Fire Pump Performance Test: Annual Flow Test Procedure (NFPA 25)

The fire pump is the heart of the protection system. The annual flow test proves the pump still operates on the NFPA 20 performance curve. NFPA 25 Chapter 8 mandates it yearly. In many facilities this gets reduced to 'dumping some water' — but it is a technical measurement procedure. Here is how to do it correctly.

Purpose

Prove the pump still operates on its original performance curve. NFPA 20 defines three points:

• Churn (shutoff): 0% flow, ~140% rated pressure
• Rated: 100% flow, 100% rated pressure
• 150%: 150% flow, ≥65% rated pressure

Annual measurement of these three points proves the curve has not dropped. A drop indicates wear, cavitation or impeller damage.

Equipment Setup

1. Test header / hose manifold: Branched off pump discharge; 4-6× 2.5" hose connections
2. Pitot gauge: Measures jet from each hose end via 2.5" playpipe nozzle
3. Flowmeter (optional, recommended): Direct flow measurement alternative to pitot
4. Suction and discharge gauges: Must be calibrated (annually)
5. Flow table: NFPA 20 Table 7.4.2 pitot-to-flow conversion

Test Procedure

1. Pre-check: Pump room clean, bleeders open, gauges zeroed
2. Churn: All discharge valves closed, start pump, run 5 min, record pressure
3. 100% flow: Open 2-3 hoses, adjust flow to rated value (pitot), record pressure
4. 150% flow: Open more hoses, bring flow to 150% rated, record pressure — must be ≥65% rated pressure
5. Shutoff: Close valves gradually, run pump 2 min for cooling, then stop
6. Report: Plot the three points and compare to original curve

Interpretation

If measured points fall >5% below original curve, internal inspection required. Disassemble pump; check impeller, wear ring, shaft seal. 10%+ drop = immediate action. Increases usually indicate gauge error or RPM drift in diesel pumps.

Field Cautions

• Discharge during test must not exceed drainage capacity — test drain sizing is critical
• Diesel pumps: monitor exhaust and fuel system during warm-up
• A test with out-of-calibration gauges invalidates the report
• Failed test: notify AHJ + insurer, initiate out-of-service procedure

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