Use and maintenance of liquid nitrogen and liquid nitrogen biological containers

Liquid nitrogen is a special industrial product. In the improvement of livestock breeds, liquid nitrogen is the main frozen storage medium for semen and embryos. In actual production, we found that due to the lack of understanding of the characteristics of liquid nitrogen and liquid nitrogen biological containers by many technicians, the irrational use phenomenon is serious, which is easy to cause waste of liquid nitrogen, increase production cost, and serious may occur. Injury accident. Below, I will introduce the following common problems in the use of liquid nitrogen and liquid nitrogen containers as follows:

First, the source of liquid nitrogen

Liquid nitrogen is derived from air. The main gas components contained in the air are divided into oxygen and nitrogen. Among them, nitrogen accounts for about 78.09% of air, nitrogen has a molecular weight of 28.0134, which is slightly lighter than air, and liquid nitrogen is liquefied nitrogen.

Second, the characteristics of liquid nitrogen

Liquid nitrogen is cooled by nitrogen compression, and its physical and chemical properties are special. The main features are as follows:

1. Ultra-low temperature: The boiling point of liquid nitrogen is minus 195.8 ° C, the weight of liquid nitrogen per liter is 808 g, and when liquid nitrogen is cooled to minus 210 ° C, it will become solid snow with frost and snow.

The ultra-low temperature properties of liquid nitrogen inhibit the metabolism of organisms such as sperm and embryos. Scientists use this feature to preserve semen and embryos for a long time. Its greatest advantage is that it can be stored for a long time, and the use is not limited by time, region and the life span of male animals. The utilization rate of public animals can be fully improved.

2. Liquid nitrogen is the same substance as nitrogen in the air that people breathe in daily life. Liquid nitrogen is a colorless, odorless, non-toxic, non-flammable, non-explosive liquid.

3. The permeability of liquid nitrogen is very weak. However, when the skin is exposed to liquid nitrogen, it is still frostbitten.

4. Swellability: Liquid nitrogen is made by air compression and cooling, and it returns to nitrogen when it is vaporized. It was determined that each liter of liquid was nitrogenated, the temperature rose by 15 degrees, and the volume expansion was about 180 times. One liter of liquid nitrogen is vaporized to 683 liters of 0 ° C nitrogen at standard atmospheric pressure, and 48 kilograms of heat per kilogram of liquid nitrogen.

5, asphyxiating: Nitrogen itself does not cause suffocation, but in a certain space, if the nitrogen is too much to isolate the oxygen, the operator will also cause suffocation. It has been determined that 10 kilograms of liquid nitrogen evaporates instantaneously in a 10 cubic meter room, which can suddenly reduce the space oxygen to 13%, resulting in space hypoxia. Under these conditions, it can cause people to suffocate and even die.

Third, the type of liquid nitrogen tank

Liquid nitrogen tanks can generally be divided into storage tanks and transport tanks. In terms of capacity, 3L, 5L, 6L, 10L, 15L, 20L, 29L, 30L, 35L, 50L, and 100L, 00L, our commonly used liquid nitrogen tanks are 3L, 5L, 10L, 30L, and storage tanks are mainly used. The static storage of indoor liquid nitrogen should not be used for long-distance transportation under working conditions; it is characterized by long storage time, such as 10 liters of liquid nitrogen tank standard storage time of 88 days - 100 days; 30 liters of liquid nitrogen storage tanks The static storage time is 243-293 days. The storage tank is short when stored in the transport tank, and it is easy to be damaged. The transport tank has a special shockproof design in order to meet the transportation conditions. It can be stored and transported. It can be used for transportation in addition to static storage. However, it should also avoid violent collision and vibration. Its disadvantage is the consumption of liquid nitrogen when used as a storage tank. Fast, storage time is short, such as 10 liters of liquid nitrogen transport tank standard storage time is 52 days - 64 days, 30 liters of liquid nitrogen transport tanks of static storage liquid nitrogen time is 156-182 days.

In the case of using liquid nitrogen in a short time or a short distance, a thermos bottle, a cup or the like can also be used. However, when storing in a thermos bottle, a small toothpick-sized groove should be cut on the edge of the stopper to facilitate the discharge of nitrogen.

Fourth, the liquid nitrogen tank can not be sealed

When liquid nitrogen is stored in a liquid nitrogen tank, care should be taken to keep a certain gap in the liquid nitrogen tank mouth. Otherwise, the gas cannot be discharged in time due to the liquid nitrogen gasification, which may easily cause an explosion accident. Generally, the lid of the liquid nitrogen tank has a certain gap, and it is not necessary to block it artificially.

Five, liquid nitrogen use precautions

1. Liquid nitrogen is a low temperature product, and it is necessary to prevent frostbite during use.

2. When operating and accessing frozen items in liquid nitrogen, the speed should be fast. Pay attention to lightly, so as not to thaw the contents and cause unnecessary loss.

3, in the use and storage of liquid nitrogen in the room, to maintain good ventilation to avoid space oxygen deficiency, resulting in suffocation.

4, because liquid nitrogen is not bactericidal, so contact with liquid nitrogen should pay attention to disinfection.

5. The liquid nitrogen tank must be fixed during transportation to prevent vibration and reverse.

6. Storage and use of liquid nitrogen in liquid nitrogen tank

When liquid nitrogen tanks are stored for a long time, care should be taken to replenish liquid nitrogen in time. The liquid nitrogen level is preferably not lower than the refrigerated article. When checking the liquid nitrogen storage amount, the weighing method or the flashlight irradiation method may be used, and the method of forming the frost height (equal to the liquid level) by using the fine wood or bamboo raft into the liquid nitrogen tank may be used. But do not insert with a hollow tube to prevent liquid nitrogen from rushing out of the tube to injure people.

Seven, the normal maintenance of liquid nitrogen tank

Generally, after using the liquid nitrogen tank for one year, it should be cleaned and disinfected once. Wash with neutral detergent first, then rinse with warm water not higher than 40 ° C, until the inner tank is fully dry before refilling liquid nitrogen.

Eight, the quality of liquid nitrogen tanks is fast and fast

1. During the use of liquid nitrogen tanks, the use of the tanks should be checked every day. Under the premise of liquid nitrogen in the tanks, it is found that there are water drops or frost on the top and top of the jars, indicating that there is a problem with the quality of the jars. , should stop using immediately.

2. When there is no water on the upper part of the lid of the liquid nitrogen tank or frosting, touch the shell with your hand. It feels that the upper part is cold and the lower part is hot. This indicates that there are some problems with the quality of the tank, that is, the daily increase of liquid nitrogen is large, so be careful to observe. After the loss of liquid nitrogen is prevented, the stored materials are damaged. If necessary, it is best to stop using them; if the upper and lower temperatures are the same, the quality of the cans is not problematic.

3. After opening the cork, the mist in the bottle mouth does not overflow, but sinks, indicating that the jar is good.

4. Use the ear to hear the sound of bubbles in the jar from the mouth of the bottle. If there is frequent bubble sound, it means there is a problem with the quality of the jar, otherwise there is no problem.

Anthocyanin

Anthocyanidin, also known as anthocyanin, is a class of water-soluble natural pigments, flavonoid compounds, widely found in plants. It is also the main coloring substance in plant petals, and most of the colorful colors of fruits, vegetables and flowers are related to it.Anthocyanins belong to the flavonoids (flavonoids) of the phenolic compounds.