If a magnetic drive pump has been out of service for an extended period (e.g., several months), careful preparation and systematic startup are essential to prevent damage and ensure smooth operation.

1. Pre-Startup Checks After Long-Term Shutdown

1. Pump Casing and Pipeline Condition

   • Residual liquid may crystallize or cause corrosion inside the pump after long-term shutdown.

   • Inspect the pump casing, suction, and discharge pipelines for sediment or residue; clean if necessary.

2. Bearings and Lubrication

   • Bearings in magnetic pumps may have minimal or dry lubrication. Long-term inactivity can cause grease to harden.

   • Check lubrication and replenish or replace grease as needed.

3. Magnetic Coupling Inspection

   • Ensure the inner and outer rotors rotate freely by hand.

   • Avoid sudden motor startup to prevent magnetic coupling damage.

4. Seal and Isolation Sleeve Check

   • Inspect the isolation sleeve for cracks or aging.

   • For corrosive fluids, check for surface damage caused during the shutdown period.

5. Electrical and Pipeline System

   • Ensure motor wiring is intact, dry, and correctly connected.

   • Verify valves are closed/open as required and pipelines are free of obstructions.

2. Restart Procedure

1. Manual Rotation Check

   • Rotate the pump shaft or rotor by hand at low speed to ensure bearings are smooth and rotors are not seized.

2. Slowly Fill the Pump

   • Before startup, fill the pump and suction line with fluid to avoid dry running.

   • For high-temperature or crystallizing fluids, pre-flush with warm water or a diluted solution.

3. Pre-Startup Inspection

   • Ensure sufficient liquid in the pump casing, suction valves open, and discharge line unobstructed.

   • Listen for abnormal friction or binding sounds.

4. Low-Speed No-Load Startup

   • Start the pump at low speed or in short bursts first.

   • Monitor the magnetic coupling for slippage or overheating.

5. Gradually Increase Operating Parameters

   • Once the pump runs smoothly with no abnormal noise or vibration, gradually open the discharge valve to restore normal flow and pressure.

   • Monitor pump and motor temperature; once stable, continuous operation can be resumed.

3. Key Precautions

1. Avoid Dry Running

   • Dry running is the most damaging condition for magnetic drive pumps, especially after long-term shutdown.

2. Monitor the Initial Operation

   • The first 5–10 minutes of operation are critical; watch for vibration, noise, and temperature rise.

3. Check for Corrosion

   • Residual or crystallized fluid may have corroded the pump casing or isolation sleeve; clean or replace components if necessary.

4. Regular Maintenance During Shutdown

   • Even if the pump is not operating, inspect bearings and pump casing monthly to extend service life.