After the FAQS technology is developed and approved, it could have wide commercial and military application in areas such as automated vehicle refueling and fuel-farm management. Ultimately, FAQS technology will improve greatly battlefield awareness, combat readiness and combat service support. Some of industry's most common techniques for gauging liquid level include ultrasonic sensors, pressure transducers and string potentiometers. Ultrasonic sensors use acoustic signals to measure the distance to the fuel's surface, while string potentiometers measure the same distance by the uptake of a string attached to a float in the fuel tank. Fuel volume is calculated using the dimension of the tank.
Pressure transducers measure the pressure exerted by a column of liquid.
The pressure is directly proportional to column height, which can be used to calculate the volume of liquid in the tank. The liquid density also must be known to calculate volume accurately from the pressure. Where applicable, SwRI engineers evaluated all three commonly used sensor types. In this evaluation, the pressure transducer also performed well. Gauging fuel level in a collapsible fuel bladder is a challenge.