Aleix Nin

In sterilization processes, simply reaching the correct temperature inside the autoclave chamber is not enough. What truly matters is whether that temperature is also achieved within the load itself – especially when sterilizing liquids.

Direct monitoring inside the product ensures that all material has been properly sterilized, minimizing microbiological risks. Additionally, this measurement is key to calculating the F₀ value and optimizing cycles by reducing time without compromising the effectiveness of the process.

For this reason, PT-100 flexible probes have become an essential accessory in laboratories and facilities that demand precision, traceability, and validation in their sterilization processes.

What Are PT-100 Probes and How Do They Work?

PT-100 probes are temperature sensors based on the electrical resistance of platinum. The name indicates a resistance of 100 ohms at 0 °C. As the temperature changes, so does the resistance, enabling accurate readings even in demanding environments.

These probes are inserted directly into the load – for example, into a flask containing culture media – so they provide the actual temperature of the product, not just the surrounding environment. This distinction is particularly relevant in liquid loads, where heat penetrates more slowly.

Additionally, the use of PT-100 probes allows cycle control through the F₀ parameter (in compatible models), which represents the accumulated lethality of the process based on the time the sample remains at a specific temperature, using 121.1 °C as a reference.

Why Is It Crucial to Measure Inside the Product?

The temperature inside the sterilization chamber does not guarantee that the core of the sample has reached sterilization temperature. In liquids, there can be a significant thermal delay: steam may reach 121 °C while the liquid is still below 100 °C.

This lag can lead to false positives if the sterilization time is counted too early.

Measuring directly inside the product allows you to:

✅ Ensure the entire sample has been properly treated.
✅ Avoid microbiological risks.
✅ Validate and optimize cycles using the F₀ value.

PT-100 Probe Models Available from RAYPA

The flexible PT-100 probes offered by RAYPA are designed to ensure precise control of the sterilization process, especially when monitoring liquid loads. For optimal functionality and proper integration with the autoclave control system, these probes must be installed at the factory.

Flexible Probe for Classic Line Autoclaves

References: PT-2, PT-2-B, PT-2-AH and PT-2-B-AH

These probes are specifically designed to monitor the sterilization of liquid loads in autoclaves from RAYPA’s Classic line.

They are available in several versions, compatible with the AES, AE-DRY, AE-B, AHS-N, AHS-DRY, and AHS-B series, with probe lengths varying according to the specific autoclave model (60 mm for benchtop models, 120 mm for vertical models).

Main Benefits:

• Effective sterilization of liquids: The probe accurately measures temperature at the center of the liquid sample, ensuring that the required temperature is reached within the load. This significantly improves the reliability of the sterilization process.
• Prevention of boilover effects: Continuous monitoring of liquid temperature minimizes the risk of overheating and spills when opening the autoclave. This protects both the operator and other contents of the autoclave chamber.
• Optimization of sterilization processes: By simultaneously controlling the temperature in the chamber and inside the liquid, it provides more precise tracking of the F₀ value and cycle lethality. This facilitates more efficient sterilization, ensuring consistent results, regardless of the number or size of the processed containers.

Flexible Probe for Top Line Autoclaves

Reference: PT-2-TLV

Specifically recommended for accurate monitoring of liquid sterilization processes in RAYPA’s Top line autoclaves.

Compatible with RAYPA’s TLV-DUAL, TLV-PD, TLV-FA, and TLV-S autoclave models, all intended for critical applications requiring rigorous control. These units allow installation of up to two probes, enhancing versatility for monitoring. Some series, such as TLV-DUAL and TLV-FA, include one flexible probe as standard equipment.

Unlike the Classic line probes, the probe length varies depending on autoclave capacity and the specific needs of each sterilization process. This provides greater versatility, facilitating placement in various types of containers or different positions within the chamber.

Modes of use:

• Single flexible probe: Allows direct monitoring of the internal temperature of the liquid sample, initiating the sterilization phase only once the desired temperature is reached. Additionally, installation of this probe enables programming cycles based on the F₀ value, optimizing lethality control and offering greater process flexibility.
• Two flexible probes: Ideal for comparing conditions between different samples, especially when containers of varying sizes or positions within the chamber are used (such as upper and lower levels). The sterilization cycle starts only when both probes detect the required temperature, ensuring uniform treatment throughout the entire load.

