What must not exceed 150% of the centrifugal fire pump's rated capacity?

The requirement that a single demand must not exceed 150% of the centrifugal fire pump's rated capacity is based on safety and operational efficiency. Centrifugal fire pumps are designed to provide a specific flow rate and pressure as part of a fire protection system. When a single demand exceeds this rating significantly, it can lead to overloading the pump, which may result in reduced performance, overheating, potential damage to the pump components, and decreased reliability during a critical situation such as a fire.

Maintaining the single demand within 150% of the rated capacity ensures that the pump operates within its optimal range and can handle varying flow requirements without compromising safety or efficiency. This regulation is critical in system design to avoid surges in demand that could incapacitate the fire suppression system during a fire emergency.

Other options such as total flow, average flow, or total pressure refer to different aspects of pump performance or system design requirements, but they do not address the fundamental operational limits placed on single demand to ensure system reliability and functionality in emergency conditions.