Blue Journey: How Siemens Energy and Pfeiffer Vacuum+Fab Solutions Are Working to Create a Sustainable Tomorrow
06-12-2025
Abstract
When striving to make fundamental changes to a working system, challenges are inevitable. This article examines how Siemens Energy has made a truly major step towards sustainability in the energy sector, by phasing out SF6 gas and introducing zero-emission clean air insulation gas technology for switchgear. With the vision of creating a sustainable energy supply for the future, the company has had to overcome many challenges along the way, including tightness verification in clean air switchgear. To solve this, Siemens Energy collaborated with Pfeiffer Vacuum+Fab Solutions to develop an innovative vacuum-based leak detection method.
Siemens Energy and the battle against SF6
Let’s make tomorrow different today. It’s a short sentence, but one which carries great weight. It describes the mission that Siemens Energy is actively pursuing to ensure a brighter future, and the resolve to take on the responsibility of delivering the energy transition.
A major part of this mission is the battle against SF6 (sulfur hexafluoride), the most potent greenhouse gas with a global warming potential (GWP) 24,300 times higher than that of CO2. In recent years, SF6 has been widely used in the electrical industry to insulate high-voltage devices.
Pressure is growing on the energy sector to decarbonize, with an EU ban on SF6 switchgear coming into effect in 2026. However, Siemens Energy is already way ahead in taking on the challenge of finding a climate-neutral solution to enable a net zero future. The Blue portfolio, consisting of SF6-free high-voltage insulation products using clean air (20% O2, 80% N2) and vacuum interruption technology, has been developed to drive sustainable change. And the first of these products were put into operation as long ago as 2010, far in advance of EU F-gas regulations.
The Blue portfolio from Siemens Energy consists of SF6-free high-voltage insulation products using clean air (20% O2, 80% N2) and vacuum interruption technology. © Siemens Energy, 2025: clean air Blue GIS
Challenges arise, solutions evolve
Whenever F-gases with a GWP above 1 escape into the atmosphere, they contribute to climate change. And as mentioned, the GWP of SF6 is extraordinarily high.
The method used worldwide to verify the tightness of flange connections, lids, tubes and other potential locations of SF6 leakages is sniffing. However, this method does not work with clean air due to its similar composition to ambient air.
Of course, no harm is caused to the environment by any leakage of clean air, and repair work does not have to be carried out with the same urgency as when SF6 is escaping. All the same, a leak of clean air will cause the total pressure in the system to drop and may activate an alarm, so it is essential to be able to verify the tightness of seals in Blue portfolio products.
Though helium is commonly used as a tracer gas to detect potential leaks with the sniffing method, an innovative alternative method has now been developed for 420 kV gas-insulated busducts with clean air. The “outside-in-leak” method used with a vacuum can measure very small leakages in a very short time and eliminates the need for huge amounts of tracer gas, gas filling procedures and the use of gas-tight sheaths. This saves both energy and time.
Technology and teamwork
After a lengthy consideration of various viable approaches, Siemens Energy turned to Pfeiffer Vacuum+Fab Solutions for advice. A leak detection expert duly visited the site to collaborate on finding the best solution.
Analysis of the alternatives led to a new idea: reversing the pressure gradient and creating a vacuum inside the tube. By implementing this procedure, existing leaks could be detected and pinpointed using a minimal amount of tracer gas. The method worked even in windy weather conditions.
The reliable and qualitative detection of leakage at the flange connection was also made possible, thus guaranteeing dependable control of the various flanges. Overall, the vacuum detection method has enabled Siemens Energy to operate more efficiently and economically and added to the success of the Blue portfolio.
Skills to save money and the planet
The training center at the Siemens Energy switchgear factory in Berlin offers a range of programs, providing comprehensive technical training in the installation, commissioning and maintenance of different high-voltage switchgear systems and setting out safety standards.
The primary focus, however, is on training modules for SF6-free Blue products to demonstrate the use of environmentally-friendly switchgear solutions and the benefits of the energy transition. The modules cover the use of helium leak detectors to maintain the integrity of the systems and how to use the sniffing and vacuum testing methods. The aim is to ensure that participants acquire the safety knowledge and skills to be able to work properly on these complex systems, and also to show that the path to sustainable energy production has been made much more straightforward.
Similarly, the Pfeiffer Academy offers a thorough grounding in the subject, as you would expect from a member of the global Busch Group, one of the world’s largest manufacturers of vacuum pumps, vacuum systems, blowers, compressors, gas abatement systems and leak detection solutions. From an introductory course on the theoretical and practical fundamentals of vacuum technology to professional training in vacuum generation, leak detection, vacuum measurement and mass spectrometry, the Academy enables participants to gain and refresh the knowledge and skills necessary for operating and maintaining vacuum components and systems.
The common understanding of the importance of energy efficiency and sustainability unites Siemens Energy and Pfeiffer in our efforts to achieve the highest possible systems integrity. Together, we offer solutions for a wide variety of applications, all tailored to the relevant client specifications and industry standards.
“We are proud that Siemens Energy relies on our helium leak detectors and builds on our solutions. We look forward to continuing our collaborative partnership and contributing to future projects that support a more sustainable world,” says Lars Lühl, Sales Engineer at Pfeiffer Vacuum+Fab Solutions.
Explanations of terms and products
SF6
Sulfur hexafluoride, commonly known as SF6, belongs to the group of per- and polyfluoroalkyl substances which have long been used in the electrical industry to insulate high-voltage electrical equipment such as switchgear or circuit breakers. Although the use of SF6 has the advantage of high dielectric strength and thermal stability, it has enormous negative effects on the environment and human health. It is considered to be the most potent greenhouse gas with a global warming potential (GWP) which is far higher than that of CO2. F-gases are also known as ‘forever chemicals’ because once they enter the atmosphere, they remain there for up to three thousand years. There are strict regulations regarding the reporting, handling, and recycling of SF6. In addition, there are higher maintenance costs and special safety measures which users are obliged to take on.
Blue portfolio (how Siemens Energy brands the product line using clean air)
The Blue portfolio comprises SF6-free high-voltage switching products that use clean air as an insulation alternative and vacuum interruption technology for switching. The switchgear factory in Berlin also manufactures vacuum interrupters, the most important part of the portfolio.
Clean air is a mixture of 20% oxygen and 80% nitrogen, which can be released into the atmosphere without any harmful effects. The benefits of using clean air instead of SF6 are enormous. As well as having a GWP below 1, clean air has zero harmful effect on human health and safety. There are no reporting regulations or legislation to follow. No compromises have been made in terms of performance and reliability. Maintenance and operational costs are massively reduced since there are no special safety requirements for gas handling, as there are with SF6. Overall, the system is future-proof.
ASM 340 by Pfeiffer
The ASM 340 is the leak detector of choice due to its multipurpose features such as its high pumping speed and wide range of applications. Used for both qualitative and quantitative measurements, the device has versatile operation modes, allowing the user to choose between sniffing and vacuum testing.
These are the two common methods for detecting leaks, differing primarily in the flow direction of the tracer gas such as helium or hydrogen. The sniffing method involves pressurizing the parts being tested with tracer gas and using a sniffer probe. The probe is used to detect the escaping gas from a potential leak on the outer surface and to identify the location of the leak. The vacuum testing method, on the other hand, involves evacuating the air inside the test part and spraying the surface with tracer gas. The leak detector is then able to measure the gas flow of the tracer gas through a potential leak into the vacuum inside the component.
