Hydrogen Valve
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What is a hydrogen valve?
Hydrogen valves are critical safety components used in various hydrogen applications. A hydrogen valve controls the flow of hydrogen (liquid/gas) within the system and thus shuts down the system in case of emergency or leakage. Hydrogen valve design must accommodate the extreme operational conditions, such as high pressure, very low temperatures, and sometimes excessive vibrations, which a hydrogen valve is subjected to. This places an emphasis on the reliability and performance criteria of the valves. At the same time, the valves must also comply with safety requirements during the entire expected lifetime.
Therefore, selecting the correct valve depending on the requirement and application is essential for a safe and stable operation of all kinds of hydrogen systems.
Which type of hydrogen valves exist?
There are different kinds of hydrogen valves available in the market for various applications.
a) Hydrogen needle valve
Hydrogen needle valves are used to regulate the flow of hydrogen in either gas or liquid form through an appliance or system. They are used for accurate flow rate control. The reason it is called a needle valve is because the valve contains a small internal plunger on one end resembling the shape of a needle. This part is within the machinery or the pipeline and cannot be seen. On the other end of the plunger, there is a handle, called the handwheel, for easy and precise rotation of the valve.
In the closed state, the plunger fits exactly into the seat, which is a part of the appliance that is being regulated. However, when the valve is rotated, the gap between the plunger and the seat widens. This allows the substance to pass through the needle valve. You can regulate the needle valve manually or automatically by using a variety of actuators. Controlling the needle valve through an automated device assists in the optimal operation of the valve for the system.
b) Hydrogen ball valve
Hydrogen ball valves are usually shut-off valves that control the fluid flow through the system by means of a rotary ball. The rotary ball is designed with a hole or bore in the center that either allows or blocks the flow of fluid. The ball is mounted against two seats and has a shaft that connects it to the control mechanism that rotates the ball. Thus, the ball valve can be manually or automatically controlled.
In the open state, the control lever arm, which is connected to the ball, is parallel to the pipe and the fluid can flow through the system. When the control lever arm is rotated by a quarter turn (90 degrees), it is moved perpendicular to the pipe and the valve is in the closed state. Ball valves can have multiple ports, which are the openings in the valve. This depends on the application.
c) Hydrogen check valve
Hydrogen check valves are one-way valves that allow the fluid to flow in one direction only and thus prevent reverse flow of fluid in the system. For the check valve to open and allow the flow of fluid, there should be a minimum upstream pressure between the inlet and outlet. This minimum upstream pressure is called the check valve’s ‘cracking pressure’. If the upstream pressure falls below the cracking pressure or there is back pressure, it will result in closing of the check valve.
d) Hydrogen pressure relief valve
A hydrogen relief valve is a safety device which is designed to protect the system when the pressure in the system increases beyond the specified design pressure or maximum allowable working pressure. Thus, when the pressure in the system rises above the set pressure, the valve automatically gets lifted and allows the flow of the medium, thereby releasing the pressure. Once the pressure in the system drops below the reseating pressure, the valve closes. Therefore, a pressure relief valve is important to prevent overpressure events and equipment failure.
e) Hydrogen flow control valve
Hydrogen flow control valves are also used to control the fluid flow in the system. A hydrogen control valve is similar to a needle valve in terms of functionality, which means it can be used for accurate flow rate control. In the closed state, it prevents the flow and as the valve is gradually opened, the flow also increases. But the major difference between a needle valve and flow control valve is that in the case of needle valve the flow is controlled in both directions (bi-directional) while a dedicated flow control valve controls flow only in one direction (allowing free flow in the opposite direction).
f) Hydrogen shut-off valve
A hydrogen shut-off valve is often designed as a hydrogen solenoid valve. This type of valve is used to safely stop or continue the flow of a medium in a system. It consists of two components, valve body and control device. The control element ensures that the valve opens and closes as required. When everything works correctly, the medium passes through the valve in a smooth manner. However, when there is any abnormal condition such as excessive fluid expansion etc., the control device closes the flow passage inside the valve. Therefore, it works similar to an electric switch, which either stops the flow completely or allows it fully. In the use case as hydrogen isolation valves, shut-off valves can be used to isolate sections of a hydrogen fuel circuit.
