11.1 Weekly Diesel (30-Minute) & Weekly/Monthly Electric (10-Minute) No-Flow (Churn) Tests

Select frequency from the installed category

A no-flow or churn test demonstrates starting and short-duration operating readiness without discharging the rated test flow. It does not establish that the pump can meet the system's hydraulic demand. NFPA 25 (2023), 8.3.1 and 8.3.2, separates frequency from duration: first determine when this pump must be tested, then run it for the required minimum time and make the pertinent observations.

Diesel pumps normally require weekly no-flow testing, with a minimum 30-minute run. An approved risk analysis can establish the permitted alternative frequency. Do not call a longer interval acceptable merely because the engine is new or has remote indication. The risk-analysis approval and applicable automated-test provisions must actually be satisfied.

Electric pumps run at least 10 minutes. The weekly categories include pumps serving buildings beyond fire department pumping capacity, pumps with limited-service controllers, vertical turbine pumps, and pumps taking suction from ground-level tanks or sources without materially useful pressure in the pump's absence. Monthly testing is permitted for other electric pumps and for the specified redundant-pump arrangements. An approved risk analysis is another permitted basis. A VFD or phase-monitoring indicator is not, by itself, the criterion allowing every electric pump to move to monthly testing.

Prepare the correct valve positions

Check the pump room and weekly inspection items, controller mode, source availability, and drainage. Keep normal suction, system discharge, and bypass control valves open as prescribed. Keep test-header outlets and test valves in their specified closed position for a no-flow test. Closing the system discharge valve merely to create “zero flow” can isolate the building from its pump. No-flow describes the absence of test demand; it does not authorize blocking the normal protective supply.

Verify the applicable cooling and relief arrangements. A small circulation-relief discharge can be necessary to prevent overheating. It is different from intentional rated-flow testing and from a main relief valve opening improperly. Observe actual temperatures and discharge. Stop or correct unsafe conditions through the proper procedure rather than continuing a timed run while the pump overheats.

Initiate automatically and observe

Start the pump automatically through the prescribed test means, such as the provided pressure-drop arrangement for a pressure-actuated controller. Record start pressure and response. A manual-start test alone does not establish pressure-start operation. Do not open an energized electric controller or defeat a pressure sensor to produce the required event. Use approved external controls and instruments and arrange qualified work for any limitation.

Qualified personnel attend the test unless the complete remotely monitored automated-test provisions apply. A timer alone does not replace attendance and observations. Watch for leakage, abnormal noise, excessive vibration, packing or seal problems, cooling issues, and driver/controller abnormalities. For diesel equipment, observe lubrication and cooling indications, fuel supply, batteries/charging, and exhaust/ventilation as applicable. For electric equipment, record the available external electrical information and phase/controller status.

A normal-looking discharge gauge does not establish adequate suction or correct speed. Record the relevant suction and discharge pressures, driver speed where required, and the other specified observations. Compare with prior tests to identify trends. If a new vibration develops, finish the safety response and evaluate the cause; do not label it harmless merely because the pump completed ten minutes.

Timing and stopping

Run an electric pump for at least ten minutes and a diesel pump for at least thirty minutes under the applicable procedure. Record actual start and stop times. A five-minute diesel test is incomplete even if the engine starts instantly. Follow manufacturer instructions and the approved controller arrangement for stopping and any necessary cooldown. Do not invent a universal cooldown duration for every engine or alter the controller's stopping logic during the visit.

Restore and classify

Confirm the controller is in the required automatic mode, supply and system valves are normal, test connections are closed, cooling and drainage arrangements are restored, and alarms/monitoring are normal. Notify the responsible parties that the test is complete and identify any remaining loss of protection. Preserve the results and access limitations in the record.

A failed automatic start can be an impairment even if someone can force the pump to run manually. An unusual indication requires evaluation of actual system effect. Apply Chapter 15 when protection is out of service and arrange the required corrective work and retest. Passing the churn test does not excuse a failed annual flow test or an inadequate supply.

Source checked October 19, 2026: NFPA 25 (2023), 8.2, 8.3.1, and 8.3.2.