Antifreeze application and rapid detection in the automotive industry

First, the application of antifreeze in the automotive industry

In winter, the temperature is low. In order to keep the car in use at low temperatures in winter, the engine coolant has added some substances that can lower the water freezing point as antifreeze, and the cooling system does not freeze when it is cold. Therefore, people sometimes refer to the coolant as "antifreeze" or "antifreeze." The full name of the antifreeze should be called antifreeze coolant, which means the coolant with antifreeze function.

1 , definition

Antifreeze, also known as coolant, is a liquid composed of antifreeze additives and additives to prevent corrosion of metals and water. It requires antifreeze, corrosion resistance, thermal conductivity and deteriorating properties. Ethylene glycol is often used as the main component, and antifreeze added with anti-corrosion and water is added.

The engine cooling system of an internal combustion vehicle is a liquid-cooled closed circulation system consisting of a cylinder, a jacket and a water tank. The working state of the cooling system directly affects the normal operation of the vehicle and the service life of the vehicle. Antifreeze is the cooling medium of the circulating cooling system of internal combustion engine. It is mainly composed of antifreeze, corrosion inhibitor, defoamer, colorant, antifungal agent and buffer. With the development of the automotive industry, the performance requirements of the engine are also getting higher and higher, not only the antifreeze has a lower freezing point and a higher boiling point, but also has better metal corrosion resistance, cavitation prevention, and anti-knot. Scalability, as well as comprehensive performance in terms of little or no environmental pollution, and a long service life.

2 , type

(1) Ethylene glycol antifreeze

Ethylene glycol is a colorless, slightly viscous liquid with a boiling point of 197.4 ° C and a freezing point of -11.5 ° C. It can be mixed with water in any ratio. After mixing, the freezing point was significantly lowered by changing the vapor pressure of the cooling water. Ethylene glycol antifreeze is easy to generate acidic substances during use and has a corrosive effect on metals. Therefore, an appropriate amount of disodium hydrogen phosphate or the like should be added to prevent corrosion. Ethylene glycol is toxic, but because of its high boiling point, it does not cause vapors to be inhaled into the body and cause poisoning. The water absorption of ethylene glycol is strong, and the storage container should be sealed to prevent overflow after water absorption. Since the boiling point of water is lower than that of ethylene glycol, water is evaporated during use. In the absence of coolant, it is sufficient to add purified water. This kind of antifreeze can be recycled after use (to prevent mixing into petroleum products). After precipitation, filtration, adding water to adjust the concentration, add preservatives, and continue to use, generally available for 3-5 years. But filter it many times to prevent damage to the car. Many people think that the freezing point of ethylene glycol is very low. The freezing point of antifreeze is a neutralization freezing point when ethylene glycol and water are mixed in different proportions. Actually, the freezing point will change the vapor pressure of cooling water. Significantly lower. The degree of reduction decreases within a certain range as the content of ethylene glycol increases, but once it exceeds a certain ratio, the freezing point will rise. When the content of ethylene glycol is 68%, the freezing point can be lowered to -68 ° C. When the limit is exceeded, the freezing point will rise. The antifreeze mixture of 40% ethylene glycol and 60% soft water has an antifreeze temperature of -25 °C; when the antifreeze solution contains 50% of water and water, the antifreeze temperature is -35 °C.

(2) Diethylene glycol antifreeze

Diethylene glycol-water antifreeze, which is less volatile and ignited, and less corrosive to metals, but diethylene glycol has lower freezing point than ethylene glycol. When preparing antifreeze at the same freezing point, it is more than ethylene glycol or alcohol. The amount is large, and the heat transfer efficiency is lowered. Therefore, this antifreeze is used less. In order to reduce costs, many manufacturers will mix ethylene glycol and diethylene glycol.

(3) Alcohol-water antifreeze

The boiling point of alcohol is 78.3 ° C and the freezing point is -114 ° C. The wine and water can be mixed in any ratio to form antifreeze with different freezing points. The more alcohol you have, the lower the freezing point. Alcohol is a flammable product. When the alcohol content in the antifreeze reaches 40% or more, it is easy to produce alcohol vapor and catch fire. Therefore, the alcohol content in the antifreeze should not exceed 40%, and the freezing point is limited to -30 °C. Alcohol-water antifreeze has the advantages of good fluidity, fast heat dissipation, convenient material selection and simple preparation. Its disadvantage is that it is easy to catch fire, the boiling point of alcohol is low, and the evaporation loss is large. After the alcohol evaporates, the antifreeze composition changes and the freezing point rises. It is not advisable to use alcohol-water antifreeze in cars driving in mountainous areas and highland areas because of the large evaporation loss of alcohol. In general, driving in the area should regularly check the alcohol content and replenish it in time.

