The purpose of the chamber for steam pasteurization is to reduce bacterial contamination to allowed level. The process of pasteurization with steam consists in drawing out the air from the vacuum chamber to a level of 90% of vacuum and heating the material at the total cross-section area of filling, to a temperature of 80 °C.
Processed medicinal herbs are fed into permeable bags in maximum layer of 80 mm, which are placed on the shelves of trolleys. The process of pasteurization begins with vacuuming or drawing the air out from the space of vacuum chamber. Vacuuming is performed by using a vacuum pump with water ring to a minimum level of 80% of vacuum. Upon attaining the desired level of negative pressure, in the space is put dry steam that penetrates deeply into the material layer for pasteurization and in a short period of time the temperature of the layer rises to the desired level, usually in the range of 70-80 ° C. The maximum possible temperature is 94 ° C and then transfers to overpressure. After reaching the set temperature and the flow of time required for successfully carried out process of pasteurization, equalization of the internal pressure of the chamber with the external pressure is carried out and with that ends the process. With pressure equalization of chamber pressure with environment pressure the intake of outside air is performed and due to preventing contamination of the treated material must be filtered through a HEPA filter.