Hyfindr Tech Talk #44 - Hydrogen On Tank Valves - Hydrogen Components Testing Machine

In this episode of Hyfindr Tech Talk, we take a deep dive into the engineering behind on-tank valves for hydrogen vehicles. Host Steven Oji is joined by Burkhard Harhoff, Director of Technology for the Hydrogen Portfolio at Poppe + Potthoff, to explore what makes these components safe, certifiable, and ready for the high pressures found in hydrogen mobility.

From internal components like solenoids and filters to thermal safety features and global regulations, this conversation demystifies what’s inside the valves that control 700 bar hydrogen tanks—and why they’re critical to fuel cell and combustion-based hydrogen mobility.

Learn About On-Tank Valves for Hydrogen Systems

Hydrogen tanks store energy at extremely high pressures, often up to 700 bar ,and the on-tank valve is the interface that connects that energy to fuel cells or engines. Burkhard explains what goes into designing a component that’s safe, certifiable, and high-performing under such demanding conditions.

Key Topics Discussed in the Tech Talk

What Is an On-Tank Valve and Where Is It Used?

The on-tank valve sits on top of hydrogen tanks in vehicles and acts as the control hub for filling, defueling, pressure regulation, and safety systems. These valves are used in:

• Hydrogen-powered fuel cell electric vehicles (FCEVs)

• Hydrogen combustion engines

• Stationary storage systems

• High-pressure hydrogen refueling stations

Valve Anatomy: Inside the On-Tank Valve

Burkhard walks through an exploded view of a 700 bar on-tank valve, identifying components such as:

• Aluminum body

• Solenoid valve (electrically controlled shut-off)

• Manual shut-off and bleed valves

• Check valves and in/out ports

• Temperature sensor

• TPRD (Thermal Pressure Relief Device)

Each part serves a purpose—whether it’s controlling flow, regulating pressure, or ensuring thermal safety under extreme operating conditions.

Thermal Safety: How Hydrogen Expands and Heats

Unlike most gases, hydrogen heats up when it expands. That creates a potential risk in type IV hydrogen tanks, which are made of carbon fiber and plastic composites. If the expansion generates too much heat, it can damage the tank wall.

To counter this, the valve includes a nozzle system that splits hydrogen flow into multiple streams, reducing heat concentration and protecting the tank structure.

Leak Prevention and Robust Filtering

Clean hydrogen is essential to safe operation. Even trace particles can damage valves or clog filters. That’s why the valve contains:

• Multiple fine filters before solenoid and manual valves

• Check valves to prevent backflow

• Dual flow paths for refueling and defueling

Hydrogen flows through separate, secure routes during filling and operation, maintaining performance and avoiding contamination or leakage.

Certification and Standards: What Regulations Apply?

Burkhard details how on-tank valves must meet strict international regulations depending on geography and use case:

• ISO 11114, ISO 19887, and CHMC 1 for material testing

• HGV 3.1, R134, and others for component performance

• TÜV SÜD and other agencies for third-party certification

• National standards like GB/T (China) or Korean equivalents

He also highlights the challenge of fragmented regulations and the industry’s push toward unified global standards to simplify development and compliance.

Performance Specs: Pressure, Kv Value, and Compactness

Important specs to consider when selecting a valve include:

• Pressure rating (350 to 700 bar depending on application)

• Kv value (flow coefficient for refueling and defueling speed)

• Form factor (valves must fit within tight packaging constraints)

Burkhard shares how Poppe + Potthoff achieves a compact height of just 38 mm, critical in vehicle design where space and efficiency are at a premium.

Thermal Pressure Relief Device (TPRD): Safety Under Fire

The TPRD is a built-in safety mechanism that vents hydrogen if the system exceeds 110°C. It works via:

• Glass bulb rupture (triggered by overheating)

• Fused metal options (alternative construction)

• Direct path to external vent for safe hydrogen evacuation

This ensures that even in extreme scenarios like fires, the hydrogen tank does not become a hazard.

In-House Testing and Pressure Simulation

Poppe + Potthoff develops its own high-pressure test benches, capable of simulating:

• Burst pressure tests

• Fatigue cycling (e.g., 0–1000 bar sinus profiles)

• Extreme temperature validation (–60°C to +110°C)

These custom tests go beyond current regulations, anticipating real-world environmental challenges like cold-start conditions in extreme climates.

Future Trends in Hydrogen Valve Design

Burkhard closes by discussing future trends in valve architecture:

• Function integration: Combining safety, flow control, and sensors into single components

• Simplified designs: Reducing complexity while enhancing reliability

• Wider operating range: Designing for more extreme temperatures and pressures

• Cost efficiency: Balancing robustness and affordability for scaling hydrogen transport

He also points to ongoing industry efforts to consolidate global standards, which will make valve development more efficient and cost-effective for OEMs worldwide.

Conclusion: Why On-Tank Valves Are Core to Hydrogen Safety

This Hyfindr Tech Talk gives a rare behind-the-scenes look into a critical hydrogen system component. Whether you’re an engineer, OEM, or hydrogen infrastructure developer, understanding on-tank valves is key to delivering safe, scalable, and certifiable hydrogen mobility solutions.

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