Operating procedures and operational risks for cryogenic liquid storage tanks

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Operational risks of cryogenic liquid storage tanks: 1. Due to the low temperature of cryogenic liquids, cotton-based anti-static insulating protective clothing should be worn [to prevent frostbite and electrostatic fires]. 2. If cryogenic oxygen storage tanks are not emptied for extended periods, hydrocarbons can accumulate within them [posing a risk of micro-explosions]. 3. Cryogenic nitrogen has a high vaporization rate and can cause asphyxiation [as nitrogen accumulates in the event of a leak]; therefore, such storage tanks should not be placed indoors but in areas with good air circulation. 4. Vacuum-insulated pipes should be used in front of cryogenic liquid pumps [unnecessary vaporization can lead to cavitation in the pump]. 5. In areas with high humidity, large amounts of condensation water can form around cryogenic pipelines and pumps; attention must be paid to potential cable leaks [which can cause electric shock injuries].

Operating procedures for cryogenic liquid pumps: 1. First, ensure that all instruments on the storage tank are accurate and that the valves function properly and reliably. 2. Before filling the tank, open the top gas vent valve, then slowly fill it with liquid. 3. Monitor the pressure changes inside the tank, ensuring that it does not exceed 90% of the design pressure. 4. Fill the tank while it is at high temperature; pay attention to the temperature inside the tank. Once the temperature suitable for filling is reached (–140 degrees Celsius), the filling speed can be increased. 5. Continuously monitor the pressure in the insulation chamber; it must not be lower than atmospheric pressure. When the pressure drops, it should be replenished promptly (with nitrogen or purified nitrogen). 6. When filling the tank, the maximum liquid level inside must not exceed the set maximum value, and the minimum liquid level during use must not be below the set value. 7. The storage tank must not be used under overpressure or negative pressure. 8. Ensure that the insulation layer and enclosure do not frost, and analyze the composition of the gas in the space promptly. 9. The liquid in the liquid oxygen storage tank should not be left unused for long periods; it is necessary to regularly refill it and drain it to prevent the concentration of harmful impurities in acetylene. 10. The acetylene content in the liquid oxygen within the liquid oxygen storage tank is analyzed on a regular basis (weekly); if any abnormalities are detected, measures are taken promptly to discharge some of the liquid oxygen so that the acetylene level in the tank remains below 0.1 ppm.