Where an autoclave is integrated into the manufacturing process or used in a laboratory setting, the operating organisation bears overall responsibility for the process, as well as for the resulting outcomes and their technical evaluation. Qualification and validation measures are usually carried out with the involvement of an appropriately qualified external service provider. As the product-specific requirements for the process can only be defined by you, close, cross-functional cooperation between your internal specialist departments, the qualification or validation partner and the autoclave manufacturer is essential.

Although the terms ‘qualification’ and ‘validation’ are frequently used in the same context or, in some cases, interchangeably, they differ in terms of their objectives and methodological approach. What both approaches have in common is the requirement for standard-compliant, traceable documentation in which both the defined tests and the results achieved are recorded in full and transparently. In practice, the relevant reports are often already an integral part of the qualification or validation plan and are used directly during implementation for the structured documentation of results.

The qualification phases – Design Qualification (DQ), Installation Qualification (IQ), Operational Qualification (OQ) and Performance Qualification (PQ) – are described, amongst other places, in DIN 58951 as well as in other relevant standards for steam sterilisers, such as DIN EN ISO 285 and DIN EN ISO 13060. Process qualification also forms a central component of DIN EN ISO 17665. This standard further defines comprehensive requirements for document control and, consequently, for consistent, structured and complete documentation of all qualification phases, including DQ, IQ, OQ and PQ.

Installation Qualification (IQ)
As part of the installation qualification (IQ), checks are carried out to ensure that the installation site is suitable, that the technical and physical requirements for the autoclave are met, and that the relevant documentation is complete. The focus here is particularly on the correct installation of the system and compliance with the specified requirements.

Operational Qualification (OQ)
Operational Qualification (OQ) serves to demonstrate that the autoclave operates reliably and reproducibly within the specified operating limits. To this end, empty-chamber measurements are carried out using data loggers, amongst other methods, to record temperature and pressure distributions. This confirms that the system meets the requirements defined during the design qualification and that all functions are performed correctly.

Design Qualification (DQ)
DQ is the upstream phase and assesses whether the planned design of the autoclave is fundamentally suitable for meeting the requirements of its intended use. It therefore does not concern installation or operation, but rather the review of the concept and design prior to implementation.

Typical elements of DQ include:

• Alignment of user requirements (URS) with the system design
• Assessment of the manufacturer’s technical specifications
• Verification of suitability for the intended sterilisation process
• Consideration of relevant standards (e.g. DIN EN ISO 17665)
• Risk analysis at the design level

If you use our configurator, the design qualification is already complete.

Performance Qualification (PQ)
Performance Qualification (PQ) demonstrates the autoclave’s performance in real-world routine operation. It ensures that the sterilisation process reliably achieves the required sterilisation effect under practical conditions, thereby guaranteeing long-term product quality and safety.
To ensure that sterilisation complies with standards – for example, in accordance with EN 285 and ISO 17665 – loading tests are carried out with data loggers inside the product. These test runs serve to provide final validation of the sterilisation process within the defined parameters and confirm its reproducibility and process reliability in routine use.

The drying options are generally only required for programmes involving solid items such as instruments or textiles. Residual moisture reduces the shelf life of the sterilised material. The higher the residual moisture, the faster the material loses its ‘sterile’ status. This applies in principle to both single-packaged and multi-packaged materials. According to standardised regulations (e.g. EN 285), packaged instruments with a residual moisture content of 0.2% or less can be stored for up to 30 days or longer; for textile materials, a residual moisture content of 1% or less is considered acceptable for storage.

For units equipped with the MS option (jacket cooling with support pressure), it is possible to programme a simplified drying procedure, referred to by some manufacturers as ‘blow-drying’. In this process, following sterilisation in instrument programmes, the steam is removed from the chamber and the sterilised items are then dried using compressed air, utilising the residual heat of the chamber and the items being sterilised, whilst taking advantage of the changing relative humidity of the compressed air as it is heated within the chamber. However, this process is significantly less efficient than drying using a vacuum! The process is not suitable for packaged items to be sterilised.

Active recooling is available as an option alongside so-called ‘self-cooling’ or slow cooling.

A liquid programme with self-cooling is suitable for liquids in open containers. With self-cooling, once sterilisation is complete, the sterilisation chamber is closed and the unit waits until it has released all the heat absorbed during the heating of the unit and the items being sterilised into the surrounding environment. With this method, the entire amount of heat is released into the room, and the cooling-down time is very long. The advantage of this cooling method is that it results in only very slight volume loss of the items being sterilised during cooling. However, a negative pressure builds up in the closed chamber, which must be equalised by venting before the chamber is opened once the removal criteria have been met. Ventilation takes place via a sterile filter, whereby air from the immediate surroundings is drawn into the chamber by the negative pressure. By adjusting the parameters, ventilation can also be programmed to take place during self-cooling. However, this has the disadvantage that potentially non-sterile air may come into contact with the items being sterilised again, e.g. if the sterile filter has not been changed for too long. All units in the Laboklav series feature this cooling mode as standard.

