Britvic’s soft-drinks plant in Rugby put vibration sensors on 107 LKH hygienic centrifugal pumps. Within months, analytics flagged a developing impeller issue. The team fixed it in a planned stop in about 45 minutes instead of an estimated six hours unplanned, about 288,000 bottles lost, four hours of extra CIP, and about 2,000 litres of water. Chris Heslop said that notification paid for the hardware and first-year analytics (Automation News; Alfa Laval case).
Britvic is a useful example of why asset selection matters in pump condition monitoring: one detectable, high-consequence fault created most of the visible economic value. It does not say which five pumps to instrument first when mounts, CapEx, and overnight response are limited. Start with a gate, then rank only the assets that pass.
Pump condition monitoring: gate first, then rank passers
Criticality alone is insufficient. Tiddens, Braaksma, and Tinga filter on failure frequency and consequence, reject undetectable-in-time failures, then test feasibility (IJPHM 2018). Technique selection also weighs detectability, noise, and existing signals (IJPHM).
Gate (any NO excludes the asset from the CBM pilot):
- Predictable failure / precursor? Does this failure mode show a measurable signature before failure?
- Enough warning time? Is that lead time long enough for a planned intervention in your plant?
- Can the plant act in time? Is there an owner, a feasible maintenance response, and enough authority and time to intervene before functional failure?
Separate two ideas:
- Fault detectability: does the failure mode have a measurable precursor at all?
- Measurement feasibility: can this plant get that signal clean and stable (networked VFD current, CIP-surviving mount, duty tag)?
Existing VFD logs or a realistic mount raise feasibility, not a precursor. An unowned weekend inbox fails gate 3.
Then rank assets that pass on three factors from your logs (High / Medium / Low; do not multiply ordinals): annual consequence (scrap, lost product, CIP, restart, downstream idle); failure frequency; instrumentation feasibility (clean, stable signal under washdown and duty).
Tie-breaker when many pass with similar ranks: start with high-consequence, high-frequency equipment. When candidates look similar, prefer the one that already has a stable signal and needs less new instrumentation. That cuts 15 passers to five without a fake score.
Two pumps, similar downtime cost, opposite CM value
Pump A feeds syrup to multiple fillers. High annual consequence. Gradual impeller/bearing wear with housing vibration rising for weeks before past failures (detectability pass). Named night-shift owner and a feasible response in the warning window (act-in-time pass). Networked drive current and CIP-stable mount (feasibility High). Gates: all YES. Rank: High / Medium / High. First-five candidate; existing signal wins ties against same-rank peers.
Pump B can stop a utility header with similar downtime cost. Sudden jams and seals with little precursor (detectability fail). Alerts land in an unowned inbox with no one able to act before the line forces the stop. Gates: NO on precursor and act-in-time. Exclude from the CBM pilot. B needs redundancy or faster changeout; sensors cannot invent warning time.
Reader offer · ends November 11Where is the hidden cost in your factory?Watch it with 3 months of Premier free →After you pick: why current and vibration mislead
Motor current does not only respond to failures; it responds strongly to operating load. Raise flow or head and torque rises; stator current rises. Cut speed or lighten the duty and current falls. Under developing cavitation, hydraulic load can drop so RMS current falls while spectral content changes (Luo et al., AME 2015). Quieter current is not automatically healthier: it may be a new recipe, CIP, or cavitation.
For engineers looking deeper, some impeller and bearing faults also create identifiable sidebands in the motor-current spectrum. The difficulty is that VFD speed and hydraulic load move those patterns too, which is why a fixed spectral rule can generate false alarms unless duty is included. LoPoFIA found impeller faults clearer at high flow and bearings clearer at low flow (Becker et al., Energies 2021; IEEE TIA 2021).
Vibration has the same duty problem. ISO 10816-7 evaluates rotodynamic pumps above 1 kW on bearing-housing vibration by magnitude and change from a known condition. A single RMS trip tuned on fill duty often fires in CIP, speed, or recipe shifts. Operators start ignoring alarms, and the value of the pump condition monitoring system collapses even if the hardware is working correctly.
