Autoclave Classes: Differences Between Class S, N, and B

Sterilization is a fundamental process in various industries, particularly in the medical, dental, and pharmaceutical fields. Proper elimination of pathogenic microorganisms is essential to prevent infections and ensure that instruments and materials that come into contact with the human body or sensitive products remain contamination-free.

Among sterilization tools, autoclaves play a vital role as they use high-pressure steam to effectively disinfect a wide range of materials. However, not all autoclaves are the same.

There are different autoclave classes, such as Class N, Class S, and Class B, each designed to meet specific requirements and cater to diverse needs. Choosing the right type of autoclave depends on several factors, including the type of load, frequency of use, and the level of sterilization required.

In this article, we will delve into the characteristics and applications of each autoclave class, helping you identify the best option for your needs.

Autoclave Classes: Main Types and Characteristics

Autoclaves are classified based on their sterilization technology and the types of materials they can process.

The three main categories—Class N, Class S, and Class B—are designed to meet different sterilization requirements, making them suitable for various settings and load types.

• Class N Autoclaves: These are designed for sterilizing solid, non-porous materials. They use a gravity displacement process without a vacuum pump, limiting their use to non-porous loads and materials without cavities. This type of autoclave is commonly found in small clinics or laboratories handling simple materials.
• Class S Autoclaves: Positioned as an intermediate option, these autoclaves are suitable for some loads with cavities or porous materials, though they have limitations compared to Class B autoclaves. They offer good adaptability to specific needs and are often used in environments requiring versatility but without the rigorous sterilization standards of hospitals.
• Class B Autoclaves: These are the most advanced and versatile, capable of sterilizing a wide range of materials, including those with cavities, packaging, and porous loads. They incorporate a pre-vacuum system that ensures the complete removal of air before steam injection, guaranteeing effective sterilization. Class B autoclaves are the ideal choice for clinics, hospitals, and laboratories that demand high sterilization standards.

Each autoclave class is designed with specific strengths and limitations, making them suitable for different practical applications.

The following sections provide an in-depth overview of each class, helping you determine the most appropriate choice for your requirements.

Class N Autoclaves

Class N autoclaves are specifically designed for basic sterilization tasks and straightforward material requirements.

These units utilize a gravity air displacement system, which removes air from the chamber without the need for a vacuum pump.

This approach is ideal for sterilizing solid, non-porous items, including simple metal instruments and unpackaged materials with no internal cavities.

Key Features of Class N Autoclaves

• Gravity Air Displacement: Class N autoclaves expel air from the chamber through the introduction of steam, without relying on a vacuum system to remove air completely. This limits their effectiveness for porous materials or items with cavities, as trapped air can hinder full steam penetration. This limits their effectiveness for porous materials or items with cavities, as trapped air can hinder full steam penetration.
• Recommended Applications: These autoclaves are ideal for sterilizing solid, non-porous instruments, such as stainless steel tools, trays, and containers that do not require complex packaging or contain internal cavities.

Limitations of Class N Autoclaves

Class N autoclaves are not suitable for sterilizing items with deep cavities, porous materials, or packaged instruments.

This limitation arises because gravity displacement does not ensure complete steam penetration in complex surfaces. As a result, Class N autoclaves are primarily used in small clinics or laboratories that do not require the sterilization of highly intricate materials.

While Class N autoclaves are restricted in their ability to sterilize complex instruments, Class B autoclaves excel in this area, as demonstrated by various clinical studies.

Class S Autoclaves

Class S autoclaves represent an intermediate category in terms of sterilization capacity and versatility. While they are more advanced than Class N models, they do not reach the level of specialization offered by Class B autoclaves. Their design allows them to handle certain porous materials and loads with cavities, though not all.

These autoclaves typically combine gravity air displacement methods with limited vacuum systems, offering greater operational flexibility compared to Class N models.

Key Features of Class S Autoclaves

• Air Displacement with Limited Vacuum Options: Some Class S models include a partial vacuum system, which enhances air removal for certain loads and allows for the sterilization of materials with simple cavities or basic packaging.
• Versatile Applications: Class S autoclaves can be used to sterilize non-porous loads, instruments with simple cavities, and, in some cases, porous and packaged materials. This flexibility makes them ideal for facilities that require a range of sterilization options without the stringent demands of a hospital setting.

