In a newly developed hydrogen train for local transport, a pressure switch from WIKA plays a crucial role. Within the scope of pressure monitoring, it performs the central safety function in the H2 supply system during the journey.
Some great benefits of hydrogen in rail transport are rather unknown to everyone. Even if the initial trains with H2 fuel cells are already in operation. They operate on non-electrified railway lines and replace the diesel trains that were used before.
Tanks predicated on carbon fibre composite technology
The tank capacity for the hydrogen should be adapted to the distances. One of WIKA?s customers has specialised in individual fuel storage systems for H2 vehicles. Their cylindrical tanks derive from carbon fibre composite technology. They’re therefore extremely robust and yet have a comparatively low weight compared to steel vessels.
Tanks of this type are also installed in the hydrogen-powered train mentioned in the beginning. This multiple-unit train, designed for commuting traffic, is filled up with the hydrogen at a special terminal. The tank pressure is 300 to 350 bar. While driving, it should be reduced to a single-digit value for the supply to the fuel cell. That is done with a pressure regulation unit downstream of the storage system.
Pressure switch in hydrogen-powered train switches the drive system off
Suitable for use in a new type of hydrogen-powered train with regards to safety ? the model PXA pressure switch from WIKA.
The pressure switch model PXA meets the requirements of the hydrogen-powered train application. With the monitoring the of tank pressure and pressure regulation in the hydrogen-powered train, the client uses the pressure switch model PXA for the safety function. The miniature instrument switches off the H2 propulsion system in two cases, according to the function:
if the tank is in danger of emptying
if the pressure becomes too high when the hydrogen is used in the propulsion system
This emergency protection could also be realised with a pressure sensor and a software. But for trains this solution would be very complicated. Additionally it is rated with an increased risk of error when compared to a switch-based safety function.
SIL-3 approval made the case for its use
The customer did not decide on the model PXA due to the measurement quality alone. The pressure switch was also considered right for the task in the hydrogen-powered train because of its SIL-3 suitability. It thus easily meets the safety-related market requirements for the H2 application (SIL-2).
Optimistic (?Ex d?) and compact design
The PXA has also been designed for ambient temperatures from -40 �C to +85 �C. Furthermore, Terrifying has IECEx approval ?Ex d? (flameproof enclosure), which the customer requires as standard. A further advantage of this instrument: The PXA could possibly be easily integrated into the storage system thanks to its extremely compact design.
Note
Further information about hydrogen and on the pressure switch model PXA are available on the WIKA website. For those who have any questions, your contact will gladly gelp you.
Also read our posts
Wika develops pressure sensor for hydrogen-powered vehicles
Hydrogen mobility: Clean engines into the future provide same convenience as engines today
Turning hydrogen into kilometres
Hydrogen and pressure sensors ? What must be observed?g