Common SF6 Gas Hazards and How to Avoid Them

Sulfur hexafluoride, a highly effective insulator and arc quencher, is commonly found in the power transmission and distribution industry. But to protect equipment, personnel, and the environment, users must be aware of the common SF₆ gas hazards and how to avoid them.

Sulfur hexafluoride (SF₆), when sealed inside power transmission and distribution(T&D) equipment, insulates switchgears, circuit breakers, and disconnectors by quenching dangerous arcs. This stable and nontoxic gas, which has excellent dielectric strength, is a key component in a power plant’s safety and efficiency. However, leaks can be dangerous on several fronts.

Here are some of the main SF₆ gas hazards, followed by ways to avoid them.

1. Global warming

Carbon dioxide is the most abundant greenhouse gas (GHG), but it doesn’t come close to SF₆ in terms of potency. This fluorinated gas can last in the atmosphere for 3,200 years before it is broken down by UV rays, and is 22,800 times more effective than CO₂ at trapping infrared radiation in the atmosphere, according to the Environmental Protection Agency. In fact, SF₆ has the highest Global Warming Potential (GWP) of any known gases.

2. Equipment failure

A leak in gas-insulated equipment means there is less gas to protect it from the effects of electrical arcs. The results are lost signals, short circuits, malfunctions, and, ultimately, equipment failure that compromise safety and operations. Even a 10% gas loss can permanently damage insulators, shields, arcing contacts, and main contacts.

With equipment failure comes repairs and replacements, expensive in terms of both time and money. There could also be property damage, such as fires, and extended power outages resulting from poorly insulated equipment — potentially a public relations nightmare.

Leaks also allow moisture to enter gas-insulated equipment. This is a major problem as the presence of water not only decreases insulation, but also combines with SF₆ gas to create toxic byproducts that corrode metal and create more leaks.

3. Health risk

SF₆ is nontoxic and poses no direct risks to people or animals. It fact, this gas is used in medical diagnostics. However, due to its heavier weight, escaped SF₆ can settle in low-lying areas and displace the oxygen there. This can cause respiratory problems in personnel working in trenches and pits, especially when breathed in large quantities.

How to Avoid SF₆ Gas Hazards

GA35 emission monitor for SF6 gas

The best way to avoid SF₆ gas hazards is to continually monitor gas-insulated equipment for both quantity (to detect leaks) and quality (for current gas conditions). Then, when the gas has dropped below a certain level of purity, technicians can clean it. Here are just a few of WIKA USA’s innovative SF₆ gas solutions for greater safety and efficiency:

• Model GDHT-20is an integrated gas transmitter that measures density, pressure, humidity, and temperature. Based on these measurements, the unit uses a virial equation to calculate density. The GDHT-20 also constantly monitors the moisture content of a chamber and will alert technicians when conditions are ripe for the formation of toxic decomposition products.
• Model GA35is especially designed to monitor SF₆ levels in ambient air within enclosed spaces. Its infrared sensor is impervious to humidity and common volatile organic compounds (VOC), and provides continuous measurements to ensure occupational safety.
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  GPU-S-3000 SF6 gas handling unit

  
  Model GAD-2000is an innovative gas dehydration system that dries SF₆ without having to stop operations. It removes a portion of the gas from gas-insulated switchgear, runs it through a series of compressors and filters, and then returns the dehydrated gas to the equipment – all with minimal human intervention.
• Model GPU-S-3000is an all-in-one gas servicing unit that fills, cleans, recovers, and stores SF₆ gas. It has additional SIL2 safety controls for the highest level of performance, which virtually eliminates operating errors and fugitive SF₆ gas emissions.

WIKA is a global leader for innovations that significantly reduces the risk of SF₆ gas hazards. For more information about our comprehensive portfolio of SF₆ gas solutions, download this brochureor contact product specialists.