Practical Recommendations for End Users

Choosing the right accessory to monitor temperature in an autoclave depends on the autoclave model, type of load, regulatory requirements, and process objectives.

👉 For liquids and culture media, a flexible PT-100 probe is always recommended.
👉 For heterogeneous loads, using two probes (in Top line models) helps identify cold spots and validate process uniformity.
👉 In laboratories subject to regulations such as GMP, FDA, or ISO 13485, it is essential to work with systems that enable F₀-based control, traceability, and report generation.

Common Errors When Using Probes in Autoclaves

Even with the appropriate probes, improper use can compromise the effectiveness of the sterilization process. Avoid the following mistakes:

🚫 Placing the probe in contact with the container wall (this distorts the measurement).
🚫 Using probes with damaged or uncalibrated cables.
🚫 Starting the cycle without confirming correct placement inside the sample.
🚫 Failing to verify probe compatibility with the autoclave model.

Expert tip

Always consult with the manufacturer or RAYPA’s technical support team to ensure you select accessories that are compatible with your specific model and application needs.

Do you have questions about which probe is best suited to your application? Our team of professionals is available to guide you and help you achieve safe, validated, and efficient sterilization.

In the field of sterilization, choosing the right autoclave is essential to ensure efficiency and safety in the process.

Two of the most common options are vertical autoclaves and benchtop horizontal autoclaves, each with specific features that make them ideal for different applications.

In this article, we will explore their differences, advantages, and recommended uses in detail.

What Is the Difference Between a Vertical and a Horizontal Autoclave?

The main difference between a vertical autoclave and a horizontal autoclave lies in the loading orientation and the sterilization chamber design:

• Vertical autoclaves: The load is inserted from the top. They are known for their large capacity, allowing for the sterilization of higher volumes of material in a single cycle.
• Benchtop horizontal autoclaves: The load is placed from the front through a swing door. These autoclaves are compact and designed for space-constrained environments, making them ideal for smaller laboratories and clinical settings.

Dimensions and Space Requirements

Vertical autoclaves require more vertical space but optimize floor usage in laboratories and workspaces. In contrast, benchtop autoclaves are more compact, take up less height, and can be placed on tables or lab benches, making them ideal for small work areas.

Capacity and Recommended Uses

• Vertical autoclaves: Designed for high-volume sterilization, they allow large quantities of materials to be processed in a single cycle. They are commonly used in laboratories, hospitals, and research facilities where efficiency is essential.
• Benchtop autoclaves: Built for smaller loads and fast sterilization cycles, they are widely used in clinics, medical offices, and small labs where a compact solution is needed.

Pros and Cons of Vertical Autoclaves

Advantages of Vertical Autoclaves:

👍 Larger capacity: Ideal for sterilizing instruments, culture media, and bulky lab materials efficiently.

👍 Space optimization: While taller, they take up less floor space, maximizing lab layout efficiency.

👍 Versatile sterilization: Suitable for various materials, including liquids and large equipment.

Disadvantages of Vertical Autoclaves:

👎 Less ergonomic loading: Top-loading requires lifting materials, which can be challenging for heavy loads. However, lifting aids like fixed or mobile hoists improve safety and ease of use.
👎 Longer handling time: Loading and unloading may take longer compared to benchtop models, depending on the material type.

Pros and Cons of Benchtop Horizontal Autoclaves

Advantages of Benchtop Autoclaves:

✅ Compact design: Ideal for space-constrained environments, as they can be placed on tables, workbenches, or lab counters.
✅ Ergonomic loading: The front-loading system allows materials to be placed individually on the tray or directly inside the autoclave, reducing the need to lift heavy loads. Additionally, a transport trolley can be used to bring the load closer to the autoclave opening for easier and safer handling.
✅ Fast sterilization cycles: Designed for efficient processing of moderate volumes, making them ideal for clinics and small laboratories.

Disadvantages of Benchtop Autoclaves:

❌ Limited capacity: The cylindrical chamber design restricts space utilization, preventing full use of the corners and limiting the height of certain containers placed at the sides of the trays.
❌ Less versatile: Less efficient for large or bulky equipment or high volumes of liquid sterilization compared to vertical autoclaves.

