What specifications are needed to reduce the hydrogen background from a hydrogen generator that vents 50mL/min into a room? Specifically, the project uses an air extraction fan in the lab to reduce hydrogen background. Lab dimensions are 4.2*4.55*2.37m.

A best practice, even for small hydrogen vents, is to vent to a dedicated vent system outside the building where possible. Several international codes and standards can be used to provide guidance; the Panel recommends discussing the configuration with a local fire official to ensure their required standards are followed. In the U.S. NFPA 2, Hydrogen Technologies Code, has information in Section 13.3 (https://www.nfpa.org/product/nfpa-2-code/p0002code). Additional best practices can be found at Best Practice Overview: Use of an Electrolyzer.

Other considerations when venting the electrolyzer to the room in addition to making sure there is adequate ventilation include proximity of ignition sources near the exhaust release point of the electrolyzer, location of room air inlets and outlet exhaust, and shutdown of the electrolyzer if exhaust is lost. Increasing ventilation to dilute the venting hydrogen can be one method to resolve the situation, but other alternatives are to redirect the vent stream to a chemical exhaust system, a fume hood, or piped directly outdoors.