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Valves play a critical role in hydrogen applications. The variety of valves in this area is impressive, ranging from simple shut-off valves to precise flow controllers, all of which must afford safety, reliability and efficiency. From hydrogen production to fuel cell technology, the correct selection and application of these valves is crucial for the success of hydrogen applications.
Solenoid valves are critical for efficient hydrogen production and utilization, emphasizing the importance of selecting the right solenoid valve for each specific application.
How do solenoid valves differ from each other?
From the outside, the different mechanisms of solenoid valves are not always visible. But what are the differences?
The solenoid coil directly controls the opening and closing mechanism of the valve.
Flow capacity is limited
Suitable for low-pressure applications
The solenoid valve controls a pilot valve, which in turn controls the operation of the main valve.
Suitable for use in applications with significant pressure differentials
Capable of handling higher pressures and volume flow rates
The valve is normally closed when not energised and opens when energised.
In the event of a power failure, the valve automatically closes, halting the flow of hydrogen
Designed for safety applications, such as shutting off gas or liquid flow in case of power loss
The valve is normally open when not energised and closes when energised.
Used in applications where the flow of hydrogen needs to be interrupted when power is applied
Ideal for applications where the default state is open, for example, to allow the flow of liquids or gas in the event of a power outage
Controls the flow of a single liquid or gas between the inlet and outlet ports.
Ideal for hydrogen applications requiring on/off control, such as directing hydrogen flow to a specific location
Used as an on/off control in simple systems
Can control the flow between the inlet and one of the outlet ports or close both outlet ports.
Used when redirection, mixing, or distribution of hydrogen or gas streams is required
Suitable for both liquids and gases
Utilizes a flexible diaphragm to control the opening and closing of the valve.
Isolation between the solenoid components and the hydrogen flow
Ideal for controlling corrosive or contaminated liquids, as the diaphragm separates the solenoid from the liquid
And what are the special circumstances of hydrogen applications that must be taken into account?
Why does backflow prevention in valves protect against unintended gas leakage?
In gas system operations, pressure differentials can often occur at the valve, resulting in a higher pressure at the valve outlet than at the inlet. A so-called back pressure (pressure higher at the outlet than at the inlet) can cause the valve to open against the flow or inadvertently slow down the closing process. Direct-acting or force pilot operated valves provide greater back-pressure safety thanks to their strong closing springs. The EN 161 standard offers a good grounding in the subject of back-pressure safety and valve classes.
What is the relationship between the ambient temperatures and the performance of your system?
In many applications, the ambient temperature plays a less significant role. If the ambient temperature rises above 50 °C, you should examine whether the solenoid valve is appropriate for these temperatures on an ongoing basis. The copper winding of the coil reacts to increasing temperature with an “increased” resistance. This then means a reduction in output and performance. In confined spaces, and with sound insulation and functional protection of hydrogen systems, heat build-up can lead to a reduction in performance and therefore functional limitations.
Why is the explosion protection of components so important for your safety?
The compact design of stationary fuel cells as well as their close proximity to the stack can lead to two challenges. On the one hand, there is the ambient temperature, which is higher than usual, and on the other hand, the large number of process interfaces. Each interface, by itself, represents a small potential hydrogen leak, the consequence of which can be accumulation of hydrogen. Because of the diffusion and temperature aspects, customers and/or testing authorities often define stack control as ATEX Zone 1 or Category 2.
How do the temperatures develop during compression and expansion of hydrogen?
The Joule-Thomson effect is a physical phenomenon that occurs when a gas expands through a choke without exchanging heat with its environment. This leads to a temperature change in the gas. With the Joule-Thomson effect, a gas can either increase or decrease in temperature, depending on its Joule-Thomson coefficient, for which the starting point is the inversion temperature of the gas. In the case of hydrogen, the inversion temperature is > -80 °C. Hydrogen therefore warms during expansion.
What is the relationship between system cleanliness and valve tightness?
Particles inside the system can lead to unintended leaks. Regardless of whether the hydrogen is pure, the system must be cleaned and purged before start-up. Even the smallest of particles damage not only the stack, but also the hard but sensitive seal surfaces of the valve seats. To prevent upstream contamination during refuelling or servicing, install filters in the systems.
How do I know which is the right solenoid valve for my hydrogen application?
