Flexi-Sensor (Fuel and Water Sender)

Flexi-Sensor (Fuel and Water Sender)
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Not your average Sender

  • Durable (shock resistant)
  • Up-Gradable output options
  • Field Serviceable
  • Custom tank Calibration available

The Royce Flexi-Sensor is a rugged Fuel or Water sender that is field replaceable without breaking the sender to tank seal. At first glance it may look like just another float style sender. But if you look closer you’ll find what you’ve been looking for. Royce has taken the proven float and reed switch technology to a whole new level. Designed with the Marine Industry in mind. The Flexi-Sensor answers these major boater concerns:

  1. Sender durability and long life.
  2. If I upgrade my instrumentation will I have to replace my sender?
  3. If my sender fails. How do I replace it quickly and easily?
  4. I have an odd shaped tank and can’t rely on my gauges to be accurate.

Design Solutions

To make our senders more durable we have replaced the standard glass reed switch with plastic over-molded switches. The over-molding process protects the fragile glass shell that encases the switch contacts. If the glass is broken from shock or vibration, this could lead to inaccurate or no gauge readings at all. Our patented design includes a Flexi-Sensor insert. The insert consists of multiple resistors and over-molded reed switches affixed to a flexible PC Board. (See diagram below for a closer look.)

Flexi-Sensor Detailed Diagram

The Flexi-Sensor insert is not only flexible it is also removable. This feature makes it possible to change our sender’s output to any of the following choices:

30-240 ohms 0-5 volts Custom Calibrated outputs
0-90 ohms 0-10 volts Dual station
0-180 ohms 4-20ma  


Using simple hand tools the current insert can be removed and replaced with a new or different output insert. This allows for quick repair or easy upgrade of the sender internal components.

*Remember all this can be done without ever removing or breaking the sender to tank seal.*

When the tank is new, the manufacturer mounts all the fittings into the tank including the sender and pressure tests it for any leaks. The Flexi-sensor is the only sender that can be replaced without compromising the gasket seal made by the tank manufacturer. Therefore, the person replacing the Flexi-Sensor does not have to pressurize the tank to test it for leaks after Installation. Note: This only applies if the tank manufacturer originally installed the sender.

The Flexi-Sensor can be calibrated to the shape of the tank. Many fuel tanks on boats are designed to fit into the hull and maximize the amount of gallons it can hold. This makes the tank shape and volume non-linier. Our engineer’s can calibrate the sender to the shape of any tank in one-inch increments. Therefore, the sender output can be set to represent the volume of the tank at every inch of fuel or water level.

Download Spec Sheet