For H2/air enclosures piping to exhaust blower, is ducting sufficient, or is industrial piping recommended to provide some small deflagration resistance (#150)?

Exhaust systems (sometimes referred to as ventilation systems) are used to exhaust hydrogen and air mixtures. Normally these are used to vent streams with less than flammable range hydrogen in air.

That is, hydrogen detectors trigger venting or the ventilation systems runs during all hydrogen operations. In these instances, low concentrations of hydrogen are expected, but deflagration is not expected in these systems and no pressure rating/deflagration protection is needed.

However, if it is determined that higher concentrations of hydrogen may be expected in the vent system, pressure-appropriate designs can be implemented, based on conditions.