Ausg. Nr._05/2024 5 Steam or water When it comes to cooking food, there are taste preferences as to whether steam-cooked or water-cooked food tastes better. When it comes to terminal sterilization, the final sterilization step before a product leaves the pharmaceutical company, the answer is not so straightforward. At first glance, a steam sterilizer hardly differs from a hot water sterilizer - both are closed stainless steel chambers that can withstand high pressures with thick walls and doors. Both systems can be used to sterilize liquid and solid products such as infusion bags and bottles, vials and ampoules. So, what are the differences between these two technologies? In a steam sterilizer behind a steel door several centimeters thick, steam at round about 130 °C swirls wildly and hits fully filled infusion bags. These were previously pushed into the sterilization chamber on a trolley and now have to endure this heat shock. Slow heating with steam at ambient pressure is unfortunately not possible, which is why this shock is unavoidable. However, the plastic bag suffers as a result, as it does not tolerate such a rapid increase in temperature very well. The bag can be damaged by this shock. It can also be gentler. Who doesn't like a perfectly tempered, gentle shower that slowly gets warmer and warmer as you shower? Exactly this "gentle" sterilization is possible with hot water sterilizers. The water is heated up more slowly and distributed over the products like in a rainforest shower, so that the products can get used to the new thermal situation. Packaging and contents heat up slowly and are not damaged as a result. Sterilization with hot water combines seemingly contradictory attributes such as product protection, killing, sterilization and short process times. Water transfers heat extremely well and therefore quickly. This means that, depending on the product, the sterilization process is faster than with a steam sterilizer. The thick steel doors are nevertheless necessary, as high pressure must be maintained even when sterilizing with hot water in order to keep the water liquid at over 130 °C. As gently and quickly as the water is heated up, it can also be cooled down again just as gently and quickly to avoid a "cold shock". Sterilize efficiently. Hot water also meets all quality requirements for terminal sterilization. The products are completely sterilized. Another important issue is energy consumption, as sterilization per se is a very energy-intensive process. The high energy consumption can certainly be reduced. Anyone who deals with this type of sterilization in time can save energy through optimization measures. Well-designed systems can use heat as efficiently as possible. It is therefore worth investing time here right from the design stage. Dry efficiently After showering, it's time to dry off. In the past, a blind eye was often turned here. This is no longer possible due to GMP Annex 1, which requires completely dry sterile goods before they can be further processed. A good solution for this is the extremely energy-saving and at the same time extremely efficient 'condensation drying with heat pump'. This technology combines qualities that seem contradictory at first glance." At low process temperatures of between 30 and 70 °C, the sterile goods are completely dried within a relatively short time. This is made possible by modern heat pump technology. On the one hand, it is responsible for high efficiency, and on the other, it ensures energy and CO2 savings of up to 75% compared to traditional exhaust air dryers. A closed air circuit further enhances this effect, as drying takes place without exhaust air. What's more, no exhaust air systems are required, which reduces construction costs. This type of drying is easy to install and operate. The basis of the success lies in a sophisticated combination of air dehumidification and air routing. The process air is extremely dry and therefore unsaturated. It is guided precisely over the products to be moistened in a closed system. Combine efficiently. Several projects consisting of a hot water sprinkler sterilizer and an air circulation drying system have already been implemented and have been in operation for years. So far, these have all been projects with a very high throughput of sterile goods. Due to this fact, the sterilizer and dryer were implemented as separate systems. Here there are fully automatic solutions that transport the sterile goods fully automatically from the sterilizer to the drying system and start the drying process automatically. It is also possible to have drying take place directly in the sterilizer by integrating air circulation drying into the sterilizer. After the water has been drained from the sterilizer, the circulating air dryer is actively switched on to dry the products in the sterilizer, saving space for an additional drying tunnel. Care must be taken to ensure that there is enough free space in the sterilizer for optimum air circulation. Conclusion Hot water irrigation sterilizers are the secret star of terminal sterilization, as they offer many advantages, especially when it comes to the gentle handling of sterile goods. The answer here is clearly water! Hall 3.1 - Booth B25 Text & Bild: Belimed Life Science Zelgstrasse 8 CH-8583 Sulgen Steam or water - that is the question!
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