Coolant level, seen from the cab
Know the coolant level before the engine does. Gill capacitive coolant level sensors put a continuous reading on the cab display or engine controller, with no moving parts in the sensing mechanism, so a top-up happens at the depot rather than a recovery on the line or at the roadside.
A sight glass nobody can read is not a check
On a fleet of UK freight locomotives, low coolant was the recurring cause of unplanned shutdowns. The tank had a sight gauge, but deposits from the water and additives obscured it over time, and the crowded, poorly lit engine compartment made it hard to read. Each shutdown meant sending another locomotive to recover the train, delays and the risk of engine damage.
Coolant leaves deposits. Water, glycol and inhibitors change over time and can coat a sight glass. The sensor has to suit the mixture and keep its reading in service.
The check has to happen every time. A level signal in the cab or the controller turns a daily visual inspection into a warning the driver sees on start-up and in service.
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 coolant level measurement, without the moving parts
Low coolant is one of the quickest ways to shut an engine down in service. Sight glasses cloud with deposits, engine bays are crowded and poorly lit, and a daily visual check is easy to miss or misread.
Gill capacitive coolant level sensors take a different approach, measuring coolant continuously along a probe rather than relying on a float to indicate the level. As the coolant rises or falls, the balance between coolant and air around the probe changes its capacitance. The sensor converts that change into a coolant level reading that can be sent to the cab display or engine 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 coolant level along the probe, capturing a gradual loss as well as a sudden drop 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 coolant 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 for integration with cab displays and engine controllers.
Not all coolant level sensors see the tank the same way
Some measure down to the surface. Others follow a float. Gill capacitive coolant level sensors take a different approach, measuring continuously along a probe immersed in the coolant. That distinction matters when you’re choosing a sensor for an engine, generator or rail coolant tank, where heat, vibration and access 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 tanks that don’t fit the mould
Header and expansion tanks are moulded to fit crowded engine bays, not designed as neat rectangles. That makes accurate coolant measurement more complex: the same change in coolant 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 coolant 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 coolant level measurements suited to the installation.
Freight locomotives that warn the driver
Gill supplied a customised LevelPro for the Class 66 diesel-electric locomotive, one of the most widely used freight locomotives in the UK. The sensor uses a 450 mm stainless steel probe, an extended 2 m flying lead with low smoke and toxicity characteristics, a plain 1 inch flange for a 5-hole SAE fitting and a 4 to 20 mA output.
The coolant level now reaches the cab, so the driver can see a low level on starting the locomotive or during operation, instead of relying on a sight gauge in a dark engine compartment.
A customised LevelPro on rail traction
Which coolant level sensor suits your tank?
LevelPro is the starting point for engine and rail coolant tanks. Where the flange, cable or fire rules call for something different, Gill builds a custom version, as it did for the Class 66 locomotive.
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
Frequently asked questions
A capacitive coolant level sensor measures the change in capacitance along a probe as coolant rises and falls around it. The reading is continuous along the probe length rather than a single trip point, and a Gill capacitive coolant level sensor has no float or switch in the tank to stick or foul. The output feeds a display or engine controller, which can raise a warning as the level falls.
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 continuous coolant level sensor can warn the driver as the level falls, rather than only when it reaches a trip point. On UK freight locomotives fitted with a customised Gill LevelPro, the coolant level is shown in the cab so the driver can see a low level on start-up or during operation. How the warning is presented depends on the display or controller the sensor feeds.
Gill capacitive level sensors are used to measure water-based coolant, including on rail traction where a customised LevelPro monitors the coolant tank. Coolant mixtures vary in glycol content and additives, so the sensor is specified and calibrated for the coolant in use. Naming the coolant type and concentration at enquiry lets the calibration match it.
Gill coolant level sensor choice depends on the vehicle or engine. LevelPro is the robust stainless steel sensor used for coolant tanks, including a customised LevelPro on rail traction. LevelDefend is a custom military-grade sensor for defence vehicles and marine craft. Naming the coolant type and glycol concentration at enquiry lets Gill engineers specify and calibrate the sensor for the coolant in use.
Gill coolant 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 coolant 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
- The coolant mixtureCoolant mixtures vary in glycol content and additives. Name the coolant and concentration so the sensor is calibrated for it.
- Probe length and flangeThe rail sensor used a 450 mm probe and a plain 1 inch flange for a 5-hole SAE fitting. Probe and flange are matched to the tank.
- Cable and fire rulesAn extended 2 m flying lead with low smoke and toxicity characteristics met the rail fire regulations. Cable is specified to the vehicle.
- Output and warningA 4 to 20 mA output fed the cab indication on the locomotives. Choose the output the display or controller expects.