At what percentage must fuel containers be filled?

Fuel containers must be filled to a maximum of 90%. This guideline is in place to allow for the expansion of fuel as temperatures change, which helps prevent spillage and ensures safe handling. Overfilling a container can lead to hazardous situations, such as leaks or spills, especially in hot weather conditions when the fuel expands. Additionally, a 90% fill level helps to create necessary headspace in the container for vapor formation, contributing to safety and compliance with regulations. Therefore, filling at this level is both a safety measure and a best practice in the handling of flammable liquids.