A fire pump is the one piece of a sprinkler system that has to start, run, and make pressure on demand, and NFPA 25 tests it more often than anything else in the building. Chapter 8 of the Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems sets a weekly or monthly no-flow run, an annual flow test against the pump's curve, and a set of checks on the controller, driver, and power supply that go with them. This article covers the intervals, what a churn test and a flow test actually measure, the 5 percent rule for degradation, and what the record has to show.
The requirements below follow the 2023 edition of NFPA 25. The Authority Having Jurisdiction (AHJ) enforces a specific edition, and the intervals for electric pumps changed between editions, so confirm which one applies.
The schedule
| Test or inspection | Interval | What it proves |
|---|---|---|
| Weekly inspection of the pump room | Weekly | Heat, valves open, power on, fuel and oil levels, no leaks |
| No-flow (churn) test, diesel engine pump | Weekly, run for 30 minutes | Starts automatically on pressure drop, runs, makes churn pressure |
| No-flow (churn) test, electric motor pump | Monthly, run for 10 minutes; weekly where the edition's conditions apply | Same |
| Annual flow test | Annual | Pump performance at no flow, rated flow, and 150 percent of rated flow, compared to the curve |
| Controller and transfer switch tests | With the flow test, annually | Automatic and manual start, alarms, transfer to alternate power |
| Diesel engine maintenance | Annual, plus the engine manufacturer's schedule | Batteries, fuel, cooling, exhaust, lubrication |
The no-flow test
The churn test starts the pump automatically by dropping the pressure in the sensing line and lets it run against a closed system. Diesel engine pumps run weekly for at least 30 minutes; electric motor pumps run monthly for at least 10 minutes, and the 2023 edition moves them to weekly where the pump serves a high-rise, uses a limited-service controller, drives a vertical turbine, or meets the other conditions listed in the chapter. While the pump runs, the technician records the suction and discharge pressures, checks the packing glands for the slight drip they should have, and on a diesel unit watches the oil pressure, engine temperature, cooling water flow, and battery charging. A pump that fails to start on the pressure drop, or that starts and shuts down, is an impairment until it is fixed.
The annual flow test
Once a year the pump is flowed at three points: no flow, 100 percent of rated capacity, and 150 percent of rated capacity, through hose streams, a flowmeter, or a test header. At each point the technician records suction and discharge pressure, flow, and on electric pumps the voltage and amperage on each phase; on diesel pumps the engine speed. The results are plotted against the manufacturer's certified curve and the original field acceptance test. The 2023 edition treats a degradation of more than 5 percent from the pressure on the acceptance test curve, or from the nameplate, as a condition that has to be investigated, and a pump that cannot make rated pressure at rated flow is a critical deficiency. The annual test also exercises the controller in automatic and manual start, tests the alarms, and on an electric pump with a transfer switch confirms the transfer to the alternate power source under load.
Why the curve matters
A fire pump can pass every churn test for years and still be losing capacity, because churn pressure only proves the pump turns. Worn impellers, a partially closed suction valve, and a suction screen full of sediment all show up as the curve sagging at 150 percent long before they show up at no flow. That is why the flow test data is worth keeping year over year and plotting: the trend is the finding. Inspect Point produces the pump curve report from the test readings and plots it against prior years and the manufacturer's curve, and the AI Inspection Assistant flags readings that fall outside the expected range; the sprinkler trade page shows the curve report.
What the record has to show
For every no-flow test: the date, the run time, the start pressure, and the readings taken while running. For the annual flow test: the three test points with all readings, the method used to flow, the curve comparison, the controller and transfer tests, and any adjustments made. NFPA 25 requires the records to be kept by the owner for at least one year after the next test of the same type, and most AHJs and insurers want the flow test history for as long as the pump has been in service. Deficiencies and impairments found during testing follow the notification and tagging rules in the standard's impairment chapter, which the deficiencies and impairments article covers.
Common questions
Can the building engineer run the weekly test?
NFPA 25 puts the responsibility on the owner and requires qualified personnel. Many owners run the weekly churn test with trained facility staff and bring a contractor in for the annual flow test.
Does the pump have to be flowed to 150 percent every year?
Yes, unless the water supply or the discharge arrangement makes it impossible, in which case the standard allows a flow test to the maximum achievable with the limitation recorded.
The pump passed churn but failed the flow test. Which is right?
The flow test. Churn only proves the pump starts and turns. The flow test proves it delivers.
See Inspect Point run on your own inspections. A 30-minute demo, no commitment.