In fire protection systems, fire pumps play a critical role in delivering adequate water pressure to suppress fires during emergencies. However, ensuring that these pumps operate reliably requires routine inspection and testing. One of the most important procedures is the fire pump churn test, also known as the no-flow test.
This test evaluates the pump’s performance when operating under no-flow conditions, confirming that the pump, driver, and controller function correctly even when water demand is absent. In this article, we’ll explain what a fire pump churn test is, why it’s important, when it should be performed, and how to carry it out in accordance with NFPA 25 and industry best practices.
A fire pump churn test is a no-flow performance test designed to ensure that the fire pump and its components are working properly when the system is not discharging water. During the test, the pump runs with the discharge valves closed, allowing it to operate against its shutoff head pressure.
This test verifies three critical aspects:
Mechanical performance – ensuring the pump, driver, and controller function smoothly.
Electrical or diesel engine reliability – confirming that the driver can start and maintain the required speed.
System readiness – ensuring the pump responds correctly when activated in an emergency.
In simple terms, the churn test checks that the pump is ready to deliver water instantly if a fire occurs.
A churn test provides multiple benefits for fire safety compliance and operational reliability:
Fire emergencies are unpredictable. If a fire pump fails when needed, the entire fire protection system becomes ineffective. Regular churn testing ensures that the pump will start and run without failure.
By running the pump without flow, technicians can identify abnormal noises, vibrations, or overheating before they escalate into costly failures.
The churn test checks that the pump achieves its rated shutoff head pressure. Any deviation from expected values may indicate wear, damage, or incorrect calibration.
According to the NFPA 25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, a weekly or monthly churn test is required depending on the type of pump driver.
Consistent testing prevents unexpected breakdowns and ensures the longevity of fire pump components, including bearings, seals, and couplings.
The frequency of churn testing depends on NFPA 25 guidelines and the type of driver powering the fire pump:
Frequency: Monthly
Reason: Electric pumps are generally more reliable and require less frequent testing.
Frequency: Weekly
Reason: Diesel engines involve more moving components and fuel systems, which are more prone to operational issues.
A churn test must also be performed anytime significant repairs, replacements, or adjustments are made to the pump, driver, or controller.
When a fire pump is installed for the first time or relocated, a churn test should be part of the initial commissioning process.
To conduct a fire pump churn test safely and effectively, follow these steps:
Review the pump’s technical documentation and NFPA 25 requirements.
Ensure all test personnel understand safety protocols.
Confirm that test instruments, gauges, and sensors are calibrated.
Verify that suction valves are open and supply water is available.
Ensure discharge valves are closed for a no-flow condition.
Confirm jockey pumps are disabled to avoid interference.
Activate the fire pump manually or simulate a system demand signal.
For diesel pumps, check fuel, oil, and coolant levels beforehand.
Pressure: Record suction, discharge, and net pressures.
Speed: Ensure the pump reaches rated speed within the expected timeframe.
Vibration & Noise: Listen for unusual sounds indicating mechanical problems.
Temperature: Monitor bearing and driver temperatures to prevent overheating.
Document all readings, anomalies, and test results in a maintenance log. This helps track performance trends and detect potential problems early.
After the test, turn off the pump safely.
Return jockey pumps and system settings to normal operation.
Verify alarms and controllers are reset.
Performing a churn test often reveals early warning signs of fire pump problems, including:
Abnormal vibrations – may indicate misalignment or bearing wear.
Unusual noises – could result from impeller damage or cavitation.
Low discharge pressure – may suggest worn impellers, clogged strainers, or valve issues.
Overheating – can result from lubrication failures or motor problems.
Delayed starts – often caused by controller malfunctions or weak batteries (for diesel pumps).
By detecting these issues early, you can schedule preventive maintenance before a critical failure occurs.
NFPA 25 sets the standard for fire pump testing, inspection, and maintenance. To ensure compliance:
Follow Required Testing Frequencies
Weekly churn tests for diesel pumps
Monthly churn tests for electric pumps
Maintain Accurate Records
Keep a detailed log of all tests, including dates, results, and corrective actions taken.
Use Qualified Technicians
Testing should be performed by trained personnel familiar with fire pump systems and safety procedures.
Integrate with Preventive Maintenance Programs
Combine churn tests with flow tests, controller checks, and fuel system inspections for a comprehensive maintenance plan.
Lubricate bearings regularly according to manufacturer guidelines.
Test automatic transfer switches for diesel-driven pumps.
Inspect batteries and fuel supply before each weekly test.
Clean strainers and filters periodically to prevent flow restrictions.
Calibrate pressure gauges and flow meters annually.
A fire pump churn test is a crucial procedure for ensuring the reliability, compliance, and performance of your fire protection system. By performing these tests regularly, you can:
Verify that the pump starts and operates correctly
Detect mechanical or electrical issues early
Maintain NFPA 25 compliance
Extend the life of your fire pump system
As a leading manufacturer of fire pumps, we recommend integrating churn tests into your routine maintenance program. Proper testing not only ensures safety but also protects lives, property, and business continuity.
