What are the precautions when using liquid nitrogen in laboratory liquid nitrogen tank?

1, liquid nitrogen is an ultra-low temperature liquid (-196℃), which will cause frostbite similar to scald when splashed on the skin, so special attention should be paid when filling and taking out liquid nitrogen;

2. Due to the large heat in the liquid nitrogen tank, it takes a long time to balance the heat when filling the liquid for the first time, so a small amount of liquid medium can be filled for pre-cooling (about 20L) first, and then slowly filled (it is not easy to form ice plugs).

3. When not in use for a long time, be sure to open the exhaust valve to avoid damage to the container due to the increase of nitrogen pressure caused by the long-term closure of the valve;

4. The room where liquid nitrogen is stored for a long time should be ventilated.

5. Self-pressurized liquid nitrogen storage tank is mainly used for transporting and storing liquid medium, and can also be used as the cold source of other refrigeration devices. The container consists of an inner container, a shell and an instrument valve. The upper part is equipped with a pressure gauge, which can conveniently observe the pressure of the inner container, and is equipped with a safety valve, which improves the safety of the container.

6. In order to reduce the loss of liquid filling in the future, please refill the liquid when there is still a small amount of liquid in the liquid nitrogen tank. Or replenish the liquid within 48 hours after using up the liquid.

7. In order to ensure the safety and reliability of the liquid nitrogen tank, this container can only contain liquid nitrogen.

8, infusion, liquid nitrogen tank surface water, frost, is a normal phenomenon. When the booster valve is opened to boost pressure, because the booster coil is attached to the inner wall of the outer cylinder, the liquid will absorb the heat of the outer cylinder and vaporize when passing through the coil, so as to achieve the purpose of boosting pressure, and spot frost may appear on the outer cylinder. After closing the booster valve, the frost spots will slowly disperse. When the booster valve is closed and there is no infusion work, there is water condensation and frost on the outer surface of the container, which indicates that the vacuum of the container has been destroyed and the container can not be used any more. You should find a professional manufacturer to repair or scrap it.

9. If the liquid nitrogen tank is not used for a long time, please discharge the liquid medium in the tank and blow dry it, then close all valves and seal them. Before filling the liquid nitrogen tank with liquid medium, the container liner, all valves and pipes must be dried with dry air, otherwise the pipes will freeze and block, which will affect the pressure increase and infusion.

10, this equipment belongs to the category of instruments and meters. When using it, handle it with care. When opening each valve, the force should be moderate but not too high and the speed should not be too fast. Especially, when connecting the metal hose with the joint at the inlet/outlet valve, do not use too much force, just screw it in place with a little force to seal it, so as not to twist or even damage the nozzle, and hold the valve body with one hand when screwing.