There is growing pressure worldwide to reduce the environmental impact of transport. Hydrogen paves the way for an era of sustainable, carbon-neutral or even carbon-free mobility, both in the short and long term. The growing demand for these zero-emission engines is currently focused primarily on commercial vehicles. In Switzerland, for example, the "H2 Mobility Initiative", in collaboration with a major automaker, aims to introduce 1,600 hydrogen-powered trucks onto the roads by 2025.
This type of hydrogen vehicle stores gas in high-pressure tanks, at around 700 bar. This compression requires the tanks to be particularly reinforced, making them expensive and heavy. The pressure in the tanks needs to be monitored, and it is imperative that they have reliable pressure-measuring instruments certified to work with hydrogen. Hydrogen atoms are extremely small and, because of this property, can even penetrate solid materials through a process known as permeation. Over time, pressure transmitters cease to function because of this process.
For this type of application, high-performance, high-precision pressure transmitters are needed to monitor vehicle tanks reliably and safely. A wide temperature range must also be covered, as large temperature fluctuations can occur in hydrogen tanks. The main factors to consider when choosing a pressure transmitter for hydrogen tanks should therefore not be overlooked:
- Pressure range: lower pressure increases sensor life.
- Temperature: the flow of gas through the sensor membrane increases at higher temperatures, so it's important to consider the type of material to be used for the parts in contact with the fluid.
- Membrane thickness: gas flow is inversely proportional to membrane thickness. Membrane thickness can also significantly double sensor life.
- Membrane surface area: gas flow is directly proportional to membrane surface area.
Wika offers the MH-3-HY pressure transmitter as a solution for such applications: a pressure sensor specially developed for use in hydrogen fuel cell vehicles, with high shock and vibration resistance. Thanks to the hermetically welded thin-film measuring cell, no additional sealing materials are required. Unlike other sensor technologies on the market, the measuring cell has no oil filling.
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