What is the maximum negative pressure allowed when defueling?

When defueling, it's crucial to maintain specific safety and performance standards, one of which involves managing pressure levels. The correct answer indicates that a maximum negative pressure of -8 psig is permitted during the defueling process.

This level of negative pressure is established to ensure that the system operates within safe limits, preventing potential hazards such as fuel vapor release or system malfunctions. At -8 psig, the pressure is sufficiently low to facilitate the safe and efficient transfer of fuel while minimizing risks associated with creating a vacuum that could disrupt fuel handling operations.

It's important to understand that setting the allowed negative pressure too far beyond this range, such as -12 psig, could lead to complications in the equipment and increase the likelihood of leaks or other failures. Therefore, maintaining the maximum negative pressure at -8 psig strikes a balance between efficiency and safety standards during defueling operations.