3 , role

Cooling effect:

Cooling is the basic function of the coolant. The engine generates a lot of heat when it is working, and 60% of the heat is dissipated into the surrounding space through the cooling system. Water and methanol coolants have a low boiling point and are prone to boiling. If the vehicle is operated under coolant boiling conditions, the engine may be damaged or even embarrassed even in a short period of time.

Antiseptic effect:

In the cooling system, the radiator, water pump, cylinder and cylinder head, water distribution pipe and other components are composed of steel, cast iron, brass, copper, aluminum, solder and other metals. The role of electrolytes is due to the different electrode potentials of different metals. Electrochemical corrosion is prone to occur; at the same time, the acidic product formed by the decomposition of the glycols in the cooling liquid and the acidic exhaust gas after the combustion of the fuel may also penetrate into the cooling system to promote corrosion of the cooling system. Corrosion of the cooling system will cause the lower water chamber of the radiator tank, the nozzle spacer, the cooling pipe, the joint and the water tank to be faulty, and corrode the product Dussel pipe, causing the engine to overheat or even smash; if the corrosion perforation, the coolant penetrates into the combustion The chamber or crankcase can cause serious damage because when the coolant or water is mixed with the body oil, oil and gel are generated, which weakens the lubrication and causes the valve, hydraulic valve push rod and piston ring to bond. Therefore, a certain amount of anti-corrosion additive is added to the coolant to prevent corrosion of the cooling system.

Anti-scaling effect:

The scale in the cooling system is derived from cations such as calcium and magnesium in the water. These alkaline earth metal cations easily react with the ions in the water to form scale under thermal load conditions. The scale can wear the water pump seal and cover the outer wall of the water jacket of the cylinder block, so that the thermal conductivity decreases, and the temperature of the high temperature zone of the cylinder head increases sharply, causing the cylinder to crack. Therefore, in order to reduce scale formation, the coolant is required to use softened deionized water during production and filling.

Antifreeze effect:

In winter, the temperature is low. In order to keep the car in use at low temperatures in winter, the engine coolant has added some substances that can lower the water freezing point as antifreeze, and the cooling system does not freeze when it is cold. Therefore, people sometimes refer to the coolant as "antifreeze" or "antifreeze."

Second, the rapid detection of antifreeze

There are two main advantages to measure the antifreeze: first, the antifreeze effect, the freezing point of water is 0 °C, the general antifreeze can reach -40 °C, and the high quality antifreeze should reach -60 °C. This is an important indicator for calibrating the quality of antifreeze; the other is the boiling point of antifreeze, the boiling point of water is 100 ° C, and the antifreeze should be at least 108 ° C, which means that the lower the freezing point, the higher the boiling point, the temperature difference The larger, the better the quality of the antifreeze.

Countries have done a lot of research on this, and continue to introduce formula patents and excellent antifreeze products. Antifreeze penetration rates in some advanced countries have reached 100%. The penetration rate of domestic antifreeze is low. A considerable amount of commercially available antifreeze is imported. Because of the high price, it is generally used for importing vehicles. Although the production of domestic antifreeze has grown rapidly in recent years, many products lack strict quality inspection and uniform inspection standards. To this end, we must absorb foreign advanced technology and combine the reality of China to develop and produce multi-functional high-efficiency antifreeze to meet the growing market demand.

ATAGO antifreeze concentration meter provides convenient and accurate rapid detection tools for manufacturers and car owners to prepare different concentrations of antifreeze according to the freezing point demand:

MASTER-BR coolant refractometer (scale visual inspection)

PAL-91S car antifreeze refractometer (digital display)

Simple measurement: 3 steps to complete

1.   Add 2-3 drops of sample

2.   Press the start START button

3.   View Results

DR-A1 digital display Abbe refractometer

It provides a reliable guarantee for the detection of raw ethylene glycol raw materials when entering the factory, and detects the purity of the ethylene glycol, thereby providing a more accurate premise for the subsequent preparation of various concentrations of ethylene glycol solution. For example, the refractive index (20 ° C) of the 100% ethylene glycol concentration is 1.43100-1.43105. If the concentration is impure, the refractive index will be low, and the purity of the ethylene glycol can be judged and the corresponding concentration can be found from the conversion table. freezing point.

RX-7000α automatic desktop digital display refractometer

It has an electric heating module to maintain a constant temperature. This product has a manual calibration function that coordinates the different standard liquid values ​​and measured values ​​measured by other refractometers.

The scale can be customized, and the linear relationship between the refractive index and the ethylene glycol concentration can be set on the instrument. The measurement will be quick and convenient. One button can get the refractive index and concentration of ethylene glycol in a few seconds. It is a refractometer. Smart products in the product.

At the same time, there is automatic temperature control function, the sample is controlled to the corresponding temperature for testing, the result is more accurate.

More details: