Where can I buy liquid nitrogen?

Chemical plants, gas markets, hospitals, beauty salons, animal husbandry stations and gas stations generally have liquid nitrogen.

Liquid nitrogen is dangerous, so special liquid nitrogen storage tanks must be used.

Because it is odorless, colorless, tasteless and non-irritating, nitrogen has no warning characteristics. Humans have no ability to detect the presence of nitrogen. Although nitrogen is non-toxic and mostly inactive, it can become a simple asphyxiant by replacing oxygen in the air and reducing it below the level necessary to sustain life. Excessive inhalation of nitrogen can lead to dizziness, nausea, vomiting, coma and death.

Death may come from wrong judgment, mental confusion or unconsciousness that prevents self-help. In the case of low oxygen concentration, unconsciousness and death will occur without warning within a few seconds. No one, including rescuers, shall enter the area with oxygen concentration below 19.5% unless equipped with self-contained breathing apparatus (SCBA) or tracheal breathing apparatus.

Knowledge of purchasing and selecting liquid nitrogen containers;

The first thing to look at is the sample size. The number of frozen samples will determine the volume of the liquid nitrogen container. If there are few samples, a small liquid nitrogen container should be selected. The size of the frozen sample also determines the size of the liquid nitrogen container. If the sample is large, a larger liquid nitrogen container should be selected. The diameter of the sample is also very important for the selection of liquid nitrogen container.

Generally speaking, the diameter of the liquid nitrogen container should be larger than the diameter of the frozen specimen. For example, if your specimen has a diameter of 90mm and you buy a liquid nitrogen container with a diameter of 80mm, your specimen will not fit in, which will not meet your needs.

And if you need to store the freezing tube, and the storage capacity is large. A large-diameter and large-volume liquid nitrogen container can be selected for storage. Drawer-type stainless steel freezers can be placed in large-diameter and large-volume liquid nitrogen containers, which are designed to store 2mm frozen tubes.

Number of specimens: preserved in liquid nitrogen. For long storage days, liquid nitrogen containers with a volume of 30 liters or 35 liters and a diameter of 50mm can be selected for storage, and the static storage days of liquid nitrogen are all over half a year.

The size of the frozen specimen also determines the size of the liquid nitrogen container. If the specimen is large, it is necessary to choose a larger liquid nitrogen container. If you buy a small liquid nitrogen container for freezing, the sample will occupy the space inside the liquid nitrogen container, and only a small amount of liquid nitrogen can be contained in the liquid nitrogen container, thus reducing the storage days of liquid nitrogen and possibly causing the frozen sample to die due to lack of liquid nitrogen. Therefore, the size of the specimen is very important for choosing the size of the liquid nitrogen container.

Specimen diameter: In general, the diameter of the liquid nitrogen container should be larger than the diameter of the frozen specimen. For example, if your specimen is 90 mm in diameter, and you buy a liquid nitrogen container with a diameter of 80 mm, your specimen will not fit in, which will not meet your needs.

Precautions:

1. Before filling the liquid nitrogen tank with liquid nitrogen, check whether the shell is sunken and the vacuum exhaust port is intact. If it is damaged, the vacuum degree will be reduced, and in severe cases, the intake air cannot be kept warm, which will frost the upper part of the tank, resulting in a large loss of liquid nitrogen and loss of the value of continuous use.

2. Be careful when filling liquid nitrogen: for new tanks or tanks in dry state, it must be filled slowly and precooled to prevent the tanks from being damaged due to too fast cooling and reduce their service life. Pay attention to the method when filling in. When filling liquid nitrogen, don't pour liquid nitrogen on the vacuum vent to avoid reducing the vacuum degree. The cover plug is made of heat insulation material, which can not only prevent the evaporation of liquid nitrogen, but also fix the lifting cylinder, so the wear should be minimized when opening and closing to prolong the service life. But also indirectly reduces the cost.

3. After the inspection of the liquid nitrogen tank, when the liquid stored in the liquid nitrogen tank enters the medium, please be sure to close the inlet/outlet valve and the booster valve, and open the vent valve. Avoid explosions and dangers in the future.

4. The transportation of liquid nitrogen tanks filled with liquid nitrogen is also very important and dangerous, so we should also pay attention to it. When transporting liquid nitrogen medium, the liquid nitrogen tank must ensure that the on-off state of each valve is the same as that during storage, and please put the bottom of the packing box under the container seat ring and fix the liquid nitrogen tank reliably on the car with a rope, so that the liquid nitrogen tank will not shake during transportation, which is safer.

5. Always check during use. You can observe with your eyes or touch the shell with your hands. If frost is found on the surface, stop using it. Especially when the inner wall of the neck tube is frosted and frozen, it is not advisable to scrape it with a knife to avoid damaging the inner wall of the neck tube and causing poor vacuum. But to take out the liquid nitrogen and let it melt naturally.

Extended data:

Liquid nitrogen preservation is a method to effectively preserve strains in liquid nitrogen (ultra-low temperature-196℃) mainly by using the principle that the metabolism of microorganisms tends to stop at low temperature below-130℃. This method is simple and efficient, and the storage period can generally reach 15 years. It is one of the recognized long-term preservation technologies at present, and is suitable for the preservation of various microbial strains. However, the use of liquid nitrogen storage requires the purchase of ultra-low temperature liquid nitrogen equipment, which consumes a lot of liquid nitrogen and has high cost.

Generally, there are glycerol, dimethyl sulfoxide, dextrin, serum protein, polyvinylpyrrolidone, Tween 80 and so on. Liquid nitrogen and glycerol (10%? 20%), different microorganisms should choose different protective agents, and the concentration of protective agents should be controlled to avoid microbial death.

References:

Baidu encyclopedia-liquid nitrogen

References:

Baidu encyclopedia-liquid nitrogen preservation method

References:

Baidu encyclopedia-liquid nitrogen