Hydrogen Check Valves

Imagine installing just any check valve in a hydrogen circuit. At first, everything seems to work fine — but over time, internal materials begin to degrade, and gas starts leaking. The result? A serious safety and performance issue caused by choosing the wrong valve. Hydrogen doesn’t forgive mistakes: its nature can compromise components that would otherwise perform well with other fluids.

That’s why, if you’re working with this gas, you need a hydrogen check valve — a valve specifically designed to withstand its unique demands. Not just any valve will do.

Hydrogen is an extremely light, reactive, and flammable gas. It can slip through the tiniest gaps and cause embrittlement in unsuitable metals (known as hydrogen embrittlement). A small selection error can lead to leaks, failures, and even major risks in an H₂ installation. In the current boom of the hydrogen economy, paying attention to every detail is essential to avoid costly surprises.

The solution? Use check valves for hydrogen — designed and engineered specifically for this application. In this article, we’ll explain what a check valve is, how it works, how it’s applied in hydrogen circuits, and, most importantly, why a standard check valve is not suitable for hydrogen. This way, you’ll avoid mistakes and ensure you’re always choosing the right solution for your H₂ projects.

Let’s take it step by step.
Don’t try to run before you can walk.

Before we dive into materials, geometries, or standards, it’s essential to understand exactly what a check valve is and how it works — and above all, why not every valve is fit for hydrogen.

Here’s a short video where we explain it using real examples (duration: ~3 minutes). If you have a moment, it’ll all become crystal clear: Video: Hydrogen check valve.
(English subtitles available.)

What is a check valve?

A check valve (also known as a non-return valve) is a component that allows fluid to flow in only one direction and prevents backflow. It has no actuator and is not operated manually — it works automatically.

When the fluid reaches a certain pressure (known as the cracking pressure), the valve opens. As soon as the flow stops or tries to reverse, the poppet immediately closes, blocking any return. In a hydrogen system, this function is especially critical to prevent gas from flowing back into sensitive equipment or unwanted areas, avoiding potential leaks or hazardous mixtures.

At Redfluid, we manufacture piston-type check valves, such as the Compact, Vertic, and High-Pressure series — each suitable for different pressure ranges. They are ideal for high-pressure systems and tight spaces. All our models are designed with a reduced bore and optimized for applications where reliability and compactness are key. For instance, our Compact series is widely used in medium-pressure hydrogen applications (up to PN 248 bar), thanks to its robust and proven design.

Why is a hydrogen-specific version necessary?

Because hydrogen, although it may seem like just another gas, follows its own rules. It’s extremely light, highly reactive, flammable, and can degrade internal materials if not properly selected. Using a generic check valve might seem acceptable, but with H₂, there’s zero margin for error. You need a hydrogen check valve specifically designed to withstand its unique challenges.

At Redfluid, we’ve been supplying our Compact series hydrogen-optimized check valve for years, with excellent results in real-world installations. While it may look similar to a standard valve used for air or inert gases, internally it’s a custom design engineered for hydrogen service — same dimensions, different heart.

Externally, a standard check valve and a hydrogen-compatible one might appear identical. But on the inside, the differences are crucial. Let’s take a look at what makes them truly different.

What have we changed in our hydrogen check valve?

Redfluid’s hydrogen check valve includes several key internal modifications compared to a standard check valve:

• Optimized piston geometry: The internal shape of the piston (poppet) has been redesigned to suit the behavior of hydrogen. This allows for a more precise sealing and a faster valve response under demanding operating conditions — even with a gas as light as hydrogen.
• Leak-proof sealing system: Instead of a conventional O-ring, we use flat compression seals (anti-extrusion or “anti-blowout” design). This type of seal offers much more reliable tightness, especially in hydrogen applications, where the gas tends to escape through even the smallest imperfections.
• Materials resistant to hydrogen embrittlement: The internal spring — which defines the cracking pressure — is not made of standard stainless steel 302 (commonly used in generic valves), as this material can become brittle over time when exposed to hydrogen. Instead, we use a specially selected stainless steel (e.g., AISI 316 certified to NACE MR0175) that offers much higher resistance to hydrogen embrittlement. Likewise, the valve body and all internal components are made from high-quality stainless steel (SS316) compatible with hydrogen, and the sealing elements are made from FKM (Viton) or other elastomers rated for H₂ service.
• Certified for explosive atmospheres (ATEX): Our hydrogen-specific version is ATEX certified, making it fully suitable for installation in classified hazardous areas or explosive environments. This provides an extra layer of safety when handling a flammable gas like hydrogen.

Would you like to explore all the available versions and configurations?
You can download the complete Redfluid hydrogen check valve catalog here:

Need a custom solution? We tailor it for you

At Redfluid, we adapt every valve to your real working conditions. We understand that hydrogen projects often require specific adjustments, which is why we offer multiple customization options:

• Custom cracking pressure: We calibrate the cracking pressure based on your needs. Just let us know the required value — and most importantly — specify that the valve is for hydrogen service. This is crucial, as it determines the selection of the spring, seals, and other internal components to ensure optimal performance with H₂.
• Tailored connections: Our standard designs use BSP and NPT threads, but if you need something different — such as flanged, metric, or special connections — we can manufacture it without issue. We adapt to your installation’s connection standards to ensure the valve fits perfectly.
• Application-specific design (not fire-safe): Please note that this hydrogen check valve is not fire-safe. It’s not intended to stop fire propagation or withstand prolonged extreme temperatures. Its purpose is clear and specific: to ensure non-return of the fluid, even under critical pressure conditions — but not to act as an emergency shut-off in fire scenarios.

Do you have questions or are you designing a hydrogen system?

We know that working with hydrogen is no easy task. And while check valves may seem like simple components, in critical applications, every detail matters: the type of seal, the spring material, the cracking pressure, or even a properly matched connection can mean the difference between a safe system and a problematic one.

If you’re working on a hydrogen project — or simply want to ensure you’re selecting the right hydrogen check valve — don’t hesitate to reach out. You can contact us directly through our contact form or give us a call.

We’ll be happy to help you find the optimal solution to ensure your hydrogen system operates safely, reliably, and without compromise.