Technical and cleanliness requirements for steam sterilization

In industries such as the pharmaceutical industry, food industry, biological products, medical and health care, and scientific research, disinfection and sterilization equipment is often used to disinfect and sterilize related items.

Among all available disinfection and sterilization methods, steam is the earliest, most reliable and most widely used method. It can kill all microorganisms, including bacterial propagules, fungi, protozoa, algae, viruses and resistance. Stronger bacterial spores, so steam sterilization is highly valued in industrial disinfection and sterilization. Early Chinese medicine sterilization almost always used steam sterilization.
Steam sterilization uses pressure steam or other moist heat sterilization media to kill microorganisms in the sterilizer. It is the most effective and widely used method in thermal sterilization.

For food, the materials that are heated during sterilization must maintain the nutrition and flavor of the food. The energy consumption of a single product of food and beverages is also an important aspect when considering the competitiveness of enterprises. For drugs, while achieving reliable disinfection and sterilization effects, they must also ensure that the drugs are not damaged and ensure the safety, effectiveness and stability of their efficacy.

Medicines, medical solutions, glassware, culture media, dressings, fabrics, metal instruments and other items that will not change or be damaged when exposed to high temperatures and moist heat can all be sterilized by steam. The widely used pressure steam sterilization and sterilization cabinet is a classic equipment for steam sterilization and sterilization. Although many new types of moist heat sterilization equipment have been developed in recent years to meet various needs, they are all based on the pressure steam sterilization and sterilization cabinet. developed on the basis of.

Steam mainly causes the death of microorganisms by coagulating their proteins. Steam has strong penetrability. Therefore, when steam condenses, it releases a large amount of latent heat, which can quickly heat objects. Steam sterilization is not only reliable, but also can lower the sterilization temperature and shorten the time. Action time. The uniformity, penetration, reliability, efficiency and other aspects of steam sterilization have become the first priority for sterilization.

The steam here refers to dry saturated steam. Instead of superheated steam used in industries producing various oil and petrochemical products and in power station steam turbines, superheated steam is not suitable for sterilization processes. Although superheated steam has a higher temperature and has more heat than saturated steam, it The heat of the superheated part is very small compared with the latent heat of vaporization released by the condensation of saturated steam. And it takes a long time to drop the superheated steam temperature to the saturation temperature. Using superheated steam for heating will reduce the heat exchange efficiency.

Of course, moist steam containing condensed water is even worse. On the one hand, the moisture contained in the moist steam itself will dissolve some impurities in the pipes. On the other hand, when the moisture reaches the vessels and medicines to be sterilized, it hinders the flow of steam to the pharmaceutical heat star. Pass, lower the temperature of the pass. When the steam contains more fine mist, it forms a barrier for gas flow and prevents heat from penetrating, and it also increases the difficulty of drying after sterilization.

The difference between the temperature at each point in the limited sterilization chamber of the sterilization cabinet and its average temperature is ≤1°C. It is also necessary to eliminate “cold spots” and the deviation between the “cold spots” and the average temperature (≤2.5°C) as much as possible. How to effectively eliminate non-condensable gases in steam, ensure the uniformity of the temperature field in the sterilization cabinet, and eliminate “cold spots” as much as possible are key points in the design of steam sterilization.

The sterilization temperature of saturated steam must be different according to the heat tolerance of microorganisms. Therefore, the required sterilization temperature and action time are also different according to the degree of contamination of the sterilized items, and the sterilization temperature and action time are also different. The choice depends on the sterilization method, item performance, packaging materials, and required sterilization process length. Generally speaking, the higher the sterilization temperature, the shorter the time required. There is a constant relationship between the temperature of saturated steam and its pressure. However, when the air in the cabinet is not eliminated or is not completely eliminated, the steam cannot reach saturation. At this time, although the pressure The meter shows that the sterilization pressure has been reached, but the steam temperature has not reached the requirements, resulting in sterilization failure. Since the steam source pressure is often higher than the sterilization pressure, and steam decompression can cause steam overheating, attention needs to be paid.