The churn test described is performed on which pump configuration?

• A. Horizontal split-case diesel fire pump
• B. Vertical turbine electric pump
• C. End-suction diesel pump
• D. Radial flow pump

Answer: (A)

Churn testing is a preparatory check of a diesel engine-driven fire pump to ensure the priming and lubrication systems operate correctly before a full test. It involves running the unit with the discharge valve closed so water in the suction and priming path circulates, allowing air to be purged and the priming pump and bearings to be checked.

This procedure is most commonly described for a horizontal split-case diesel fire pump because this configuration provides easy access to the priming line and a clear view of the pump internals, making it straightforward to bleed air, verify priming, and confirm smooth operation before moving on to heavier testing. Other configurations, like vertical turbine electric pumps, end-suction diesel pumps, or radial flow pumps, don’t present the same convenient priming setup, so churn testing isn’t the standard approach for them.