Choosing the right fuel level sensor is about more than just measuring depth, but also about matching the technology to your environment, your tank’s geometry, and the fluid itself. At Rochester Sensors, two of our most popular technologies are Capacitance and Hydrostatic sensing.
While both provide high-accuracy, solid-state (no moving parts) measurements, they solve very different problems. Here, we’ll compare two of our flagship models – the T/LL130 (Capacitance) and the T/LL200 (Hydrostatic) – to help you decide which belongs in your tank.
1. The Capacitance Choice: T/LL130 Series
Best for: Performance, Vibration Resistance, and Variable Mounting.
The T/LL130 is a dielectric sensor. It features a probe (the electrode) that sits inside a tube. As the fuel level rises, it changes the electrical capacitance between the probe and the tube.
- When to use it: Use the T/LL130 when you need a rugged, rigid sensor for mobile applications like construction machinery, off-highway vehicles, or generators. Because it has no moving parts, it is immune to the mechanical wear-and-tear that kills traditional float sensors.
- Tank Shape: Ideal for standard tanks where a straight probe can reach the bottom. One major advantage of the T/LL130 is its mounting versatility. It can be mounted at any angle from vertical to horizontal, making it a lifesaver for tanks with limited overhead clearance.
- Fluid Compatibility: Perfect for diesel, kerosene, and petrol. However, because capacitance depends on the fluid’s properties, if you switch fuel types (e.g., from standard diesel to a high-biofuel blend), you may need to use the T/LL133 variant, which allows for easy recalibration via a simple button press.
2. The Hydrostatic Choice: T/LL200 Series
Best for: Difficult Access, Deep Tanks, and Vented Environments.
The T/LL200 works on the principle of pressure. A sensing head sits at the bottom of the tank and measures the head pressure of the liquid above it. The more fuel in the tank, the higher the pressure.
- When to use it: The T/LL200 is the problem solver for difficult installations. It uses a flexible sensor tube, which is a game-changer if you have a tank located in a tight space where you cannot physically drop a 1-metre rigid probe in from the top. You can simply feed the flexible line into the tank.
- Tank Shape: Because it measures pressure at the bottom, it is incredibly accurate for deep tanks (up to 4,000mm for diesel). It’s also the go-to choice for irregularly shaped tanks where a straight probe might hit a baffle or an internal curve.
- Fluid Compatibility: Like the capacitance model, it handles diesel, petrol, and water. However, hydrostatic sensors are density-dependent. They measure the weight of the fluid. This makes them exceptionally stable in vented, static tanks like those used for standby power or large-scale fuel storage.
Comparison at a Glance
| Feature | T/LL130 (Capacitance) | T/LL200 (Hydrostatic) |
| Probe Type | Rigid Tube (Stainless Steel) | Flexible Tube |
| Max Depth | Up to 1000mm (Mobile) / 2000mm (Static) | Up to 4000mm (Diesel) |
| Mounting Angle | Any angle above horizontal | Vertical (Drops to the bottom) |
| Best Feature | Extreme vibration resistance | Easy install in tight overhead spaces |
| Ideal Application | Construction, Gen-sets, Military | Deep static tanks, Baffled tanks |
So, which should you choose?
Choose the T/LL130 if you have a standard-depth tank in a high-vibration environment and need a sensor that can be mounted at an angle. It is the set-and-forget solution for heavy machinery.
Choose the T/LL200 if you are dealing with a very deep tank, or if your tank is tucked away in a position where you don’t have the headroom to install a rigid probe. Its flexible design makes installation in cramped engine rooms or basement storage areas remarkably easy.
Still unsure which sensor fits your specific tank dimensions? Contact the Rochester Sensors team for a technical consultation.
