NFPA 20 requires the discharge components to be capable of handling the maximum total discharge head at what condition?

NFPA 20 requires the discharge components to be capable of handling the maximum total discharge head at what condition?

• A. Idle speed
• B. Zero speed
• C. Start-up speed
• D. Rated speed

Answer: (D)

The key idea is that discharge components are designed for the pump’s defined operating point. NFPA 20 requires that the discharge piping and fittings be able to withstand the maximum total discharge head the pump can generate at its rated speed. This is the pressure the system is expected to experience during normal operation when the pump is delivering its rated flow, including static head plus friction losses (and velocity head at the discharge). Why this is the best choice: rated speed represents the pump’s designated design condition. At other conditions—idle, zero speed, or startup—the system pressure is not steady-state and is not the intended design point for the discharge hardware. By sizing for the maximum head at the rated speed, you ensure the discharge components can safely handle the actual operating pressure the system will see during normal use. Transient spikes can occur, but NFPA 20’s requirement targets the steady-state maximum at the rated operating point.

The key idea is that discharge components are designed for the pump’s defined operating point. NFPA 20 requires that the discharge piping and fittings be able to withstand the maximum total discharge head the pump can generate at its rated speed. This is the pressure the system is expected to experience during normal operation when the pump is delivering its rated flow, including static head plus friction losses (and velocity head at the discharge).

Why this is the best choice: rated speed represents the pump’s designated design condition. At other conditions—idle, zero speed, or startup—the system pressure is not steady-state and is not the intended design point for the discharge hardware. By sizing for the maximum head at the rated speed, you ensure the discharge components can safely handle the actual operating pressure the system will see during normal use.

Transient spikes can occur, but NFPA 20’s requirement targets the steady-state maximum at the rated operating point.