Some working principles of sterilizers

Thermal sterilization method

Thermal sterilization is the use of high temperature so that the bacterial protein coagulation or denaturation, enzyme inactivity, metabolic disorders, resulting in bacterial death. Thermal sterilization method includes moist heat sterilization method and dry heat sterilization method. Wet heat can make the bacterial protein coagulation, deformation; dry heat can make the bacterial protein oxidation, denaturation, carbonization and electrolyte concentration caused by cell death. Heat sterilization is convenient, effective and non-toxic, and is the main sterilization method used in hospital disinfection and supply centers. Pressure steam sterilization method is the preferred sterilization method for moisture and heat resistant medical devices.

Pressure steam sterilization uses moist heat sterilization method, which is better than dry heat at the same temperature for the following reasons:

The temperature required for protein coagulation and its water content, the greater the water content, the lower the temperature required for coagulation. Moist heat sterilization of bacterial proteins can absorb water, and thus easier to solidify than in the same temperature of dry heat in the air.

Moist heat sterilization process steam release a lot of latent heat, further increase the temperature. At the same temperature, the time required for moist heat sterilization is shorter than dry heat.

Moist heat gas penetration than dry heat gas, so moist heat than dry heat effect. High-pressure steam can kill all microorganisms, even including bacterial spores, fungal spores and other heat-resistant individuals. Sterilization of steam temperature with the increase in steam pressure and rise, by increasing the steam pressure, sterilization time can be greatly reduced. Therefore, it is one of the most effective and widely used sterilization methods.

Low Temperature Sterilization Method

Low-temperature sterilization is a method that kills pathogenic microorganisms using a chemical sterilizing agent. The temperature required to sterilize the chemical agent is low, and it is usually called low-temperature sterilization method or chemical sterilization method. Low-temperature sterilization using chemical disinfectants can kill all microorganisms, to achieve the level of sterilization guarantee, this kind of chemical agents with sterilization effect are formaldehyde, glutaraldehyde, ethylene oxide, peroxyacetic acid and so on. Chemical sterilization is used for sterilization of instruments that cannot tolerate high temperature, hot and humid materials.

Commonly used low-temperature sterilization methods are hydrogen peroxide plasma low-temperature sterilization, ethylene oxide sterilization, low-temperature formaldehyde steam sterilization.

Hydrogen peroxide plasma low-temperature sterilization through the hydrogen peroxide liquid dispersion into a gas state after the sterilization of goods, through the generation of plasma for the second stage of sterilization. The plasma process also accelerates and completely breaks down the residue of hydrogen peroxide gas on instruments and packaging materials. The plasma sterilization method is characterized by rapid action, reliable sterilization, low action temperature, and cleanliness without toxic residue. It is suitable for endoscopes, heat-resistant equipment, various metal instruments, glass and other items; it can absorb moisture and gas.

Ethylene oxide sterilization

Ethylene oxide is a colorless gas with odor similar to ether and tasteless at low concentration. It has strong penetrating power and can penetrate cellophane, polyethylene or PVC film, etc. It can produce non-specific alkylation effect on microorganisms' protein, DNA and RNA, so that they will lose the basic reaction base of metabolism and be killed, with strong bactericidal power, wide spectrum of killing surface, reliable sterilizing effect, and less damage to sterilized articles.