Liquid Nitrogen Tank

When liquid nitrogen needs to be transferred to another cryogenic storage tank, tanker, vaporizer, or end-use system, the internal pressure of the Liquid Nitrogen Storage Tank (LN2 Storage Tank) must be increased. The required pressure depends on the application and operational requirements but must never exceed the rated working pressure of the cryogenic pressure vessel.

1. Check Instrumentation
Ensure the pressure gauge and liquid level gauge are functioning properly. These instruments are critical for safe operation of the vacuum insulated cryogenic tank.
2. Verify Gas Outlet Valve Position
Ensure the gas outlet valve is fully open to allow proper pressure and gas flow within the cryogenic liquid nitrogen storage tank.
3. Open Pressure Building Valve Slowly
Slowly open the pressure building valve (pressure builder inlet valve), allowing liquid nitrogen to enter the pressure building vaporizer. The liquid nitrogen vaporizes and increases the internal pressure of the bulk liquid nitrogen tank.
If the liquid discharge rate is high and tank pressure drops rapidly, open the pressure building valve further to increase vaporization rate.
Once the required working pressure is reached, partially close or fully close the pressure building valve. The remaining liquid inside the vaporizer will continue to vaporize and maintain the required pressure.
During the pressurization process, continuously monitor the pressure gauge to ensure safe and stable operation of the cryogenic storage vessel.

The bulk liquid nitrogen storage tank supports three discharge methods depending on application requirements:

1. Discharge via Cryogenic Vaporizer (Primary Method)
When the tank pressure reaches the required level, open the liquid outlet valve to supply liquid nitrogen to the vaporizer. The vaporizer converts the cryogenic liquid nitrogen into gas, which is then delivered to the point of use.
This is the primary discharge method for industrial gas storage tanks equipped with vaporizers.

2. Discharge via Liquid Transfer Valve

Liquid nitrogen can be transferred to tanker trucks or other cryogenic liquid nitrogen storage tanks using a cryogenic transfer hose.

This procedure is similar to liquid filling, except the liquid inlet/outlet valve is used for liquid discharge instead of filling.

3. Discharge via Liquid Discharge Valve or Dewar Filling Line

This method is used to fill smaller containers such as Dewar flasks or mobile cryogenic containers.

Connect the flexible metal hose of the Dewar container to the liquid discharge valve or Dewar filling connection. Open the liquid outlet valve to transfer liquid nitrogen.

For small discharge volumes, pressurization of the LN2 storage tank may not be required, depending on system conditions.

The vacuum insulated cryogenic liquid nitrogen storage tank supports two storage modes:

1. Atmospheric Pressure Storage
During atmospheric pressure storage, the vent valve remains slightly open to release naturally evaporated nitrogen gas. This prevents pressure buildup inside the cryogenic storage vessel.
Due to advanced vacuum insulation, evaporation loss is minimal. The vent valve should be adjusted to maintain stable tank pressure.

2. Pressurized Storage
During pressurized storage, the vent valve remains closed, allowing natural evaporation gas to remain inside the tank, gradually increasing internal pressure.
The pressure gauge will indicate the rising pressure. When tank pressure reaches the rated working pressure, the vent valve must be opened immediately to release excess pressure and ensure safe operation of the cryogenic liquid nitrogen tank.
Simultaneous Filling and Discharge Operation of LN2 Storage Tank
In many industrial applications, continuous nitrogen supply is required. This requirement can be achieved by installing multiple liquid nitrogen storage tanks operating in parallel.
With two or more cryogenic LN2 storage tanks, one tank can supply liquid or gas while another tank is being refilled, ensuring uninterrupted gas supply.
This configuration is widely used in:
Industrial gas supply systems
Semiconductor manufacturing
Food freezing systems
Chemical processing plants
Medical gas supply systems

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