How to Size a Filter for Hydrogen Applications?

For correct filter sizing, three additional factors in addition to pressure and temperature rating must be considered:

• Flow volume – flow volume needs to be known to calculate the basic sizing of the flow orifice and passages
• Particle Size and filtration Quality - This has also an impact on the flow resistance of a filter unit. Smaller particles require better filtration quality. This leads to higher density in the filtration materials, which increases pressure losses.  This needs to be compensated by larger filtration surfaces. This, however, increases the overall size of the housing parts and the overall footprint.
• Maximum acceptable pressure drop caused by the filter element - The pressure drop is simply a loss of pressure while fluid is passing through the filter. It makes sense to keep this pressure loss as low as possible due to the fact that a small pressure drop of the Filter element requires a larger filtration surface, which in turn increases the overall footprint.

F581 High Pressure Filter Datasheet

So, it is always a fine balance between a smaller and cheaper footprint versus increased pressure losses.

In general, it is recommended to use mesh or fibre based metal filter elements. This is especially important for filtration upstream of the car filling nozzle.  Upstream, pressure pulses before the start of the fuelling procedure are used to check the tightness of the connection between the vehicle and the dispenser. When sintered powder Filter elements are installed, there is a high risk that the pressure pulse will cause sinter particles to burst out of the filter element and flow directly into the vehicle tank.