Hydrogen Pressure Measurement

• As the market for hydrogen fuel cell vehicles and equipment grows, so does the need for hydrogen compatible pressure sensors.
• Accurate and reliable hydrogen pressure measurement is essential to safely monitor common uses such as dispensing and high pressure storage.
• We offer a range of pressure instrumentation with the correct wetted materials type, which prevents pressure sensors from facing hydrogen permeation and embrittlement.

Hydrogen gas presents difficulties when it comes to pressure sensors. This needs careful consideration when selecting the best sensor configuration for hydrogen pressure measurement applications. Two of the most common concerns for pressure sensors in hydrogen pressure measurement applications are hydrogen embrittlement and hydrogen permeation.

Hydrogen is a common renewable fuel source for:

• forklifts & lift trucks
• power generation
• commercial vehicles (buses, trucks, etc.)
• automobiles

Hydrogen Permeation and Hydrogen Embrittlement

Hydrogen permeation occurs when hydrogen atoms (H2) split into two separate hydrogen ions (H⁺). This separation occurs under specific process conditions, most commonly when under high pressure and high temperature. These hydrogen ions are small enough to pass through the molecular structure of a sensor’s thin metal diaphragm.

Hydrogen embrittlement is the degradation of the mechanical properties of the metal in the sensor diaphragms as a result from direct contact with hydrogen. So, the correct material selection is necessary in combating hydrogen embrittlement. Due to hydrogen embrittlement, users should avoid certain common sensor materials. For example, 17-4 stainless steel and nickel-based alloys like Inconel 718 are not good choices for hydrogen applications. To learn more about wetted materials choices, you can read our article here: psctexas.com/wetted-materials-options-for-pressure-sensors/.

We offer a complete line of pressure sensors, transducers, and transmitters that are able to overcome these complications. Moreover, our pressure solutions from Core Sensors, provide a high-quality and long-life solution for many hydrogen pressure measurement applications.

Design and Material Selection for Hydrogen Pressure Measurement Applications

Users should avoid fluid-filled sensor diaphragms since they are highly susceptible to hydrogen permeation. Hydrogen ions that pass through the thin diaphragm will form hydrogen bubbles in the fill-fluid, which can cause zero and span shifts. Over time, these bubbles can expand and cause the diaphragm to bulge and eventually fail. As a result, the fill fluid will leak and potentially contaminate the process.

Our pressure transducers utilize a solid piece of 316L stainless steel, which is free of fluid filled cavities, sealing materials such as o-rings, and weld joints. This solid piece of stainless steel is able to contain the hydrogen within the pressure port. Therefore, this design reduces the possibility of the media permeating the thin diaphragms that are common in oil-filled sensor designs.

High Pressure Hydrogen Measurement

Hydrogen as a fuel needs to be a high pressure – typically 350 Bar (~5,000 PSI) and 700 Bar (~10,000 PSI). This is because compression of hydrogen helps increase the amount of hydrogen that can be in storage on site, in tanks, etc. So, highly reliable hydrogen pressure measurement is necessary to safely monitor these tanks and other high pressure hydrogen applications.

Additionally, we offer an F250C female autoclave process connection option for pressures 10,000 PSI and above. This process connection features all 304 and 316L stainless steel wetted parts. In effect, this ensures protection from embrittlement and permeation, resulting in a long term monitoring solution.

Industrial Applications that Require Hydrogen Pressure Measurement

For industrial applications where hazardous certification approvals are not necessary, the CS10 Industrial Pressure Transducer can meet the demands of hydrogen pressure measurement applications. Pressure ranges are available from 50 to 20,000 PSI in solid 316L SS. There are also a variety of electrical connections available, from standard DIN connections to M12x1 and integral cable for a higher IP67 rating. Custom configurations are available for OEM projects. Additionally, customers can choose various output signals including:

• 4-20mA loop power for long distance transmissions
• voltage outputs for low power and low current consumption applications

Hazardous Area Approval for Non-Incendive Applications

The CS50 Non-Incendive Pressure Transducer is ideal for hydrogen pressure measurement applications requiring pressure sensor with non-incendive approval. This sensor line can have an all solid 316L stainless steel body with a variety of configurable options. Hazardous approvals include:

• CSA Class I, Division 2, Groups A, B, C, D T4
• ANSI/UL 122701 Single Seal
• ABS (American Bureau of Shipping)
• CE

Common Model Number Configurations

We are able to customize pressure sensor configurations to best fit your application and installation requirements. Below is a list of common model numbers and the typical use in hydrogen fuel cell applications: