The core reason NFPA 20 and EIT Standard specifies fire pump characteristics is to guarantee that a fire pump will be reliable, predictable, and safe during a fire.
There are three critical performance points on the pump curve:
- Shutoff point (Zero Flow, or Churn point)
- Rule: Pressure must not exceed 140% of the pump’s rated pressure.
- Why: This is a safety limit to prevent the pump from over-pressurizing and damaging the system piping.
- Rated Point (100% Flow)
- Rule: The pump must deliver its rated flow at its rated pressure.
- Why: This is the primary design point for the fire protection system.
- Overload Point (150% Flow)
- Rule: Pressure must not drop below 65% of the pump’s rated pressure.
- Why: This ensures the pump can still provide enough pressure and flow even more-than-designed scenario where many sprinkler heads or fire hoses have activated.
Related notes:
Centrifugal pump characteristic curve – HQ curve
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