Valves that are used in hydrogen applications have to have a wide range of specific properties. This means it is not always easy to select the most appropriate valve. In our guide, we detail the most important criteria to help you to choose the right solenoid valve for your application.
The product selection guide for hydrogen valves explains the following aspects of the valves:
Pressure ranges
Media temperature
Materials compatibility
Volume flow rates
Reaction times
Service life and switching cycles
Energy consumption
Certifications and approvals
Connection types
Download the guide to assess the detailed information that will help you to find the optimal solution for your hydrogen application.
In hydrogen applications of all kinds, reliable and safe control is essential. With solenoid valves, you have many application options within your processes. But which solenoid valve is suitable and what do I need to consider? Bürkert is ready to meet your challenge.
Find the right solenoid valve for your hydrogen application now
Control and process valves for hydrogen applications
Control and process valves can be deployed in practically all applications in the hydrogen value chain. The pneumatic or electromotive valves control flow quickly, precisely, and with high repeatability, ensuring stable processes. Regardless of whether they are deployed to deal with challenging gases or liquids, they ensure that your hydrogen plant operates efficiently and reliably.
What types of control and process valves are available?
Various control and process valve variants are available for hydrogen applications, each one optimised for meeting specific requirements. These include valves for pressure control, sealing off gases and liquids, check valves and safety valves. We basically distinguish between:
Specialized in the pneumatic or electromotive shut-off and control of generated gases in hydrogen processes.
Suitable for very high flow rates, pressures, and temperatures.
Quick and easy opening and closing ensure safe gas shut-off
Electromotive-driven process valves are particularly suited for applications requiring highly precise gas flow control
Fast response times and seamless integration into automation systems are advantageous in dynamic processes
Position feedback indicators enable precise and rapid tracking of valve positions
Variants include angle seat valves, globe valves, and diaphragm valves tailored to specific applications
Electropneumatic process valves are ideal for applications that demand ultra-precise gas flow control.
Their fast response times and seamless integration into automation systems are particularly advantageous in dynamic processes
Position feedback indicators enable precise and rapid tracking of valve positions
Variants: angle seat valves, globe valves, diaphragm valves depending on the application
Did you know?
The relationship between pressure and temperature in hydrogen applications
Control valves are placed under particularly high demands in hydrogen applications. They must withstand pressures of up to 40 bar, as well as operate safely at high temperatures. The relationship between pressure and temperature is of particular importance when it comes to the control of gases. For example, in order to maintain oxygen in a gaseous state, the temperature must be lowered when the pressure is increased. The ideal gas law describes this pressure-temperature relationship of gases. Thus, an increase in pressure at constant gas quantity and constant volume leads to an increase in temperature, and vice versa.
H2 applications require valves to have an exceptional level of tightness
Unlike in other applications, the production or use of hydrogen requires an especially high level of valve tightness. If leaks occur, this presents an extreme hazard or reduces the efficiency of the system. Control valves therefore need to have a tightness of 10–4 mbar∙l/s.
Which certifications are particularly important for control valves used in hydrogen applications?
ISO 15848 – Defines test procedures and leakage classes for industrial armatures and valves
Directive (TA) – Air – Regulates emissions from industrial plants
ATEX – Certification for components used in potentially explosive atmospheres
ASME B16.34 – Sets requirements for valves in pressure applications
PED – Regulates the design and use of pressure equipment, including valves
Manufacturer's Declaration – Certifications from valve manufacturers regarding performance, quality, and reliability
The process and control valves from Bürkert measure up to these exacting standards at all times.
Electromotive control valves in operation – what is possible?
Before being used in series, fuel cell systems must be tested under a wide variety of conditions and with a large number of parameters. On the basis of the test results, the performance, range or service life of the fuel cell stacks can then be assessed and optimised. The test facilities for these tasks need to be very flexible, which the numerous fluidic components from Bürkert, such as flow controllers or valves allow. They must not only work precisely and reliably, but must also be tailored to the specific application range. In the case of hydrogen, for example, the materials used must not become brittle, and where deionised water is concerned, the materials must not corrode.
The technical report from the field shows how Segula Technologies GmbH is using adjustable fluidic components to build in flexibility into the design of their H2 test benches.
Companies in the hydrogen industry are constantly facing new challenges. The solutions, especially in the field of fluidic applications, can be diverse. How Segula Technolgies GmbH from Rüsselsheim has found the right solution is described in the technical report.
