Dry heat sterilization method refers to the dry environment (such as flame or dry hot air) sterilization technology. There are generally flame sterilization method and dry hot air sterilization method.
1. flame sterilization method refers to the sterilization method of direct flame burning. The method of sterilization is rapid, reliable, simple, suitable for flame-resistant materials (such as metal, glass and porcelain, etc.) items and utensils sterilization, not suitable for sterilization of drugs.
2. dry hot air sterilization method refers to the use of high temperature dry hot air sterilization method. The method is suitable for high-temperature glass and metal products and does not allow hot and humid gas penetration of grease (such as oil ointment mechanism, injection oil, etc.) and high-temperature-resistant powder chemicals sterilization, is not suitable for rubber, plastics, and most of the sterilization of drugs.
In the dry heat state, due to poor heat penetration, microorganisms are more heat-resistant, must be subjected to high temperatures for a long time to achieve the purpose of sterilization. Therefore. Dry heat air sterilization method using the temperature is generally higher than the wet heat sterilization method. In order to ensure the sterilization effect, the general provisions: 135-140 ℃ sterilization 3-5h; 160-170 ℃ sterilization 2-4h; 180-200 ℃ sterilization 0.5-1h.
Dry heat sterilization
Bacterial propagation in the dry state, 80 ℃ ~ 100 ℃ 1 hour can be killed; bud cells need to be heated to 160 ℃ ~ 170 ℃ 2 hours to Killed. Dry heat sterilization methods are ① incineration: incineration by fire is a thorough sterilization method, destructive, only for discarded items or animal carcasses, etc.; ② cauterization: direct flame sterilization, suitable for laboratory metal instruments (forceps, scissors, inoculation rings, etc.), glass test tube mouths and bottles, etc., sterilization; ③ dry baking: in the dry oven (hot air sterilizer) in the, heated to 160 ℃ ~ 170 ℃ to maintain 2 hours, can kill all microorganisms, including germ cells. Applicable to high-temperature resistant glassware, porcelain, glass syringes, etc.; ④ infrared (infrared): is the wavelength of 770nm ~ 1000μm of electromagnetic waves, 1μm ~ 10μm wavelength of the strongest thermal effect. Infrared heat effect can only be produced on the irradiated surface, can not make the object uniformly heated, commonly used in bowls, chopsticks and other utensils sterilization; ⑤ microwave (microwave): wavelengths of 1mm ~ 1000mm electromagnetic waves collectively referred to as microwave, can penetrate the glass, plastic film and ceramics and other substances, but can not penetrate the surface of the metal. The heat effect of the microwave oven is not uniformly distributed, the sterilization effect is not reliable, used for non-metallic instruments and utensils disinfection.
Dry heat sterilization requires higher temperature and longer time than moist heat sterilization.
Dry baking
Use of dry oven, heating 160 ~ 180 ℃ for 2 hours, can kill all microorganisms, including bacillus. It is mainly used to sterilize glassware, porcelain, etc.
Cauterization and incineration
Cauterization is a direct flame to kill microorganisms, suitable for microbiology laboratories, inoculation needles and other metal equipment that are not afraid of heat sterilization. Incineration is a thorough sterilization method, but is limited to the treatment of discarded contaminated items, such as useless clothing, paper, garbage and so on. Incineration should be carried out in a special incinerator.
Infrared
Infrared radiation is a 0.77 ~ 1000 micron wavelength electromagnetic waves, has a good thermal effect, especially 1 ~ 10 micron wavelength of the strongest thermal effect. Also considered a dry heat sterilization. Infrared light is generated by infrared bulbs, without air conduction, so the heating speed is fast, but the thermal effect can only be generated on the irradiated surface, so it can not make an object uniformly heated from front to back and left to right. Infrared sterilization effect is similar to dry heat, the use of infrared oven sterilization of the required temperature and time is also the same as dry baking. Mostly used for sterilization of medical equipment.
People who are exposed to infrared radiation for a long time will feel eye fatigue and headache; long-term exposure will cause intraocular damage. Therefore, workers should at least wear protective goggles to prevent infrared damage.
Microwave
Microwave is a wavelength of 1 millimeter to 1 meter electromagnetic waves, high frequency, can penetrate glass, plastic film and ceramics and other materials, but can not penetrate the metal surface. Microwave can make the medium messy polar molecules in the microwave field under the action of the frequency of the wave back and forth movement, mutual collision and friction and generate heat, the temperature of the medium can be increased, and thus at lower temperatures can play a role in sterilization. It is generally believed that its sterilization mechanism in addition to the thermal effect, there are electromagnetic **** vibration effect, field effect, such as the role of commitment. Sterilization in the commonly used microwave 2450MHZ and 915MHZ two kinds. Microwave irradiation is used for food processing. In the hospital can be used for laboratory supplies, non-metallic instruments, sterile sick room food utensils, medicine cups and other supplies disinfection.
Microwave long-term irradiation can cause eye clouding, testicular damage and neurological disorders and other systemic reactions, so the door must be closed before starting the operation.