Which of the listed pumping arrangements will be hazardous when two similar centrifugal pumps are used to discharge a cargo of flammable liquid?

Correct Answer: Option B — Each pump operating at a different pressure and discharging into a common line.

Operating centrifugal pumps at different pressures into a common discharge line can cause the pump with lower pressure to experience backflow or deadheading. This creates excessive heat and mechanical stress, which, when handling flammable liquids, poses a significant fire and explosion hazard due to potential seal failure.