Want more information on 219 854 2? Feel free to contact us.
Sulfur hexafluoride (SF6) is a synthetic fluorinated compound with an extremely stable molecular structure. Because of its unique dielectric properties, electric utilities rely heavily on SF6 in electric power systems for voltage electrical insulation, current interruption, and arc quenching in the transmission and distribution of electricity. Yet, it is also the most potent greenhouse gas known to-date. Over a 100-year period, SF6 is 23,500 times more effective at trapping infrared radiation than an equivalent amount of carbon dioxide (CO2). SF6 is also a very stable chemical, with an atmospheric lifetime of 3,200 years. As the gas is emitted, it accumulates in the atmosphere in an essentially un-degraded state for many centuries. Thus, a relatively small amount of SF6 can have a significant impact on global climate change.
More information on long-lived fluorinated greenhouse gases, their emissions, emission sources, and trends is available on EPA’s overview of greenhouse gases page.
Since the 1950’s, the U.S. electric power industry has used SF6 in circuit breakers, gas-insulated substations and other switchgear used in the transmission system to manage the high voltages carried between generating stations and customer load centers. Disconnectors and ground switches use SF6 primarily for insulation, and individually, they contain only slightly less SF6 than a circuit breaker. These devices are used to isolate portions of the transmission system where current flow has been interrupted (using a circuit breaker). Gas-insulated substations also use a significant amount of SF6, and GIS installations house SF6-insulated circuit breakers, busbars and monitoring equipment. The largest use of SF6 occurs in high-voltage circuit breakers, where, in addition to providing insulation, SF6 is used to quench the arc formed when an energized circuit breaker is opened.
Several factors affect SF6 emissions from electric power systems, such as the type and age of the SF6-containing equipment (e.g., old circuit breakers can contain up to 2,000 pounds of SF6, while modern breakers usually contain less than 100 pounds) and the handling and maintenance procedures practiced by electric utilities. Because of its long-life span and high global warming potential (GWP), even a relatively small amount of SF6 can impact the climate.
The electric power industry can reduce the nation’s SF6 emissions through cost-effective operational improvements and equipment upgrades. Through improvements in the leak rate of new equipment, refurbishing older equipment, and the use of more efficient operation and maintenance techniques, utilities often find economical solutions to reduce SF6 emissions.
Under the partnership, EPA shares information on best management practices and technical issues to help reduce emissions. Some cost-effective options to reduce SF6 emissions are:
Reducing SF6 emissions helps electric power systems:
SF6 is used in several different industries including:
The most common use for and largest emission source of SF6, both domestically and internationally, is as an electrical insulator in high voltage equipment that transmits and distributes electricity. Approximately 75 percent of all SF6 emissions in the United States is attributed to the electrical transmission and distribution sector in 2021 based on the Inventory of U.S. Greenhouse Gas Emissions and Sinks.
SF6 containing equipment is designed to avoid emitting any of this gas into the atmosphere. However, SF6 gas can inadvertently escape into the atmosphere as leaks develop during various stages of the equipment's lifecycle. In some cases, significant leaks can occur from aging equipment. Gas can be released at the time of equipment manufacturing, installation, maintenance and servicing, and de-commissioning.
A potent insulator and arc quencher, SF6 gas is widely used in the world of transmission and distribution, as well as other applications. Find the answers to frequently asked questions about this gas’s attributes, risks, and best practices.
Sulfur hexafluoride (SF6) has extremely good electrical and thermal insulation properties. For that reason, it is widely used in médium-and high-voltage electrical power transmission and distribution (T&D). But it requires careful handling. Here are 15 FAQs about this gas, its chemical properties, and how to use it safely and efficiently.
Sulfur hexafluoride is an octahedral (eight faces and six vertices) molecule. It consists of six fluorine atoms surrounding a sulfur atom. The chemical can occur in nature, but most SF6 gas is manufactured. Researchers in Paris were the first to synthesize SF6 in 1900. Large-scale production of this gas in the U.S. began in the 1950s.
