Why Pressure Sensors Are Needed For Hydrogen Measurement

As the market for hydrogen fuel cell powered vehicles and equipment continues to grow, so does the need for hydrogen compatible pressure sensors to safely monitor common uses such as dispensing and high pressure storage.

Hydrogen is commonly used as an alternative fuel source in:

  • Forklifts & lift trucks
  • Power generation
  • Commercial vehicles (buses, trucks, etc.)
  • Automobiles

 

Hydrogen gas presents difficulties when it comes to pressure sensors that needs to be considered when selecting the correct sensor configuration. Two of the most common sensor concerns in Hydrogen applications are hydrogen embrittlement and hydrogen permeation.

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

Hydrogen embrittlement is the degradation of the mechanical properties of the sensor diaphragms metal resulting from direct contact with hydrogen. Correct material selection is ideal in combating hydrogen embrittlement. Common sensor materials such as 17-4 stainless steel and nickel-based alloys such as Inconel 718 should be avoided.

Core Sensors has a complete line of pressure sensors, transducers and transmitters designed to overcome these complications and provide a high quality/long life solution for your hydrogen application.

DESIGN/MATERIAL SELECTION

Fluid filled sensor diaphragms are highly susceptible to hydrogen permeation and should be avoided. Hydrogen ions that pass through the thin diaphragm will form hydrogen bubbles in the fill fluid causing zero and span shifts. Over time these bubbles can expand and cause the diaphragm to bulge and eventually fail, resulting in the fill fluid leaking and contaminating the process.

Core Sensors utilizes 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 contains the hydrogen within the pressure port and reduces the possibility of the media permeating the thin diaphragms that are common in oil filled sensor designs.

HIGH PRESSURE HYDROGEN MEASUREMENT

Hydrogen is compressed to a high pressure, typically 350 Bar (~5,000 PSI) and 700 Bar (~10,000 PSI), to help increase the amount of hydrogen that can be stored on site. Highly reliable pressure sensors are required to safely monitor these tanks and other high pressure hydrogen applications. Core Sensors offers 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 to ensure protection from embrittlement and permeation, resulting in a long term monitoring solution.

INDUSTRIAL APPLICATIONS

For industrial applications where hazardous certification approvals are not required, the CS10 Industrial Pressure Transducer can be packaged to meet the demands of hydrogen environments. Pressure ranges are available from 50 PSI up to 20,000 PSI in solid 316L SS. Customers have the choice of various output signals including 4-20mA loop powered for long distance transmissions and voltage outputs for low power and low current consumption applications. A variety of electrical connections are available from standard DIN connections to M12x1 and integral cable for a higher IP67 rating. Custom configurations are available for OEM projects.

HAZARDOUS – NON-INCENDIVE

For hydrogen applications requiring non-incendive approved equipment, the CS50 Non-Incendive Pressure Transducer is recommended. This sensor line can be configured with all solid 316L stainless steel material and 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

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