Would you like additional technical information?
Click here for process and control valves for your hydrogen application
You can rely on Bürkert to help you overcome the fluidics challenges in your hydrogen application. With over 25 years of expertise in the hydrogen sector, we are ideally placed to take on your fluidics challenges.
High-pressure and ultra-high-pressure valves for hydrogen applications
High-pressure and ultra-high-pressure valves are essential components in various applications, such as the transportation, storage, and extraction of hydrogen. They reliably control and shut off compressed hydrogen at pressures of up to 1,034 bar (15,000 psi) within the supply chain. The proper selection and implementation of these valves are crucial for the safe and reliable operation of the system. The valves are subjected to stringent testing requirements in terms of tightness and material tolerances. A well-established service plan helps maintain the operational readiness and reliability of your hydrogen system, addressing not only wear and tear but also ensuring that the system remains available and functional for use.
Where do ultra-high-pressure and high-pressure valves fit within the hydrogen value chain?
Immediately after it has been produced in the electrolysis plant, hydrogen is compressed to 160 bar using compressors for economical storage. For easier transportation, compression and storage is achieved in cylinder bundles at pressures of up to 350 bar. The extraction from the storage tanks in industrial facilities takes place using high-pressure valves that are operated pneumatically or magnetically. In
H2 refuelling stations and dispensers, compression is carried out using diaphragm compressors at pressures of 500 to 1,000 bar. This allows for natural overflow into the vehicle tank. High-pressure valves control the discharge process from the compressor into the vehicle tank.
Producing green hydrogen – electrolysis
Low pressure valves(< 40 bar)
High pressure valves(> 40 bar)
Buffer tank (30–40 bar)
Heat and energy generation for buildings
Industrial use of hydrogen
Compressor Compression from 30–40 bar to 200–300 bar
Transport
Storage
Compressor Compression from 200–300 bar to 500–600 bar or 1,000–1,100 bar
Compressor Compression from 30–40 bar to 80–100 bar
Hydrogen grid 80–100 bar
Storage
Compressor Compression from 80–100 bar to 500–600 bar or 1,000–1,100 bar
Refuelling Pressure reduction from 500–600 bar or 1,000–1,100 to 350 or 700 bar
Buffer tank
Use of hydrogen for mobility
Hydrogen pipeline 30–40 bar
Industry
Pressure control station Pressure control station reduces the pressure from 80–100 bar to 1–40 bar
Compressor Compression from 30–40 bar to 500–600 bar or 1,000–1,100 bar
As part of electrolysis, hydrogen is produced under moderate pressure and a large nominal diameter. After compression, the high-pressure valves not only regulate pressure but also meet the requirements of a customer-defined Ex zone.
Control of the pressure and flow of the generated hydrogen
The necessary requirements up to DN 50
Explosion protection for Zone 1 (Cat. 1) and Zone 2 (Cat. 3)
Several applications require a compressed form of hydrogen. These include transport and storage to save space; the process of filling vehicles with hydrogen as a fuel; and some industrial applications.
Pressure control to ensure a consistently optimal pressure level
Reliable shut-off
Requirement: >350 bar and minimal seat leakage
When connecting trailer tanks to the stationary system, safety is the top priority. Shut-off hand valves are mounted on the outlet side of the trailer tank. The tank or industrial system is connected on the inlet side via flexible pressure lines. Magnetic or pneumatic high-pressure valves ensure automated operation of the system. Pneumatic valves are typically controlled via valve islands using nitrogen as the medium so as to prevent an explosive atmosphere. Explosion-proof variants of solenoid valves provide an alternative solution without the need for protective gas.
Pressure control to ensure a consistently optimal pressure level
Safe shut-off of gases
Requirement: >350 bar and minimal seat leakage
When refuelling hydrogen vehicles, hydrogen is filled from the buffer tank into the tank at pressures of 500 to 1,000 bar. High-pressure valves are responsible for the shut-off between the buffer tank and vehicle tank. The outgoing hydrogen is cooled to -40°C to prevent overheating of the vehicle tank (maximum 85°C).
Requirement: 500–1,000 bar
Media temperature: -40°C
Did you know?
What happens in explosive decompression?