SF6 is colorless, odorless, nonflammable, and nontoxic. It is virtually inert, which means it is stable and does not react with other chemicals under normal conditions.
First, dielectricity is the ability to transmit electricity without conductivity, and dielectric strength refers to how well something can withstand high voltage without breaking down. Electronegativity is the ability to capture free electrons, and fluorine is the most electronegative element known on earth. SF6 has six fluorine molecules that can break away from sulfur, capture electrons during an arc, and then return to its original state. The gas’s electronegativity and high dielectric strength are why it is such a popular insulating gas for use in power T&D equipment.
For more c4f8 gas suppliersinformation, please contact us. We will provide professional answers.
When switching or opening an electrical circuit that deals with more than 250 volts, as the contacts start to open, an arc forms between them. This arc can be more than 2,000°C (3,632°F), which is hot enough to melt and make the metal contacts stick to one another. When SF6 gas captures free electrons, it mitigates the effects of arcing.
SF6 is biologically inert and, therefore, is nontoxic to humans and animals. In fact, it is used in medical diagnostics as an ultrasound contrast agent and as a tamponade gas (to plug fluid flow) in ophthalmology.
Not much. The gas itself is nontoxic and will not harm humans or animals. However, SF6 is much heavier than air and, therefore, can displace oxygen in the lungs and lead to asphyxiation if inhaled in extremely large quantities.
This gas does not deplete the ozone layer or cause air pollution. It is, however, almost 24,000 times more effective than carbon dioxide (CO2) at trapping heat, making SF6 a very potent greenhouse gas. That’s why it’s so important to always monitor the SF6 level in electrical switchgears for leaks.
8. Can SF6 gas harm equipment?
As an inert gas, pure SF6 does not damage metals. However, if the gas has been contaminated with water, some of the byproducts generated during arc-quenching cycles are corrosive. See #13 for more information on water as an impurity.
SF6 is routinely used as an electrical and heat insulator in medium- and high-voltage T&D applications. These include:
Besides electrical T&D applications, SF6 is commonly found in radiological instruments, particle accelerators, equipment for semiconductor production, and magnesium and aluminum casting. It is also used as insulation in windows to dampen sound, and as a tracer gas in mining.
SF6 is extremely effective at quenching the arc generated when switching or opening electrical circuits. It also has very high thermal conductivity, especially at high temperatures, and, therefore, dissipates heat much better than air, nitrogen, helium, or other gases. In addition, equipment insulated with SF6 has lower operating noise, does not emit hot gases, and require relatively little maintenance.
Continuous online monitoring of SF6 density inside the chamber provides accurate and reliable information about gas conditions and possible leaks. Commercially available integrated gas transmitterscan measure gas pressure, humidity, and temperature, and use these parameters to calculate gas density.
In a dry environment, SF6 can quickly break apart to capture free electrons, and then recombine. However, when moisture enters a breaker, the sulfur and fluorine molecules grab water’s oxygen molecules to form byproducts during high-temperature episodes. One result is that there is now less of the gas to act as insulator. The second problem is the byproducts themselves, many of which are toxic and corrosive. These byproducts include thionyl tetrafluoride (SOF4), thionyl fluoride (SOF2), sulfuryl fluoride (SO2F2), sulfur dioxide (SO2), and disulfur decafluoride (S2F10).
Use equipment specifically designed to handle SF6 gas. WIKA has the gas handling equipment for all sizes of T&D equipment. The GPU-2000, one of our SF6 solutions, recovers and fills the gas in switchers and cleans the gas of impurities. The GAD-2000is able to dehydrate SF6 without having to take equipment offline.
The IEC(International Electrotechnical Commission) has several SF6 standards in place including:
Click here to download the white paper “GPU-2000: WIKA’s Optimal Solution for Comprehensive SF6 Gas Handling”
The company is the world’s best calibration gas supplier supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.