Watch the reservoir, save the pump
Know the reservoir level before the pump runs short. Gill capacitive hydraulic oil level sensors measure continuously along the probe, with no moving parts in the sensing mechanism, delivering dependable level measurement for plant, presses and mills working in demanding conditions.
A leak shows up in the reservoir first
Hoses chafe, seals weep and fittings loosen. On mobile plant, presses, mills and steering systems, a falling reservoir level is often the first measurable sign of a leak, ahead of a pressure fault. A continuous level signal lets the control system warn early, or stop the machine before the pump runs short of oil.
Heat and constant movement. Hydraulic reservoirs run hot, and the oil level moves every time a cylinder extends or retracts. The sensor needs a signal the system can average and trend.
Harsh mounting positions. Reservoirs on mills, crushers and mobile plant see vibration, shock and dust. The sensor body, seals and cable have to match the machine.
Your liquid.
The right fit.From tank dimensions to output and supply voltage, share the details and our engineers will help you find the sensor configuration that fits.
Dependable reservoir level measurement, without the moving parts
A falling reservoir level is often the first sign of a chafed hose, a weeping seal or a loose fitting. Catch it late and the pump draws air, pressure drops and the machine stops, while a float switch in hot, moving oil can stick or report only a single trip point.
Gill capacitive hydraulic oil level sensors take a different approach, measuring hydraulic oil continuously along a probe rather than relying on a float to indicate the level. As the hydraulic oil rises or falls, the balance between hydraulic oil and air around the probe changes its capacitance. The sensor converts that change into a hydraulic oil level reading that can be sent to the machine controller. With no float, arm or reed switch in the measurement mechanism, there are fewer mechanical components to stick or wear, and the fully sealed electronics support use in demanding operating environments.
Continuous measurement. Track reservoir level along the probe, capturing the slow fall of a leak as well as normal cylinder movement rather than relying on discrete switching points.
Calibrated for the application. Factory calibration is matched to the probe length and intended application, helping deliver a reservoir level reading suited to the tank being monitored.
Outputs to suit your system. Depending on the model, choose from 0 to 10 V, 4 to 20 mA or RS232 outputs, or an output matched to the controller on a custom build.
Not all hydraulic oil level sensors see the reservoir the same way
Some measure down to the surface. Others follow a float. Gill capacitive hydraulic oil level sensors take a different approach, measuring continuously along a probe immersed in the hydraulic oil. That distinction matters when you’re choosing a sensor for a hydraulic reservoir on plant, presses or mills, where heat, constant oil movement and the mounting position all influence which technology makes sense.
| Method | Our approachGill capacitive | Radar | Ultrasonic | Float or reed switch |
|---|---|---|---|---|
| How it reads the level | Reads the change in capacitance along a probe in the liquid | Times a microwave pulse reflected off the surface from above | Times a sound pulse echoing off the surface from above | A float rides the surface and moves an arm, stem or switch |
| Moving parts | None | None | None | Float and pivot or stem |
| Foam on the surface | Measures the liquid along the probe, not the top of the foam | Heavy foam can weaken the echo | Foam can absorb the echo | The float can sit on the foam |
| Vibration and slosh | Continuous signal the receiving system can average | A moving surface can scatter the echo | A moving surface can scatter the echo | The float swings and the reading jumps |
| Small or cramped tanks | One compact probe through a single fitting | Needs headroom and a clear beam path | Needs headroom for its dead zone | Needs room for the float to travel |
| Shaped tanks | Calibrated against the tank profile | Set up for the vessel geometry | Set up for the vessel geometry | Arm geometry limits accuracy |
| Watch out for | Calibration to the liquid, and a probe matched to conductive or fouling liquids | Weaker echoes from low-dielectric liquids such as fuels and oils, false echoes from internal structures, size and cost | Vapour, condensation, temperature layers and internal obstructions | Sticking, wear, deposits and readings in steps |
| Where it fits best | Vehicle, plant, marine, UAV and machinery tanks | Large storage tanks and process vessels | Open tanks, sumps and channels with a calm surface | Simple, low-cost tanks and alarms |
Why engineers choose Gill capacitive
- Nothing moves, so nothing sticks, wears or fouls
- Reads the liquid, not the foam or the ripple on top
- One compact probe that fits tanks other methods cannot
- Calibrated to the liquid and to the shape of the tank
If your vessel is better served by a non-contact method, our engineers will say so plainly.
Engineered for reservoirs that don’t fit the mould
Hydraulic reservoirs are built to fit whatever space the machine leaves, not designed as neat rectangles. That makes accurate oil measurement more complex: the same change in oil height can represent very different changes in volume, depending on the tank’s geometry. Gill level sensors can be configured to account for the tank’s shape, translating measured level into a more meaningful indication of how much oil it contains.
Tank profiling across the range. GSLevel, Gill’s configuration software for its liquid level sensor range, includes tank profiling to support volumetric output rather than height alone.
Profile it your way. Use the configuration wizard or upload a CSV file describing the tank’s cross-section.
Calibrated to your tank. LevelDefend and custom level sensors can be calibrated to the customer’s tank geometry, helping deliver reservoir level measurements suited to the installation.
