1. Weekly No-Flow (Churn) Test:
Purpose: This test is primarily designed to ensure the engine starts reliably and runs properly for a minimum duration without actually flowing large amounts of water through the system piping. It verifies the readiness of the engine, batteries, fuel supply, and basic pump operation.
Procedure: The pump is started and run without discharging water through the main fire protection system piping. Water typically circulates within the pump casing or through a small bypass line (using the circulation relief valve) to prevent the pump from overheating due to lack of flow (churn).
Duration: For diesel engine-driven pumps, NFPA 25 typically requires this test to be run for at least 30 minutes.
What’s Checked: During this test, personnel should observe and record:
Successful automatic or manual start.
Engine operating parameters (oil pressure, coolant temperature, speed/RPM).
Battery charging system operation (voltage and amperage readings).
Time taken for the engine to reach operating speed.
General condition (leaks, vibrations, unusual noises).
Fuel level.
Discharge pressure (at churn conditions).
Operation of the circulation relief valve (ensuring some water is flowing to prevent overheating).
2. Annual Flow Test:
Purpose: This is a much more comprehensive test designed to verify that the fire pump and its water supply can meet the system’s hydraulic demand. It confirms the pump’s performance across its operating curve (pressure and flow capabilities).
Procedure: Water is flowed from the pump through designated test outlets (like a test header with hoses and nozzles, or sometimes flowed back to the water source like a tank or reservoir if designed for it). Measurements are taken at specific flow rates.
Flow Rates Tested: The test typically involves measuring the pump’s performance at three key points:
No-Flow (Churn): Verifying maximum pressure at zero flow.
100% Rated Flow: Ensuring the pump delivers its rated water volume (GPM or L/min) at its rated pressure (psi or bar).
150% Rated Flow (Overload): Confirming the pump can deliver 150% of its rated volume at a pressure not less than 65% of its rated pressure (as per typical pump curves).
What’s Checked: During this test, personnel measure and record:
Suction pressure.
Discharge pressure.
Flow rate (using flow meters or pitot gauges).
Engine speed (RPM).
Engine operating parameters under load (oil pressure, coolant temperature).
Time taken to reach stable operating conditions.
The performance is compared against the pump’s original certified shop test curve and the results from the initial field acceptance test to detect any degradation.
Additional Information can be found on these YouTube links listed below.