The Oxide of Ethylene is sold pure or in mixtures.
The most common mixtures may consist of: Carbon dioxide and Freons. However, at present the use of freons is banned as they are harmful to the environment.
The Ethylene oxide may come in the following way:
- Small doses: glass ampoules (for manual sterilization) and metallic diposable cartridges (to be used in small and medium sterilizers).
- In bulk: cylinders or tanks, intended for large capacity chambers.
According to either the technology applied or to the type of gas used, ethylene oxide sterilizers may be divided into two groups:
- Ethylene oxide in mixtures: they work under positive pressure..
- Pure ethylene oxide: they work under negative pressure.
The safer and most reliable way to sterilize using this gas is by using sterilization equipment which not only prevent the operator from contacting the gas but they also guarantee to maintain the working place and the environment safe. The use of sterilizers also help to improve the sterilization process by setting the right parameters, such as: gas concentration, humidity, time of exposure and temperature. These conditions may vary according to the manufacturer’s instructions for each of the sterilizers on the market.
Bio-Gas sterilizers have been built to run under negative pressure confirming our concern in terms of safety.
A suitable Ethylene Oxide sterilizer should feature the following sequences:
- Heating of the chamber upto the chosen temperature.
- Initial vacuum.
- Injection of the gas.
- Countdown of the chosen sterilization time.
- Extraction of the ethylene oxide gas from the chamber. (In Biogas sterilizer this is done by taking out the gas into bubbling water so the ethylene oxide becomes etilenglicol, a neutral gas; then the clearing of the chamber is done by alternate cycles of vaccuum and entrance of filtered air).
- Final ventilation of the sterilized material. (In Biogas sterilizers the sterilization and ventilation are carried out inside the same chamber avoiding the handling of non-aereated material. Moreover, the ventilation program can be set from 1 to 20 hours).
Another way of using the ethylene oxide is the method which consists in the use of glass ampoules placed inside a containing bag. This simple and practical system can be carried out anywhere and specially where there would be not enough resources available to install a sterilizer.
Even though there is, currently, a trend towards the use of sterilization equipment due to that they provide safety for the operator, It is important to highlight that the sterilization system with ampoules is the ideal method to be used in emergency or catastrophe situations.