Fluid Level Sensors

All cars with an internal combustion engine use a fluid level sensors to monitor the amount of fuel in the gas-tank. Some cars have fluid level sensors to determine when washer fluid, coolant or brake fluid are getting low. Some sensors use floats that move up and down with the fluid surface and use position sensors to produce an output relating to the position of the float. Others monitor the capacitance of a rod inserted in the fluid. As more fluid surrounds the rod, the capacitance increases. Ultrasonic fluid level sensors work like acoustic distance sensors that measure the distance between the tank wall and the fluid surface. Optical sensors is used in fluids that must be isolated from the surrounding environment. In these types of sensors, a laser or LED sends a ray that is captured on the opposite end of the fluid reservoir. The amount of light reaching the sensor is inversely proportional to the amount of fluid in the tank.