Catalytic recombiners are effective at preventing flammable hydrogen mixtures and also sometimes useful to monitor hydrogen concentrations through heat evolution when an oxidizer is present. Careful considerations must be made when integrating these elements into a design, so that they do not become a source ignition (and/or flame arrestors prevent propagation of a flame front) and the catalyst will not be fouled by process conditions such as water condensation. It is important to understand the limitations of these systems since in all instances there is a maximum flow that can be catalytically converted, above which combustible hydrogen mixtures are still possible. In a fully enclosed space, additional considerations for ventilation would be necessary.