According to NFPA 20, what are the pressure requirements for the discharge components of a fire pump?

According to NFPA 20, what are the pressure requirements for the discharge components of a fire pump?

• A. Maximum total discharge head at rated speed
• B. Discharge head at zero speed
• C. Minimum discharge head
• D. Discharge pressure equals system design pressure

Answer: (A)

The key idea is that discharge components must be able to withstand the highest pressure the pump can generate when it is operating at its rated speed. In a fire pump, the pump can produce substantial head, and the pressure in the discharge piping reaches its peak when flow is low and the pump is delivering near its maximum head. Designing the discharge components for this maximum discharge head ensures the piping, valves, fittings, and other components won’t fail during operation or a fire event. This focus isn’t about what happens when the pump is not running (discharge head at zero speed) or about the minimum pressure the system would see. It’s about the worst-case pressure the pump can impose at its rated speed. It also isn’t simply equating discharge pressure to the system design pressure, because the pump can generate, and thus require components to withstand, pressures higher than the system’s nominal design.

The key idea is that discharge components must be able to withstand the highest pressure the pump can generate when it is operating at its rated speed. In a fire pump, the pump can produce substantial head, and the pressure in the discharge piping reaches its peak when flow is low and the pump is delivering near its maximum head. Designing the discharge components for this maximum discharge head ensures the piping, valves, fittings, and other components won’t fail during operation or a fire event.

This focus isn’t about what happens when the pump is not running (discharge head at zero speed) or about the minimum pressure the system would see. It’s about the worst-case pressure the pump can impose at its rated speed. It also isn’t simply equating discharge pressure to the system design pressure, because the pump can generate, and thus require components to withstand, pressures higher than the system’s nominal design.