Guidelines for Storage and Startup of Screw Air Compressors at -40°C (6-12 Month Storage)

The core principle for storing a screw air compressor at -40°C for 6-12 months is to completely drain moisture to prevent freezing and insulate against low temperatures to avoid component damage. Multiple thawing and inspection steps must be completed before startup—direct startup is strictly prohibited.

I. Key Pre-Storage Operations (Core Damage Prevention Steps)

1. Completely Drain Oil-Gas Separator and Oil Tank: Run the air compressor until the oil temperature reaches 40-50°C, then shut it down. Open the bottom drain valve of the oil-gas separator and the oil drain valve of the oil tank to fully drain the lubricating oil (low temperatures will thicken or even solidify the oil, clogging the oil circuit).

2. Drain All Air and Water Circuits (if applicable): Open the bottom drain valve of the air receiver, all stage air valves, and the cooler drain valve. Purge the air circuit with compressed air to ensure no residual moisture (moisture will freeze and expand at -40°C, cracking pipes or the air receiver).

3. Replace Desiccant (if equipped): Remove the desiccant from the adsorption dryer and replace it with a new one to prevent the dryer from being damaged by frozen moisture adsorbed by the old desiccant.

4. Cleaning and Sealing: Clean dust and oil stains from the unit body. Seal the air inlet and outlet with waterproof and breathable film or special plugs to prevent dust and moisture from entering; apply anti-rust grease to exposed metal parts (e.g., bolts, joints).

5. Optimize Storage Environment: Prioritize indoor storage. If outdoor storage is the only option, build a windproof and insulated shed, use elevated supports (e.g., wooden blocks) at the bottom to isolate ground cold, and cover the unit body with flame-retardant insulation cotton.

II.Maintenance During Storage (Prevent Damage from Long-Term Inactivity)

- Inspect Every 3 Months: Open the drain valve to confirm no water accumulation, check if the insulation covering is intact, and manually rotate the motor fan (jogging) 2-3 times to prevent bearing rust from long-term inactivity.

- Avoid Direct Sunlight or Snowmelt Scouring: Prevent the unit shell from cracking due to sudden temperature changes (snowmelt during the day, freezing at night).

III.Mandatory Steps Before Low-Temperature Startup (Direct Startup is Forbidden)

1. Environment Preheating: Move the air compressor to a room with a temperature above 5°C, or use a hot air blower to continuously blow hot air (temperature ≤60°C) onto the unit body, oil tank, and oil-gas separator. Preheat for at least 4-6 hours to ensure all internal frozen components are fully thawed.

2. Replace with New Oil: Fill with low-temperature-adapted special lubricating oil according to the air compressor model (e.g., viscosity grade ISO VG32 or lower; confirm the oil’s minimum service temperature is below -40°C). Residual old oil from before storage is strictly prohibited.

3. Thorough Drainage: Open all drain valves and oil drain valves again to confirm no ice-water mixture is discharged. If there is residue, purge again with compressed air.

4. Manual Jogging: Rotate the motor coupling or fan to ensure smooth operation without jamming (if jamming occurs, continue preheating; forced startup is not allowed).

5. No-Load Test Run: Close the exhaust valve, start the air compressor, and run it under no-load for 5-10 minutes. Check if the oil pressure, oil temperature (required to rise above 30°C), and motor current are normal. If no abnormalities are found, slowly open the exhaust valve for load operation.