Autoclaving is a common sterilization method for biological experiments. It can be divided into three types: portable, vertical and horizontal depending on the size of the volume. The autoclave is widely used in the sterilization of instruments, dressings, utensils, liquid medicines, culture media, etc. in various colleges and universities, medical and health, food and chemical, biological research and other units. Don't pay attention to it. If you are not careful, it may cause a big disaster!
What should I pay attention to during use?
1. Sterilization temperature should be a temperature range, not a fixed value
Usually, the autoclaving temperature is a fixed value. For example, the sterilization requirements for the test tube slant medium and the shake flask liquid medium are: 121 ° C, 20 min, but at 121 ° C is only the lower limit of the sterilization temperature, the actual sterilization The temperature fluctuates between 121 ° C and 124 ° C (or 123 ° C). If it is an automatic temperature control type sterilization pot, set the lower limit of sterilization temperature to 121 °C, when the temperature rises to 124 °C (or 123 °C), the automatic power off stops heating, when the temperature drops to 121 °C, automatically Start heating; if it is a manual temperature control type sterilizer, when the temperature rises to 124 °C, manually turn off the power to stop heating, when the temperature drops to 121 °C, manually turn on the power to start heating.
2. Different requirements for different types of high pressure steam sterilizers for discharging cold air
1) Non-automatic temperature control type sterilizer is mostly small sterilizer
For this type of sterilizing pot, cold air must be drained. If the cold air is not drained, the cold air will expand and contribute to the working pressure of the pressure cooker. At this time, the pressure and temperature cannot be matched one by one. The displayed temperature is higher than the actual temperature in the pot. The working temperature is high, and the working temperature of the sterilizer cannot reach the set sterilization temperature, which will affect the sterilization effect.
2) Automatic temperature control type sterilizer
The automatic temperature-controlled sterilizer monitors the temperature change in the pot through the thermal electrode. The temperature displayed on the display is the actual working temperature in the pot. When the cold air is not discharged, the temperature requirement for sterilization can also be ensured. Since the saturated steam has the best sterilization effect, when using the automatic temperature control type sterilizer, the cold air should also be discharged to improve the sterilization effect. The drain valve is usually provided under the pot, and the drain can be drained during sterilization. The valve rotates a little to the left (to the right for drainage), allowing a small amount of steam to be discharged. Some sterilization devices are equipped with an adjustable exhaust valve. When sterilizing, the exhaust valve is always in a slightly open state, which can be discharged cold. The role of air.
The first time a security check is necessary
Non-automatic temperature control type sterilization pot:
1 Manually open the safety valve to see if the safety valve is normal;
2 During the heating and heating process, see if the rise of the gauge pointer is blocked or not, and it can be used normally without being blocked.
Simple safety check of automatic temperature control sterilizer:
1 Manually open the safety valve to see if the safety valve is normal;
2 When adding water, observe whether the water level indicator shows the water level normally;
3 Under the premise of eliminating cold air, observe the temperature on the display and the difference between the temperature indicated by the pressure gauge. Normally, the temperature on the pressure gauge is slightly higher than the temperature on the display. If the pressure difference does not exceed 3 °C, Can be used normally.
Factors affecting the effectiveness of sterilization
(1) Water: If the water temperature is too high, it may cause the predetermined vacuum level to change, and the water temperature should be as low as possible. The water used in the sterilizer should be of the applied water quality and the temperature should not exceed 15 °C. The hardness of water is between 0.7 and 2.0 mmoL / L. Hardness values ​​outside this range may cause problems such as scale and corrosion. Thereby shortening the service life of the sterilizer, the water used should be filtered and treated, and the pot body should be kept clean.
(2) Degree of drying of steam The sterilizer should use saturated steam with a degree of drying of not less than 0.9, that is, the moisture content of steam does not exceed 10%, and the degree of drying is not less than 0.95 under metal load, in order to maintain a linear relationship between temperature and pressure.
(3) Sterilization time The sterilization time refers to the time required for sterilization after the sterilization chamber reaches the specified temperature in the sterilization process.
During operation, attention should be paid to the steam inlet velocity and pressure, and the pressure and temperature are generally increased simultaneously.
Do you have to pay attention to the sterilization of liquid substances?
In actual work, it is often necessary to sterilize the liquid. In the instructions of the autoclave, it is indicated that the bottle-shaped liquid can be sterilized, but in the experiment, an unexpected situation is encountered: sterilization with an open glass bottle, the result The liquid in the glass bottle is reduced by 1/3; the plastic film is used to tightly seal the mouth of the bottle, and the plastic film in the seal is broken in the middle, and the liquid in the glass bottle is still reduced by 1/3. When sterilizing liquid substances, when the sterilization is finished, pay attention to the pressure relief should not be too fast, try to close the exhaust valve, keep the natural pressure drop, and maintain the original balance of the system to prevent liquid reduction or splashing.
summary
In order to ensure the safe and effective work of the autoclave, the daily maintenance and maintenance of the sterilizer should be strengthened, and various control valves should be regularly tested to ensure their normal working condition.
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