Abnormal Noise During the Operation of Liquid Nitrogen Storage Tanks: Causes and Solutions

Abnormal Noise During the Operation of Liquid Nitrogen Storage Tanks: Causes and Solutions

Abnormal noise in a liquid nitrogen (LN₂) storage tank during use is often an indication of changes in internal pressure, phase transitions, or mechanical issues. Identifying the source of the sound is crucial to prevent operational risks and ensure the stability of the storage system.

1. Common Causes of Abnormal Noise

(1) Rapid Boil-Off and Pressure Fluctuation
When ambient heat enters the tank—especially if the vacuum insulation has degraded—the liquid nitrogen vaporizes rapidly. Sudden pressure fluctuations may produce popping, cracking, or “hissing” sounds.

(2) Thermal Contraction of Internal Structural Components
Rapid temperature change causes metal supports, inner shell, and piping structures to contract, leading to clicking or creaking noises. This is typical during early stages of pre-cooling or during sudden filling.

(3) Ice Accumulation and Break-Off
Moisture entering the tank neck or valves can freeze. Ice breaking or shedding may cause sharp cracking sounds.

(4) Vacuum Degradation in the Interlayer
If the vacuum layer loses insulation performance, the inner tank wall experiences increased heat penetration. This causes uneven cooling and repeated boil-off cycles, generating intermittent knocking or gurgling noises.

(5) Gas-Liquid Oscillation in the Neck or Vent Line
Incorrect venting, blockage, or high flow rates can cause oscillation of nitrogen gas, producing a howling or vibrating noise.

(6) Valve Malfunction or Partial Obstruction
Frosted, damaged, or partially blocked valves may chatter or resonate when gas flows through them.

2. Solutions and Troubleshooting Measures

(1) Check Pressure Levels and Safety Valve Performance

Ensure tank pressure is within the normal operating range.

Inspect venting and safety valves for icing or obstruction.

If the pressure rises abnormally, temporarily open the vent to stabilize the system.

(2) Inspect Vacuum Integrity

Touch the outer shell; if warm, vacuum loss is likely.

Tanks with severe vacuum degradation must be repaired or refurbished by a certified manufacturer.

(3) Ensure Proper Pre-Cooling and Filling Procedures

Follow slow, controlled pre-cooling to reduce excessive thermal contraction noise.

Avoid rapid filling that triggers violent gas-liquid interaction.

(4) Remove Moisture and Ice

Defrost valves and neck tubing as needed.

Replace damaged sealing components to prevent moisture ingress.

(5) Clean or Replace Valves and Transfer Lines

Remove blockages and frost from valve internals.

Replace worn valve cores that cause vibration or noise.

(6) Monitor for Persistent Structural Noise

Occasional thermal contraction noise is normal.

Continuous or intensifying noise may indicate insulation problems or mechanical loosening of internal supports.

3. Preventive Measures

Maintain a clean, dry operating environment to minimize frost accumulation.

Perform regular vacuum checks and insulation inspections.

Avoid frequent deep pressure cycling that stresses tank walls.

Use high-quality, compatible valves and piping to reduce resonance issues.

Follow proper shutdown and standby procedures to prevent moisture intrusion.

Conclusion

Abnormal sounds in a liquid nitrogen storage tank are usually caused by pressure fluctuations, thermal contraction, vacuum degradation, ice formation, or valve issues. Timely diagnosis and corrective measures ensure safe, stable, and long-term operation of cryogenic LN₂ storage systems.

References

EN 13458 – Cryogenic Vessels: Static Vacuum Insulated Vessels.

ISO 21029 – Cryogenic Vessels — Vacuum Insulated Vessels.

NFPA 55 – Compressed Gases and Cryogenic Fluids Code.

Barron, R. F. (1999). Cryogenic Systems, 2nd Edition. CRC Press.

Hord, J. (2011). Handling and Storage of Cryogenic Liquids.