The sensors we use
Oil condition, machine vibration and temperature are measured with six types of sensor. Which ones are needed depends on the machine and the risk to be monitored. All sensors connect to the same monitoring system.
Viscosity and oil condition sensor
It measures the oil's viscosity, density and dielectric value. It shows whether the oil is thickening, thinning or ageing. It gives the first warning of fuel dilution or a suspected coolant leak.
- Viscosity: 1–1000 cSt (±5%)
- Density: 600–1250 kg/m³ (±3%)
- Dielectric constant: 1–6 (±3%)
- Fitted on the sump or the oil circulation line. In hydraulics, on the return or bypass line (max. 15 bar)
Moisture-in-oil sensor
It measures dissolved water in ppm and saturation as water activity (aw). It shows coolant leaks, seal problems and condensation before the oil turns cloudy.
- Dissolved water: 0–5000 ppm
- Water activity: 0–1 aw (±0.03)
- It also measures oil temperature.
- Fitted on the oil tank or the circulation line
Particle counter
It counts solid particles in the oil. It reports the result as an ISO 4406 cleanliness code. It shows filter failure and contamination from dust or worn seals. It matters most where hydraulic valves and pumps are in use.
- Counting range: 1–100 µm
- Output: ISO 4406 code
- Fitted on the return or bypass line of the hydraulic unit
Wear-metal sensor
It counts ferrous and non-ferrous metal particles in the oil and follows their size distribution. It shows rising gear and bearing wear as a trend. It does not identify which metal a particle is.
- Output: wear-particle count and trend
- Fitted on the gearbox oil line
Vibration sensor
It measures vibration on the machine housing as RMS velocity (mm/s). It shows rising vibration from imbalance, looseness or bearing problems. It does no spectrum (FFT) analysis.
- Measurement: overall RMS velocity
- Reference: ISO 20816-3, ISO 10816-7 for pumps
- Fitted on motor and pump bearing housings
Temperature sensor
It measures bearing, housing and oil temperature. It shows heat from lubrication, load or cooling problems early. It is read together with vibration and oil data.
- Measurement: bearing, housing and oil temperature
- Fitted on bearing housings and the oil tank
Mounting the oil sensor
Oil sensors screw into a threaded port on the oil line or the sump. The measuring probe sits in the oil and measures the flowing oil continuously. A sealing ring keeps the connection tight.
- 1Connector · The sensor cable connects here
- 2Sensor body · Stays outside the oil line
- 3Sealing ring · Prevents oil leaks at the connection
- 4Oil line · The sensor screws into the pipe or sump wall
- 5Measuring probe · Sits in the flowing oil and takes the measurement
- 6Oil flow · The probe measures the oil passing through the line
What we do not measure: metal identification (which metal a particle is), acid and base number (TAN/TBN) and vibration spectrum analysis (FFT). These tests need a laboratory and a specialist. DataMonitor does not replace them. It works alongside them. The system watches for warning signs and gives early warning. It does not diagnose faults.
The sensors required for the machine are defined on site and listed in the quote.