In a newly developed hydrogen train for local transport, a pressure switch from WIKA plays an essential role. Within the scope of pressure monitoring, it performs the central safety function in the H2 supply system through the journey.
The advantages of hydrogen in rail transport are rather unknown to everyone. Even if the first trains with H2 fuel cells are already in operation. They operate on non-electrified railway lines and replace the diesel trains which were used before.
Tanks predicated on carbon fibre composite technology
The tank convenience of the hydrogen should be adapted to the distances. Among WIKA?s customers has specialised in individual fuel storage systems for H2 vehicles. Their cylindrical tanks derive from carbon fibre composite technology. They are therefore extremely robust and yet have a relatively low weight in comparison to steel vessels.
Tanks of this type may also be installed in the hydrogen-powered train mentioned at the beginning. This multiple-unit train, created for commuting traffic, is filled with the hydrogen at a special terminal. The tank pressure is 300 to 350 bar. While driving, it must 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 kind of hydrogen-powered train in terms of 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, based on the function:
if the tank is at risk of emptying
if the pressure becomes too much once the hydrogen is transferred to the propulsion system
Such an 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 a higher risk of error when compared to a switch-based safety function.
SIL-3 approval made the case for its use
The customer didn’t choose the model PXA due to the measurement quality alone. The pressure switch was also considered right for the task in the hydrogen-powered train due to the SIL-3 suitability. It thus easily meets the safety-related market requirements for the H2 application (SIL-2).
Flameproof enclosure (?Ex d?) and compact design
The PXA has also been designed for ambient temperatures from -40 �C to +85 �C. In addition, the pressure switch has IECEx approval ?Ex d? ( Strategy ), which the customer requires as standard. An additional advantage of this instrument: The PXA could possibly be easily built-into the storage system thanks to its extremely compact design.
Note
Incompetent on the subject of hydrogen and on the pressure switch model PXA are available on the WIKA website. When you have any questions, your contact will gladly gelp you.
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