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Hydrogen valves for your H₂ applications

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 for 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. 

Image with solenoid valves for hydrogen applications

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?  

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. 

Choosing the right solenoid valveChoosing the right solenoid valve

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.

Picture with Control and process valves for hydrogen applications

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:

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. 

Click here to download

 

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.

overview of high pressure valves

 

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

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:

Do you need more information? 

Download the full hydrogen catalogue here

 

Or visit our hydrogen-industry website to find the right solution for you 

Innovative solutions for a clean future with hydrogenInnovative solutions for a clean future with hydrogen

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.