The hydrometer is a laboratory material that is used to measure the relative gravity of a series of specific liquids based on the concept and principles of buoyancy. These are calibrated and graduated, with one or more scales, such as specific gravity. The hydrometer achieves this by measuring the amount of water that moves inside.
The density meters are calibrated in view of their being used for different uses, for example, a lactometer. The purpose of a lactometer is to measure the density, or creaminess, of the milk. It can also function as a sacrometer to measure the density of sugar in a liquid. And it has even been used as a breathalyzer to measure high levels of alcohol.
In themselves, density meters follow Archimedes’ principle , which is that any solid that is suspended in a fluid can be driven by a force equal to the fluid’s weight, displaced by the submerged part of the suspended solid. Generally speaking, the lower the amount of density the fluid has, the deeper the gauge will sink at a given weight. For this, the stem must be calibrated to give a numerical reading.
Next, we’ll break down everything about the hydrometer in detail. We will go from its functions, elements, uses, application, types and much more. That, like many other laboratory elements, such as the galvanometer , is interesting to study. Join us!
What is a densimeter?
As explained above, the density meter is a laboratory instrument used to measure the relative density, or specific gravity, of a certain range of liquids. What is being studied is the relationship between the density of this liquid and that of water.
The hydrometer is usually made of glass and consists of a cylindrical stem next to a bulb loaded with a heavy material so that it can float upright once it is introduced into the liquid. In order for it to work, the liquid must be poured into a hydrometer cylinder and it will gently drop into the liquid until it floats freely. Subsequently, the point where the surface of the liquid touches the stem of the hydrometer will be observed.
The hydrometer usually contains a scale inside the stem, so that the specific gravity can be read and thus safeguard the data for future comparison. Both the hydrometer, and the bottles for the measurement of the degree, include Bbaume, twaddle, rangefinders, beer and brine.
In practice, the floating glass bulb is inserted into a cylindrical glass tube fitted with a rubber ball at the upper end so that it can suck liquid into the tube. The depth of the bulb dip has to be calibrated, as mentioned above, or you won’t be able to read the desired characteristics. This is extremely important because we remember that not all laboratory tools are 100% accurate, and the better the measurement technique, the closer to the true results of the study.
Among the instruments that are known, we find the battery density meter, which is capable of measuring the specific gravity of the liquid in a battery, managing to know its state. We also find the radiator hydrometer, with which we seek to know the freezing point of the radiator solution. From what we see, it is a versatile instrument, in which it has even been calibrated to test an alcohol solution to know the percentage of sugar.
How is the hydrometer composed?
The hydrometer consists of a glass tube that is hollow and sealed with a lower portion to float. It has a ballast, such as lead or mercury, to achieve stability. Finally, we find a narrow stem with graduations intended for measurement. The liquid to be tested should be poured into a fresh stop, often cylindrical in shape, so that the instrument gradually descends into the liquid until it floats freely.
In general, the density meter can contain any number of scales along the stem, as long as they correspond to the characteristics and properties that correlate with the density to be read.
History of the densimeter
The person who is awarded the idea and creation of this impressive laboratory material is the French chemist Antoine Baumé , who is named after the hydrometer. The first version of the French was calibrated to measure specific gravity on equidistant scales, it had a scale for liquids heavier than water and another for those that were lighter.
The date dates to the end of the 4th or early 5th century. Later, as the years passed, new versions of the French’s work appeared, in which Jacques Alexandre César stands out, at the end of the 18th century. His version was described as an automatic device capable of reading the alcohol content in a liquid. It was so impressive, and had a weight in history, that its use was made mandatory by British law at the time.
Densimeter scales
Modern instruments themselves are oriented to read specific gravity. However, in the past they were used, although there are still some who still apply the same principles, to read scales in certain industries. These scales include the following:
- Brix scale . It is used to read fruit juices, wines and the sugar industry in general.
- API gravity . Its use is universal, and it is focused on the oil industry.
- Plato scale. Mainly its purpose is in the production of beers to measure sugar levels
- Baumé scale . It was previously used in the fields of industrial chemistry and pharmacology.
- Twaddel scale . Previously used in the bleaching and dyeing industries.
- Oechsle scale . Its favorite use is to measure the density of the grape must.
Densimeter operation
The hydrometer contains a long glass cylinder that is weighed at the bottom to give it some stability while in water. It contains a scale for gravity carved along its side, this with the ability to translate the data into numbers. The instrument is placed in any container intended for reading, which has to be transparent, and the value can be read on the surface of the liquid.
In view of the hydrometer working properly, and having no precision errors, it should be corrected and calibrated according to the temperature. This is because the density of a liquid tends to change with temperature. The people who operate these tools must be aware of the foundations and theories of physics, or they will not get desired results. Although it is easy to handle, it does not mean that there is a whole range of elements both physical and chemical behind.
Types of densimeter
Lactometer
The lactometer, also known as a galactometer, is a type of hydrometer used to analyze milk. The specific gravity of milk does not give a conclusive indication of its composition, this because milk contains a variety of substances that are usually heavier or lighter than water.
Therefore, additional tests are needed to read the fat content in an overall composition. The tool is graduated in one hundred parts. For it to work, the milk must be poured and allowed to stand until it has acquired the composition of a cream. Finally, the lactometer is deposited to determine the quality of the milk.
Breathalyser
A breathalyzer, or alcohol meter, is another type of hydrometer used to determine the concentration of alcohol in a liquid. This tool actually only measures the density of the fluid and then certain assumptions are made to estimate the amount of alcohol present. These contain scales marked with percentages by volume of the potential of alcohol, following the principles of specific gravity.
Specific gravity, measured in ‘ potential alcohol’ , is supposedly caused by the introduction of dissolved sugars. For it to work, a reading must be taken before and after fermentation in view of reading the approximate alcohol content. Sure, subtracting the post-fermentation reading from the pre-fermentation reading of the liquid.
Saccharometer
This is a type of hydrometer that is used to determine the amount of sugar in a solution. The tool is credited with its creation to Thomas Thomson , and is used primarily by winemakers and brewers. They can also focus on reading sorbets and ice cream.
This consists of a large glass bulb with a thin stem that rises from the top with calibrated markings. The sugar level is determined by reading the value where the surface of this liquid intersects the scale.
Thermohydrometro
This tool contains a thermometer enclosed in the flotation section and is used to measure the density of petroleum products, such as fuel oils. For its application, the sample must be heated in a temperature jacket with a thermometer behind it, since the density depends on the temperature.
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