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Pressure switch in hydrogen-powered train ensures safety

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 through the journey.
The benefits of hydrogen in rail transport are rather unknown to the general public. 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 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’re therefore extremely robust yet have a relatively low weight compared to steel vessels.
Tanks of this type may also be installed in the hydrogen-powered train mentioned at the beginning. This multiple-unit train, designed for commuting traffic, is filled with the hydrogen at a particular 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. This 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 regarding safety ? the model PXA pressure switch from WIKA.
The pressure switch model PXA meets certain requirements of the hydrogen-powered train application. With ไดอะแฟรม 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, with respect to the function:
if the tank is at risk of emptying
if the pressure becomes too much when the hydrogen is transferred to the propulsion system
This emergency protection could also be realised with a pressure sensor and a software. But also 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 because of 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 its SIL-3 suitability. เพรสเชอร์เกจ meets the safety-related market requirements for the H2 application (SIL-2).
Flameproof enclosure (?Ex d?) and compact design
The PXA has also been created for ambient temperatures from -40 �C to +85 �C. Furthermore, the pressure switch has IECEx approval ?Ex d? (flameproof enclosure), which the customer requires as standard. An additional advantage of this instrument: The PXA could be easily built-into the storage system thanks to its extremely compact design.
Note
Further information about hydrogen and on the pressure switch model PXA can be found on the WIKA website. Should you have any questions, your contact will gladly gelp you.
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