hydrometer

A hydrometer is a submersible body, mostly in the shape of a jar, with a protruding stem, in which a scale is placed. The immersion depth of the flask (and therefore also the stem with the scale) in the liquid depends on the density of the liquid. Hydrometers are used to measure the density of liquids based on Archimedes' law.

An aerometer is a hydrometer that determines the density of gases or the composition of liquid mixtures.[1]

A hydrometer is a hydrometer that determines the density of gases, the composition of liquid mixtures and the content of dissolved solids.[1]

Hydrometers are used for operational and orientation measurements when determining the density or concentration of certain types of liquid substances. They are produced in different measurement ranges. The designation of the liquid for which the hydrometer is intended is usually indicated on the back of the scale.

Physically, the hydrometer is a glass flask, sealed at both ends. In the lower part there are closed metal balls, which serve to equalize the weight of the bank in relation to its volume. On the narrowed part of the tube there is a scale in units of density (kg/m3). When measuring density, the hydrometer floats in the liquid so that only the stem of the flask with the scale protrudes from the liquid. The position of the liquid level relative to the scale shows the density of the liquid.