During slow cooling, once the sterilisation phase is complete, the excess pressure in the sterilisation chamber is equalised via the steam outlet valve. Once a pressure just above ambient pressure or a temperature just above the boiling point has been reached, the release of pressure is stopped and the sterilisation chamber remains closed until the removal criteria are met. This creates a vacuum, which must be equalised before the chamber seal is opened. Pressure equalisation takes place automatically once the end of the programme has been confirmed. The chamber lid or door is also automatically unlocked and released. During the cooling phase, slight volume losses occur in the items being sterilised, and the concentrations of solutions may change slightly. However, the slow cooling process is significantly faster than natural cooling. In the case of units permanently connected to the exhaust system, a large proportion of the waste heat is discharged into the exhaust system and does not place a burden on the air conditioning via the ventilation and air-conditioning systems. In units manufactured by SHP Steriltechnik AG, the exhaust system is automatically monitored by a temperature sensor and protected against thermal overload. The programme sequence with slow cooling is suitable for liquids in open or lightly sealed vessels; ‘lightly sealed’ means that the vessels are loosely sealed, for example, with a cellulose or rubber stopper, or that a lid seals the vessel only to the extent that pressure equalisation between the interior of the vessel and the chamber volume is possible.

When using liquid programmes with the Option M – Rapid Cooling with Jacket Cooling – the cooling phase is activated once the sterilisation phase is complete. At this stage, both the pressure-relief mechanisms in the sterilisation chamber and the additional option of dissipating heat via the sterilisation chamber’s cooling jacket are utilised to enable highly efficient – and therefore very rapid – cooling of the liquid items being sterilised. High-purity deionised water from the feed water tank is used for cooling via the cooling jacket. This water is recirculated back into the tank, with the heat being temporarily stored so that it is available to the process again during the heating phase of the subsequent programme cycle. This enables savings of up to 12 % of the heating energy compared to similar products from other manufacturers, which reduces operating costs and benefits the environment. The heat discharged into the exhaust system via the steam outlet valve also reduces the load on the ventilation and air-conditioning systems and is not released into the room as heat. During the heat recovery process, the feed water is simultaneously degassed and the feed water storage tank is disinfected. Degassing enables a further energy saving of up to 3 %. The cooling rate and the ratio of energy dissipated to waste to energy stored can be programmed via parameters. When this option is used, volume losses occur in the liquid items being sterilised. These increase as the cooling rate rises. The standard settings are configured such that a volume loss of approx. 8–15 % is to be expected. The variations in volume loss result primarily from the size of the individual volumes used, as well as the shape of the liquid containers and the load quantity. If volume loss and, where applicable, the concentration of the aqueous solutions used are critical to the overall process, the processes should be tested and validated in advance. Further options can help to limit or prevent volume loss. Rapid cooling with jacket cooling is suitable for liquids in open or lightly sealed vessels. The processes run fully automatically and can be adjusted at any time via parameter settings. With equipment from SHP Steriltechnik AG, such adjustments can also be made via remote maintenance.

The use of liquid programmes with the aid of the Option MS – Rapid cooling with jacket cooling and support pressure – builds on the programmes using Option M. The Option M is extended in that, upon entering the ‘Cooling’ phase, a slight overpressure above the saturated vapour pressure is built up using sterile compressed air. This prevents delayed boiling during cooling. The support pressure can be set as a fixed value, which is regulated until the end of the cooling phase, or as an accompanying support pressure, so that the difference between saturated vapour pressure and support pressure is regulated. The latter, in turn, helps to reduce energy consumption and the operating hours of the connected compressor supplying the compressed air. This enables faster cooling with reduced volume loss of the sterilised material. The sterilising filter for compressed air filtration is integrated into the unit; a filter counter monitors the number of permitted cycles and signals when the filter needs changing. The options for programme flexibility already included under Option M, designed to optimise the process sequence, are also fully included.

