In 1928, the American Chemist Corporation. Freons and their impact on humans. Comments for those who don't believe in conspiracy theories

And for sure, even without knowing the device of refrigeration systems, they heard such a thing as a refrigerant. A refrigerant is a substance circulating in a refrigeration machine, which, when boiling and then evaporating, takes heat from the cooled object, and after the condensation process transfers it to the environment.
In different periods of time, various types of refrigerants were used, but all of them were either dangerous to humans or did not ensure the smooth operation of refrigeration systems. Finally found golden mean, freon was created.
Freon is a group of fluorine- and chlorine-containing hydrocarbons based on CH3-CH3 ethane and CH4 methane, which are used as refrigerants in refrigeration equipment.

Name history

In 1928, the American chemist of the corporation General Motors (General Motors Research) Thomas Midgley Jr. (Thomas Midgley, Jr. 1889-1944) managed to isolate and synthesize a chemical compound in his laboratory, which later became known as Freon. After some time, the "Kinetic Chemical Company", which was engaged in industrial production new gas - Freon-12, introduced the designation of the refrigerant with the letter R (Refrigerant - cooler, refrigerant).

This name became widespread and over time, the full name of the refrigerants began to be written in a composite version - trademark manufacturer and common designation of the refrigerant. For example: The brand name GENETRON®AZ-20 corresponds to R-410a refrigerant, which consists of R-32 (50%) and R-125 (50%) refrigerants.

There is also a trademark with the same name as that of the chemical compound - FREON® (Freon), the main copyright holder of which is American company"DuPont" ("DuPont"). This coincidence in the name still causes confusion and controversy - whether arbitrary refrigerants can be called freon.
Freons: types, properties
Physical properties of freon: colorless gases or liquids, odorless. They are highly soluble in nonpolar organic solvents, very poorly soluble in water and polar solvents.
Freon chemical properties:
— Freons are inert due to which they do not burn in air and in contact with an open fire. However, when freons are heated above 250 ° C, very toxic products are formed, for example, phosgene COCl2, which was used as a chemical warfare agent during the First World War.
- Resistant to acids and alkalis.

Freon types:

- trichlorofluoromethane (bale temperature - 23.8 ° C) - Freon R11, Freon-11, Freon-11

Refrigerant R11 - fluorotrichloromethane, a heavy gas, belongs to the group of chlorofluorocarbons.
R11 refrigerant is harmless to the human body, it is non-explosive, it is unlimitedly soluble in mineral oil. Insoluble in water. The dehydrated refrigerant is neutral to all metals, with the exception of alloys containing more than 20% magnesium.
The first widely used freon. In view of the relatively high boiling point, it can be used in refrigeration units with lower pressure, which simplifies their design.
- difluorodichloromethane (bp - 29.8 ° C) - Freon R12, Freon-12, Freon-12
A colorless gas with a specific odor. One of the most common and safe refrigerants in operation. It is non-explosive, at t > 330 °С it decomposes with the formation of hydrogen chloride, hydrogen fluoride and traces of poisonous gas - phosgene. It is characterized by fluidity, which contributes to its penetration through the smallest leaks. At the same time, due to the increased fluidity of R12, refrigeration oils penetrate into all rubbing parts, reducing their wear. With a volume fraction in the air of more than 30%, suffocation occurs due to a lack of oxygen. Soluble in oil, slightly soluble in water. They are used in single-stage refrigerating machines with a condensing temperature not exceeding 75 ° C and a boiling point not lower than -30 ° C, in household refrigerators, air conditioners.
- trifluorochloromethane (bale temperature - 81.5 ° C) - Freon R13, Freon-13, Freon-13
Freon R-13 is a colorless gas with a faint smell of carbon tetrachloride. It is used as a refrigerant in medium and low temperature technology. In contact with an open flame, the refrigerant decomposes to form highly toxic chemical compounds.
In recent years, R13 has begun to be replaced by R23, which, compared to R13 at temperatures from -50 to -100 ° C, has a lower viscosity and significantly higher heat transfer coefficients, which makes it possible to reduce the size of heat exchangers.

- tetrafluoromethane (bale temperature - 128 ° C) - Freon R14, Freon-14, Freon-14
Refrigerant R14 is a colorless gas with a slight smell of carbon tetrachloride. Tetrafluoromethane is the simplest of the fluorocarbons. It has high chemical resistance. On contact with a flame, it decomposes to form highly toxic products. nonflammable gas. At room temperature, it is a chemically inert, colorless, odorless gas.
Refrigerant R14 is used to obtain temperatures from -120 to -150 °C.

