisture. In addition, the load deviates from the validated configuration. Maintain sufficient clearance between trays and pouches.
When do I use a clear-view pouch and when a sterilization container?
Clear-view sterilization pouches or sterilization paper are suitable for individual instruments or small groups; containers for larger, heavier sets. Both must be qualified as sterile barrier systems per DIN EN 11607. The choice depends on the instrument range, storage requirements and the validated process.
What is a reference load and why should I document it?
A reference load is a defined, typical loading pattern documented with a photo and item list. This keeps every cycle reproducible and consistent with the validated configuration. It is a prerequisite for validation and subsequent batch release.
What type of water must I use for the autoclave?
Use distilled or fully demineralized (deionized) water with low conductivity. It must meet the feed water limits specified in DIN EN 13060 (based on DIN EN 285). Tap water is unsuitable and can damage the device.
Why is tap water unsuitable for the autoclave?
Tap water contains minerals and salts that exceed the feed water limits specified in DIN EN 13060. This causes staining and corrosion on instruments and chamber as well as error messages on the device. Only distilled or fully demineralized water is suitable.
Is a water treatment system for the autoclave worthwhile?
A water treatment system continuously provides feed water with low conductivity and hardness, thus reliably meeting the requirements of DIN EN 13060. This protects instruments and chamber from staining and corrosion and reduces error messages caused by poor water quality.
What sterilization programmes does a Klasse B autoclave have?
Common programmes include a 134-degree wrapped (Universal) programme for wrapped instruments and mixed loads, a 134-degree unwrapped programme for solid items, a 121-degree programme for heat-sensitive products and a prion programme for TSE risk. In addition, there is a vacuum test and, where applicable, rapid programmes.
Which programme do I use for wrapped instruments?
For wrapped instruments and mixed loads, use the standard 134-degree wrapped (Universal) programme. The holding time is at least 5 minutes per KRINKO/BfArM, otherwise according to the validated process and manufacturer specifications. It is the most commonly used programme in practice.
When do I use the 121-degree programme on the autoclave?
The 121-degree programme is intended for heat-sensitive products that cannot withstand 134 degrees but are approved for steam sterilization by the manufacturer. It may only be used with explicit approval from the instrument manufacturer, as not all products are validated for this process.
How long is the holding time at 134 degrees in the autoclave?
The holding time (plateau time) at 134 degrees is at least 5 minutes per KRINKO/BfArM; otherwise it is governed by the validated process and manufacturer specifications. During this phase, micro-organisms are reliably killed. The basis is DIN EN 13060 and DIN EN ISO 17665.
What does plateau time or holding time mean in steam sterilization?
The plateau or holding time is the period during which temperature and pressure are maintained at the sterilization level after the target temperature has been reached throughout the chamber. Only during this phase are micro-organisms, including spores, reliably killed.
Is the rapid programme suitable for wrapped or hollow instruments?
Rapid programmes are usually approved only for unwrapped, solid instruments. For wrapped or hollow critical medical devices a full Klasse B cycle with fractionated vacuum and drying is required. The approvals of both the device and instrument manufacturer as well as the validated process are authoritative.
What is the prion programme on the autoclave and when do I need it?
The prion programme operates at 134 degrees with an extended holding time of 18 minutes and is used in case of prion or TSE risk. Steam sterilization has limited efficacy here and forms part of a coordinated package of measures including a suitable, partially prion-inactivating cleaning procedure.
How long does a sterilization cycle in a Klasse B autoclave take?
The duration depends on the model, programme and load. For a full load of wrapped instruments, typical values are approximately 30 to 50 minutes for medium-sized chambers; smaller devices are considerably faster. The total duration includes vacuum phases, heating, holding time and drying.
Why does a Klasse B cycle take longer than with simpler devices?
The Klasse B cycle includes fractionated vacuum with multiple evacuation phases and an adequate drying phase. These steps are necessary to ensure that steam reaches wrapped and hollow instruments and that items are removed dry. The longer run time is a prerequisite for reliable sterility.
Why are instruments still wet after sterilization?
Residual moisture can be caused by overly dense or incorrect loading, a shortened drying phase, pouch orientation or a gasket or device issue. Wet packages are considered unsafe and must not be released. Check loading and programme; if the problem persists, contact service.
Why is the drying phase at the end of the sterilization cycle so important?
A wet package loses its microbial barrier because micro-organisms can migrate through damp material. Instruments must therefore be removed dry, and dryness is part of the visual inspection during release. An adequate drying phase is therefore mandatory.
How does an autoclave or steam sterilization work?
An autoclave sterilizes with saturated steam under pressure, typically at 121 to 134 degrees. The hot steam transfers its energy to the instruments and kills all micro-organisms, including spores. In a Klasse B device, fractionated vacuum ensures complete steam penetration.
What happens after sterilization before the instruments may be used?
After the cycle, the documented release is carried out by a person authorized in writing. The load and process parameters are checked against the validated configuration, indicators are evaluated, and packaging and labelling are inspected. Instruments are only considered sterile for use after successful release.
Who is authorized to release sterilized instruments?
The release of critical instruments is carried out by a person authorized in writing who is demonstrably qualified. This person checks conformity with the validated configuration, the batch-related indicators and the packaging and labelling. Batch, date and release are documented and archived.
What is checked during batch release after sterilization?
