How To Use Gas Sterilization
Since ethylene oxide is flammable, explosive, and toxic to humans, it must be carried out in a closed ethylene oxide sterilizer.
(1) Ethylene oxide sterilizer and its application:
(1) There are many types of ethylene oxide sterilizers in use. Large containers have tens of cubic meters, medium containers have 1 to 10 cubic meters, and small containers have a few tenths to 1 cubic meter. They have different uses.
Large ethylene oxide sterilizer: Generally used for sterilization of large quantities of items, with a dosage of 0.8kg/m³ to 1.2kg/m³, and at 55℃ to 60℃ for 6 hours.
(3) Medium ethylene oxide sterilizer: Generally used for sterilization of disposable medical supplies. This sterilization equipment is complete and highly automated, and can use pure ethylene oxide or a mixture of ethylene oxide and carbon dioxide. The sterilization conditions are generally required to be: concentration, 800 mg/L~1000 mg/L, temperature, 55℃~60℃, relative humidity 60%~80%, and action time 6 hours. Vacuuming is required after sterilization is completed. Sterilized items are usually sealed with plastic film that can pass ethylene oxide. If the small package is equipped with a filter membrane that can filter air, the sterilization effect will be better.
(4) Small ethylene oxide sterilizers are mostly used in medical and health departments to process small amounts of medical equipment and supplies. They have 100% pure ethylene oxide or a mixture of ethylene oxide and carbon dioxide. This type of sterilizer has a relatively high degree of automation and can automatically evacuate, automatically add drugs, automatically adjust temperature and relative humidity, and automatically control the sterilization time.
(5) The requirements for medium and small ethylene oxide sterilizers are: good pressure resistance and sealing performance, should be able to withstand a water pressure test of 1.25 times the working pressure, no deformation and leakage, and can be vacuumed to above 53.3 kPa; accurate dosage, good thermal insulation performance, and can adjust the temperature and relative humidity in the sterilizer; when flushing with external air after disinfection, the input air passes through a high-efficiency filter and can filter out more than 99.6% of particles ≥0.3µm; the discharged residual ethylene oxide is harmlessly treated, and the residual ethylene oxide in the sterilized items should be less than 15.2mg/m; the concentration of ethylene oxide in the sterilization environment should be less than 2mg/m.
(2) Preparation and packaging of items before sterilization: The items to be sterilized must be thoroughly cleaned. Note that they cannot be cleaned with saline. There should be no water droplets or too much water on the sterilized items to avoid dilution and hydrolysis of ethylene oxide. Ethylene oxide can be used to sterilize almost all medical supplies, but it is not suitable for the sterilization of food, liquids, oils, talcum powder and animal feed. Packaging materials suitable for ethylene oxide sterilization include paper, composite dialysis paper, cloth, non-woven fabrics, ventilated rigid containers, polyethylene, etc.; packaging materials that cannot be used for ethylene oxide sterilization include metal foil, polyvinyl chloride, cellophane, nylon, polyester, polyvinylidene chloride, and impermeable polypropylene. Changes in packaging materials should be verified to ensure the reliability of sterilization of sterilized items.
(3) Loading of sterilized items: There should be gaps on the top, bottom, left and right sides of the items loaded in the sterilization cabinet (sterilized items cannot touch the cabinet wall), and the items should be placed in a metal mesh basket or on a metal mesh rack; the amount of items loaded should not exceed 80% of the total volume of the cabinet.
(4) Sterilization: It should be carried out in accordance with the operating instructions of the ethylene oxide sterilizer manufacturer; select appropriate sterilization parameters according to the type of sterilized items, packaging, loading volume and method.
(1) The relationship between concentration, temperature and sterilization time: Within a certain range, the increase in temperature and concentration can shorten the sterilization time. When using ethylene oxide for sterilization, the temperature, concentration and time parameters must be reasonably selected.
(2) Control the relative humidity of the sterilization environment and the moisture content of the items: The moisture content of the bacteria themselves and the moisture content of the sterilized items have a significant impact on the sterilization effect of ethylene oxide. In general, a relative humidity of 60% to 80% is best. Too little moisture will affect the penetration of ethylene oxide and the alkylation of ethylene oxide, reducing its bactericidal ability; too much moisture will dilute and hydrolyze ethylene oxide, also affecting the sterilization effect. In order to achieve the ideal humidity level, the first step is to pre-wet the sterilized items. Generally, the sterilized items are required to be placed in an environment with a relative humidity of 50% for at least 2 hours; the second step is to use a humidifier to ensure the ideal humidity level in the cabinet.
(3) Pay attention to the effect of external protective substances on the sterilization effect: The more organic matter on the surface of the bacteria, the more difficult it is to kill; organic matter can not only affect the penetration of ethylene oxide, but also consume part of ethylene oxide. Microorganisms in inorganic salts or organic crystals are difficult to kill with ethylene oxide. Therefore, before ethylene oxide sterilization, the organic and inorganic dirt on the items must be thoroughly cleaned to ensure successful sterilization.
