When does a warning condition exist?

• A. When any detector head reaches 5 ppm
• B. When any detector head exceeds 50 ppm
• C. When any detector head reaches a level greater than 10 ppm
• D. When all heads drop below 0 ppm

Answer: (C)

In gas detector systems, a warning condition is triggered when gas levels rise enough to signal caution but not yet reach dangerous or alarm levels. Here, any detector head reading greater than 10 ppm sets off a warning, meaning a single elevated reading in any monitored area prompts attention and preventive action. This threshold helps give early notice so you can assess and mitigate exposure before higher, more hazardous levels occur. Thresholds like 5 ppm would cause more frequent warnings and might be nuisance, while 50 ppm would be too high for a warning and delay needed precautions. The idea that all heads drop below 0 ppm isn’t feasible, so it wouldn’t describe a warning state.