Usually, the arises to measure liquid levels in containers, in large industries; where large volumes of liquids are stored, in small scale industries and residential buildings in developing countries that sees many households implementing their own domestic water supply system. Measurements by humans may be influenced by sentiments, fatigues, lack of concentration, and so on, which has led to economic losses due lost liquid and wasted electric power. Therefore, researches have been directed toward development of automatic liquid level sensing technologies. This paper thus attempts to review available current technologies in automatic liquid level detection systems published in reputable literature. The reviewed technologies are based on optical devices such as light emitting diode (LED), LASER, photocell, photodiode, light dependent resistor (LDR), fibre optics cable and ultrasonic sensors. Other liquid level detection schemes studied are bases on capacitance measurement, edge detection technique in a computer vision system for inspecting the over and under fill liquid level of bottles. This paper also compared the full scale length to resolution ratio of some of the proposals reviewed in a discussion of performance characteristics of liquid level sensors. Finally, evaluated energy cost savings possible when liquid level sensors are used in water pumping systems. This paper will assist instrumentation researchers to know the state of the art in level sensing technology, and practitioners in selecting the right kind of level sensors for a particular application
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