What are the main use cases for each type of hydrogen valve?
Liquid hydrogen valves are used in hydrogen fueling stations, pressure fluid handling systems, and compression systems. Likewise, we would find a liquid hydrogen valve used for flow control in e.g. hydrogen fuel cell test systems, hydrogen fueling stations, storage and manufacturing systems. This applies specifically to use cases where hydrogen is handled and processed in liquid form, following compression or cryogenic liquefaction.
Hydrogen gas valves as found in electrolysis and hydrogen storage systems, and these are often designed as ball-type valves. A hydrogen gas valve may be used as a shut-off valve in low pressure applications within the realm of hydrogen storage and transportation, or in situations where expansion of hydrogen fuel from liquid to gaseous state must be expected.
High pressure hydrogen valves are used as pressure relief valves, e.g. in hydrogen boilers and plants, on pressure tanks, for process technology, storage and transportation of hydrogen. A hydrogen tank valve would normally be designed as a ball-type shut-off valve. Hydrogen valve use cases are outlined in the following table:
| Type of Valve | Use Cases |
| Hydrogen Needle Valve | Hydrogen fueling stations, Pressure fluid handling system, Compression systems |
| Hydrogen Ball Valve | Electrolysis, Hydrogen storage |
| Hydrogen Check Valve | Hydrogen Refilling stations, Fuel cells, Hydrogen processing, Process system control and shut-off |
| Hydrogen Pressure Relief Valve Valve | Hydrogen boilers and plants, Pressure tanks, Process technology, Storage and transportation of hydrogen |
| Hydrogen Flow Control Valves | Hydrogen fuel cell test systems, Hydrogen fueling, storage and manufacturing systems |
| Hydrogen Shut-off Valves | Hydrogen Storage and transportation |
What are the main performance criteria of each type of valve?
Hydrogen valve specifications known to be key performance criteria according to the type of valve are listed in the following table:
| Type of Valve | Key Performance Criteria |
| Hydrogen Needle Valve | Operating pressure, port and orifice size of valve, fluid temperature and valve material |
| Hydrogen Ball Valve | Sealing material, circuit function, operating pressure, fluid temperature, valve connection type and valve material |
| Hydrogen Check Valve | Maximum fluid pressure, Cracking pressure, valve material, flow characteristics |
| Hydrogen Pressure Relief Valve | Set pressure, Back pressure, blow-off capacity, valve and seal material, fluid temperature |
| Hydrogen Flow Control Valves | Operating pressure, port and orifice size of valve, fluid temperature and valve material |
| Hydrogen Shut-off Valves | Operating pressure, port and orifice size of valve, fluid temperature and valve material |
What are EC-79 directive for hydrogen valves?
Hydrogen valve manufacturers competing in the market must comply with the EC-79 safety-related regulation for hydrogen-powered vehicles and hydrogen systems. This EC 79 directive also applies to components designed for those types of vehicles. Both liquid and compressed gaseous hydrogen are included in this regulation.
EC79 type-approval applies to all types of hydrogen valves, among other components. Read the full text of the REGULATION (EC) No 79/2009 on type-approval of hydrogen-powered motor vehicles
EC-79 requirements
- Hydrogen components should be able to withstand electrical, mechanical, thermal and chemical operating conditions without leaking or visible deformation.
- Hydrogen systems should be protected against over-pressurization.
- The materials used for hydrogen components and systems which will be in direct contact with hydrogen should be compatible with hydrogen.
- Hydrogen components and systems should be able to reliably withstand expected temperatures and pressures during their expected lifetime.
- The flow direction should be clearly indicated for hydrogen components with directional flow.
- Hydrogen components and systems should be designed in such a way that they can be installed and protected against damage.
The tests conducted on hydrogen valves for EC-79 type approval include Pressure test, Seat leakage test, Ozone aging test, Temperature cycle test, Hydrogen compatibility test etc. for liquid hydrogen. For gaseous hydrogen, tests such as material tests, corrosion resistance test, endurance test etc. is conducted.
Last update: 01.02.2023
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