Which hydraulic oil level sensor suits your reservoir?
LevelPro covers standard hydraulic reservoirs. Where temperature, mounting or immersion rule a standard model out, Gill builds a custom sensor for the reservoir.
LevelPro
Best for general fuel, oil, water and coolant tanks
LevelPro is the general-purpose sensor in the Gill range, built in corrosion-resistant stainless steel and fully sealed. It measures fuel, oil, water and other liquids continuously in vehicles, tanks and industrial equipment, with 0 to 10 V or 4 to 20 mA output and RS232 for configuration.
- Stainless steel
- IP66 and IP68
- 0 to 10 V
- 4 to 20 mA
- RS232
- Tank profiling
Custom level sensors
Best when no standard model fits the tank
Gill designs custom level sensors where the tank, mounting, temperature or interface rules out a standard model. Flanges, probe length, cable, sealing and outputs can all be changed, and extra measurements such as temperature can be designed into the probe.
- Custom flange
- Custom probe length
- Integrated temperature option
A level sensor inside a cement grinding mill
For a new cement grinding roller mill prototype, Gill designed a heavy-duty hydraulic oil level sensor for the grinding wheel bearing housing. It uses a one-piece 316 stainless steel construction with a 5 mm probe wall, internal seals so the whole sensor can sit submerged in oil to IP68, and five inlet and outlet holes to speed its response to moving oil.
A PT1000 temperature sensor is built into the probe tip. The sensor is factory calibrated for a 0.25 V to 4.75 V analogue output over a 49 mm measurement range, and operates up to 125 °C.
Level and oil temperature from one fitting
Frequently asked questions
Continuous hydraulic oil level monitoring shows a falling reservoir level as it happens, which is often the earliest sign of a leak. A control system that sees the level can warn the operator or stop the machine before the pump draws air and the system loses pressure. A periodic sight glass check only catches the problem if someone looks at the right moment.
A Gill level sensor can measure an irregular-shaped tank because tank profiling turns the level reading into a volumetric output. GSLevel, the configuration software for the Gill liquid level sensor range, profiles the tank through a configuration wizard or from a CSV file of the tank’s cross section. LevelDefend and custom builds are calibrated to the customer’s tank, so a tank drawing at enquiry lets an engineer confirm the approach.
A Gill hydraulic oil level sensor can be built with an integrated temperature sensor where the application needs one. On a heavy-duty sensor for a cement grinding mill, Gill designed a PT1000 temperature sensor into the probe so the customer received oil level and oil temperature from one fitting. Integrated temperature is specified as part of a custom build rather than as a standard option.
LevelPro is the Gill level sensor for general hydraulic oil, engine oil and fuel measurement. It is built in corrosion-resistant stainless steel, sealed to IP66 and IP68 and offers 0 to 10 V or 4 to 20 mA output from a +5 to +32 V DC supply. Where temperature, mounting or immersion rule LevelPro out, Gill designs a custom level sensor for the reservoir.
Gill hydraulic oil level sensor choice depends on the machine. LevelPro is the robust stainless steel sensor for standard reservoirs on plant, presses and mills. LevelDefend is a custom military-grade sensor for defence vehicles and marine craft. Where a reservoir needs a special probe length, fitting or integrated temperature measurement, Gill engineers can specify a custom build matched to the reservoir and the machine controller.
A Gill hydraulic oil level sensor gives a continuous level reading, so the machine controller can see a slow fall in reservoir level as well as the normal rise and fall as cylinders extend and retract. A gradual drop that does not recover is often the first sign of a chafed hose, weeping seal or loose fitting. A single-point float switch only reports when the level crosses its trip point. LevelPro suits most standard reservoirs.
Gill hydraulic oil level sensors offer a choice of outputs, and the choice depends on the model. LevelPro provides 0 to 10 V, 4 to 20 mA or RS232. LevelLite adds CAN alongside RS232, voltage and current options, which suits vehicle networks and telematics. LevelSlick offers voltage, current or resistive output, and LevelDefend is built with the output the customer’s system requires. A 4 to 20 mA current output needs a 250 ohm load resistor.
A Gill hydraulic oil level sensor in the LevelPro or LevelLite range runs from a +5 to +32 V DC supply, which covers 12 V and 24 V vehicle and plant systems. One LevelPro output type uses a +9 to +32 V DC supply instead. LevelSlick and LevelDefend supply requirements are set out on the datasheet or the build specification, so confirm the figure for the model and configuration being specified.
Talk to an engineer
Tell us what you need to measure, where and under what conditions. We’ll help you work out the appropriate approach.
We aim to respond in one working day.
What our engineers will ask about
- Probe length and angleThe probe has to suit the reservoir and can be mounted vertically or through a side wall at an angle, as on a cement mill application.
- Oil temperatureConfirm the operating temperature. A custom Gill hydraulic oil level sensor has been designed for operation up to 125 °C, with the probe section rated to 150 °C.
- Temperature as well as levelWhere the system needs oil temperature too, a PT1000 temperature sensor can be designed into the probe as part of a custom build.
- Sealing and outputLevelPro is sealed to IP66 and IP68. Custom builds can be sealed for full immersion in oil, with an output matched to the controller.