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. This article shows 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, not more than 140% of rated pressure (101–140% for listed pumps; FM Global DS 3-7 3.1.5)
• 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.

FM Global DS 2-81 (2.9.5) calls for the same annual performance test at three points: churn, rated capacity and maximum pump capacity. At each point record suction and discharge pressure, flow and speed, plus voltage and current for electric pumps. Compare the results with the manufacturer's curve and earlier tests; if a flow meter is used, calibrate it every 3 years. For diesel pumps, speed at rated flow must be within 10% of rated speed.

Equipment Setup

1. Test header / hose manifold: Branched off pump discharge; typically 4–6 × 2.5" hose connections
2. Pitot gauge: Measures the velocity pressure of the jet at each hose end, used with a 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 Annex A.14.2.6.3 pitot-to-flow formula and worked example

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 net pressure at any flow point is below 95% of the original curve, the result is unacceptable; the owner is notified in writing and the cause is investigated (NFPA 25-2026 8.3.7.2.3–8.3.7.2.4). The investigation may involve disassembling the pump to check impeller, wear ring and shaft seal. Failure to provide the maximum system demand is an impairment; degraded performance that still provides the maximum system demand is a noncritical deficiency. An unexpected increase usually points first to gauge error; on diesel pumps speed drift can give the same picture.

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 the AHJ and insurer, start the out-of-service (impairment) procedure and plan interim measures (fire department connection, temporary pump) until repair is complete

Annual Flow Test Form

The form below has one row for each of the three measurement points in the “Test Procedure” section.

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