The use of liquid programmes with the aid of the Option MSL – rapid cooling with jacket cooling, holding pressure and fan – builds on the hardware options M and S. However, the process differs fundamentally from these. Firstly, Option L comprises, on the hardware side, a fan built into the sterilisation chamber. This serves to create turbulence and mix steam and compressed air, which, for physical reasons, tend to separate. This makes it possible to ensure efficient heat transfer via the steam to the items being sterilised at pressures above the saturated vapour pressure. This ensures that liquids in pressure-tight, sealed vessels can be sterilised safely without damaging the vessels. Temperature stratification within the chamber is prevented. All other rapid cooling methods are also available.

Prions are misfolded, infectious protein particles which, despite lacking genetic material, can cause serious diseases such as Creutzfeldt-Jakob or BSE. They are extremely resistant to heat, radiation and chemical sterilisation methods, as they can convert normal proteins into their pathological form. Prions therefore require strict hygiene measures and specific sterilisation protocols to reliably prevent the transmission of infection.

Viruses are tiny infectious particles without their own metabolism, which can only replicate within living host cells. They consist of genetic material in the form of DNA or RNA, which is surrounded by a protein shell (capsid) and is sometimes additionally enclosed by a membrane shell (envelope). As they do not possess their own synthetic apparatus, viruses are entirely dependent on the cellular mechanisms of their host cells and exhibit a high host specificity.

In microbiology, bacteria are cultured using special nutrient media, which provide them with nutrients, salts, trace elements and growth factors. Depending on the purpose, liquid media such as broth or solid media containing agar are used, on which bacteria grow as visible colonies. In addition, there are different types of culture media, including selective, synthetic, non-synthetic and indicator media.
Bacterial growth occurs through binary fission and proceeds in several phases: initially, the cells adapt to their environment during the lag phase before multiplying rapidly in the exponential phase. As nutrient levels decline, growth slows down during the lag phase, transitions into the stationary phase and finally ends in the die-off phase.

Bacteria are prokaryotes, whilst the cells of higher organisms such as plants, animals and fungi are eukaryotes. Prokaryotes do not possess a membrane-bound cell nucleus; their DNA is present freely within the cell as a nucleoid. Furthermore, they lack membrane-bound organelles such as mitochondria or the endoplasmic reticulum, which are characteristic of eukaryotic cells. The cell wall of most bacteria consists of murein (peptidoglycan) and provides them with stability and compressive strength. These structural differences influence, amongst other things, staining behaviour and antibiotic susceptibility, and are therefore crucial for diagnosis and treatment.

Bacteria are classified morphologically into three basic forms: cocci, rods and spiral-shaped bacteria. Cocci are spherical and occur singly, in pairs (diplococci), in chains (streptococci), clusters (staphylococci) or bundles, which is important for microscopic identification. Rod-shaped bacteria are elongated and may be smooth, club-shaped or filamentous. Spiral-shaped bacteria such as spirilla, spirochaetes or vibrio have curved or spiral shapes, which often give them particular motility. This morphological classification is a first step towards classification and helps to narrow down the range of possible pathogens.

The microorganisms most resistant to moist heat are bacterial spores, particularly those of heat-resistant species such as Geobacillus stearothermophilus, and, to an even greater extent, prions. Vegetative bacteria, many viruses and fungi are reliably inactivated at significantly lower temperatures and for shorter durations. Spores possess special protective structures and a greatly reduced water content, which makes the denaturation of proteins more difficult. Sterilisation parameters are therefore selected so that even this most robust group is reliably killed. In practice, D-values (the time required to reduce the bacterial count by a factor of ten) and F-values (equivalent killing effect relative to a reference temperature) are often used as a guide.

Parasites can be divided into three main groups: protozoa, helminths and arthropods. Protozoa are single-celled parasites such as Plasmodium (malaria) or Toxoplasma gondii, which often live intracellularly or in specialised compartments of the host and can cause severe or chronic diseases. Helminths are multicellular worms, such as tapeworms, roundworms or flukes, which colonise the gut, blood vessels or organs and persist for long periods; their pathogenicity is based on chronic nutrient deprivation, tissue damage and immune reactions. Arthropods such as ticks, mosquitoes, lice or mites are either parasites themselves (e.g. scabies mites) or act as vectors by transmitting pathogens such as Borrelia, TBE viruses or Plasmodium whilst feeding on blood.

