Leak Check and Evacuation) Multiple Evacuation Procedure

 

1. When to Use Triple Evacuation

• Water-Cooled Condenser Rupture:

  • A significant amount of water might be present in the system.

• System Running at a Vacuum:

  • If the system has been leaking and pulling water vapor into the low side.

• System Open to Atmosphere:

  • If the system was open for an extended period, allowing moisture to enter.

2. Triple Evacuation Procedure

• Step 1: Initial Vacuum to 1500 Microns

  • Vacuum: Pull a vacuum to 1500 microns.
  • Break Vacuum: Add dry nitrogen to 2 PSIG.
    • This helps to mix the dry nitrogen with any remaining moisture.

• Optional Step: Run Compressor

  • Purpose: Dislodge water from the oil.
  • Method: Run the compressor for a few seconds to mix the oil and water.

• Step 2: Second Vacuum to 1500 Microns

  • Vacuum: Pull a second vacuum to 1500 microns.
  • Break Vacuum: Again, add dry nitrogen to 2 PSIG.

• Step 3: Final Deep Vacuum

  • Vacuum: Pull a final vacuum down to 500 microns.
  • Check Vacuum: Ensure the system holds the vacuum. If not, continue to pump and wait.

3. Detailed Steps with Diagrams

• Initial Setup:

  • Connect the vacuum pump to the system.
  • Use a manifold with appropriate connections for nitrogen and vacuum pump.

• Evacuation to 1500 Microns:

  • Start the vacuum pump and open the manifold valves.
  • Pull the vacuum down to 1500 microns.
  • Shut off the vacuum pump.

• Add Nitrogen:

  • Set nitrogen regulator to a low pressure (around 10 PSIG).
  • Use a Y-fitting or four-port manifold to control nitrogen and vacuum flow.
  • Open the valve to add nitrogen into the system, breaking the vacuum.

• Running Compressor (Optional):

  • Ensure some pressure in the system from nitrogen.
  • Run the compressor for about 5 seconds to stir up water in the oil.

• Second Vacuum to 1500 Microns:

  • Open the valve to the vacuum pump and pull another vacuum down to 1500 microns.
  • Shut off the vacuum pump and add nitrogen again.

• Final Deep Vacuum:

  • Open the valve to the vacuum pump and pull a deep vacuum to 500 microns.
  • Ensure the system holds the vacuum to confirm all moisture and non-condensables are removed.

4. Final Steps and Verification

• Hold Vacuum:

  • Verify the system holds a vacuum below 500 microns.
  • If the vacuum holds steady, the system is moisture-free and ready for charging.

• Charging:

  • Proceed with charging the system once the vacuum holds.