What is the maximum allowable percentage of oxygen in a tank?

The maximum allowable percentage of oxygen in a tank is critical for maintaining safety standards, especially in environments where flammable or hazardous materials are present. The correct answer is 5% because it is a widely accepted limit for ensuring that the atmosphere within the tank remains safe and does not support combustion.

When working with flammable liquids, as found in many tank operations, maintaining low oxygen levels helps prevent the risk of fires or explosions. If the oxygen concentration exceeds this limit, the likelihood of ignition increases significantly if an ignition source is present.

While options like 10%, 15%, or even 20% may appear plausible, they do not adhere to the stringent safety protocols established for tank environments. Higher percentages of oxygen can lead to dangerous situations, as they create a more conducive environment for combustion, which is why the maximum is set at 5%. This limit serves as a precautionary measure, emphasizing the importance of monitoring and maintaining the right atmospheric conditions within tanks.