- tetrafluoroethane (bale temperature - 26.3 ° C) - Freon R134a, Freon-134a, Freon-134a
Refrigerant R134A has a chemical name - "tetrafluoroethane". Its chemical formula is as follows: CF3CFH2. The refrigerant R134A is a colorless and odorless gas. The first of the refrigerants in the production of which chlorine is not used.
R134A is non-toxic and non-flammable over the full operating temperature range, however, if air enters the cooling system, flammable mixtures are formed due to its compression.
R134A is the primary replacement for R12 in refrigeration applications that operate in the medium temperature range. This refrigerant is used in domestic and industrial refrigeration systems, as well as filling automobile air conditioners.
R134A refrigerant is also used for retrofit equipment that operates at lower temperatures. However, if the compressor is not replaced at the same time, the cooling capacity of the system will be somewhat reduced.

R134 refrigerant is long term applications, as it is safe to use, harmless to the environment. It can be used in automotive air conditioning systems, commercial domestic refrigeration medium and high temperature categories. The latest refrigerants like R134A have excellent thermodynamic properties. It is also worth noting that along with the convenience of working with this refrigerant, it can be refueled without any problems in case of a leak.

- chlorodifluoromethane (bp - 40.8 ° C) - Freon R22, Freon-22, Freon-22
The refrigerant R22 has the chemical formula CF2ClH and is essentially a colorless gas with a slight odor of chloroform, it is colorless and can liquefy at high pressure.
At the moment R22 refrigerant is the most demanded and popular refrigerant. Compared to R12 and R502 refrigerants, it is safer in terms of negative impact on environment.
The popularity of R22 refrigerant is due to a number of its advantages:
— does not possess toxic properties, is not explosive;
- during the operation of the refrigeration unit, it has a low temperature of the discharge gas;
— has good thermodynamic and thermophysical characteristics;
- chemically neutral to various materials.
This type of refrigerant is usually used when working on screw and reciprocating compressors with low temperatures, as well as in the circuits of various climatic equipment and in household refrigeration units.
The R22 refrigerant is interchangeable with the R407c, R507, R410a and R404a refrigerants, however, it is necessary to completely change the oil and filters, as well as flush the system with a special flushing refrigerant, since the oils of these refrigerants are not compatible, which, when mixed, can cause the ester substance to coagulate. At maintenance and practical operation of equipment in which R22 freon is used, it is recommended to use mineral or alkylbenzene oils.
R22 has a higher condensing pressure than R12, so the latter cannot be replaced by R22.
-chlorofluorocarbonate (bale temperature - 51.4 ° C) - Freon R407C, Freon-R410A, Freon-R410A

The R410A refrigerant is a close to azeotropic mixture of R125 and R32 refrigerants, due to which, in the event of a leak, it can be refueled without problems in the system. None of its components contain chlorine, so it is safe for the ozone layer. This refrigerant replaces R-22, which depletes the ozone layer and is restricted by the Montreal Protocol.
The main advantage of R410A freon is its high specific cooling capacity. Its cooling capacity is 50% higher than that of R407C and R22, and 100% higher than that of R134A (for a condensing temperature of 54 °C). High refrigeration capacity makes it possible to install fewer compressors in the chiller to achieve a given capacity.

An additional positive factor when choosing R410A is its ability to conduct highly efficient heat transfer. The thermal conductivity of R410A (both in the saturated vapor state and in the liquid state) is higher than that of most refrigerants, and this, in turn, has a positive effect on the efficiency of the entire refrigeration circuit.

The cooling capacity of R410A at condensing temperatures of 54°C is almost 50% higher than that of R22. At the same time, its working pressure is approximately 35% -45% higher. In this regard, when calculating the design of compressors and heat exchangers, it is necessary to make adjustments. Therefore, R410A cannot be used as a replacement for R22 in this type of unit. However, despite this remark, in everyday practice, such a replacement is carried out quite often in household climate equipment, which still works. True, experts find it difficult to answer the question of how long equipment can last on this refrigerant and how much the likelihood of leakage increases when R410A is used in the refrigeration circuit of the system.
Due to the higher density of R410A refrigerant compared to R22 refrigerant, piping, compressors and heat exchangers are calculated in a more compact design.
The R410A refrigerant is not compatible with mineral oils, but is soluble only in a special polyester oil, which costs an order of magnitude more expensive. However, R410A has a high specific refrigerating capacity (one and a half times higher than R407C and R22, two times higher than R134A), which allows the use of a compressor with a lower volumetric capacity.

During sea trials on the nuclear submarine "Nerpa" an unauthorized operation occurred automated system fire extinguishing and release of freon used in the system. The victims of the accident were 20 people - three military personnel and 17 civilian specialists.

