All about condition monitoring
What condition monitoring is, how it relates to predictive maintenance, exactly what we measure and answers to the most common questions.
updateLast updated: 1 July 2026
Condition monitoring is the continuous measurement of the state of rotating equipment such as pumps, motors, blowers and compressors using sensors. Vibration, temperature and other parameters are analysed to detect problems such as imbalance, misalignment, bearing damage or cavitation before they lead to a standstill. The method is defined in the ISO 20816 standard.
Predictive maintenance is maintenance based on the actual condition of a machine instead of fixed intervals. Sensors continuously measure vibration and temperature; analysing that data predicts when a failure will occur, so you intervene exactly on time. Condition monitoring is the technique that makes predictive maintenance possible.
Reactive, preventive or predictive?
There are three ways to plan maintenance. Reactive waits for the failure, preventive follows a fixed calendar, predictive acts on the machine's actual condition. Condition monitoring is the predictive approach.
| Approach | When to act | Cost of unplanned downtime | Insight into wear |
|---|---|---|---|
| Reactive | Only at failure | High | None |
| Preventive | On a fixed interval | Medium | Limited |
| Predictive (condition monitoring) | Based on actual condition | Low | Continuous |
You run the machine until it fails. No upfront cost, but the downtime arrives unannounced, often at the worst moment, with consequential damage and emergency repairs.
You replace parts on a fixed interval, regardless of their actual condition. Predictable, but you sometimes replace too early or just too late.
You maintain based on what the sensors actually measure. Acting exactly when needed, not earlier, not later. That is what Ronds steers on.
What exactly do we measure?
Vibration tells you the most about a machine's health. We look at two vibration quantities plus temperature, each sensitive to a different type of emerging fault.
Vibration acceleration
Sensitive to high-frequency faults: emerging bearing and gear damage, long before they are audible.
Vibration velocity
The measure of overall machine condition, in mm/s, assessed against the limit values of ISO 20816. Also sensitive to low-frequency faults such as imbalance, alignment and loose foundations.
Temperature
Confirms friction and lubrication problems and monitors the condition of bearings and motors.
The vibration assessment follows the international standard ISO 20816 for measuring and evaluating the vibration of rotating machines.
Which faults does vibration analysis detect?
Every emerging fault has its own vibration pattern. By reading that pattern, a specialist sees not only that something is wrong, but what and how serious, often weeks to months before the eventual failure.
Imbalance
A heavy or unevenly distributed spot on the rotor. Produces a strong vibration at the rotational frequency and accelerates wear of bearings and seals.
Misalignment
Shaft and drive are not perfectly in line. Recognisable by vibrations at twice the rotational speed, often specifically in the axial direction.
Bearing damage
Early pitting and wear in the raceway reveal themselves as high-frequency peaks, long before the bearing becomes audible or noticeable.
Looseness and play
Loose bolts, worn fits or a weak foundation. Visible as a series of harmonics in the vibration spectrum.
Cavitation in pumps
When suction pressure is too low, vapour bubbles implode against the impeller. This produces a noisy, broadband signal and erodes the material over time.
Gear damage
Damaged or worn teeth in a gearbox. Cause peaks at the gear mesh frequency and the sidebands around it.