pump — vibration_health (accelerometer-bearing)
Physics
Section titled “Physics”A centrifugal pump’s shaft runs in rolling-element bearings; imbalance, misalignment, and developing bearing defects each inject mechanical energy into the bearing housing at characteristic frequencies (1x/2x running speed for imbalance/misalignment, and BPFO/BPFI/BSF/FTF defect frequencies that scale with running speed and bearing geometry once a race or rolling element starts to pit). A piezoelectric accelerometer bolted to the bearing housing senses this as broadband acceleration; integrating to velocity and taking the RMS over the 10-1000 Hz band (per ISO 20816-3) gives the overall severity number, while narrowband FFT peaks at 1x/2x shaft speed and at the bearing defect frequencies explain why the RMS moved. Typical pump bearing defect frequencies run 3-10x running speed; at a common 1800-3600 RPM (30-60 Hz) pump motor speed that puts the highest fault frequency of interest in the few-hundred-Hz range, so the accelerometer itself is sampled at 4000 Hz (>>2x that, with headroom for harmonics), while the edge node aggregates this down to 1 Hz velocity-RMS features and a periodic (e.g. hourly) spectrum snapshot for the historian, since raw high-rate waveform does not need to leave the sensor node continuously.
Sensor
Section titled “Sensor”- Spec: piezoelectric accelerometer, IEPE/4-20mA output, 0.5-10 kHz bandwidth, top-mount or side-mount stud/magnetic
- Signal: scalar (mm/s), range n/a
Example parts
Section titled “Example parts”- ifm electronic VSE100 vibration sensor with integrated 4-20 mA velocity RMS output — screw-mount accelerometer with onboard velocity integration; confirm thread (M8/M10) against the pump’s tapped mounting boss
- Banner Engineering QM30VT1 vibration/temperature sensor (velocity RMS + bearing temperature in one housing)
- PCB Piezotronics 622B01 industrial ICP accelerometer (100 mV/g, 0.5 Hz-10 kHz)
Mounting
Section titled “Mounting”Stud-mount or adhesive-mount the accelerometer directly on the pump’s outboard bearing housing, radially (perpendicular to the shaft), at the point closest to the bearing itself and on a flat, clean, unpainted metal surface for good high-frequency coupling. Torque a stud-mount sensor to the manufacturer’s spec; a loose or adhesive-only mount attenuates the high-frequency bearing-defect energy before it reaches the accelerometer.
Wiring
Section titled “Wiring”2-wire shielded IEPE cable (constant-current loop) to a dedicated vibration input module on the edge box; for a 4-20 mA output part, wire to a standard analog current-loop input instead. Keep the vibration cable run separated from motor power/VFD cabling to avoid electrical noise coupling into the high-frequency signal.
Validation
Section titled “Validation”with the pump running at normal load, compare the detector’s reported velocity-RMS value against a handheld calibrated vibration meter placed at the same point on the bearing housing
Expected: detector velocity-RMS within +/-10% of the handheld meter reading, and the reported ISO 20816 zone matches the zone the handheld reading falls into for the configured iso_group/support
Safety notes
Section titled “Safety notes”- de-energize and lock out the pump motor starter (LOTO) before mounting a stud-type sensor that requires drilling or tapping the bearing housing
- verify the pump is not handling a hazardous or high-temperature process fluid before working near the housing; let a hot pump cool or use PPE rated for the surface temperature
- route and strain-relieve the sensor cable clear of the rotating shaft and coupling guard so it cannot be caught by the rotating assembly
150–650 USD, difficulty 3/5, ~30 min install downtime.