Breathalyzers used on opaque liquids are set to read at the top of the thinnest point. These instruments are set to read at the top. Accurate measurement values can be obtained when the liquid has formed a coating on the pipe.

The size of the fine point of the breathalyzer depends on the purity of the surface of the liquid as well as how clean the breathalyzer is. With larger impurities of the medium or instrument an irregular shape may occur and the measurement may be inaccurate. Tougro to be measured should not have bubbles

The hydrometer or hydrometer (also called "hydrometer") is a special instrument used to determine the density of various liquids. Its operation is based on Archimedes' principle, where a body immersed in a liquid is said to float (equilibrate) until the weight of the displaced liquid equals the weight of that body (in this case, the instrument). In general, dilators are divided into two basic categories: a) "constant volume and variable weight dilators" to which the Nicholson and Fahrenheit dilators belong and b) "constant weight and variable volume dilators", to which the "Böhme dilator" and the "Guy-Lyssac" breathalyzer. Any other arbitrary ones can be created in this category, i.e. with arbitrary calibration.

Dilutometers are mainly used in industrial measurements mainly because they avoid creating reading errors mainly due to capillary effects.