Antifreeze requirements, density measurement

Antifreeze – all-season liquid for cooling of automobile engines. The density of antifreeze is the main indicator affecting its quality. The higher the density of the cooler, the lower the temperature threshold of freezing solution.

antifreeze Density

General information on antifreeze

In summer, the most economical method of engine cooling is water. At low temperatures of atmospheric air, in order to avoid defrosting of the unit, alcohol – containing water-soluble mixtures-antifreezes are used.

The most common types of non-freezing compounds are chemical compounds of ethylene glycols with distilled water. Ethylene glycols are transparent liquids of yellow color, boil at a temperature – plus 197°C, crystallize – at minus 70°C, the density of substances – 1,112 g/cm3.

By changing the volume ratio of liquid and alcohol, you can reduce or increase the density value, and thus – to control the physical properties of the coolers.

Our industry on the basis of glycols produces two brands of low-freezing liquids – OZH–40 and OZH–65, with a crystallization threshold – 40 and – 65°C, respectively. For easy recognition of the type of antifreeze reagents are painted in different colors: brand 40 – blue, 65 – red.

The density of the solution is not the only indicator of the quality of the liquid. In the factory acceptance of non-freezing compounds is carried out on a number of characteristics:

  1. Homogeneity of mixtures.
  2. volume Ratio of active components (alcohol, water, additives).
  3. the Upper and lower temperature limit of the change in the aggregate state of the solution (boiling, crystallization).
  4. Compatibility of chemical properties of coolers with physical and chemical characteristics in contact with the liquid of engine materials. (copper, brass, rubber, etc.).

Antifreeze must meet the following operational requirements:

  • maximum thermal conductivity;
  • optimum viscosity – 1 mm2/s;
  • freezing point not lower than 65°C;
  • boiling of the liquid is not higher than 120°C;
  • high physical stability.

Of all these properties, only two parameters are available for the average consumer – measurement of the density of the solution and assessment of the appearance of the liquid.

antifreeze density Meter

Checking the quality and density of antifreeze at home

When studying the appearance of the cooling solution, first of all you need to pay attention to its color. The color of the emulsion should be a rich natural shade and meet the characteristics reflected in the regulations.

The second essential sign of the product’s good quality is the absence of oil stains and inorganic inclusions on the surface of the liquid.

The temperature threshold of freezing of the mixture can be determined using special devices – a hydrometer or Refractometer. The first determines the alcohol content in percent, the second – fixes the crystallization temperature in degrees Celsius.

hydrometer Design

Hydrometer – a special device that serves to analyze the density of liquid substances. The device consists of a glass sealed bulb with a measuring scale, the inner space of which is filled with lead shot.

Hydrometer antifreeze density

The amount of metal crumb is a calculated value depending on the type of liquid under study. The device is set up (calibrated) by specialists to work only with a certain substance.

The principle of operation of the device is based on the law of Archimedes. On the body immersed in the liquid, the buoyant force equal in magnitude to the specific mass of the mixture under consideration acts. Different solutions are not similar to each other density values, and therefore float the hydrometer will be different.

In some liquids, the float can sink, and in others will run on the surface at different distances from the boundary of the watershed (scale device). Therefore, if you want to investigate the density of antifreeze, then when buying the device, you should specify this reagent.

Refractometer Overview

Refractometer – another device for measuring the density of antifreeze. The principle of operation of the device is based on the deviation (refraction) of the light beam during the transition from one aqueous medium to another. The value of the refractive angle depends on the temperature of the medium and the chemical composition of the emulsion.

Device for antifreeze density

The device consists of the following parts:

  • polymer body;
  • Refractometer with glass prism;
  • pipettes;
  • adjusting screwdriver;
  • napkins.

The refractive index depends on the consistency and physico-chemical properties of the tested liquid.

When the initial concentration of the solution increases, the degree of curvature of the light beam increases. The greater the bending angle, the higher the antifreeze density parameter.

Measurement of antifreeze density without devices

There are two ways to measure the density of automotive coolant:

1). Pour the antifreeze into a wide and high glass vessel (glass, test tube, etc.). Lower the hydrometer into the liquid. Wait for the float to float. To determine the scale of the instrument the density of the solution. During the experiment, you need to control the position of the device in the container, it should not touch the walls of the glass.

antifreeze density Check

2). Apply a drop of distilled water to the Refractometer prism with a pipette. Bring the eyepiece to the eye. The lens will be visible division with numbers, and part of the scale will be painted blue. The line on the border between light and dark colors will serve as an indicator for density measurement.

The contact line, in the case of clean water, shall be zero on the instrument scale. Now, if the water is replaced with antifreeze, this value will change in a big way (above 0°C). The result will be an indicator of the quality of the liquid.

How not to buy a fake

High-quality antifreeze has the required number of special additives and a factory-specified density. All this ensures reliable protection of the car engine from sudden temperature changes.

Even at low rates exceeding the recommended values, the solution, in the case of freezing, will turn into a plastic jelly-like mass and will not damage the structural elements of the motor.

If, instead of the conditioned liquid in the cooling system to fill the counterfeit, then the temperature drops below 0°C, such a mixture will expand and increase in volume. Reaching the critical threshold, the icy antifreeze will break the cooling jacket, radiator and engine water pump.

Check the quality of the coolant when buying a mobile hydrometer (bulb with pear) or litmus test paper. It is when immersed in a liquid must change its neutral color to the color of the purchased antifreeze.

A more complex method of verification will be more convenient to carry out at home. It is intended for the study of the solution for the presence in its composition of sulfuric or perchloric acid.

Antifreeze is poured into a separate capacious container. Add a small amount of soda to it. If the cooler is normal, then no reaction will follow, and if the liquid begins to foam and hiss – this is an undeniable fact of the presence of acid reagents in the mixture.

When choosing antifreeze, it is recommended to buy only in proven places, and to acquire brands of cooler from well-known manufacturers.

Алексей Назаров/ автор статьи

Руководитель сети СТО с огромным стажем работы.

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