What is the maximum allowable concentration of carbon monoxide in a flue vent?

The maximum allowable concentration of carbon monoxide in a flue vent being no greater than 0.04% and 400 PPM is established to ensure safety and prevent health hazards associated with carbon monoxide exposure. Carbon monoxide is a colorless, odorless gas that can be harmful or even fatal when inhaled at elevated levels. The specified limits are based on guidelines and regulations set forth by safety organizations, including the American National Standards Institute (ANSI) and the National Fire Protection Association (NFPA).

Maintaining the carbon monoxide levels within this specified range in flue vents is crucial because it correlates with acceptable exposure levels for occupants and proper functioning of heating appliances. Higher concentrations could indicate incomplete combustion or a malfunctioning heating system, leading to dangerous situations both for the immediate environment and public health.

The other options present higher acceptable limits, which may not adequately address safety concerns regarding carbon monoxide exposure. Hence, the choice indicating a concentration of no greater than 0.04% and 400 PPM is aligned with health and safety standards aimed at minimizing risks associated with carbon monoxide emissions from gas appliances.