What is a hydrogen high pressure solenoid valve?
20.11.2023 We as Eugen Seitz AG produce high pressure solenoid valves for hydrogen – our HyValves. But what exactly is a solenoid valve? How does it work? What are the application areas of a hydrogen solenoid valve? Let us give you the answers.
To control the flow of hydrogen gas a high pressure solenoid valve is used. Solenoid valves operate electromechanically. The solenoid generates a magnetic field that moves a plunger inside the valve, which opens or closes the valve allowing hydrogen to flow through or blocking it. Due to the compact design of a solenoid valve, it is commonly used in systems that require precise control of the fluid's flow. Our HyValves are especially great for applications that depend on fast and safe switching, low energy consumption, high reliability, and good medium compatibility. Therefore, they are ideally used for hydrogen-based industrial and automotive applications, for example hydrogen refueling stations.
How does a high pressure solenoid valve work?
There are two main types of working principles commonly used for hydrogen applications, direct-acting and pilot-operated. The main difference between those two is that pilot-operated valves employ the use of the process fluid to assist in the opening and the closing of the valve along with the magnetic field, whereas direct-acting valves rely only on the magnetic force from the solenoid to open or closed the orifice.
SeitzValve offers products for both categories. Check out our Products.
- Direct acting: A direct-acting solenoid valve generates an electromagnetic force by passing an electric current through a solenoid coil. The solenoid coil is wound around a movable plunger within the valve. When an electric current passes through the solenoid coil, the solenoid valve is activated, and a magnetic field is created that pulls a piston or plunger into the solenoid. The plunger's movement opens or closes the valve, allowing or preventing the flow of hydrogen gas through the valve. A spring returns the valve to its original position when the solenoid is de-energized. An example of such a valve is our HyValve 1000 DN0.5.
- Pilot operated: Unlike a direct-acting solenoid valve, a pilot-operated solenoid valve, controls the flow of fluid through the main valve by using a small auxiliary valve (the “pilot valve”). When the solenoid is activated, it opens the pilot valve, allowing a little amount of fluid to enter the main valve. This causes the change in system line pressure which opens the primary valve, allowing fluid to flow through. When the solenoid is de-energized, the pilot valve closes, causing the main valve to close and cease the flow of fluid. An example of such a valve is our HyValve 1000 DN6.
What are the application areas of our solenoid valves?
Hydrogen gas pressure solenoid valves are used in a wide range of industrial and automotive applications. It is mainly used where precise control over the flow of a fluid (liquid or gas) is required. This includes hydrogen refueling stations. Our hydrogen high pressure valves are installed in stations all around the world. They allow or stop the flow of hydrogen and generate therefore a great refueling experience.
What are the critical KPIs for hydrogen solenoid valves?
The performance criteria of a hydrogen gas pressure solenoid valve vary depending on the specific application and requirements. However, following six key performance indicators (KPIs) are commonly used to evaluate the performance of these valves:
- Orifice size: The size of the valve opening that controls the flow of hydrogen, typically measured in millimetres or inches.
- Maximum allowable working pressure: The highest pressure the valve can withstand while still maintaining a safe and reliable operation.
- Mass flow coefficient: A measure of the valve's ability to control the flow of hydrogen.
- Pressure drop: The difference in pressure between the inlet and outlet of the valve, measured in bars or pounds per square inch.
- Internal and external valve leakage: The amount of hydrogen that leaks through the valve, measured in cubic centimetres per minute or cubic feet per hour.
- Lifetime (number of cycles): The number of times the valve can be opened and closed before it needs to be replaced, typically measured in millions of cycles.
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What are the Key technical parameters for hydrogen solenoid valves?
Seven technical parameters are required to ensure that the used high pressure solenoid valve is appropriate for the specific application:
- Type of fluid to be controlled: The type of fluid, whether it is a liquid or gas, and its properties, such as viscosity and density, will affect the performance of the solenoid valve.
- Temperature range of fluid: The range of temperatures at which the fluid will be flowing through the solenoid valve, as this can affect the valve's performance and durability.
- Temperature range of environment: The range of temperatures in the environment in which the solenoid valve will be installed, as this can also affect the valve's performance and durability.
- Minimum and maximum flow required: The range of flow rates that the solenoid valve will need to handle.
- Minimum and maximum inlet pressure: The range of inlet pressures that the solenoid valve will need to handle.
- Minimum and maximum outlet pressure: The range of outlet pressures that the solenoid valve will need to maintain.
- Inlet and outlet pipeline size: The size of the inlet and outlet pipelines, as it will affect the flow rate and pressure drop through the solenoid valve.
What is the importance of the right material?
Hydrogen gas poses two specific difficulties. Due to its small size, hydrogen can diffuse rapidly into or through most materials, which can cause leaks or other problems. Hydrogen is also known to affect some materials by increasing their brittleness, a phenomenon known as hydrogen embrittlement. This can cause the valve to become fragile and more prone to failure. Therefore, the right choice of the material – metal and polymer - is of high importance.
The valve body and other components must be made of materials that are resistant to hydrogen diffusion and hydrogen embrittlement. Seitz' valves are made of stainless steel (1.4404 or 1.4435). On top of that the polymer used in the valve construction is approved against explosive decompression.
All our used materials for hydrogen solenoid valves meet other important requirements, such as high-pressure resistance, temperature resistance and corrosion resistance. The valve should be able to withstand the conditions of the application, both in terms of pressure, temperature, and chemical exposure.
What testing conditions and procedures does it need for hydrogen solenoid valves?
When producing high pressure solenoid valves for hydrogen applications, we ensure that various testing have been performed on each individual valve according to the latest release of ISO 19880-3. This standard specifies the testing procedures and acceptance criteria for high-pressure valves used in hydrogen systems.
The standard covers various aspects of valve performance, including pressure and leak testing, flow testing, and endurance testing. Pressure testing is done to ensure that the valve can withstand the maximum allowable working pressure without any leakage or damage. The leak testing is done to check for any internal or external leakage of hydrogen. Flow testing is done to check if the valve can control the flow of hydrogen according to the specified flow rate. Endurance testing is done to check the life cycle of the valve.
Additionally, the solenoid valves for hydrogen are tested to environmental circumstances, such as vibration and temperature, to ensure that they can withstand the conditions of the intended application.
What are necessary safety parameters?
Hydrogen has certain characteristics that lead to challenges with the gas. It is a colourless and odourless gas that evaporates very easily and is also extremely flammable. Therefore, our hydrogen solenoid valves comply with the ATEX directive 2014/34/EU for category 2 equipment. This directive sets safety requirements for equipment used in potentially explosive atmospheres, including hydrogen.
Globally, IECEx in combination with country-specific directives certifies the use of our high pressure valves within hydrogen refueling stations. The IECEx system provides certification of equipment and service facilities for use in explosive atmospheres, including hydrogen. In addition to compliance with these directives, it is important to ensure that the HyValves are installed and maintained according to our instructions. This involves correct valve handling and storage, as well as frequent checks to ensure they are in good operating order.
Our HyValve products are certified with:
- CE
- EX (ATEX)
- IECEx
- CCC
- KCs
This article is based on our FAQ together with HyFindr.
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