Basic concepts and main types of level measurement

　　Level measuring instruments are commonplace and familiar to instrument users. However, the concepts and main types of level measurement are not well understood or even unheard of. In this regard, this article introduces the basic concepts and main types of level measurement as follows:

Level Meter

1. Basic Concepts of Level Measurement Level
　　refers to the general term for the level of liquid medium, solid material level or granular material level in a container and the interface between two different liquid media.
　　Liquid level refers to the height of the liquid medium in a container.
　　Material level refers to the accumulation height of solid or granular materials in a container.
　　Interface level refers to the height of the interface between two immiscible liquid media.

2. Main types of level measurement Level
　　measurement can be divided into continuous measurement and fixed-point measurement according to the measurement method. According to its working principle, it can be divided into the following types:
　　(1) Direct reading type It measures the liquid level based on the principle of fluid connectivity.
　　(2) Buoyancy type It measures the liquid level based on the principle that the height of the float changes with the liquid level or the buoyancy of the liquid on the float (or sinker) immersed in the liquid changes with the liquid level. The former is called constant buoyancy type and the latter is called variable buoyancy type.
　　(3) Differential pressure type (static pressure type) It measures the level based on the principle that the static (differential) pressure at a certain point changes due to the change in the height of the liquid column or material accumulation.
　　(4) Electrical type It measures the level based on the principle of converting the level change into various electrical quantity changes.
　　(5) Nuclear radiation type It measures the liquid level based on the principle that when the nuclear radiation of isotope rays passes through the material, its intensity changes with the thickness of the material layer.
　　(6) Acoustic type It measures the level based on the change in acoustic impedance and reflection distance caused by the level change.