How to Choose the Right Autoclave

Choosing between a vertical autoclave and a benchtop horizontal autoclave depends on several key factors:

• Load volume: If you need to sterilize large quantities of material in a single cycle, a vertical autoclave is the best option.
• Available space: For environments with limited space, a benchtop autoclave may be the most suitable alternative.
• Application type: Laboratories handling bulky materials or large volumes of liquids will benefit from the higher efficiency of vertical autoclaves.

Autoclave Vertical vs Horizontal: Which One Should You Choose?

When comparing an autoclave vertical vs horizontal, the decision ultimately depends on your sterilization needs. If you prioritize capacity and efficiency, a vertical autoclave is the better choice. However, if you require a compact, front-loading system, a benchtop horizontal autoclave will be more practical.

In a nutshell

Both types of autoclaves provide effective sterilization solutions, but the right choice depends on your specific needs.

If you require a high-capacity solution for large sterilization loads, a vertical autoclave is the ideal option.

On the other hand, if you need a compact and efficient unit for moderate loads, a benchtop horizontal autoclave is the best alternative.

Still unsure which autoclave to choose? At RAYPA, we help you find the best sterilization solution for your laboratory. Contact us today for expert advice.

The efficiency and operational safety of an autoclave—an essential piece of equipment for sterilizing medical instruments, laboratory tools, and other critical environments—are intrinsically linked to the rigorous implementation of proper care and cleaning practices.

The accumulation of residues can not only negatively affect the performance of the equipment but also pose a significant risk to operator safety and the integrity of the sterilization process.

This article aims to provide a comprehensive guide on cleaning and maintaining autoclaves, covering general considerations as well as specific recommendations to ensure the durability, reliability, and effectiveness of these devices.

Always refer to the manufacturer’s manual

The first step should always be consulting the specific user and maintenance manuals for the equipment in question. These documents provide detailed information on routine care practices, appropriate consumables, and technical installation specifications.

Additionally, following these guidelines helps maintain the validity of the equipment’s warranty and ensures that all procedures align with industry standards and regulations.

What products are needed to clean an autoclave?

To prevent damage to the equipment and ensure optimal performance, it is essential to use specialized cleaning products that do not compromise the integrity of its components.

Avoid using materials or substances that may be abrasive or corrosive to the autoclave.

Some recommended products for cleaning an autoclave include:

• Soft cloths or cotton towels.
• Distilled water to prevent mineral buildup that could clog the drainage valve.
• Neutral detergent or a non-abrasive cleaning product recommended by the manufacturer.
• Protective gloves for the user.

What does autoclave cleaning involve?

Routine cleaning consists of a series of simple manual operations that must be performed carefully to avoid damaging the equipment. It is important to follow general precautions such as:

• Avoiding direct water jets, whether high-pressure or spray.
• Preventing the accumulation of limescale or other residues in the sterilization chamber, lid, and gasket.

Recommended cleaning procedures:

1. Cleaning the gasket, interior of the lid, and external surfaces. To remove limescale deposits from the gasket and the lid’s interior, use a clean cotton cloth dampened with water. For external surfaces, use a soft cloth dampened with water, and if necessary, add a small amount of neutral detergent.

In both cases, it is crucial to thoroughly dry all surfaces and remove any remaining residue before using the autoclave. Occasionally, external surfaces can also be disinfected with denatured alcohol.

2. Cleaning the sterilization chamber and accessories. To clean the sterilization chamber, heating element cover, baskets, and internal surfaces, use a clean cotton cloth dampened with water, adding a small amount of neutral detergent if needed. Once finished, carefully rinse all surfaces with distilled water to remove any residue.

Avoid using sharp or pointed objects to remove scale buildup. If significant limescale deposits are observed, check the quality of the water being used.

3. Cleaning the water reservoirs. In autoclaves equipped with clean and waste water tanks, these should be emptied and cleaned regularly. It is essential not to empty the tank while the equipment is under pressure, as the steam and hot water could cause burns.

4. Cleaning the drainage filter. With regular use, various types of residues may accumulate in the drainage filter, potentially clogging the system. In such cases, the filter should be removed according to the manufacturer’s instructions and carefully cleaned under running water.

