hydrometer (redirected from Hydrometer Analysis)

hydrometer (hīdrŏm`ətər), device used to determine directly the specific gravity of a liquid. It usually consists of a thin glass tube closed at both ends, with one end enlarged into a bulb that contains fine lead shot or mercury to cause the instrument to float upright in a liquid. In the glass tube is a scale so calibrated that the reading on it level with the surface of the liquid in which the hydrometer is floating indicates the number of times heavier or lighter the liquid is than water, i.e., the specific gravity of the liquid. The hydrometer is based on Archimedes' principle. The level at which the hydrometer floats depends only on the density of the liquid. Hence this level can be used to measure both the density and the specific gravity, which is proportional to it. Commercial hydrometers are usually calibrated for ordinary room temperature, which is taken to be 20°C; (68°F;), or for 4°C; (39.2°F;). Because of the variation in the depth to which the instrument sinks in heavy and in light liquids, one type is made for use in liquids more dense than water and another for use in those less dense than water. The so-called bulb hydrometer consists of a small commercial hydrometer contained in a larger glass tube into which the solution to be tested is drawn by the action of a rubber bulb. It is used to measure the specific gravity of the sulfuric acid solution in automobile batteries. The two Baumé hydrometers (invented by Antoine Baumé), one for specific-gravity determinations in liquids denser than water and the other for liquids less dense than water, are calibrated with the special Baumé scale (also constructed by him).

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hydrometer

an instrument for measuring the relative density of a liquid, usually consisting of a sealed graduated tube with a weighted bulb on one end, the relative density being indicated by the length of the unsubmerged stem

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hydrometer [hī′dräm·əd·ər]

(engineering)

A direct-reading instrument for indicating the density, specific gravity, or some similar characteristic of liquids.

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Hydrometer

A direct-reading instrument for indicating the density, specific gravity, or some similar characteristic of liquids. Almost all hydrometers are made of a high-grade glass tubing. The main body is the float section in the bottom of which ballast, such as small shot, is secured. A small-diameter tube, the stem, extends from the upper end of the float section. Inside the stem is the scale, printed on heavy-grade paper, and well-secured within the stem so its position will not change. When the hydrometer is placed in a liquid, the stem extends vertically above the surface for a portion of its length.

Hydrometers may be classified according to the indication provided by graduations of the scale as follows: (1) density hydrometers, to indicate densities at a particular temperature, and usually for a particular liquid; (2) specific gravity hydrometers to indicate specific gravity of a liquid, with reference to water, at a particular temperature; (3) percentage hydrometers to indicate, at a particular temperature, the percentage of a substance such as salt, sugar, or alcohol dissolved in water (alcoholometers are an example); and (4) arbitrary scale hydrometers, indicating the density, specific gravity, or concentration of a liquid in terms of an arbitrarily defined scale, at a defined temperature. The last group includes the saccharimeter (indicates percentage of pure sucrose solutions); the Baumé hydrometer (measures specific gravity of liquids lighter than water); the lactometer (tests milk); and the barkometer (tests tanning extracts).