If two centrifugal pumps, driven by two independent electric motors, operating at unequal speeds are discharging an inflammable liquid through a common discharge line, the higher speed pump may cause the slower pump to do which of the following?

Correct Answer: Option D — overheat

Operating centrifugal pumps at unequal speeds into a common line allows the higher-pressure pump to dominate the flow. This backs up the slower pump, forcing it to run near shut-off head with minimal flow, which rapidly generates heat and causes the pump to overheat.