The external measuring level meter is completely different from the instrument principle used at home and abroad for detecting liquid level in storage tank or its communicating vessel. It is the use of harmless to the human body micro-vibration principle, in the outer side of the container wall below the surface of the liquid level of continuous measurement of the precise height, and completely without contact with the liquid and gas in the container, It can be widely used in continuous and accurate measurement of liquid level and interface height in various containers. This technique establishes the law and mathematical model of the mechanical vibration characteristic and the liquid level corresponding to the liquid and thin shell structure tank in the container, which is the first in the world. Experts called it "a technological revolution in liquid level measurement", and said that "to create a new way of instrumentation development", in the "technology to occupy the international leading level."
When the measuring head of the external measuring instrument detects a small mechanical vibration on the wall of the vessel (which is determined by the vibration characteristics of the liquid and the vibration characteristics of the vessel), the external measuring level instrument will analyze the information through a special algorithm, discriminate and eliminate the false waveform which is independent of the change of liquid level, and extract its liquid level characteristic quantity, and then calculate the height of the liquid surface.