Limitations of Class S Autoclaves

While Class S autoclaves offer greater versatility than Class N models, they do not provide the same level of effectiveness for complex materials as Class B autoclaves.

This means they may not be the best choice for densely packaged materials or instruments with deep, intricate cavities. Their performance depends largely on the specific load type and the autoclave model.

Class S autoclaves are an intermediate solution, making them ideal for clinics or laboratories needing more flexibility than Class N models provide, but without the highest sterilization standards offered by Class B autoclaves.

Class B Autoclaves

Class B autoclaves are the most advanced and versatile sterilization systems available.

Designed to meet the highest hygiene standards, these autoclaves can sterilize a wide range of materials, including those that pose particular challenges, such as porous items, instruments with deep cavities, and packaged objects.

They feature a pre-vacuum system that ensures complete air removal from the chamber, enabling uniform and efficient steam penetration throughout the entire load.

Key Features of Class B Autoclaves

• Pre-Vacuum System: This system ensures the complete evacuation of air before steam is introduced, eliminating potential air pockets that could compromise the sterilization process. It allows for effective treatment of complex materials, ensuring uniform sterilization even in the most challenging areas.
• Material Versatility: Class B autoclaves are capable of sterilizing a wide variety of loads, including porous materials, instruments with long and narrow cavities, and packaged items. Their versatility makes them essential in medical and hospital settings where a diverse range of instruments and the highest sterilization standards are required.

Typical Applications of Class B Autoclaves

Due to their ability to handle complex loads, Class B autoclaves are widely used in hospitals, clinics, and laboratories that demand professional-grade sterilization.

They are ideal for sterilizing everything from surgical and dental instruments to textiles and packaged materials, ensuring the safety of each processed item.

In conclusion, Class B autoclaves are the best choice for those seeking a comprehensive and reliable sterilization solution for a wide variety of materials.

Although they are more expensive than Class N or S autoclaves, their ability to meet the most stringent sterilization requirements justifies the investment in high-level healthcare environments.

Which Autoclave Class Should You Choose?

Choosing the right autoclave depends largely on the types of materials you need to sterilize and the specific requirements of your work environment.

Here are some key factors to consider when deciding between a Class N, Class S, or Class B autoclave:

1. Type of Load and Material: Class N autoclaves are ideal for solid, non-porous instruments, such as tools without cavities. If you occasionally need to sterilize instruments with cavities or porous materials, Class S autoclaves provide a suitable intermediate option. For complete sterilization of porous materials, packaged instruments, or those with complex cavities, Class B autoclaves are the best choice.
2. Required Sterilization Level: If your environment demands high sterilization standards, such as in hospitals or specialized clinics, Class B autoclaves are essential. Conversely, small clinics or laboratories handling straightforward materials may find a Class N autoclave sufficient.
3. Frequency and Versatility of Use: Class S and Class B autoclaves offer greater versatility and can handle a broader range of loads, making them ideal for settings with varied sterilization needs. Class N autoclaves, on the other hand, are better suited for specific tasks and have more limited sterilization capabilities.

Advantages and Limitations of Each Autoclave Class

• Class N: A cost-effective option for basic applications but limited in the types of materials it can sterilize.
• Class S: Strikes a balance between capacity and cost, making it suitable for clinics with specific sterilization needs that do not require the highest standards.
• Class B: The most comprehensive choice, capable of sterilizing all types of materials and ensuring maximum efficiency in demanding environments.

Ultimately, selecting the right autoclave requires a clear understanding of the materials, environmental requirements, and budget constraints.

Each autoclave class has a specific role in the market, and understanding their features is essential for ensuring effective and safe sterilization across various applications.

Our range of medical autoclaves is certified under ISO 13485:2016 for medical devices and is designed for use in hospitals, clinics and healthcare centers. These units are available for purchase in many countries, excluding those in the European Union.

If you have any questions, do not hesitate to reach out to our experts. Working together, we can identify and provide a solution that ensures both efficiency and safety in all your sterilization operations.