Sulfur Hexafluoride

A:Prevention of asphyxiation, frostbite, and poisoning from decomposition products constitutes the three key safety priorities;

PPE:

Routine operations: Cold-resistant gloves, safety goggles, and face shields;

Entering GIS rooms/maintenance: Wear portable SF₆ leak detectors and HF/SO₂ decomposition product detectors; use self-contained breathing apparatus (SCBA) when necessary;

Storage: Store in a dedicated, cool, and well-ventilated gas cylinder room (≤30°C); secure cylinders in an upright position away from heat sources and flammable materials; maintain residual pressure (≥0.1 MPa) in cylinders to prevent the backflow of air or moisture;

Leak response:

Minor leaks: Ventilate to dilute the gas and evacuate personnel upwind;

Major leaks: Evacuate immediately and shut off the gas source; enter wearing SCBA and use an alkaline solution spray (e.g., limewater) for absorption (SF₆ is insoluble in water, but decomposition products HF and SO₂ can be neutralized by alkaline solutions);

Firefighting: The gas itself is non-flammable, but cylinders exposed to fire heat may explode-use water mist to cool the cylinders and evacuate personnel.

A:Pure SF₆ is non-toxic, non-flammable, and non-irritating in its "static" state;

⚠️ Core Risk: Decomposition products resulting from electric arcs or high temperatures. Under the influence of electric arcs (approx. 2000–3000°C) or electrical discharges, SF₆ decomposes to form a series of highly toxic and strongly corrosive substances:

SF₄ (Sulfur tetrafluoride): Highly irritating; reacts with water to form HF and SO₂; corrodes lung tissue;

SOF₂ (Thionyl fluoride): Highly toxic; neurotoxic; LD₅₀ (rat inhalation) approx. 100 ppm·h;

SO₂F₂ (Sulfuryl fluoride): Highly toxic; strongly irritating to the lungs;

HF (Hydrogen fluoride): Highly corrosive; causes burns to the respiratory tract and skin;

SO₂ (Sulfur dioxide): Irritating gas.

Occupational Exposure Limits:

China GBZ 2.1: Maximum allowable concentration of SF₆ in the workplace is 6000 mg/m³ (approx. 1000 ppm);

However, limits for decomposition products (such as HF and SO₂) are extremely strict (HF TWA 2 mg/m³; SO₂ TWA 5 mg/m³).

GHS Labeling: Warning; H280 (Contains gas under pressure; may explode if heated) + H373 (May cause damage to organs through prolonged or repeated exposure-specifically the auditory system, due to high-frequency noise).

A: SF₆ is one of the six greenhouse gases regulated by the Kyoto Protocol and a potent greenhouse gas addressed by the Kigali Amendment to the Montreal Protocol. Emission reduction requirements: Under China's "dual carbon" goals, power grid enterprises must strictly adhere to the *Technical Specification for SF₆ Gas Recovery and Treatment* (GB/T 39228), which prohibits direct discharge into the atmosphere. Recovery and treatment: Specialized SF₆ recovery units must be used during maintenance, achieving a recovery rate of ≥99%. Alternative technologies: Environmentally friendly insulating gases-such as dry air, N₂/N₂O mixtures, and g³ (C₄F₇N/CO₂)-are being promoted; however, SF₆ remains irreplaceable in the ultra-high voltage (UHV) sector. Monitoring: GIS rooms must be equipped with SF₆ leak alarm systems (with an alarm threshold of 1000 ppm), and decomposition products (HF, SO₂) must be monitored regularly.