SU992063A1 - Method of control of air sterilization process - Google Patents

Description

The invention relates to the sterilization of medical devices with dry hot air, specifically to medical air sterilizers with forced circulation.

There is a known method of controlling the process of air sterilization according to the mismatch of the value of the coolant Cl set and measured in the sterilizer.

The disadvantage of this method is that it does not take into account the temporal delay: the temperature of objects is delayed relative to the temperature of the circulating air, since the start of the process is determined by the moment when the specified temperature is reached by the heat transfer medium at one strictly defined point of the working chamber.

The closest technical. The essence of the invention is a method of controlling the process of air sterilization, which involves measuring the temperature of the coolant at the sterilizer outlet and determining the initial point of the sterilization process by the difference simultaneously, the measured temperature values

static and dynamic coolant chambers 2.

The disadvantage of this method is that it is designed for steam sterilization. For example, when steam sterilizing hermetically 3akf oils, powders, and other materials that are poured into glassware, the temperature of the static chamber will not

10 an indicator of the temperature state of the object being sterilized, since steam will not penetrate into the charge due to the tightness of the glass envelope of the object being sterilized and in this case as well. The static chamber will no longer be a simulator of the material being sterilized depending on the amount of air absorbed by medical objects and, therefore, the coincidence of temperatures in the static and dynamic chambers of the sterilizer will not capture the moments when the object reaches the specified temperature.

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However, in medical practice there is a need to sterilize objects that are impermeable to steam, for example, closed Petri dishes, assembled syringes, hermetically sealed 30 hydrophobic materials (ointments, powders, etc.), glassware, surgical and viewing instruments and many other products that lose their functional properties during steam sterilization. For this purpose, an air sterilization method is used, in which the sterilizing agent is dry hot air (1B-200 C). The purpose of the invention is to improve the accuracy of sterilization. The goal is achieved by the method of controlling the air sterilization process, which involves measuring the temperature of the heat carrier at the sterilizer outlet and determining the initial moment of the sterilization process, changes the air heating depending on the mismatch between the current and the set temperature at the sterilizer inlet, and determining the initial moment of the process sterilization is carried out depending on the magnitude of the mismatch of a given and the current value of the temperature of the coolant at Exit sterilizer. The essence of the invention is that the moment of coincidence of the air flow temperature at the inlet and exit from the sterilizer means nastutenie moment of thermal equilibrium of the system Air-objects of sterilization, which, in turn, determines the moment when the sterilized material reaches the specified sterilization temperature. The method is carried out as follows. In an air sterilizer with a closed forced circulation system, the circulating air is heated to a predetermined sterilization temperature and the prescribed temperature of the air flow at the inlet to the sterilization chamber is maintained during the entire process. At the moment of coincidence of the air flow temperatures at the inlet and outlet of the sterilization chamber, a time relay is activated, which determines the sterilization exposure time. FIG. 1 shows an air compressor with forced circulation of a heat carrier; in fig. 2 is a block diagram of a sterilization process control device. The sterilizer contains a heat-insulated chamber with 1GS orifices and 3 for incoming and outgoing air streams, a device of closed forced air circulation consisting of a fan 4, air channels 5, heating elements 6, sterilization objects 7, sensors 8 and for measuring temperature inlet and outlet air flows and a sterilization process control device; the latter includes temperature sensors 8 and 9, setting units 10, comparison units 11 and 12, amplifying switching unit 13, heating elements 6, time relay 1.4. The principle of operation of the sterilizer is as follows. The signal of the downstream temperature sensor 8 and the predetermined signal from the setting device 10 are compared in comparison unit 11. The error signal is supplied to the amplifier-switching unit 13, which, by the amount of the error, controls the heating elements b. The signal from the effluent temperature sensor 9 and the predetermined signal from setpoint 10 are compared in comparison unit 12. When the air flow at the outlet from the chamber reaches a predetermined temperature, the comparison unit 12 generates a turn-on signal for the relay 14. The process time parameters are set by the dial. In this way, . The sterilization process control device records the end of the transition process in the sterilization chamber, regardless of the degree of sterilizer loading, by issuing a command to start the main technological operation - sterilization exposure, shifted in time by the amount of time lag of sterilization objects. For bacteriological quality control of sterilization, Petri dishes that are infected with a spore suspension of Bac.subtilis resistant to dry heated air — strain P. are used. The infection density is 500–2000 m. on the object. Petri dishes are used as loading. The temperature control is carried out by an automatic recording device by someone 4. Temperature sensors are placed at observation points. The time of sterilization exposure is counted from the moment the temperature of the coolant flow at the inlet and outlet of the sterilizer coincides. After the time of sterilization exposure, the biotests are removed, cooled to room temperature, and filled with a liquid nutrient medium (casein broth with 0.5% glucose). Sowing a thermostapert for 14 days, after which make final conclusions about the quality of sterilization of objects. Before testing, it was determined that the maximum possible load of this apparatus is 1800 Petri dishes. 1 The results of bacteriological control are given in the table.

Air Cup Sterilizer

On the basis of the tests performed, it was established that the method of controlling the process of air sterilization guarantees high-quality sterilization of objects, regardless of the degree of loading of the working chamber with the products being sterilized.

Claims (2)

Invention Formula The method of controlling the process of air sterilization, which involves measuring the temperature of the coolant at the outlet of the sterilizer and determining the initial moment of sterilization, characterized in that. that, in order to increase accuracy, air heating is changed from the mismatch of the current and the setpoint temperature at the inlet of the sterilizer, and the determination of the initial moment of the sterilization process is carried out depending on the magnitude of the mismatch between the target and the current value of the coolant temperature at the sterilizer outlet. Sources of information taken into account in the examination 1. V. Vashkov. Means and methods of sterilization, apply more to medicine. M., Medicine, 1973, p. 72-84. 2. Patent of Great Britain 1180586, cl. A 61 L 3/02, 19b7. eight