Construction of an ethylene oxide sterilization plant in Europe


The main points to take into account during the creation of an Ethylene Oxide sterilization plant in Europe

Through this article, we don’t pretend to go into details mainly because the creation of an Ethylene Oxide sterilization facility is a major project, on which it will be necessary to take into account several aspects that will lead to important decisions: safety, standards, main equipment, utilities, staff training ….

In other word, we would like to give the main indications to make you easier such a project management. Remember that Ethylene Oxide known as EtO or EO is a dangerous gas, carcinogenic, inflammable and so explosive, hence the importance of spare no expense to have a very safe EtO sterilization plant.

 Logo ATEX Atmosfera explosiva

Main standards of an EtO sterilization plant / ATEX directive

In addition to the national standards of the country, it will be necessary to take into account any European standard to set up a safe and state-of-the-art Ethyne Oxide plant. Needless to say, the ATEX directive has to be part of these standards that should be followed, as it is the most important directive (and mandatory) in Europe regarding facilities and equipment under potential risks of explosion (ATEX Directive 2014/34/EU).

One of the main goal of that directive is to divide the classified areas where a risk of having a potential explosive atmosphere according the occurrence probability. Each equipment, detectors, lights, door motorization…, should be designed and installed in accordance with the ATEX zone of their location.

Apart from the ATEX directive, the installation should comply with other normatives like ISO 11135-1 (Sterilization of health care products / EO), EN 1127-1 (Explosive atmospheres. Explosion prevention and protection), EN ISO 13849-1 (Safety of machinery), EN 1422 (Ethylene Oxide Sterilizers), among other….


Different area characteristics of an Ethylene Oxide - EO sterilization facility

Turnkey EtO sterilization solution - RSD Industrial sterilization

An EO industrial sterilization site uses to be composed of the following main areas:

  • Gas room (ATEX classified): Location of the gas bottles.
  • Autoclave room (ATEX classified) including the ancillary equipment like vacuum pump and vaporizer skids: Area where the sterilization is performed. The industrial autoclaves can be supplied with different capacities, based on the customer production. RSD offers chambers from 4 until 32 euro pallets.
  • Air purification system (ATEX classified): its goal is to treat the Ethylene Oxide gas coming from the sterilizers and the degassing cells, in order to reduce as much as possible, the EtO emissions to the atmosphere. We always recommend a catalytic system to treat EtO, as it could handle either high or low concentration, guaranteeing a high efficiency. A scrubber technology can be used as well, especially when the budget is limited, but the efficiency and reliability are much lower than the other treatment process.
  • Laboratory area: A proper laboratory placed in the sterilization building is always welcome so as not to depend on an external entity to get the microbiological result of the sterilized batches.
  • Control room: It is the brain of the installation, as all the operations of the sterilization process are managed from this room.
  • Warehouses: The first warehouse is used as a product preparation area, the second one is the treated product stock.
  • Technical area: This area uses to be composed of the maintenance and utility rooms

 If the process is not All-in-one:

  • Preconditioning cell (No ATEX): It makes possible an effective EtO gas absorption during the exposition phase of the sterilization process. It consists in humidifying the products (with pure steam) to open the spore and so prepare them before being treated. 
  • Degassing cell (No ATEX): It enables the elimination of the EtO residuals in the products & packaging after the sterilization process. It consists in removing as much as EtO possible at the post sterilization phase (usually <1ppm in the room). This contaminated air should be treated with a catalyzer.


Some of the most important good practices to take into account for the building design:

  • Floor of the chamber room: It should be prepared to withstand the weight of the sterilizer once the jacket is full of water. It could reach several tons, so the floor should use reinforced concrete.
  • When the sterilizer is deep, thermal dilatations of the sterilizer have to be seriously considered.
  • The ATEX classification of the gas room should be carefully analyzed, because it is the area of most of the manual operations are performed, and by consequent hazard situations could rise. RSD decided to use the strict Atex zone 1, considering a high probability of having a potential explosive atmosphere.
  • A reliable and efficient HVAC system should be installed in the ATEX zones, to evacuate the gas in case of problem.
  • A monitoring device has to be installed, to measure the LEL (Low Explosive Limit) levels in the premises and so to alert of an important EtO gas concentration. PPM level detection system (for toxicity) must be installed as well for staff protection to warn in case of a low EO concentration in the atmosphere.


Required utilities for the sterilization process

Reliable and well-designed utilities are necessary to ensure an optimal sterilization process. Indeed, the sterilization equipment needs several utilities to run a cycle, the following one are the most important:

  • Chilled water for vacuum pumps and sometimes for the jacket, 7-12ºC.
  • Hot water at 80ºC for jacket heating, and to heat any fluid that should be injected into the chamber. Plant steam could be used as an alternative as well (3 bars).
  • Nitrogen for chamber inertization and vaporizer & EtO drum cleaning. CO2 could be used as well.
  • Pure steam for product humidification.
  • Filtered air, for air washings.


Trained staff for Ethylene Oxide sterilization process

It is primordial to have a well trained staff on the process, in order to be reactive in case of incident. In Europe, the ATEX directive says that there is an obligation to train the staff regarding safety aspect. The best way is to ask for training courses that can give notified body like INERIS or LOM. They are able to deliver official certificates, under Ism-ATEX certification. With INERIS, different levels can be enquired, either for electrical or mechanical aspects:

Certificado ATEX - INERIS

  • Level 0: Staff involved in ATEX.
  • Level 1: Manager in ATEX. It uses to be focused on in-situ technical operations.
  • Level 2: Authorized staff in ATEX. This level should supervise the level 1.
  • Level 3: ATEX trainer. This certificate gives the possibility to train Level 0, 1 and 2.

 RSD has Level 1 and 2 M&E for the whole staff.

Apart of this kind of safety training, it is obvious that the company has interests on giving trainings, to provide information about the process, equipment, product to sterilize, maintenance, calibration operations, validations. It allows to quickly solve production issues that could face the company during sterilization routine operations.


The last, but not the least: The safety aspects for an Ethylene oxide sterilization facility

For an ethylene oxide sterilization plant in Europe, the Explosive Protection Document (E.P.D) is mandatory, and should integrate the ATEX aspects. Even if the final user has to require ATEX certificates to the classified equipment manufacturers, the final responsibility is up to the one that has to use them for production.

This important document should have the following items, among others:

  • An explosion risk assessment,
  • Definition of the ATEX zone (explosion hazard),
  • Fulfilment of the EC directive requirements,
  • Means of escape,
  • Organizational measures to reduce the explosion risks like training, procedures, instructions and maintenance,
  • Early warning devices operation,
  • Marking of areas,
  • Installation of equipment that are ATEX certified, according to each location and classification,
  • The dangerous substance (EtO in our case) properties,

The insurance company could also have a huge impact on the building design. It usually requires additional safeties like deluge system, thickness of the classified rooms, distances to respect between ATEX and non-ATEX areas, etc.

Obviously, a state-of-the-art installation integrates quality and maintenance aspects, giving a higher safety, reliability and efficiency as they use to contribute to production increases even if the investment is higher.

Needless to say that safety should be first on an EtO sterilization plant.


The creation of an Ethylene Oxide sterilization plant is a major project on which it is important to be surrounded by qualified and trusting partners to help you to get a reliable and safe installation.

RSD, expert in EtO sterilization, offers its customized services and solutions for medical device and pharmaceutical industries.

Contact-us for more information.


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