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In the rapidly evolving landscape of hydrogen technology, pressure sensors play a pivotal role in ensuring the safety and efficiency of hydrogen transportation and storage. As the demand for hydrogen as a clean energy source grows, so does the need for advanced sensor technology that can accurately monitor and control hydrogen pressure in various applications.
Ashcroft, in partnership with our parent company Nagano Keiki Co. LTD, has been designing advanced pressure sensors for the hydrogen market for 20 years. This extensive experience has resulted in several technology patents from Nagano Keiki, which enhance our ability to provide sensors specifically engineered with the right metallurgy for high-pressure applications.
This puts Ashcroft in a unique position to guide our customers through the process of selecting the best types of pressure sensors for complex hydrogen systems. Read this article to explore key design challenges for pressure sensors used in hydrogen transportation, distribution and storage, as well as onboard engine applications. We will also review recent advancements that can enhance the safety and efficiency of your hydrogen applications.
Pressure sensor challenges in hydrogen systems
Hydrogen is a small and highly reactive molecule that can degrade materials used in pressure sensors. Two critical challenges that sensor designers encounter are hydrogen embrittlement and hydrogen permeation, both of which significantly impact material integrity and performance.
- Hydrogen embrittlement. This phenomenon is also known as hydrogen-induced cracking, which reduces the material's ductility and strength. Hydrogen's small size allows it to penetrate metal flaws, form new molecules, and apply pressure, causing cracking and brittle failures at stress levels below the material's yield strength.
- Hydrogen permeation. Permeation occurs when the H2 molecule breaks down into smaller H+ ions, which can penetrate the diaphragm’s metal lattice structure. These ions recombine in the fill fluid to form H2 molecules, creating hydrogen bubbles that lead to Zero and Span shifts.
For these reasons and others, pressure sensors used in hydrogen applications must be made from materials that can withstand prolonged exposure to hydrogen without degrading.
Figure 1. Hydrogen embrittlement example.
Figure 2. Hydrogen permeation example.
High-pressure conditions in hydrogen applications
Hydrogen systems frequently function under extremely high-pressure conditions, often reaching around 700 bar (10,000 psi) in applications such as fuel cell vehicles. This high-pressure environment is a critical aspect of hydrogen technology because it enables the efficient storage and transport of hydrogen gas, which is essential for its use as a clean energy source.
The ability to maintain appropriate pressure levels is crucial for the performance and reliability of hydrogen-powered systems, and it presents unique challenges in terms of material integrity and system safety.
Gas leaks, temperature spikes from rapid refueling, and hydrogen embrittlement in storage materials are some of the common risks associated with hydrogen. Extensive research has been conducted to identify advanced materials and strategies to reduce the risk of these safety hazards, particularly in hydrogen refueling stations and energy storage applications.
Pressure sensor advancements for hydrogen applications
316L stainless steel is commonly employed in high-pressure hydrogen applications; however, it is not an extremely strong material. A pressure sensor requires a diaphragm that must flex with exceptional precision and in applications above 5,000 psi, a material stronger and more resilient than 316L stainless steel material directly provides an improvement in accuracy and long-term performance. Advances in material science have led to the development of high-pressure hydrogen-resistant alloys and composites and extensive testing led Nagano Keiki to a superalloy called Alloy 286 (A286).
A286 is a highly corrosion-resistant, iron-based superalloy (and is classified as an austenitic stainless steel). The International Journal of Hydrogen Energy found that A286 is less mechanically affected by hydrogen and is known to minimize the risk of hydrogen embrittlement and permeation. This makes it very suitable for hydrogen systems with extremely high pressures exceeding 700 bar.
Further research by Sandia National Laboratory found that A286 alloy in the aged condition (as utilized by Ashcroft) maintains exceptional resilience to hydrogen embrittlement. As we continue to use materials like A286 and implement safety protocols for pressure instruments, hydrogen's energy potential may soon be accessible for everyday applications.
Hydrogen applications for pressure sensors made with A286
The U.S. Department of Energy considers hydrogen storage technologies essential in facilitating the adoption of fuel cells across different sectors, including transportation and stationary power solutions, among others.
- Storage tanks: Monitoring pressure in large, high-pressure storage tanks (350–700 bar or 5,000–10,000 psi)
- Fuel cell systems: Monitoring pressure in hydrogen fuel cell stacks and supply lines
- Refueling stations: Monitoring pressure at distribution stations
- Liquid Storage: Requires cryogenic conditions; hydrogen boils at −252.8 °C at atmospheric pressure
Pressure sensors with superior material and accuracy
Nagano Keiki's in-house testing confirmed the research findings described above and created several technology patents for the development of Ashcroft pressure sensors for high-pressure applications. We found that pressure sensors providing the greatest advantages for hydrogen systems are those that use A286 material for pressure resistance (up to 700 bar) and intelligent Chemical Vapor Deposition (CVD) technology for reliability, high accuracy and repeatability.
One example is the Ashcroft® E2F Explosion-Proof Pressure Transducer. Using proven CVD thin film sensor technology, this instrument is manufactured to Ashcroft's TruAccuracy™ terminal point standard. This simple standard ensures reliable and repeatable measurements, eliminates any confusion caused by statistically derived accuracy specifications and requires no additional calibration at the time of installation.
Ashcroft offers the A286 diaphragm with other pressure sensor models for applications within the hydrogen sector. Visit the Hydrogen page on our website to learn more.
Ready to learn more about pressure sensors for hydrogen applications?
The development of pressure sensor technology is critical for the safe and efficient operation of hydrogen systems. By addressing the inherent challenges and leveraging recent technological advancements, Ashcroft continues to produce sensors that meet the challenging demands of your hydrogen applications. As research continues and technology progresses, we can expect further improvements in sensor technology that will continue to push the boundaries of what is possible in hydrogen safety and efficiency.
To learn more, check out some of our other related articles:
- How Are Pressure Transducers Affected by Hydrogen Permeation?
- Choosing Pressure Transducers for Hazardous Locations
- What is CVD Technology?
For personalized assistance, feel free to reach out directly to one of our experts. In the meantime, download our hydrogen guide to understand the applications, hazards and considerations for selecting the right instruments for hydrogen systems.
