Ethylene Oxide (EtO) sterilizers are crucial equipment in various industries, especially in the medical and pharmaceutical sectors, where ensuring the sterility of products is of utmost importance. As a leading supplier of Eto Sterilization Machine, I understand the significance of operating these machines correctly. In this blog, I will share comprehensive guidelines on how to operate an Ethylene Oxide Sterilizer correctly.
Pre - operation Preparations
1. Training
Before operating an EtO sterilizer, operators must receive thorough training. This training should cover the basic principles of ethylene oxide sterilization, the structure and function of the sterilizer, safety regulations, and emergency response procedures. Training can be provided by the equipment supplier, internal training programs, or external professional institutions. A well - trained operator is the first step towards correct operation.
2. Inspection of the Sterilizer
- Mechanical Inspection: Check the physical condition of the sterilizer, including the door seals, pipes, valves, and control panels. Ensure that there are no visible damages, leaks, or loose connections. For example, a damaged door seal can lead to gas leakage during the sterilization process, which not only affects the sterilization effect but also poses a safety hazard.
- Electrical Inspection: Examine the electrical system of the sterilizer. Make sure that all electrical components are functioning properly, and there are no short - circuits or open - circuits. Check the grounding of the equipment to prevent electrical accidents.
- Gas Supply Inspection: If the sterilizer uses ethylene oxide gas, verify the gas supply system. Check the gas cylinder or gas pipeline for leaks, and ensure that the gas pressure is within the specified range.
3. Preparation of Sterilization Items
- Cleaning: Thoroughly clean the items to be sterilized before placing them in the sterilizer. Remove any visible dirt, debris, or organic matter. This is because dirt and organic matter can interfere with the contact between ethylene oxide and the microorganisms on the surface of the items, reducing the sterilization efficiency.
- Packaging: Use appropriate packaging materials for the items. The packaging should be permeable to ethylene oxide gas but can prevent the re - entry of microorganisms after sterilization. Common packaging materials include Tyvek envelopes and porous wraps. Make sure that the items are properly arranged in the packaging to ensure uniform gas penetration.
Loading the Sterilizer
1. Loading Pattern
- Uniform Distribution: Place the sterilization items evenly inside the sterilizer chamber. Avoid over - loading or unevenly stacking the items, as this can create areas with poor gas circulation and lead to incomplete sterilization. For example, if all the items are concentrated on one side of the chamber, the gas may not be able to reach the other side effectively.
- Space between Items: Leave sufficient space between the items to allow for free gas flow. A general rule of thumb is to leave at least 2 - 3 cm of space between adjacent items.
2. Loading Quantity
Do not exceed the maximum loading capacity specified by the sterilizer manufacturer. Over - loading can not only affect the sterilization quality but also put additional stress on the equipment, potentially leading to mechanical failures.
Setting the Sterilization Parameters
1. Temperature
The temperature inside the sterilizer chamber plays a crucial role in the sterilization process. Ethylene oxide sterilization is usually carried out at a temperature range of 37 - 63 °C. Higher temperatures can increase the reactivity of ethylene oxide and shorten the sterilization time, but they may also damage heat - sensitive items. Therefore, the appropriate temperature should be selected according to the nature of the items to be sterilized.
2. Humidity
Proper humidity is essential for effective ethylene oxide sterilization. The relative humidity inside the chamber should be maintained at 30 - 80%. Humidity helps to enhance the penetration of ethylene oxide into the items and improves the inactivation of microorganisms. The sterilizer may have a built - in humidification system to adjust the humidity level automatically.
3. Gas Concentration
The concentration of ethylene oxide gas in the chamber is another important parameter. The typical gas concentration for sterilization ranges from 450 - 1200 mg/L. The specific concentration should be determined based on the type of items, the level of microbial contamination, and the sterilization time. Higher gas concentrations can achieve faster sterilization, but they also increase the risk of gas residues on the items.
4. Sterilization Time
The sterilization time depends on several factors, including the temperature, gas concentration, and the nature of the items. Generally, the sterilization time can range from 2 - 12 hours. Longer sterilization times are usually required for larger or more complex items.
