Liquid nitrogen supply tank is a cryogenic tank used for liquid nitrogen supply, and it is manufactured to supplement liquid nitrogen for other containers.
It is equipped with an automatic pressurization system. When other liquid nitrogen containers such as laboratory storage cells are short of liquid nitrogen, open the corresponding valve and put in a small amount of gasified liquid nitrogen to exchange the liquid nitrogen for regasification. Enter the inner tank, gradually form the pressure that can output liquid nitrogen smoothly.
This pressure is usually ≥0.05MPa, less than 0.09MPa!
When there is no demand for liquid replenishment in other cryogenic containers, the pressure of the liquid nitrogen supply tank will return to 0, that is, there is no pressure value!
But sometimes users will find that the liquid nitrogen supply tank seems to be pressurized quietly inside, even though it has not opened the valve to deliver liquid nitrogen to other liquid nitrogen containers, and even emits the exhaust sound that only occurs when the high pressure is released. Why is this? Is the pressure really too high? Didn’t it mean that the liquid nitrogen supply container is pressure-free when there is no rehydration?
What is certain is that the continuous exhaust of the liquid nitrogen supply tank means that the pressure is too high!
As for the cause of the high pressure, the high probability is that after the completion of the last liquid replenishment, only the booster valve and the liquid outlet valve were closed, and the vent valve was not opened, which resulted in the residual pressure not being released and entering the inner tank to cause pressure. Gradually accumulated to close to 0.09MPa, the liquid nitrogen supply tank opened the safety valve for self-protection, and performed pressure relief and exhaust operation.
In addition, users need to understand that although the liquid nitrogen supply tank is self-pressurized, its pressure setting value will not be higher than 0.1MPa. Like the optimized and improved Dewar bottle, the stable low pressure is safer, the internal liquid nitrogen is vaporized and transported to store liquid nitrogen internally, and the purity of the liquid is more guaranteed!