Cold storage shutdown and sealing plan | Long term shutdown, cross season shutdown, and sea transportation sealing protection for foreign trade units
Long term shutdown and sealing of cold storage, with the core goal of preventing refrigerant migration, freezing oil absorption and acidification, internal corrosion of pipelines, and avoiding liquid hammer failure during the next start-up.
Short term shutdown (7-30 days): Keep the crankcase heater continuously energized, cut off the supply of liquid to the solenoid valve, maintain oil temperature, and reduce the dissolution of refrigerant into the refrigeration oil.
If the long-term storage exceeds 3 months, priority should be given to refrigerant recovery, and all refrigerants should be recovered into the storage tank. The system should maintain a slight positive pressure nitrogen gas storage to isolate air and water vapor.
Xitelide exports new machines overseas and seals them by sea. They are filled with positive nitrogen pressure of 0.03-0.05MPa before leaving the factory, and the sealing covers at both ends of the pipe are locked. After arrival, check whether the nitrogen pressure is lost first.
Before sealing, sample and test the frozen oleic acid value and moisture content. If the indicators exceed the standard, the oil must be replaced before sealing; The old unit is stored with oil for a long time, and POE oil will continue to absorb moisture and hydrolyze.
Long term storage of the unit, closure of all water circuit valves, cleaning of the water-cooled condenser and water pipes to prevent freezing and cracking of copper pipes in a low-temperature environment.
Many cold storage facilities shut down during the off-season and directly cut off power, causing the heating of the crankcase to stop. The temperature difference between day and night changes, and a large amount of refrigerant dissolves into the crankcase oil. It is highly likely that the valve plate will be damaged by the liquid during the next year's start-up.
After the foreign trade project arrives at the port, if it is not installed temporarily, the sealing plug cannot be removed. If the nitrogen pressure is lost, it needs to be vacuumed and nitrogen filled again for protection.
Record of sealing ledger: sealing date, nitrogen pressure, refrigeration oil detection data, valve status. Before resuming work and starting up, preheat the crankcase for more than 8 hours before jogging and testing the machine.
Parallel multi head units should be sealed. It is recommended to isolate each head separately and maintain nitrogen pressure in the unit head to facilitate quick identification of which pipeline has a slight leak in the future.
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FAQ
What are the key protections for short-term downtime of 7-30 days? Continuously power on the crankcase heating and turn off the supply solenoid valve.
What is recommended for sealing for more than 3 months? Recycle refrigerant and seal the pipeline with slightly positive nitrogen pressure.
3. What is the pressure range for nitrogen storage in sea freight for the new aircraft? 0.03-0.05MPa micro positive pressure.
What are the hidden dangers of direct power outages and shutdowns during the off-season? The refrigerant dissolves a large amount of oil, making it prone to liquid hammer when turned on.
What should be done in advance before resuming work and starting up? Pre heat the crankcase for no less than 8 hours.
How to deal with the long-term sealed water circuit of water-cooled units? Drain the accumulated water in the pipeline to prevent the copper pipe from freezing and cracking.
What does the loss of nitrogen pressure mean? Sealing failure, air vapor has entered the pipeline.