In 1928, the American chemist of the corporation "General Motors" ("General Motors Research") Thomas Midgley Jr. (Thomas Midgley, Jr.) for the first time isolated and synthesized in his laboratory a chemical compound, later called "freon" (from the Latin frigor - cold). Later, a whole group of similar compounds was synthesized; the Latin letter R and a numeric code were used to designate them.

Freons (their other name is chlorofluorocarbons) are colorless gases or odorless liquids, as a rule, highly soluble in organic solvents, as well as in many lubricating oils and practically insoluble in water. Freons are a mixture of methane and ethane, in which hydrogen atoms are replaced by fluorine and chlorine atoms.

More than 40 different freons are known, most of which are produced by industry. Among them, there are several types of freon, differing in chemical formulas and physical properties.

The most common connections are:

trichlorofluoromethane (boiling point - 23.8 ° C) - Freon R-11, Freon-11, Freon-11
difluorodichloromethane (bp. - 29.8 ° C) - Freon R-12, Freon-12, Freon-12
trifluorochloromethane (bp. - 81.5 ° C) - Freon R-13, Freon-13, Freon-13
tetrafluoromethane (bp. - 128 ° C) - Freon R-14, Freon-14, Freon-14
difluorochloromethane (bp - 40.8 ° C) - Freon R-22, Freon-22, Freon-22
chlorofluorocarbonate (bale temperature - 51.4 ° C) - Freon R-410A, Freon‑R410A, Freon‑R410A.

Due to their thermodynamic properties, freons have found a wide practical use as coolants in refrigerators, air conditioners, in perfumery and medicine to create aerosols. All refrigerants used in household appliances are non-flammable and harmless to humans. In addition to being used as coolants, freons are used as propellants to extinguish fires (for example, freon 13B1). In industry, freons R-12, R-22, R-134a, R‑407C, R‑410A are most often used.

In 1987, in accordance with the United Nations Environment Program (UNEP), the "Montreal Protocol on Substances that Deplete the Ozone Layer" came into force, providing for a gradual reduction in the production and consumption of a number of chlorofluorocarbons. In particular, in accordance with this protocol, freon R-12 (as the most conducive to the destruction of the ozone layer) and R-22, as well as other freons that destroy the ozone layer, ceased to be used in household appliances. However, they continue to be used in fire fighting.

Freon 22 (Freon 22) belongs to substances of the 4th hazard class on the scale of "harmfulness" of freons. These substances have a narcotic effect, cause weakness, turning into agitation, confusion, drowsiness, and at high concentrations - suffocation. If it comes into contact with the skin, liquid freon can cause "frostbite" (blisters, necrosis).

Freons are very chemically inert, so they do not burn in air, they are explosion-proof even when in contact with an open flame. However, when freons are heated above 250 ° C, very toxic products are formed, for example, phosgene COCl2, which was used as a chemical warfare agent during the First World War.

Under the influence of temperatures above 400 ° C, freon can decompose with the formation of highly toxic products: tetrafluoroethylene (hazard class 4), hydrogen chloride (hazard class 2), hydrogen fluoride (hazard class 1).

When determining the toxic hazard of freons, two main aspects are taken into account: the toxicity of the freon itself and the toxicity of its decomposition products. The degree of decomposition of freons during fire extinguishing largely depends on the phase of fire development and the time of freon supply. The use of freons in fire extinguishing is practically safe, since the fire extinguishing concentrations for freons 23, 318 and 218 are an order of magnitude less than lethal concentrations with exposure duration up to 4 hours.

Approximately 5% of the mass of freon applied to extinguish a fire undergoes thermal decomposition. Therefore, the toxicity of the environment formed when extinguishing a fire with freons will be much lower than the toxicity of pyrolysis and decomposition products.

Toxicity also significantly depends on the degree of purification of freons from impurities of chemicals that pollute the main substance during production processes that pose the greatest risk. At temperatures of 180-380°C and above, due to the thermal-oxidative degradation of freons, concomitant impurities are released into the environment: hydrogen fluoride, tetrafluoroethylene, 2-trifluoromethyl, pentafluoropropene, etc., which determine the picture of intoxication.

In terms of toxicokinetics, freons are similar to inert gases. Only with prolonged inhalation, low concentration freons can have an adverse effect on the cardiovascular, central nervous system, lungs. With inhalation exposure to high concentrations of freons, the toxic effect - oxygen starvation - develops as a result of oxygen displacement. The time of safe exposure to freons R-125, R-227ea, etc. at concentrations in the indoor atmosphere of 9-10.5% is 5 minutes.

The material was prepared on the basis of information from open sources