Medical sterilizer EO

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Overview
Approximately 60% of medical devices worldwide are sterilized with ethylene oxide (EO). Two EO sterilization approaches are commonly used: the vacuum process and the overpressure process. Selection depends on device and packaging characteristics, production volume and integration requirements. Sterisys provides consulting, EO sterilization testing and system design support to determine the most suitable process.

EO vacuum sterilization process
The EO vacuum process is well suited for medium to large production volumes. Devices are typically sterilized in tertiary packaging on pallets; pallet layout (single or double rows, longitudinal or crosswise) is defined per customer requirements. Chamber dimensions and layout are specified in collaboration with the customer.

Vacuum sterilization process phases

• Preconditioning: preparing devices and packaging for sterilization
• Sterilization: EO exposure under negative pressure
• Degassing: removal of residual EO from devices in accordance with EN ISO 10993-7

Standard EO gas concentrations for EO vacuum sterilization

• 100% EO (delivered in drums)
• 90% EO / 10% CO2 blends

Due to the high EO concentrations used in vacuum sterilization, systems must be designed and manufactured to comply with ATEX requirements. Sterisys supports plant and production-flow design using 3D modelling and integrates sterilization chambers, preconditioning and degassing chambers, gas treatment units and control rooms into customer infrastructure.

EO overpressure sterilization process
The EO overpressure process is particularly suited for small to medium production volumes. Devices are mainly sterilized in primary packaging using low-concentration gas blends (for example 7% EO / 93% CO2). During the cycle the gas holding phase is maintained at overpressure (example: 1.75 bar). Chamber size, baskets and trolleys are designed to customer requirements. Sterisys supports integration into new or existing production lines.

Benefits of the overpressure process

• Low EO concentration: ATEX requirements may be avoided under certain conditions (example: max. EO concentration ≤ 8% and/or LEL < 2.6%)
• Preconditioning, sterilization and degassing can be performed in the same chamber (space savings)
• Lower overall investment costs compared with vacuum systems
• Shorter cycle times versus vacuum process

EO dual sterilization process
Sterisys offers EO dual systems that allow operation in both overpressure and vacuum modes within a single machine, avoiding the need to purchase two separate sterilizers.

System features

• Reproducibility: processes can be precisely parameterized, reproduced and documented
• Individual consultation: analysis of customer requirements and tailored advice on process, system and subsystems
• Know-how: systems and subsystems are developed, manufactured and commissioned according to applicable standards and regulations
• Subsystems: gas treatment units are mandatory; external preconditioning and degassing chambers and other subsystems can be connected per customer needs

Associated equipment / subsystems

• Preconditioning and degassing cells for preparation and post-processing of medical devices
• Gas treatment unit for professional EO exhaust treatment in line with current requirements
• EO monitoring system for workplace safety and reliable area monitoring

Technical specifications

• Applicable sterilization processes: EO vacuum sterilization, EO overpressure sterilization (optional EO dual system)
• Vacuum process typical EO concentrations: 100% EO (drums) or 90% EO / 10% CO2
• Overpressure process example gas blend: 7% EO / 93% CO2
• Overpressure example holding pressure: approx. 1.75 bar
• Degassing standard: EN ISO 10993-7
• ATEX: required for high EO concentrations (vacuum process); overpressure process may avoid ATEX if EO concentration ≤ 8% and LEL < 2.6%
• Packaging level: vacuum process — tertiary packaging on pallets; overpressure process — primary packaging
• Production volume suitability: vacuum — medium to large; overpressure — small to medium
• Design & integration: chamber size, baskets, trolleys and subsystems customized per customer; 3D modelling used for layout and flow design