01
Prevent corrosion and cavitation
Track rising oil moisture caused by damaged seals, condensation, cleaning or cooler leakage before pumps, cylinders and valves are affected.
ifm · Condition monitoring
ifm Oil Condition Monitoring
Move from periodic oil sampling toward continuous condition insight by monitoring the two contamination mechanisms that matter most in hydraulic and lubrication systems: water ingress and particulate contamination. ifm combines LDH oil-humidity sensing with LDP optical particle monitoring for condition-based maintenance.
Oil moistureParticle contaminationTemperatureIO-Link on current LDH1xxPredictive maintenance
LDH humidity0…100 % RHRelative moisture saturation in oil
LDH temperature-40…120 °CCurrent LDH1xx measuring range
LDP classificationISO 4406 / SAEParticle size and count classification
Maintenance strategyCondition basedTrend oil condition instead of relying only on calendar intervals
Machine protection
Monitor water ingress and wear particles before they become machine damage
Oil condition is not one measurement. Moisture and particles indicate different failure mechanisms, so the correct architecture depends on what you need to detect.
02
Protect bearings and gearboxes
Moisture degrades lubricity while particles can indicate wear or poor filtration. Continuous trending supports planned maintenance.
03
Verify filter effectiveness
LDP particle monitoring helps show whether contamination is increasing and whether filtration is keeping the oil cleanliness under control.
04
Reduce unplanned service
Trend oil condition in mobile hydraulics and large gearboxes where unexpected downtime can cost more than the maintenance itself.
Two complementary measurements
Moisture tells you about water ingress; particles tell you about contamination and wear
The LDH1xx measures relative moisture saturation and temperature in the oil. The LDP uses optical particle measurement to classify contamination by particle size and count. Neither should be treated as a complete oil laboratory analysis on its own.
LDH1xxRelative humidity and oil temperature, with IO-Link on the current LDH112 / LDH122 generation.
LDP100Optical particle monitoring for cleanliness / contamination trending and filter-performance visibility.
Trend, don't guessUse change over time together with machine condition and oil-management limits rather than a single isolated reading.
Representative locationSensor placement must expose the device to representative, mixed oil rather than a stagnant or stratified pocket.
Current routes
Select the measurement according to the contamination mechanism
Oil moisture · IO-Link
LDH122
1/2" NPT route for relative oil humidity and temperature.
- 0…100 % relative humidity
- -40…120 °C
- IO-Link + digital output
- 0.1 % process-value resolution
Oil moisture
LDH112 / LDH1xx
G 1/2 and related family routes for the same core humidity / temperature task.
- Confirm exact process connection
- Mineral oils / synthetic esters / biodegradable oils by model
- Use current datasheet for output variant
Particle contamination
LDP100
Optical particle monitor for cleanliness classes, filter condition and wear-particle trending.
- Particle size and count
- ISO 4406:99 / SAE AS4059E classification route
- Hydraulic oils, lubricants and suitable coolants
Installation
Oil-condition data is only useful when the measurement point is representative
LDH placement matters
ifm recommends installing the humidity sensor where oil is representative and consistently surrounds the sensing element, for example near the return flow or a suitable rinse line.
ImmersionKeep the sensing element fully submerged during operation.
Flow / mixingAvoid stagnant pockets and account for possible stratification.
Heat sourcesAvoid locations where external heat can distort the temperature / humidity relationship.
Minimum oil levelInstall below the minimum level under all expected machine conditions.
Particle monitoringReview bypass / sampling arrangement and required flow conditions for the LDP installation.
Selection logic
Indicator selection by maintenance requirement
| Question | Primary ifm route | What it tells you | What it does not replace |
|---|---|---|---|
| Is water entering the oil? | LDH1xx | Relative moisture saturation + temperature | Full chemical oil analysis |
| Is particulate contamination increasing? | LDP100 | Particle size/count and cleanliness trend | Root-cause machine diagnosis by itself |
| Is the pump / bearing mechanically degrading? | VVB / VSE vibration route | Mechanical vibration / condition indicators | Oil contamination measurement |
| Do I need pressure / flow / temperature context? | Process sensors | Operating conditions around the oil circuit | Direct oil-quality assessment |
Requirement capture
Inputs required to define an oil-condition architecture
Oil typeMineral, synthetic ester, biodegradable oil and grade.
Failure concernWater ingress, filtration, wear debris, overheating or combined monitoring.
TemperatureNormal and maximum oil temperature.
Pressure / locationTank, return line, rinse line or bypass measurement point.
Existing controlsPLC, IO-Link master, analogue input or condition-monitoring system.
Maintenance targetAlarm-only, trending, predictive maintenance or filter effectiveness.