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Straight into the future: inclination sensors in hydrogen transportation

The use of hydrogen as an energy carrier plays a decisive role in the transformation to a more sustainable energy future. Hydrogen transportation and storage are key components of this value chain. Safety and efficiency are key requirements here. High-precision inclination sensors can be a key technology for meeting these requirements, as they can significantly improve the monitoring and control of transportation processes.

Why does the inclination have to be monitored during hydrogen transportation?

On a chemical and physical level, there are special features that can lead to major problems if handled incorrectly.

  • Hydrogen, for example, is the lightest and smallest element in the periodic table. Due to its low density and high diffusion rate, hydrogen can escape through small openings and pores, increasing the risk of leaks. In the case of inclinations, these can potentially increase, especially if the hydrogen is present in liquid form.
  • In addition, liquid hydrogen is stored and transported at extremely low temperatures (approx. -253 °C). These temperatures require special materials and insulation to minimize evaporation and energy loss. A slope can affect the temperature distribution within the tank, contributing to uneven thermal stresses and potentially the formation of cracks or leaks.
  • The very low boiling point of -252.9 °C poses a further danger in closed containers. Even a small amount of heat can cause the hydrogen to vaporize. If the transport container is tilted, the liquid phase can separate from the gaseous phase, which favors an uneven pressure build-up, which in turn could lead to a failure of the seals or safety valves.
  • The high chemical reactivity also presents design engineers with challenges. In the presence of catalysts, hydrogen embrittlement can occur, causing adjacent metals to lose their ductility. An inclination can also increase mechanical stresses and deformations in the materials, which together increase the likelihood of cracks and fractures in the transport containers.
  • Hydrogen belongs to the group of highly flammable substances and forms explosive mixtures with air in a concentration range of 4 to 75 percent by volume. Local concentrations that lie within the explosion range could be achieved by a tilt. A spark or static discharge could then trigger an explosion.

Inclination sensors of the KAS4000 series

These points impressively underline the need for precise monitoring and control of tilt angles in hydrogen transportation. Suitable sensors are widely available and differ in many ways. In general, however, it can be said that inclination sensors by definition measure the angle of an object relative to gravity. They often work on the basis of MEMS (Micro-Electro-Mechanical Systems) and are highly precise. As a rule, they consist of a sensor element that reacts to changes in inclination and an electronic evaluation unit that processes and forwards the signals.

One example of this is the new KAS4000 series from Swiss manufacturer KELAG Künzli, distributed by the sensor specialists at a.b.jödden in Krefeld.

This model series has the typical features of its predecessors and adds some functions that can play an important role in the transportation sector.

Figure 1 Innovative three-layer structure of the KAS4000 series

The biaxial inclination and acceleration sensors measure statically (inclination) and dynamically (acceleration). The angle measurement is sine compensated. A high repeat accuracy of 0.01 % and the high long-term stability of 0.03 %/a are the result of a new, unique technology:

The sensors are based on an advanced, three-layer “Micro Machined” technology. This three-dimensional structure is hermetically sealed with glass inserts. This complex design results in a long-term stable, high-resolution and shock-resistant sensor. Gas damping reduces vibrations and prevents overshooting and disruptive resonance vibrations.

The integration of inclination sensors in hydrogen transportation requires the fulfillment of specific requirements:

  • Precision and sensitivity: Sensors must be extremely precise and sensitive in order to reliably detect even the smallest changes in inclination.
  • Robustness and reliability: As the sensors are operated in challenging environments, they must be robust and reliable against vibrations, temperature fluctuations and mechanical loads.
  • Safety standards: The sensors must comply with the strict safety and explosion protection requirements of the hydrogen transportation industry.

Precise, reliable measurements are easily possible with this type of sensor technology. But the safety aspect can also be served:

The entire structure is fully encapsulated in a housing made of solid, impact-resistant POM (polyoxymethylene), the M8 connector is closed. This means that the design already achieves protection class IP68, and if an explosion protection class is required, additional, correspondingly certified housings can be used. These are also available with optical apertures. This means that the latest Quality of Life feature of the KAS4000 series can also be used:

An included infrared interface enables adjustment and calibration without removal. This means that the maximum measurable inclination angle of ± 90° can be reduced precisely to the corresponding application. This also increases accuracy. This technology can also be used to set up the system at the factory at any time.

Figure 2 KAS4000

Conclusion

High-precision tilt sensors are an indispensable tool in the hydrogen transportation industry, helping to ensure safe and efficient transportation. The continuous improvement and integration of these technologies will be crucial to meet the growing demands and safety standards in the hydrogen economy. Through investment in research and development and collaboration between industry and academia, these challenges can be overcome and the benefits of hydrogen as a sustainable energy carrier can be fully realized.

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