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Industrial Sterilization for medical devices and pharmaceutical products

A wide range of medical devices and pharmaceutical products are sterilized by ethylene oxide exposure. Sterilization with ethylene oxide, also known as EO or EtO sterilization, is an established sterilization modality in this industry and provides clear advantages over other processes. Thanks to the low process temperature (below 55°C), the use of EO is far superior to other methods in terms of material compatibility – which means that it is ideally suited for the sterilization of thermolabile products. 

However, due to the composition of ethylene oxide, a range of technical and regulatory requirements have to be fulfilled and taken into account. STERISYS is specialized in this domain and we develop and manufacture our equipment in accordance with all relevant standards and guidelines. 

As a leading provider of ready-to-use ethylene oxide sterilization systems, we develop innovative and flexible solutions and deliver them to international medical device manufacturers and sterilization service providers.

Key benefits of our solutions:

  • Safe and efficient sterilization of medical devices and pharmaceutical products;
  • High degree of flexibility regarding cycle parameterization;
  • Reliable reproducibility of the sterilization cycles;
  • Long-term viability and conservation of value, thanks to state-of-the-art components and proven industry standards;
  • Conformity with all relevant standards and guidelines (ATEX / EN1422:2014 /ISO 11135:2020-04 / FDA 21 CFR Part /GAMP 5);
  • Manufacturing of customized sterilization units of all sizes, made to order in our factory in Belgium.


Overpressure and vacuum sterilization systems

STERISYS offers two different EO sterilization processes

  • the EO overpressure process and
  • the EO vacuum process. 

Based on the requirements of the customer and a process-oriented analysis, STERISYS determines together with the customer the type of sterilization process and the dimension of the unit.

The EO overpressure sterilization system

The EO overpressure sterilization process is particularly suitable for small to mid-sized product volumes that are mainly sterilized in their primary packaging.

The overpressure process works for example with a gas blend of 6% EO and 94% CO2. Moreover, in comparison to the vacuum process, the gas holding phase during the sterilization cycle is held at an overpressure of 1.75 bar.

Benefits of the overpressure process:

  • Due to the low EO concentration, the ATEX guidelines are not applicable (conditions: max. EO gas concentration = 8% and/or LEL < 2.6%).
  • The entire sterilization process – preconditioning-, sterilization- and degassing-process – can be carried out in the sterilization chamber. No external preconditioning or degassing cells are required.  
  • The EO overpressure sterilizer can be easily integrated into the customer’s existing production flow.
  • The overall investment costs are lower.
  • Compared to the EO vacuum process, the cycle times are shorter thus the products reach the market more quickly.

We always start with the product to be sterilized. Based on the material- and packaging-type, product size, intended production volume and purpose of the product, we develop a sterilization unit perfectly suited to customers’ requirements. Beside the sterilization chamber STERISYS also designs and produces the suitable baskets and trolleys to store, transport and especially sterilize the medical devices. 

But most importantly, we base these decisions upon how the entire sterilization equipment can be seamlessly integrated into your new or even existing infrastructure and production flow.

The overpressure sterilization system is controlled and monitored by the STERISYS sysREG NT control system. This system offers all functions to ensure an operation in accordance with EN1422 including the appropriate logging of the sterilization cycles.


The EO vacuum sterilization system

The EO vacuum sterilization process is particularly suitable for a high throughput production. In this case, the medical devices are generally sterilized in their tertiary packaging, means on pallets. These pallets are positioned in one or two rows in the sterilization chamber, oriented lengthwise or crosswise, depending on the space and customer requirements. 

The exact chamber size will be jointly defined with the customer, based on the production volume and type and height of the pallets (European, US, customized).

Commonly used EO gas concentrations for the EO vacuum sterilization process:

  • 100% EO gas in liquid form, packed in drums.
  • 90% EO – 10% CO2 gas blend.

