Precautions and methods for using high-pressure sterilizers

High pressure steam sterilization is a commonly used sterilization method in biological experiments, which can be divided into three types based on their capacity: handheld, vertical, and horizontal. High pressure sterilization pots are widely used in various universities, medical and health institutions, food and chemical engineering, biological research and other units for sterilization treatment of instruments, dressings, containers, medicinal liquids, culture media and other items. Don't underestimate it, if you're not careful, it could lead to a big disaster!

What should be noted during use?

1The sterilization temperature should be a temperature range, not a fixed value.

Usually, the sterilization temperature of high-pressure steam is a fixed value. For example, the sterilization requirements for test tube slant culture medium and shake flask liquid culture medium are:121℃，20minBut in121℃Just the lower limit of sterilization temperature, the actual sterilization temperature is121℃～124℃(or123℃）Fluctuations between them. If it is an automatic temperature control sterilization pot, set the lower limit of sterilization temperature to121℃Later, when the temperature rises to124℃(or123℃）When the temperature drops, it will automatically shut down and stop heating121℃At this time, it automatically starts heating; If it is a manually controlled sterilization pot, when the temperature rises to124℃When the temperature drops, manually cut off the power and stop heating121℃At that time, manually turn on the power and start heating.

2Different types of high-pressure steam sterilization pots have different requirements for the discharge of cold air

1）Non automatic temperature control sterilization pots are mostly small sterilization pots

For this type of sterilization pot, the cold air must be completely discharged. If the cold air is not completely discharged, the thermal expansion of the cold air will contribute to the working pressure of the pressure pot. At this time, the pressure and temperature cannot correspond one-to-one, and the displayed temperature is higher than the actual working temperature inside the pot. The working temperature of the sterilization pot cannot reach the set sterilization temperature, which will affect the sterilization effect.

2）Automatic temperature control sterilization pot

The automatic temperature control sterilization pot monitors the temperature changes inside the pot through thermal sensitive electrodes, and the temperature displayed on the screen is the true working temperature inside the pot. It can ensure the sterilization temperature requirements even if the cold air is not completely discharged. Due to the good sterilization effect of saturated steam, when using an automatic temperature controlled sterilization pot, cold air should also be discharged to improve the sterilization effect. There is usually a drainage and exhaust valve under the pot. During sterilization, the drainage valve can be rotated slightly to the left (to the right for drainage) to allow a small amount of steam to be discharged. Some sterilization equipment also has an adjustable exhaust valve. During sterilization, the exhaust valve should always be kept slightly open to discharge cold air.

It is necessary to conduct a safety check for first-time use

Non automatic temperature control sterilization pot:

①Manually open the safety valve and check if it is functioning properly;

②During the heating process, check if there is any obstruction in the rise of the pressure gauge pointer. If there is no obstruction, it can be used normally.

Simple safety inspection of automatic temperature control sterilization pot:

①Manually open the safety valve and check if it is functioning properly;

②When adding water, observe whether the water level indicator light displays the water level condition normally;

③On the premise of excluding cold air, Observe the difference between the temperature on the display screen and the temperature indicated on the pressure gauge. Normally, the temperature on the pressure gauge is slightly higher than the temperature on the display screen. If this pressure difference does not exceed3℃Can be used normally.

Factors affecting sterilization effectiveness

（1）Water: Excessive water temperature may cause a change in the predetermined vacuum level, and the water temperature should be kept as low as possible. The water used in the sterilization pot should meet the quality of the applied water and the temperature should not exceed15℃The hardness value of water is0.7～2.0mmoL /Lbetween. Hardness values beyond this range may cause problems such as scale and corrosion. In order to shorten the service life of the sterilization pot, the water used needs to be filtered and treated, and the pot body should be kept clean.

（2）The drying degree of steam sterilization pot should be no less than0.9Saturated steam, i.e. steam with a water content not exceeding10%Under metal load conditions, the degree of dryness shall not be less than0.95To maintain a linear relationship between temperature and pressure.

（3）Sterilization time refers to the time required for sterilization in the sterilization chamber after reaching the specified temperature during the sterilization process. During operation, attention should be paid to observing the steam inlet velocity and pressure,Generally, the pressure and temperature rise synchronously.

What should be paid attention to when sterilizing liquid substances?

In practical work, it is often necessary to sterilize liquids. The instruction manual of the high-pressure sterilization pot indicates that it can sterilize bottle shaped liquids. However, in the experiment, an unexpected situation was encountered: using an open glass bottle for sterilization resulted in a reduction in the liquid in the glass bottle1/3Seal the bottle tightly with plastic film, the middle of the sealing plastic film breaks, and the liquid in the glass bottle still decreases1/3When sterilizing liquid substances, be careful not to release pressure too quickly after sterilization, try to close the exhaust valve as small as possible, maintain natural pressure reduction, and maintain the original balance of the system to prevent liquid reduction or splashing.

Summary

To ensure the safe and effective operation of high-pressure sterilization pots, daily maintenance and upkeep of the pots should be strengthened, and various control valves should be regularly inspected to ensure their normal working condition.