Measurement instruments that continuously measure and monitor liquid levels in tanks, vessels, and piping during manufacturing processes. Using measurement principles such as float type, capacitive type, ultrasonic type, radar type, and differential pressure type, they accurately detect liquid surface heights of water, oil, chemicals, solvents, and other liquids. Used for liquid level management in raw material tanks, intermediate storage tanks, and waste liquid tanks of manufacturing equipment, reaction vessel monitoring in chemical plants, and storage tank management in food factories. Models with analog output (4-20mA) and digital communication functions enable integration with control systems, realizing automatic liquid supply/drainage control and abnormal alarm functions. Distinguished from flow meters and pressure gauges by different measurement targets, these are measurement instruments specifically designed for liquid surface height and position detection.