• Avoid scalding/burns caused by steam, hot liquids or hot objects
• Preventing infections caused by sterile equipment, steam or exhaust air filters
• Preventing damage to health caused by hazardous substances (e.g. medicines) in items being sterilised
• Postural problems caused by poor posture when loading and unloading
• Installing autoclaves safely (stability, valve alignment, no hazardous substances in the vicinity, protection against external influences)
• Before commissioning, check the sealing surfaces and the closure mechanism for damage and contamination; clean the items to be sterilised if necessary
• In the event of malfunctions or faulty autoclaves, take them out of service immediately, mark them clearly and have them inspected by a qualified person
• Place the items to be sterilised in suitable containers and position them securely in the chamber
• Select the correct programme
• Position the temperature probe correctly (liquids: reference vessel of at least the same size; solids: inside the pressure vessel; porous materials: inside where possible). For waste, solids and textiles, the temperature probe must be positioned on the mounting bracket.
  In the case of freestanding appliances, the temperature probe is often placed inside a bin bag. The bin bag collapses under the effect of steam, causing it to press against or stick to the probe.
• No hazardous substances, explosive mixtures, flammable liquids, highly reactive substances or heat-sensitive materials autoclave
• When autoclavising liquids, do not open the lid until the temperature has fallen below the boiling point (water < 95 or 80°C)
• Before opening the locking mechanism Check that there is no pressure (pressure gauge)
• Never force the autoclave open
• When opening or unloading, wear face protection and heat-resistant gloves
• Replace the exhaust air filter regularly, as indicated by the service interval display
• After finishing work Wash your hands, disinfect them and apply skincare
• Take care when moving heavy parts of the appliance (e.g. lids) or when lids or doors close automatically
• If the RCD trips when the appliance is switched on or when a programme is started, the appliance must be taken out of service and removed from the room. Inspections must only be carried out by a qualified person. There is a risk of electric shock.

The standard DIN EN 285:2021-12 applies to large sterilisers with a working chamber volume of more than 60 litres, which are predominantly used in hospitals. In contrast, DIN EN 13060 applies to small sterilisers with a volume of less than 60 litres, such as those typically used in doctors’ surgeries.

Both standards set out fundamental requirements for the design of the equipment and define clear performance criteria, in particular a sterility assurance level of SAL 10^–6. Furthermore, they regulate the necessary test procedures as well as comprehensive safety requirements to ensure reliable and safe operation.

The validation and monitoring of the sterilisation process, on the other hand, is carried out in accordance with DIN EN ISO 17665:2024-09, which defines the requirements for process validation, routine checks and proof of sterility.

Sterilisers are classified into different types, each of which is suitable for different applications. 

Type B is designed for all types of items to be sterilised, including solid, hollow and porous materials as well as packaged and unpackaged products.
Type N, on the other hand, is suitable exclusively for unpackaged, solid instruments without cavities or porous structures.
Type S is intended for specific products defined by the manufacturer, for which the sterilisation cycles have been validated. Each of these types has specified test loads and programmes that ensure safe and standard-compliant sterilisation.

Please note: DIN EN 13060 applies only to the medical use of small sterilisers, not to laboratory and biotechnology applications.

To ensure safe sterilisation, the steam must be saturated (dryness index ≥ 0.95), the proportion of non-condensable gases must not exceed 3.5 vol.%, superheat at 134 °C must not exceed 25 K, and pressure fluctuations must be within ±10 %. The feedwater should also contain a maximum residue level of 10 mg/l, no more than 1 mg/l SiO₂ and 0.2 mg/l iron.

Steam disinfection units are subject to DIN 58949-3:2020-09, which specifies the design, safety, operation and efficacy testing of the equipment. The standard does not prescribe fixed temperatures, but rather defines test procedures to ensure disinfection performance. Legally, its use is governed by the Infection Protection Act. The standard is primarily used for the disinfection of textiles, bedding and infectious materials, although the type of material, packaging and loading affect its effectiveness.

In Germany, the DIN 58950:2021-06 standard applies to pharmaceutical sterilisers. This standard applies to steam sterilisers with horizontal loading and a nominal size of 6 dm × 6 dm × 6 dm (internal volume ≥ 216 dm³) or greater, which are intended for pharmaceutical items to be sterilised and are operated using saturated steam, steam/air mixtures or hot water spray.

The standard 58950:2021-06 requires a sterility assurance level (SAL) of ≤ 10 ^-6 at 121 °C for 15 minutes and is supplemented by DIN EN 285:2021-12 and the GMP guidelines. It sets out specific requirements for validation, process monitoring and documentation, particularly for liquid and porous goods.

There is currently no international standard comparable in content to DIN 58950.

The standard DIN 58951:2024-07 applies to the sterilisation of general laboratory equipment, whilst DIN EN 12128:1998-05, DIN EN 12347:1998-06 and DIN EN 12740:1999-10 specifically regulate biotechnology sterilisers. They set out requirements for steam quality, validation procedures and specific test loads for glassware, media and cultures.