Validating Your Steam Sterilization Process

According to international regulations, your steam sterilization process must be validated at least once a year to ensure a sterile result. This requires accurate measuring equipment to gather data on temperature, pressure and time throughout the process.

The data you gather is then evaluated and compared to the relevant regulations in order to determine the quality of your sterilization – and thereby ensure compliance.

IQ, OQ and PQ Qualifications

Unlike qualifications of your autoclave, where you only have to perform installation qualifications (IQ) and operational qualifications (OQ), the validation of your process also requires a performance qualification (PQ).

• Installation Qualification:
  Verifies that the system is installed properly
• Operational Qualification:
  Verifies that your system works as intended
• Performance Qualification:
  Verifies the effectiveness of your sterilization process for a specific cycle or load. To perform a PQ, you need high-end measuring equipment to accurately determine your result

The results from your validation analysis are then used to control whether or not your autoclave complies with international standards, such as ISO 17665.

Ensuring Saturated Steam in your Autoclave

Furthermore, it is critical that you are able to determine whether the steam used in your autoclave is saturated. Non-saturated steam places the entire sterilization process at risk, as the steam may not sufficiently reach every area of the equipment that’s meant to be sterilized.

To obtain saturated steam, use temperature mapping equipment, validated software, and potentially, an electronic Bowie Dick Test system. These systems will ensure that you comply with the required norms and prove that your steam is saturated – and thereby ready to sterilize.

Controlling Steam Quality with a Bowie Dick Test

To ensure properly sterilized products, testing an autoclave’s steam penetration ability is crucial. This requires running a Bowie Dick test program.

The Bowie Dick test is an important daily routine control conducted on autoclaves. The purpose of which is to ensue proper penetration of steam, to allow it to successfully reach every corner of the chamber, as well as the product. Fully sterilizing it upon contact.

A Bowie Dick test is, however, only as reliable as the piece of third party equipment gathering the data. Which is why Ellab has developed the Bowie Dick Sensor, a highly innovative solution for electronic Bowie Dick testing.

Documenting the Process

For steam sterilization to be effective, the steam within your autoclave has to be saturated as this transfers far more energy from the steam to the product. To facilitate the validation of this parameter, the ValSuite® Pro software includes a saturated steam analysis that automatically correlates the temperature and pressure from within your autoclave.

To document the validation of the steam sterilization adequately, a diagram can be created that showcases all sensor ID’s in their exact position within your autoclave. This setup is easily performed in ValSuite Pro by integrating the session data with predefined schematics, pictures and Word documents.

ValSuite also allows you to easily generate and print various reports that can be kept on hand for audits and general documentation purposes.

Ensuring Accuracy with Calibration

A typical, but critical, factor when validating steam sterilization is the calibration of temperature sensors. It is essential that operators can demonstrate that the sensors were within an acceptable accuracy range when they were used.

This means calibrating shortly before the validation run (Pre Calibration) and then checking the accuracy afterwards to ensure that they are still within the predefined tolerances (Post Calibration). Using the built-in calibration functionality in ValSuite, operators can calibrate Ellab sensors at regular intervals.

The software then generates an easy-to-read calibration report that includes all measurements and tolerances that were defined by operators. It is recommended that Ellab sensors and probes are sent in at least once a year for factory calibration (which includes a traceable calibration certificate) to ensure that they function at optimal capacity.

Guidelines

The requirements for testing or validating autoclaves depend on the type of use and the country. Commonly used standards and guidelines are ISO EN 285, ISO EN 17665, ISO EN 11138, HTM 2010 and PDA Technical Report No. 1 Validation of Moist Heat Sterilization Processes.

Guidelines state that 11 temperature-measuring points are needed when performing a heat distribution study of an autoclave that is from 1.5 to 2.5 m3.

This number is reached by placing one sensor in each of the eight corners in the autoclave, one in the center, one close to the drain and one next to the autoclave’s temperature sensor.

How a Steam Sterilizer/Autoclave works

A steam sterilizer (or autoclave) is a high-pressure vessel with a sealed lid/door and gasket (the sterilizing chamber). The chamber is also equipped with an air removal system and a control system consisting of a timer, pressure control valve and safety valve. Autoclaves make use of pressurized steam at around 115-134 °C to heat the load and achieve sterilization.

Sterilizers come in many sizes, from small bench-top portable laboratory autoclaves to large production autoclaves. The larger autoclaves are usually built into the walls, from which “contaminated” products enter one side and the sterilized product exits on the other (inside a clean room).

They are typically used for sterilizing large volume of utensils and are rather advanced in design and control. They tend to be cylindrical, as this design has proven to be very strong when it comes to high and low amounts of pressure. Steam sterilizers are typically used for sterilizing products within the medical and pharmaceutical industries.