For stubborn residues or to remove larger debris, a pointed instrument may be required. If the filter is clogged with agar, we recommend using hot water. If, after cleaning, the filter remains obstructed or does not show improvement, it should be replaced with an original spare part.

How often should an autoclave be cleaned?

The cleaning and maintenance schedule of an autoclave should be adjusted based on workload intensity and the type of sterilization processes performed.

In general, we recommend the following routine maintenance schedule for your autoclave:

• Daily: Clean the gasket, interior of the lid, and external surfaces.
• Weekly: Clean the sterilization chamber and accessories. Additionally, replace the water in the tanks for models that require it.
• Monthly: Clean the drainage filter.

Maintenance tips after cleaning an autoclave

Regular inspections are essential to proactively identify and address any signs of wear, residue buildup, or equipment malfunctions.

Adopting systematic cleaning practices, along with timely replacement of worn components and precise calibration of the equipment’s controls and sensors, are key aspects of an effective and efficient maintenance program.

The rigorous implementation of these maintenance actions—performed with the necessary frequency and attention—helps extend the equipment’s lifespan, enhances its performance, and ensures safe and effective sterilization processes that comply with the highest quality and safety standards.

At RAYPA, we recommend conducting a comprehensive annual inspection, focusing on verifying the optimal operation of safety mechanisms, assessing the condition of the door gasket, replacing the bacteriological filter, and performing a meticulous calibration of the temperature probes.

If you have any questions regarding the cleaning or maintenance of your autoclave, do not hesitate to contact us. Our experts are ready to assist you with troubleshooting, training, and supplying high-quality original spare parts.

Have you ever wondered if your autoclave is running as smoothly as it should be? Have you faced any hiccups while using it? Knowing the common pitfalls that users experience with autoclaves can save you a lot of trouble.

The use of autoclaves is crucial across various industrial sectors, ranging from hospitals and microbiology laboratories to the pharmaceutical industry and research centers. These devices are essential for sterilizing medical implants, instruments, and waste, ensuring the complete inactivation of any microorganisms and guaranteeing a safe, contamination-free environment. But let’s face it, improper use of these essential machines can throw a wrench in the works, seriously affecting their efficiency.

At RAYPA, we pride ourselves on our expertise in laboratory autoclaves. Over the years, we’ve pinpointed the most frequent mistakes that users make. Our goal? To arm you with practical tips that ensure every sterilization cycle is not just safe, but flawless.

1. Overloading the Autoclave

Overloading the autoclave is a common cause of incomplete sterilizations. Attempting to sterilize too many items at once not only unnecessarily prolongs the heating phase but also hinders the free circulation of steam within the chamber. It is crucial that all internal and external surfaces of the items are accessible to steam to achieve proper sterilization.

The solution is practical and straightforward. It is essential to distribute the items evenly within the autoclave, ensuring that a minimum space is left between them to facilitate optimal steam circulation. Additionally, it is always advisable to place chemical and biological indicators within the load to verify that sterilization has been effective. Furthermore, it is imperative to adhere to the manufacturer’s recommendations regarding the maximum load capacity for each autoclave model.

Following these guidelines will not only ensure successful sterilization but also extend the life of your autoclave.

2. Using an incorrect sterilization cycle

Selecting an inappropriate sterilization cycle is a common error that can severely compromise the effectiveness of a sterilization process.

Each type of load requires a specific set of parameters and processes to ensure a complete sterilization of the load. Among the most important are the removal of non-condensable gases, the duration of the sterilization phase, the sterilization temperature, the pressure during the sterilization phase, and the use of the drying function at the end of the cycle. Using an incorrect cycle can result in incomplete sterilization and cause undesirable changes in the material composition or even structural damage to the processed items.

A clear example of this error is using a program designed for solid loads when sterilizing liquids. Liquids require a cooling phase with slow depressurization and, in some cases, the use of pressure support. Another common mistake is applying the same cycle duration parameters for both large and small volumes of liquids. This is problematic because large volumes take longer to heat and therefore require extended times for proper sterilization.

The key to avoid this error is training and attention to detail. It is essential to familiarize yourself with the different sterilization cycles available in an autoclave model and understand which is most suitable for each type of load. This involves carefully consulting the specifications provided by both the material and the autoclave manufacturer. Ensure that cycle selection is based on compatibility with the material, considering factors such as heat resistance and moisture sensitivity.

