The churn test is the most frequently performed fire pump test, and the one most often documented badly. Frequencies below follow NFPA 25 as adopted by your AHJ, so confirm locally.
Fire Pump Churn Test: What It Is and How Often to Run One
A churn test, more precisely a no-flow test, runs the fire pump against a closed discharge valve: churn (shutoff) pressure, no water to the system. You're proving it still starts when called and that nothing mechanical has drifted since last time. Performance is the annual flow test's job.
How often a churn test is required
Under NFPA 25 as commonly adopted:
- Diesel engine-driven pumps: weekly. Fuel, batteries, cooling and exhaust give a diesel driver more ways to fail.
- Electric motor-driven pumps: monthly in current editions. Older editions required weekly and some jurisdictions still enforce it, so check what your AHJ has adopted.
- Certain electric installations: still weekly. Pumps with limited-service controllers, vertical turbine pumps, and pumps serving buildings beyond what the fire department can supply by pumper stay on a weekly no-flow test.
Run time is typically 10 minutes for electric and 30 minutes for diesel.
What the test involves
- Notify the monitoring company and building management.
- Confirm the pump starts automatically on a pressure drop. Don't hit the manual start; automatic start is what you're proving.
- Run it for the required duration.
- Record suction and discharge pressure.
- Check the packing glands for a slight, steady drip. No drip means the packing is overtightened and the shaft will overheat.
- Check bearing temperature, and listen for unusual noise or vibration.
- For diesel: oil pressure, water and oil temperature, RPM, fuel level, battery condition, exhaust system.
- Confirm it shuts down cleanly and the system returns to normal.
- Document the readings and restore monitoring.
What to record
An inspector-proof record covers date and time, who ran it, the pump identifier, whether the pump started automatically, suction and discharge pressure, run duration, and any deficiency with its corrective action. Diesel adds the engine readings.
Frequency is what makes this painful. A weekly diesel test is 52 records a year per pump, and paper logs quietly fall apart across a portfolio. They're also the first thing an AHJ asks to see.
The trend line is where those records pay off. A tech running Friday churn tests on a hospital diesel pump logs 132 psi at churn one week, 128 the next, then 121. Any one of those readings passes on its own. Read as a line, they don't — the wear rings are opening up. Catch that at week three and the pump comes out on a scheduled Tuesday, not during a fire watch.
Common deficiencies
- Pump started manually, so automatic start was never proven
- No packing gland drip, or excessive drip
- Churn pressure drifting from prior readings, an early sign of impeller or driver trouble
- Diesel batteries weak or not holding charge
- Readings captured but never trended, so a slow decline goes unnoticed
Churn test vs annual flow test
The churn test proves the pump runs. The annual flow test proves it still performs: you flow water at 100% and 150% of rated capacity and compare against the original manufacturer's curve. A pump can pass churn every week for a year and still fail its annual flow test. Installation and acceptance live in NFPA 20; everything above is NFPA 25.
Frequently asked questions
Can building staff perform the churn test?
Many jurisdictions allow trained building personnel to run the no-flow test, leaving periodic and annual testing to a qualified contractor. Check with your AHJ.
Does the churn test need to be witnessed?
Usually not, though the record still has to exist and be available. Annual flow tests get witnessed far more often.
What if a weekly test is missed?
Document why, run it as soon as practical, and note the gap. An unexplained hole in the log is worse than a documented one.
Software built for fire pump records
Essential is all-in-one fire pump testing software. Churn tests schedule themselves, readings get captured on mobile, and churn pressure trends across tests so drift surfaces long before the annual flow test finds it.