Elastomeres are permeable to atomic and molecular hydrogen. Even at low gas pressures, hydrogen penetrates elastomer seal material. When there is a sudden drop in pressure, the stored hydrogen is not able to escape quickly enough. The seal is damaged to such an extent in this process, that it loses its sealing effectiveness. Bubble formation on the seal material is a characteristic sign of explosive decompression. The damage occurs due to high differential pressure during the switching process. This is why it is so important to ensure that the proper material is selected for valves. PEEK is the first choice for very high pressures.
How is hydrogen embrittlement prevented in solenoid valves?
Hydrogen embrittlement refers to the alteration of mechanical properties due to the penetration of hydrogen atoms into the metallic lattice of stainless steel. A high operational H2 system pressure exacerbates this process. As a result of so-called hydrogen-induced stress corrosion cracking, micro-cracks may form in the metal, affecting its mechanical properties. The yield strength of the stainless steel decreases, and the material becomes brittle. One component in a solenoid valve that is particularly dynamically loaded is, for example, the core guiding tube with a stopper. It not only bears the load cycles but it is also made of both magnetic and non-magnetic steel. To avoid weak points that can potentially arise during welding processes, the components in hydrogen high-pressure valves are bolted and sealed together.
How does seat tightness affect the service life of a valve?
In this context, the pressure range and the maximum expected leakage are important factors. External tightness can generally be achieved without compromising service life in the range of 1 x 10-5 mbar l/s. It is more complicated when it comes to the dynamic sealing points at the valve seat. Pressures up to 1,000 bar or media temperatures of -40°C require hard seals and precise mechanics to achieve a seat leakage of 10-4 ml/s. The high closing forces place extreme stress on both metal and plastic seals. This means that, with an increasing number of switching cycles, valves in the hydrogen sector require regular servicing interruptions; otherwise, low seat leakage cannot be ensured. We recommend inspection after approximately 80,000 to 100,000 switching cycles.
What effect does icing have on safe operation?
Hydrogen produced during electrolysis has a pressure of 30 to 40 bar. For economical use, it must be stored and transported. For this purpose, it is compressed in two or three stages to 160 or 350 bar using gas compressors and is then transported in cylinder bundles or stored in high-pressure containers. For refuelling station operation, the storage pressure for the intermediate or buffer storage (capacity of 0.4 to 1.2 tons) is increased to 500 or 1,034 bar (15,000 psi). This allows passive refuelling (without a compressor) by means of overflow. With the supply from the buffer storage, approximately 30 refuels can be achieved. The maximum permissible temperature of the vehicles is 85°C. The hydrogen is cooled to between -10 and -40°C after compression, since it expands in the tank and the temperature thus increases at the filling nozzle. The high-pressure valves ice up from the outside in the process, because condensate from the environment precipitates on the cold valve body. Plastic sleeves protect the valve from icing up, thus increasing its service life.
What is special about ultra-high-pressure valves and high-pressure valves?
Learn all about high-pressure valves in this video. How are they are built to withstand extreme pressures? How are you able to guarantee maximum safety in hydrogen applications? All this and more regarding the technology and benefits of these little powerhouses. Watch this video with expert Markus Wirth (Product Manager – Solenoid Valves) in conversation with Hyfindr.
Bürkert’s high-pressure and ultra-high-pressure valves are capable of this.
80,000 switching cycles
ensure high system availability & reduced maintenance requirements
Rapid detection
of leaks through special control holes at sealing points
Maximum safety
thanks to Dynamic Sealing Package* for temperatures of between -40 to +80°C (for ex, up to +60°C)
*Dynamic sealing ring on the spindle
Would you like additional technical information?
Download our overview of the ultra-high-pressure and high-pressure valves:
Ultra- and high-pressure valves for hydrogen applications
In hydrogen applications of all kinds, reliable fluidic solutions are essential. Whether valves, sensors, automation or even complete fluidic systems - Bürkert is ready for your challenge.
Or visit our hydrogen-industry website to find the right solution for you
Hydrogen is of great significance as an energy source on the way to climate change: it is carbon-free and can therefore support the urgent need for decarbonisation - especially if it is manufactured from renewable energies. However, for economical generation and usage of green hydrogen, safe, low-maintenance and, above all, efficient plants and systems are needed in order to obtain as high a degree of efficiency as possible.