At what percentage of the lower flammability limit must the flammable gas detection system activate in hydrogen fuel gas rooms?

The correct percentage at which the flammable gas detection system must activate in hydrogen fuel gas rooms is based on safety regulations and industry standards aimed at preventing potential explosive hazards. The lower flammability limit (LFL) of hydrogen is typically around 4% in air. Activating the detection system at 25% of the LFL, which corresponds to 1% hydrogen in air, provides an early warning of a potentially hazardous situation.

This proactive approach allows for timely intervention before concentrations reach levels that pose a risk of ignition or explosion. By setting the threshold at 25%, safety protocols ensure that there is sufficient time for operators to take action, such as ventilating the area or shutting down processes, thereby minimizing the risk of creating a dangerous environment.

In contrast, activating the system at higher percentages (such as 50%, 75%, or 100% of the LFL) would either delay the response to a potential leak or failure to detect earlier hazards, which could lead to dangerous situations that could have been avoided. Therefore, activating the detection system at 25% of the lower flammability limit aligns with best practices in safety management for flammable gases like hydrogen.