Temperature and Humidity Distribution Testing
The temperature setting range of the ETO Sterilization Chamber should be between 30-60°C. It is recommended to perform temperature distribution testing of the sterilizer’s internal surface and temperature and humidity distribution testing inside the sterilization chamber to ensure the effectiveness of the heating and humidifying systems.
a) Internal Surface Temperature Test of ETO Sterilization Chamber:
- During the test, the sterilization chamber should be empty, but auxiliary devices required for sterilization can be installed. The sterilization chamber door should be closed.
- The temperature of any preheating stage as specified by the sterilizer manufacturer should be recorded. The temperature of all internal surfaces of the sterilization chamber should not exceed the set temperature of the sterilization phase by ±5°C.
b) Temperature and Humidity Test in the ETO Sterilization Chamber:
- During the test, the ETO Sterilization Chamber should be empty, but auxiliary devices required for sterilization can be installed. The sterilization chamber door should be closed.
- Use temperature and humidity sensors placed in specified positions to compare with the control temperature inside the chamber. The temperature sensors should be placed at locations likely to represent the maximum temperature differences, such as unheated parts of the chamber, near the cabinet doors, and near steam or gas entry points. Other sensors should be evenly distributed throughout the usable volume of the sterilization chamber, including the middle, top, bottom, front, and rear. The number of sensors should meet the requirements in Appendix C of GB18279.1.
- The position of each measurement should be recorded, and the temperature and humidity in different areas of the sterilization chamber should be recorded to identify potential hot spots and cold spots.
- The indoor temperature range of the sterilization chamber when empty should not exceed ±2°C of the set temperature or ±3°C of the average temperature inside the chamber.
Vacuum Pumping Rate
- The vacuum system during the vacuum pumping phase should be able to evacuate the empty sterilization chamber to -75 kPa or lower. A pressure gauge should be connected to the vacuum test inlet to observe whether it meets the required standard.
- The manufacturer should confirm the time required to reach -50 kPa and -75 kPa under empty load conditions. A timing device can be used to monitor the vacuum pumping phase, and the preset parameters should be reached within the specified time.
ETO Sterilization Cabinet Leakage Test
The ETO Sterilization Cabinet leakage test includes both vacuum (negative pressure) leakage testing and pressure (positive pressure) leakage testing (if applicable). When the sterilizer’s working pressure is greater than 5 kPa, a pressure (positive pressure) leakage test should be performed.
- The vacuum leakage test should be conducted before the sterilant injection phase and the humidification phase, with the testing method following the provisions of Appendix D.1 of YY0503. The preset pressure during the test should be less than -20 kPa and at least 20 kPa lower than the preset sterilization pressure. Once the preset pressure is reached, all valves connected to the sterilization chamber should be closed, and the vacuum pump should stop working. The pressure in the sterilization chamber should be monitored, and the pressure rise within 5 minutes should not exceed 0.3 kPa/min. The pressure variation during the entire test should not exceed 0.1 kPa/min.
- Positive pressure leakage testing (if applicable) should be conducted before the vacuum pumping phase. The preset pressure for the test should be within 10% of the sterilizer’s preset working pressure. The pressure drop within 5 minutes should not exceed 0.3 kPa/min. At the same time, according to the method in Appendix D.2 of YY0503, the sterilization time should be set to at least 65 minutes, using inert gas (such as air) to replace EO gas and run a normal sterilization cycle. After the sterilization phase reaches temperature stability for 2 minutes, the pressure in the sterilization chamber should be recorded. It should be recorded again after 60 minutes ± 1 minute. The pressure variation rate should not exceed 0.1 kPa/min.Auxiliary System Verification
During the operational verification, the performance of related auxiliary systems should be confirmed, including but not limited to: the quality of steam provided, the ability of the EO vaporizer to reach the minimum gas input temperature, the reliability of the sterilizer’s air filtration and water supply systems, and the ability of the steam generator to maintain the required supply quality under maximum sterilization load conditions.
Examples of acceptable auxiliary system performance: a) When steam is injected during the processing phase, the humidity in the sterilization chamber should show a noticeable change, and the chamber should maintain pressure within ±2.5 kPa of the set pressure. b) The temperature of the injected EO gas should be higher than the minimum value set for the vaporizer (usually 10.7°C at atmospheric pressure) to ensure that the EO injected is in gaseous form, not liquid. c) The filtration effectiveness of the air filtration system should meet the requirement of a filtration rate of at least 99.5% for particles greater than 0.3 microns. d) The water supply system should use purified water meeting the requirements of the 2020 edition of the Chinese Pharmacopoeia. e) The steam vapor pressure used for humidification in the sterilizer should not exceed 50 kPa.
ETO Sterilization Cabinet Software
During the sterilization process, the sterilization equipment software will control and monitor the sterilization process and evaluate the parameters of the sterilization cycle. Therefore, during the operational qualification process, the sterilization equipment software should be tested under all failure conditions (such as computerized measurement and control systems). Refer to the sterilizer’s user manual and equipment specifications, and test the software system’s functions in areas such as alarm handling, error processing, information management, parameter settings, historical record interfaces, sensor control and monitoring, and operational control and monitoring under conditions challenging the equipment’s operational limits.
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References
Anhui Province medical device ethylene oxide sterilization confirmation work guide