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 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 convenience of 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 yet have a comparatively low weight compared to steel vessels.
Tanks of the 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 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. This is done via a pressure regulation unit downstream of the storage system.
Pressure switch in hydrogen-powered train switches the drive system off
Suitable for used 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 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, depending on function:
if the tank is in danger of emptying
if the pressure becomes too much when the hydrogen is used in the propulsion system
This emergency protection could also be realised with a pressure sensor and a software. But also for trains this solution will be very complicated. It is also 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 decide on the model PXA due to the measurement quality alone. The pressure switch was also considered right for the duty in the hydrogen-powered train due to its 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 in addition has been created for ambient temperatures from -40 �C to +85 �C. Furthermore, the pressure switch has IECEx approval ?Ex d? ( Delivered ), 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
Further information on the subject of hydrogen and on the pressure switch model PXA can be found on the WIKA website. When you have any questions, your contact will gladly gelp you.
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