The automatic relief valve for fire pumps with a rated capacity not exceeding how many gpm must have a nominal size of 3/4 inch?

The correct choice identifies that the automatic relief valve for fire pumps with a rated capacity not exceeding 2500 gallons per minute must have a nominal size of 3/4 inch. This specification is important in the context of fire protection systems, where the design and sizing of valves are critical for maintaining proper water flow and pressure during operation.

The nominal size of the valve is determined based on industry standards and is established to ensure that the valve can adequately relieve pressure while managing the flow without causing unnecessary turbulence or restrictions. For fire pumps, especially those rated up to 2500 gpm, a 3/4 inch valve strikes a balance between efficient operation and the necessary capacity to handle the potential pressure buildup that can occur during abrupt changes in flow scenarios.

Understanding this specification helps ensure that the fire protection system meets regulatory requirements and operates effectively to protect life and property in the event of a fire. This knowledge is essential for sprinkler fitters as they design, install, and maintain these systems.