These three terms get used interchangeably on site, which causes real confusion when scoping a test or reading a quote. They describe different things, but they’re nested — understanding how they fit together tells you exactly what you’re paying for and what your NOC record needs.
Side by side
| Churn (no-flow) test | Flow test | Annual performance test | |
|---|---|---|---|
| Water flowing? | No — pump runs at shut-off | Yes | Yes (plus the no-flow point) |
| What it measures | Auto-start, shut-off pressure, relief valve, packing, bearings | How much the pump can deliver | Net pressure at churn, 100% & 150% vs the certified curve |
| Frequency | Weekly (diesel/VT) or monthly (electric) | Term for any flow-based test | Annually (+ 3-yearly hose-stream verification) |
| What it proves | The pump starts | The pump moves water | The pump still meets its duty |
| Used for NOC / insurance? | Logged, but not sufficient alone | — | Yes — the primary record |
How they nest together
Think of it as one curve with three marks on it. The churn point is the far-left, zero-flow end. The 100% rated point is the middle — the primary acceptance check, where net pressure must be within 95% of the certified curve. The 150% peak point is the far right, where the pump must still hold at least 65% of rated head and where a weak suction supply reveals itself. A flow test that captures all three and plots them against the manufacturer’s curve is the annual performance test.
So which one do you actually need?
For routine readiness, the churn test on its weekly/monthly cycle confirms the pump will start. For compliance — Fire NOC renewal, insurance, and proof the pump can perform — you need the annual full-flow performance test. A churn test alone is necessary but not sufficient; it can’t tell you whether a worn impeller has quietly cost you 20% of your capacity, because that only shows up under flow.
Want the test that proves performance, not just start-up? Elion runs the full three-point performance test with NABL-calibrated instruments and delivers the plotted curve your NOC and insurer expect.
Frequently asked questions
What is the difference between a churn test and a flow test?
A churn test runs the pump at shut-off with no flow to confirm it starts and holds pressure; a flow test runs water through the pump to measure delivery. The churn reading is the zero-flow point of the full performance test.
Is a performance test the same as a flow test?
The annual performance test is a flow test taken at three defined points — churn, 100% and 150% — and plotted against the certified curve. “Flow test” is the broader term for any test where water moves.
Which test do I need for Fire NOC?
The annual full-flow performance test — it proves the pump still meets duty and is the record NOC and insurance reviews rely on.
Does a monthly churn test replace the annual test?
No. The churn test confirms the pump starts; only the annual performance test confirms it can still deliver rated head at peak demand.