Although the self-pressurized liquid nitrogen tank is also developed on the basis of the Dewar vacuum jacket, its shape and structure are not like conventional liquid nitrogen tanks.
It has valves and casters, is made of stainless steel, and cannot store liquid nitrogen and samples. What is it used for?
Answer: For liquid nitrogen transfer!
That is to fill other liquid nitrogen containers with liquid nitrogen, similar to the role of liquid nitrogen pumps, but self-pressurized liquid nitrogen tanks are more efficient than liquid nitrogen pumps!
It has its own pressurization system inside. This system does not transmit liquid nitrogen and does not open, so it is usually in a pressure-free state.
Only when liquid nitrogen needs to be delivered, the booster valve is opened to carry out the liquid nitrogen delivery operation. At this time, it is in a low pressure state.
The specific operations are as follows:
1.Close the vent valve first to prevent the newly added pressure from being released;
2.Open the booster valve, mobilize the booster system, and the pressure of the inner tank will gradually rise;
3.Observe the pressure gauge and see the pressure data of the inner tank;
4.If the pressure gauge indicates ≥0.05MPa, you can open the inlet and outlet valves to release liquid nitrogen;
On the contrary, if the value of the pressure gauge is less than 0.05MPa, it means that the pressure is not enough, and it is necessary to continue to pressurize.
Note: There is a limit to the supercharging, which cannot be close to 0.09MPa!
After the liquid nitrogen delivery is completed, close the booster valve, the inlet and outlet valves, and open the empty valve in turn, stop the booster first, then stop the infusion, then release the pressure and residual liquid, and the pressurized liquid nitrogen tank will return to a static and pressure-free state.
Now, you understand what the self-pressurized liquid nitrogen tank is for!