Ruhrpumpen’s Fire Campus

Operation Within 150% of the Rated Pump Curve

According to NFPA 20, fire pumps are permitted to operate at any point along the pump curve up to 150% of the rated flow capacity. This provision offers flexibility in system design and operation, allowing pumps to accommodate variable flow demands without compromising performance or certification.

Key Points:

• Rated Flow vs. Duty Point:

The rated flow is the flow rate at which the pump is officially listed or certified. The duty point, however, may sometimes exceed this value to meet specific system requirements. NFPA 20 allows pumps to safely operate up to 150% of their listed flow, provided the pump curve supports this range.

• Performance and Safety:

Operating within 150% of the pump curve ensures that the pump can deliver the necessary pressure and flow for effective fire suppression while maintaining mechanical integrity and reliability.

• Testing and Certification:

Fire pumps certified under NFPA 20 undergo rigorous testing across their operating range. This testing includes flows up to 150% of the rated capacity, verifying the pump’s ability to perform reliably without excessive vibration, overheating, or mechanical failure.

• System Design Flexibility:

This allowance enables designers to select pumps that can handle variations in system demand, accommodating future expansions or higher-than-anticipated flow requirements without the need for immediate equipment replacement.

Practical Implications

For projects where the duty point exceeds the listed flow rate, engineers and system designers can confidently specify pumps within the 150% operating range. This approach optimizes system efficiency and cost while ensuring compliance with safety standards.

For example, a pump listed at 3,500 GPM may be operated at a duty point of 4,000 GPM (approximately 114% of the rated flow) in compliance with NFPA 20, enabling tailored fire protection solutions without compromising performance.

Conclusion

NFPA 20’s allowance for fire pump operation up to 150% of the rated pump curve offers critical flexibility in fire protection system design and operation. By adhering to these guidelines, engineers and safety professionals can ensure that fire pumps deliver optimal performance, reliability, and compliance under varying operational conditions.