Boundaries: when vibration, mounts, and VFD current stop paying off
ISO 10816-7 excludes positive-displacement, slurry/submersible, and large hydro units. Vibration is low value with no mechanical precursor, intermittent duty, or structural noise dominating the housing. Mount near bearings and establish and trend against a known-good baseline (r/AskEngineers). Kits on low-consequence redundant utilities often fail without an interpreter or work-order path (r/IndustrialMaintenance).
VFD current alarms poorly when speed or load change without a state tag, or when CIP and production share one threshold. Lab mics track cavitation, but plant noise contaminates them (Al-Obaidi, Archives of Acoustics 2023). On a noisy floor, sound is a supporting screen, not a sole tear-down trigger.
What Britvic discloses (and what you still must fill)
Disclosed: Rugby 24/7; hundreds of pumps; 107 LKH; vibration via CM Connect; impeller alert within months; ~45 min planned versus ~6 h unplanned; ~288k bottles; ~4 h CIP / ~2,000 L water; Heslop payback quote (Automation News; Alfa Laval).
Not disclosed: alert rule, anomaly-to-stop lead time, spectral evidence, impeller verification, CapEx, bottle/water calc, which pump, operating state at alert, false-alarm history. Fill those in the gate and rank.
Signal comparison after the gate
| Factor | Vibration | Motor current | Acoustic |
|---|---|---|---|
| Install | Near-bearing mount | Often in VFD/MCC logs | Easy mic; hard noise isolation |
| Washdown | Must survive CIP | Better when body mounts limited | Site-specific sealing |
| Precursor modes | Bearings, imbalance, impeller | Impeller clogging/cracks, bearings, cavitation | Cavitation (lab) |
| Process sensitivity | High if baseline ignores duty | High: flow/head/speed | High on noisy floors |
| Baseline need | Magnitude + change (ISO) | Duty tag (Becker) | Quiet reference rare live |
| False-positive risk | Fixed trips across CIP/speed | Load change vs fault | Ambient plant noise |
| Existing data | Often limited unless a route or fixed system already exists | Often if drives networked | Rarely archived |
Illustrative expected value (not Britvic’s numbers)
PdM cases treat detection probability and false alarms as first-class: sensitivity cuts surprise breakdowns; specificity protects trust (WCM PdM business case).
Expected annual value ≈ failure frequency (/y) × avoidable downtime hours × line contribution ($/h) × P(early detection)
This is gross expected avoided-loss value; sensor, software, and maintenance costs are not yet subtracted.
Plant X (hypothetical): Pump A 0.5/y × 6 h × $4,000/h × 0.7 ≈ $8,400/y. Pump B 1.0/y × 6 h × $4,000/h × 0.1 ≈ $2,400/y. Frequency prefers B; detection probability reverses the ranking. Use your logs. Optional: NLN-EMP labeled vibration and current.
Ranking sheet (copy for the first five)
| Pump ID / duty | Precursor? | Warning time? | Can act in time? | Pass? | Annual consequence | Failure frequency | Instr. feasibility | Primary signal | Duty tag |
|---|---|---|---|---|---|---|---|---|---|
| Y/N | Y/N | Y/N | H/M/L | H/M/L | H/M/L | ||||
Keep the top five passers for hardware. When more than five share the same H/M/L ranks, apply the tie-breaker: high consequence and high frequency first, then the asset with a stable existing signal and less new instrumentation. Over 30-60 days, count alerts that match real degradation, process-state dismissals, hours from alert to planned work, and whether planned work replaced an unplanned stop.
The best first asset is not necessarily the pump with the highest downtime cost. It is the high-consequence pump whose failure gives you a usable warning, and where the plant can still do something with that warning.
Sources
- Automation News: Britvic
- Alfa Laval Britvic case
- ISO 10816-7:2009
- Becker et al., Energies 2021
- Becker et al., IEEE TIA 2021
- Luo et al., AME 2015
- Al-Obaidi, Archives of Acoustics 2023
- Tiddens et al., IJPHM 2018
- CM technique selection, IJPHM
- WCM PdM business case PDF
- NLN-EMP dataset
- r/AskEngineers sensor placement
- r/IndustrialMaintenance BOP vibration