The checks include conformity of the load and process parameters with the validated configuration, the batch-related indicators (Class 1 process indicator; for critical B additionally a PCD such as the Helix test), dryness and integrity of the packaging with intact seal seams, and complete labelling.
What is a Class 1 process indicator?
A Class 1 process indicator shows by colour change that an item has undergone a sterilization process. It distinguishes treated from untreated items but does not by itself prove successful sterilization. It is part of the batch-related checks during release.
What is a Helix test and what is it used for?
The Helix test is a Process Challenge Device (PCD) with a Class 2 indicator that simulates steam penetration in narrow, long lumens. When sterilizing critical B medical devices it is used in addition to the process indicator to verify hollow-body sterilization on a per-batch basis.
What is a PCD in sterilization?
A PCD (Process Challenge Device) is a test body that replicates a particularly difficult-to-sterilize location, such as a narrow lumen. For critical B loads, a PCD such as the Helix test with a Class 2 indicator is used on a per-batch basis to demonstrate steam penetration.
How do I monitor sterilization during routine operation?
Routine monitoring relies on physical process data (temperature, pressure, time), batch-related chemical indicators and daily checks such as the vacuum test. Biological indicators are used only as needed or as part of the validated process; the requirements are defined during validation.
What does the vacuum test on the autoclave indicate?
The vacuum test (leak test) checks whether the chamber maintains a vacuum without air ingress. If it fails, residual air can prevent steam penetration and compromise sterilization, often due to a leaking door gasket. It is one of the daily routine checks.
Must the autoclave be validated before routine operation?
Yes. Under MPBetreibV Section 8, the reprocessing of critical medical devices must be carried out using suitable, validated procedures. A validated sterilization process is a prerequisite for any routine operation; without initial validation at the point of use, routine operation with critical instruments is not permitted.
What does the initial validation of a Klasse B autoclave involve?
The initial validation comprises installation, operational and performance qualification at the point of use, including vacuum test, empty-chamber profile and multiple sterilization runs with your instruments as the load. It demonstrates that the process meets the requirements under real on-site conditions. The basis is MPBetreibV Section 8 and DIN EN ISO 17665.
Why must the autoclave be validated on site and not at the factory?
Validation checks the actual conditions at the point of use, i.e. installation, loading and process sequence with your instruments. These real-world conditions cannot be replicated at the factory, which is why even a factory-tested new device must be validated at its installation site. Initial validation is a legal requirement.
How often must an autoclave be re-validated?
In addition to the initial validation, periodic performance re-qualification is required; there is no fixed standard interval, but in practice approximately 12 to 24 months is common. A re-validation is also necessary after any significant change to the device or process.
What daily routine checks are required before the first sterilization run?
Before the first sterilization run of the day, daily checks must be performed and documented, including a function test, inspection of the recording device and, where applicable, further device-specific tests. These checks ensure proper operation throughout the day.
Which standard applies to steam sterilization in a small autoclave?
DIN EN 13060 applies to small steam sterilizers, defining classes B, S and N. For the validation and routine monitoring of steam sterilization processes, DIN EN ISO 17665 is additionally authoritative. Together with KRINKO/BfArM 2012, they form the technical basis.
What does the KRINKO/BfArM recommendation say about sterilization of critical instruments?
The KRINKO/BfArM 2012 recommendation stipulates that critical medical devices must be reprocessed using validated procedures. For wrapped and hollow-body instruments, the Klasse B steam sterilizer compliant with DIN EN 13060 is the reliable standard (Section 2.2.5). MPBetreibV Section 8 applies in addition.
Is a Klasse N autoclave sufficient for a medical practice?
No. Klasse N may only sterilize unwrapped, solid instruments and is not approved for wrapped or hollow critical medical devices. For the reprocessing of critical instruments in human medicine, a Klasse B autoclave compliant with DIN EN 13060 is required.
Is a washer-disinfector sufficient or do I need to sterilize as well?
A washer-disinfector (WD) cleans and disinfects instruments and is an important reprocessing step per DIN EN ISO 15883, but it does not replace sterilization. Critical instruments that enter sterile body areas must subsequently be sterilized in a Klasse B autoclave.
How do I tell that sterilization was successful?
The device displays a success message such as cycle complete and the door unlocks. Definitive assurance, however, comes only from the release: comparison with the validated configuration, evaluation of the indicators and visual inspection of dryness, packaging and labelling. In case of a fault, an error code is displayed.
What should I do if the autoclave reports a vacuum test error?
A vacuum test error usually indicates that air is entering the chamber and the door gasket needs adjusting or replacing. Since residual air compromises steam penetration, sterilization must not proceed in this state. If the error cannot be resolved, contact service.
What materials may be sterilized in a Klasse B autoclave?
Stainless-steel instruments and heat-resistant plastics marked as autoclavable by the manufacturer that withstand the respective programme temperature are suitable. For heat-sensitive but approved products, the 121-degree programme can be used. The reprocessing instructions of the instrument manufacturer are always authoritative.
How long do sterilized instruments remain sterile after sterilization?
The shelf life depends on the packaging and storage conditions. Sterile barrier systems per DIN EN 11607 must be stored dry, dust-free and undamaged. The expiry date, shelf life and conditions are defined within your reprocessing and storage rules; damaged or moist packages are considered non-sterile.