Due to these high EO concentrations the vacuum sterilization equipment must be designed and manufactured in accordance with the ATEX guidelines. According to the current state of the art, the EO vacuum sterilization processes consists of three process phases:

  • Preconditioning process: the medical devices are prepared for the actual sterilization process (preheating and humidification of the products). 
  • Sterilization process: the products are sterilized in negative pressure in the sterilization chamber with an appropriate EO exposure time. 
  • Degassing process: elimination of the residual EO emission in the exposed products to meet the residual limits outlined in the EN ISO 10993-7.

After the determination of the size of the sterilization chamber and the associated equipment, STERISYS supports its customers also in implementing the entire sterilization equipment (including all related process components – preconditioning and degassing cells, gas treatment system, control room, etc.) into the customers’ existing or new infrastructure. With our 3D-CAD tools, we can even visualize our customers future sterilization unit and complete plant early on. 

Depending on the size and complexity of the EO sterilization equipment, the system is controlled and monitored either by the “stand-alone” sysREG NT control software or by a centralized SCADA system using the STERISYS sysREG NTX software. The latter ensures a centralized control and monitoring of the entire sterilization plant.

EO Dual sterilization process

The innovative Dual-EO-sterilizer has the ability to operate both, overpressure and vacuum sterilization cycles – depending on the products to be sterilized. 

Other process elements

Preconditioning cells

The preconditioning process is part of the 3-phase-vacuum process model and is performed before the actual sterilization process. In an external preconditioning cell, the product load is being prepared for the following sterilization process. This means, the products are preheated to a homogeneous temperature and humidified to predefined conditions, as required by ISO 11135:2014. Its purpose is to create ideal prerequisite conditions for the actual sterilization process, rendering the process efficient.


Degassing cells

The degassing process is also part of the 3-phase vacuum process model and is performed after the sterilization process. The degassing process is used to accelerate the outgassing of the exposed products and to eliminate residual EO emissions to meet the limits outlined in the EN ISO 10993-7. The process is performed by defined air changes and continuous supply of fresh air into the degassing cell in accordance with EN 11135:2014 | EN10993-7.


EO gas treatment systems

The EO gas treatment systems enables the customer to treat the highly concentrated EO gases generated by the sterilizers and the low concentrated exhaust gases generated by the degassing cells and the transfer room in accordance with the German TA Luft regulation [Technical Instructions on Air Quality Control] (EO <= 0.5 mg/m³).
STERISYS offers various gas treatment systems depending on the sterilization process and the dimension of the sterilization plant:

  • Electrical- or gas-operated catalyzer, if necessary combined with a “peak-shaver” (water buffer tank) 
  • Scrubber system;
  • Gas incineration system.

EO monitoring systems

The operator of an EO sterilization plant has to ensure the compliance with the local requirements in terms of maximum EO concentration at working place and to assure a safe working environment. 

We recommend our clients the use of an EO monitoring system, which provides a considerable assistance in complying with all regulations and norms and allows moreover the following min./max. EO concentration levels detection:

  •  Acceptance level:                 0,2 mg/m3 (0,1 ppm)
  • Tolerance level:                     2,0 mg/m3 (1,0 ppm)

This gas chromatographic system can be equipped with up to 12 measurement channels and a 3-level alarm detection per channel. 

The STERISYS sysREG software

As one of the major suppliers of EO sterilization equipment, the STERISYS delivery scope includes also different process control and monitoring solutions. 

Depending on the size and/or complexity of the EO sterilization equipment, STERISYS offers the following two software architectures:

  • The STERISYS sysREG NT stand-alone control architecture uses a SIEMENS TIA Portal PLC control platform for each sterilizer and related other process units. A HMI unit per main process unit allows the operator to control the sterilization process (process control, monitoring, parametrisation, protocol generation, etc.) 
  • The centralized STERISYS SCADA sysREG NTX control and monitoring system is based on a SIEMENS WINCC architecture mainly completed by one WINCC server and one or several HMI clients. The centralized SCADA system enables the operator to control and monitor the entire sterilization system, including the preconditioning and degassing cells, the gas treatment system and all other related equipment.