Common examples that require specific cycles include liquids, sealed containers, items with complex geometries, bagged objects, and textile materials.

By following these guidelines, you will not only ensure effective sterilization but also protect the integrity of the processed instruments.

3. Moisture in textile loads and porous objects after completing a sterilization cycle

The presence of residual moisture in textile loads and porous objects at the end of a sterilization cycle indicates a suboptimal process or malfunction of the autoclave. These materials should be completely dry upon completion of the sterilization process. Residual moisture, in the form of condensed water, acts as a barrier that impedes the free circulation of steam and poses a significant risk for recontamination when the load is removed. This residual moisture can serve as a breeding ground for microorganisms, compromising the purpose of sterilization.

To prevent this issue, it is essential always to use a program that includes fractional pre-vacuum and final drying. This cycle is designed to first remove all cold air from the chamber through multiple vacuum pulses, followed by the injection of saturated steam produced by a steam generator, and subsequently, the removal and expulsion of all residual moisture through a drying system.

This ensures that items are removed completely dry and in optimal condition for subsequent use or safe storage. Additionally, depending on the volume and complexity of the load, the final drying phase may need to be extended.

Moreover, the arrangement of items in the autoclave influences the effectiveness of the drying process. It is crucial to ensure that packages or containers are not too tightly packed or poorly distributed, allowing for adequate steam circulation. Proper spacing facilitates uniform and complete drying.

If, after implementing these recommendations, the items still exhibit moisture after the drying cycle, it is necessary to inspect the condition of the equipment and perform any necessary adjustments or repairs.

Implementing these measures ensures that sterilizations are always successfully completed, avoiding the issue of a wet load at the end of the cycle and the associated risks of incomplete sterilization or recontamination.

4. Overlooking the importance of water quality

The quality of water used in autoclaves is a pivotal factor that is frequently underestimated. It plays a crucial role in both the effectiveness of the sterilization process and the longevity of the equipment.

When water that fails to meet recommended standards is utilized, lime deposits can accumulate on the chamber walls and internal components of the autoclave. This accumulation can lead to reduced efficiency, excessive mineral transfer to processed items, and eventual malfunctions. Such issues not only degrade the autoclave’s performance but also compromise the quality of sterilization.

To mitigate these risks, it is imperative to use demineralized or purified water in autoclaves. This type of water contains very low concentrations of salts and other impurities that could interfere with the sterilization process. Additionally, it is essential to implement a water quality control regimen, conducting periodic tests to ensure its consistent purity.

The specific type of water required will depend on the manufacturer’s recommendations and the intended use of the autoclave. Generally, autoclaves for medical purposes or those utilizing a steam generator should exclusively use purified water.

To address water quality concerns, RAYPA provides validated water softeners and purifiers designed for use with our equipment. Our installation guides and instruction manuals for each model offer clear guidance on this aspect. For further assistance, our engineering team is available to provide expert advice.

Maintaining rigorous attention to water quality not only prevents issues related to mineral buildup and corrosion but also ensures effective sterilization and prolongs the lifespan of the autoclave.

5. Neglecting regular maintenance and calibration

Ensuring the optimal performance of an autoclave is essential for conducting effective and safe sterilizations. However, neglecting regular maintenance and calibration can lead to a gradual decline in efficiency and potential equipment failures, ultimately compromising the sterilization process. Issues such as the deterioration of seals and valves or the miscalibration of temperature and pressure controls can remain undetected until they cause significant failures or ineffective sterilization.

Implementing a rigorous maintenance and calibration program is paramount. This program should adhere to the autoclave manufacturer’s guidelines and encompass critical activities such as regular equipment cleaning, inspection and replacement of seals and valves, and periodic calibration. Accurate calibration of sensors is crucial to ensure that sterilization cycles operate under precise temperature and pressure conditions required for effective sterilization.

Establishing and following a meticulous maintenance schedule will not only prolong the autoclave’s operational lifespan but also maintain high standards of sterilization. This is vital not only for compliance with safety and health regulations across various industries but also for ensuring consistent reliability in every sterilization cycle performed.

If you encounter these or other issues with your autoclave, please contact us. Our team of specialists is ready to address your concerns and assist you in restoring your autoclave to optimal functionality.