Starting the Sterilization Cycle
1. Initiating the Cycle
After setting the sterilization parameters, start the sterilization cycle according to the operating instructions of the sterilizer. The sterilizer will first evacuate the air from the chamber to create a vacuum, which helps to improve the gas penetration. Then, the ethylene oxide gas will be injected into the chamber, and the temperature, humidity, and gas concentration will be maintained at the set values for the specified sterilization time.
2. Monitoring the Cycle
- Parameter Monitoring: Continuously monitor the temperature, humidity, gas concentration, and pressure inside the chamber during the sterilization cycle. The sterilizer usually has a control panel or a monitoring system that can display these parameters in real - time. If any parameter deviates from the set range, take appropriate measures to adjust it.
- Cycle Progress Monitoring: Keep track of the progress of the sterilization cycle. The sterilizer may have indicators or alarms to show the different stages of the cycle, such as pre - conditioning, gas injection, sterilization, and aeration.
Aeration Process
1. Purpose of Aeration
After the sterilization cycle is completed, the items need to undergo an aeration process to remove the residual ethylene oxide gas. Ethylene oxide is a toxic and carcinogenic substance, and residual gas on the items can pose a health risk to users.
2. Aeration Conditions
- Temperature and Ventilation: Aeration is usually carried out at a temperature of 50 - 60 °C with good ventilation. Higher temperatures can accelerate the evaporation of ethylene oxide, and ventilation helps to remove the gas from the aeration area.
- Aeration Time: The aeration time can range from several hours to several days, depending on the type of items, the gas concentration during sterilization, and the aeration conditions. Some items may require longer aeration times to ensure that the residual gas levels are below the safety limits.
Post - operation Procedures
1. Unloading the Sterilized Items
After the aeration process is completed, carefully unload the sterilized items from the sterilizer. Check the packaging of the items to ensure that it is intact and there are no signs of damage or re - contamination.
2. Cleaning and Maintenance of the Sterilizer
- Chamber Cleaning: Clean the inside of the sterilizer chamber after each use. Use a mild detergent and a soft cloth to wipe the chamber walls, shelves, and other components. Remove any residual gas or debris from the chamber.
- Equipment Maintenance: Regularly perform maintenance on the sterilizer, including lubricating moving parts, replacing worn - out seals and gaskets, and calibrating the sensors and control systems. Follow the maintenance schedule recommended by the equipment manufacturer.
Safety Precautions
1. Personal Protection
Operators should wear appropriate personal protective equipment (PPE) when operating the ethylene oxide sterilizer. This includes gloves, goggles, and respirators. The respirator should be able to filter ethylene oxide gas to protect the operator from inhalation exposure.
2. Ventilation
Ensure that the operating area of the sterilizer is well - ventilated. Install exhaust systems to remove any leaked ethylene oxide gas from the area. The ventilation rate should be sufficient to maintain the ethylene oxide concentration in the air below the occupational exposure limit.
3. Emergency Response
Develop an emergency response plan for potential ethylene oxide leaks or other accidents. Train the operators on how to respond to emergencies, including shutting off the gas supply, evacuating the area, and using emergency equipment such as fire extinguishers and spill - control kits.
Conclusion
Operating an Ethylene Oxide Sterilizer correctly is a complex but essential process. By following the above - mentioned guidelines, operators can ensure the effective sterilization of items, the safety of the equipment, and the protection of the environment and personnel. As a supplier of Eto Sterilization Machine, we are committed to providing high - quality equipment and comprehensive technical support. If you have any questions about the operation of ethylene oxide sterilizers or are interested in purchasing our products, please feel free to contact us for further discussions and procurement negotiations.
References
- Block, S. S. (Ed.). (2001). Disinfection, Sterilization, and Preservation. Lippincott Williams & Wilkins.
- Rutala, W. A., & Weber, D. J. (2004). Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008. Centers for Disease Control and Prevention.
- ANSI/AAMI/ISO 11135:2014. Sterilization of health care products - Ethylene oxide - Requirements for development, validation and routine control of a sterilization process for medical devices.