The Gobius C measures from the outside through the tank wall. No holes, no interference with the tank, no risk of leakage—that's why it's often the only practical solution for existing, hard-to-reach tanks. The trade-off is an installation where preparation determines the outcome.
Why the adhesive surface is everything
The sensor sends a signal through the tank wall and evaluates what comes back. For this to work, the transition from the sensor to the tank wall must be clean—without an air gap, without contamination, without unevenness.
An air gap of fractions of a millimeter is enough for the signal to be reflected at the interface instead of entering the tank. The result is not an incorrect measurement, but no measurement at all—or one that doesn't move.
That's why the sensor comes with a cleaning cloth and additional adhesive tape. Both are not accessories, but part of the procedure.
Finding the right spot
Four criteria for the mounting location:
- Flat. A curved surface cannot be fully adhered.
- Uniform wall thickness. At a seam, reinforcement, or weld, the wall thickness changes—and with it, the signal.
- Clear path upwards. The sensor measures from bottom to top through the liquid. Fixtures, baffles, or a pipe in the measurement path create false echoes.
- Accessible. Calibration is done on the installed sensor—and you don't want to be lying under the floor while doing it.
NoteThe maximum tank depth is two meters. For deeper tanks, the measurement in the upper area is no longer accurate—in which case a different method should be chosen instead of shifting the position.
Plastic and metal tanks
For plastic tanks, direct measurement works. For metal tanks, the method is different: there is a mounting adapter that can be adapted to the standard drill holes in metal tanks—usually 1 1/4 inch.
Before ordering, it must therefore be clarified what material the tank is made of and whether a suitable bore is present. This is one of the few points where the answer determines the accessories and not vice versa.
Setup via app
The sensor is configured via Bluetooth using a smartphone. The app is available in ten languages and offers two functions that make everyday life easier: a tank calculator that determines the volume from the dimensions, and wave motion damping that smooths out fluctuating values.
The sensible order of steps:
- Adhere the sensor and check the connection before adjusting anything.
- Enter tank geometry so the calculator knows a volume.
- Calibrate at known levels—ideally once empty and once full.
- Set damping after observing how much values fluctuate in motion.
- Set alarms—two separate input and output alarms for empty and full tanks are available.
Connection to existing instruments
The sensor outputs common analog signals: 0–190 Ohm, 240–33 Ohm, 4–20 mA, and 0–5 V. This allows it to be connected to common analog round instruments without having to replace the display.
This is often the decisive point in a refit: an existing instrument panel remains, only the measuring point is replaced—and without opening the tank.
The operating voltage is 9–30 V DC, and the current consumption in standby is 20 mA. The resolution is ±2 to 3 mm, and the protection class is IP44—meaning splash-proof, not intended for continuous wetness.
The variants
The sensor is available in several versions: with analog outputs for classic instruments, in a version for NMEA-2000 networks, and in a basic version. The choice depends on the display side—i.e., where the value should go: to a round instrument, to the chart plotter, or to a simple display.
Typical errors
- Glued to an unclean surface. An air gap of fractions of a millimeter is enough for nothing to register.
- Mounted on a seam or reinforcement. Changing wall thickness distorts the signal.
- Overlooked obstruction in the measurement path. Baffles and pipes create false echoes.
- Planned for a metal tank without an adapter. The mounting adapter for standard boreholes is available for this purpose.
- Tank depth exceeds two meters. Beyond that, no other mounting location helps.
