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Frequently Asked Questions
Why is a flow test necessary?
Because a pump can start and build pressure while having lost significant capacity. Only running it at rated and peak flow and comparing against the original curve reveals that. A weekly no-flow run proves the set starts; it proves nothing about whether it can still deliver the design duty.
Why test beyond rated flow?
Because peak flow is the condition that matters in a real fire, when many outlets are open, and it is where degradation shows first. A pump can meet its rated point and fall short at peak, so testing only at rated capacity gives false reassurance about the case the system exists for.
How is flow measured during the test?
By a flow meter in the test line, or by pitot readings taken at the test header outlets, combined with suction and discharge pressure gauges. Those readings produce the points plotted against the original acceptance curve, which is what turns a test into evidence rather than an observation.
What is a closed-loop flow meter?
An arrangement that measures flow while returning the water to the suction supply rather than discharging it, which avoids wasting large volumes and simplifies testing where discharge is impractical. Many authorities still require periodic open discharge testing as well, to prove the suction supply itself can deliver.
Where should a test header be located?
Where the discharged water can go safely without causing damage, flooding or a hazard - typically an external wall with a clear discharge area. Access for hoses and for the personnel conducting the test is part of the siting decision, and it is easier to get right at design stage than afterwards.
How often should flow testing be done?
Annually is typical, alongside more frequent no-flow running, though the exact regime follows the governing code and the authority having jurisdiction. Results are recorded and compared over time, since the trend across successive tests is often more informative than any single result.
What does a failed test usually indicate?
Most often a suction supply problem, a partly closed valve, or wear ring clearance loss in the pump. Because the whole system is tested together, a poor result identifies that something is wrong rather than what - which is why suction pressure is recorded alongside discharge as part of the same test.