Factory acceptance testing (FAT) of oil flowmeters before delivery is a critical quality assurance step that confirms the meter meets its performance specifications before it is installed in service. During FAT, the meter is connected to a calibration test rig and subjected to a series of tests at multiple flow rates and fluid conditions that simulate the intended service conditions as closely as possible. The results are documented in a calibration certificate that becomes part of the meter's permanent documentation record and provides traceability to national or international measurement standards.
The standard FAT tests for an oil flowmeter typically include a linearity test—measuring the meter's output at 3–5 flow rates across its operating range—and a repeatability test, which confirms that the meter returns the same reading when the same flow condition is repeated multiple times. The meters are tested with a calibration fluid whose properties (typically viscosity and density) match or bracket those of the intended service fluid, or a viscosity correction is applied to extrapolate the calibration to the service fluid conditions. All test results are compared against the specified accuracy and repeatability requirements, and the meter is accepted if it meets these criteria. Meters that fail to meet the specifications are adjusted, repaired, or rejected.
Additional FAT tests may include a pressure test to verify the integrity of the meter body and seals under maximum operating pressure, a hydrostatic test at 1.5 times the maximum allowable working pressure to prove pressure containment, and a materials test to confirm that the wetted materials match the specified requirements. For hazardous area meters, ATEX/IECEx certification documentation and compliance checks must be verified. The customer's quality assurance representative or an independent inspector may witness the FAT to provide additional assurance. Taking the time to specify comprehensive FAT requirements and witness testing before accepting delivery of critical oil flowmeters reduces the risk of performance problems during commissioning and provides confidence in the measurement system from its first day in service.