What Is a Hydrometer?

The hydrometer is made according to Archimedes' law and the condition that an object floats on the liquid surface and is an instrument for measuring the density of a liquid. It is a closed glass tube with uniform thickness at one end, scale paper attached to the inner wall, uneven scale, dense top and bottom, and a slightly swollen bubble at the other end. The lead is filled with small lead particles or mercury to make the glass tube Immerse in the liquid under test to a sufficient depth and float in the liquid stably, that is, when it is subjected to any shaking, it can automatically return to a vertical rest position. When the hydrometer floats in the liquid, its gravity is equal to the gravity of the liquid it drains. So immersed in different depths in different liquids, the pressure is different, the hydrometer uses this relationship to scale.

The hydrometer is made according to Archimedes' law and the condition that an object floats on the liquid surface and is an instrument for measuring the density of a liquid. It is a closed glass tube with uniform thickness at one end, scale paper attached to the inner wall, uneven scale, dense top and bottom, and a slightly swollen bubble at the other end, containing small lead particles or mercury in the bubble, so that the glass tube can Immerse in the liquid under test to a sufficient depth and float in the liquid stably, that is, when it is subjected to any shaking, it can automatically return to a vertical rest position. When the hydrometer floats in the liquid, its gravity is equal to the gravity of the liquid it drains. So immersed in different depths in different liquids, the pressure is different, the hydrometer uses this relationship to scale.

Chinese name

Hydrometer

Foreign name

densimeter; gravimeter; density gauge

Alias

Density meter

Use

Measuring the density of a substance

Hydrometer measurement principle

The long tube of the hydrometer is usually marked with the following numerical scales ... 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 ... When the hydrometer is settled to a scale of 0.9 in the liquid, it is immediately known that the measured liquid density is 0.9. With this instrument, the object will only sink to a depth that is exactly the same as its own weight. Therefore, hydrometers sink deeper in liquids with a lower specific gravity than in heavier liquids. For example, it sinks deeper in alcohol than in watered alcohol; it is shallower in pure milk than in watered milk. Insert the hydrometer into various liquids with decreasing specific gravity in sequence, such as sulfuric acid (1.8), water (1.0), ether (0.717), etc., and the depth of its sinking gradually deepens. Therefore, the larger specific gravity must be at the lower part of the scale, and the smaller specific gravity is at the upper part. Of course, the scale itself must first be calibrated, and it must be calibrated according to the specific gravity of various liquids, or directly according to the special properties of the measured liquid, such as the alcohol content of alcohol, the fat content of milk, and the pure acid content of sulfuric acid. Wait for calibration.

Density meter

There are two commonly used hydrometers. A type used to measure the density of a liquid with a density greater than 1, known as a "hydrometer". It has more lead shots or mercury at the bottom. The smallest scale of this hydrometer is "1", it is at the highest position of the scale line, from top to bottom, in order, 1.1, 1.2, 1.3 ... Put this hydrometer in water, its Scale lines greater than 1 are all below the water surface. Another is used to measure the density of liquids with a density of less than 1, called "specific light gauge". There is less lead shot or mercury in the lower part. The maximum scale line of this hydrometer is "1". This scale line is at the lowest position, and it is, 0.9, 0.8, 0.7 ... When the hydrometer is placed in water, all the scale lines less than 1 are on the water surface. When using it, you should pay attention to choosing this re-calculator according to whether the density of the liquid is greater than 1 or less than 1. At present, the textbook no longer talks about the specific gravity unit but the density unit, but the density meter is still used when measuring the density, and the measured values are not much different.

Electronic hydrometer is suitable for: porous particles / dedicated specific gravity balance / specific gravity meter / density meter, cement industry / dedicated specific gravity balance / specific gravity meter / density meter, fireproofing material / dedicated specific gravity balance / specific gravity meter / density meter, stone industry / special Specific gravity balance / specific gravity meter / densitometer, powder theoretical true density research laboratory / special specific gravity balance / specific gravity meter / densitometer principle: According to ASTM C 97-02, GB / T9966.3-2001, G208-94, 217-81 It is stipulated that Archimedes' immersion liquid replacement method is used, combined with a special pycnometer and a specific gravity balance, to accurately read the measured values. Technical data: The true density of the powder is one of the physical properties of the powder material. The basic physical property parameters of the powder particle size and porosity testing are indispensable. When measuring the specific surface area of the powder, data on the true density of the powder are needed for calculation. Many inorganic non-metal materials are manufactured using powder raw materials, so it is necessary to determine the true density of the powder in scientific research or production. In the manufacture of cement or ceramic materials, it is necessary to measure the fineness of the clay particle distribution ball mill slurry, and true density data is required. For cement materials, the final product is powder. Measuring the true density of cement is of great significance to both the production unit and the unit of use. The true density of fire-resistant materials is shortened according to ASTM D 5004-1989 to shorten the lengthy test time of traditional true density tests. The required test results can be directly displayed without calculation. Test conditions: In the immersion method, it is very important to choose a liquid that does not dissolve the sample surface and easily wet the surface of the sample particles. For ceramic raw materials such as feldspar, quartz and ceramic products, distilled water can be used as the liquid medium. For materials that may work, such as cement, organic liquid media such as kerosene or dimethylbenzene can be used. Organic solvents are generally used for inorganic powders. When the powder is completely immersed in the liquid, its bubbles must be completely eliminated to determine its excluded volume. Grind into a powder with a porcelain mortar and pass through a 240-mesh standard sieve. Put the powder sample into a weighing bottle, put it in a 105 ° C infrared moisture meter, and dry it. . ^[1]