SF6 (sulfur hexafluoride) is a critical insulating gas in Gas-Insulated Switchgear (GIS), but its high global warming potential (GWP) requires proper recovery to meet environmental regulations (e.g., IEC 60480, EPA standards) and protect equipment performance. Below is a practical, compliant process for SF6 gas recovery in GIS.

1. Pre-Recovery Preparation

First, gather essential equipment: a certified SF6 gas recovery machine (rated for GIS pressure), vacuum pump, gas storage cylinders (leak-tested), and personal protective equipment (PPE: gloves, goggles, respirator). Inspect the GIS system to confirm no active faults—shut down power to the target compartment and isolate it with lockout-tagout (LOTO). Check all valves (inlet, outlet, recovery) for blockages or damage to avoid leaks during operation.

2. Step-by-Step Recovery Process

Step 1: Connect Equipment

Attach the recovery machine’s inlet hose to the GIS compartment’s SF6 valve using a leak-tight fitting (e.g., brass couplings). Connect the outlet hose to the storage cylinder, and the vacuum pump to the recovery machine’s auxiliary port. Ensure all connections are tightened to prevent SF6 escape—use a portable SF6 detector to verify no initial leaks.

Step 2: Depressurize and Recover

Open the GIS compartment valve slowly to release pressure gradually (avoid rapid depressurization, which damages equipment). Start the recovery machine: it will draw SF6 gas, filter out moisture and impurities (via built-in dryers/filters), and compress it into the storage cylinder. Monitor the machine’s pressure gauge—stop when the GIS compartment pressure drops to ≤ 5 mbar (to maximize recovery efficiency).

Step 3: Vacuum the Compartment

After SF6 recovery, start the vacuum pump to evacuate residual gas from the GIS compartment. Maintain vacuum (≤ 1 mbar) for 30–60 minutes to remove trace SF6, which prevents contamination if the compartment is refilled later.

3. Post-Recovery Checks & Compliance

Use an SF6 leak detector to scan all connections and the GIS compartment—ensure leakage rate ≤ 1×10⁻⁸ mbar·L/s (meets international standards). Label the storage cylinder with “SF6 Gas – Recycled” and record key data: recovery date, volume recovered, and leak test results (for regulatory audits). Dispose of any contaminated SF6 via a certified recycler (do not vent to the atmosphere).

Proper SF6 recovery in GIS protects the environment, extends equipment life, and avoids non-compliance fines. Always follow the recovery machine’s user manual and local regulations—for complex GIS systems, consult a trained technician.