Characteristics of Freon R22 Refrigerant

Freon is a widely used refrigerant. It is the collective term of saturated hydrocarbons, characterized by micro-toxicity, odorlessness, no danger of explosion, good chemical stability, no reaction to water, and no corrosion to metal. There is a great variety of Freon and in order to avoid sophistication of writing its molecular formula and for easy memorizing, people have invented a series of simplified code for different types of Freon such as R12, R22 and R502, etc. The following is an example of R22 (CHLF2) to introduce its characteristics, and other refrigerants are similar.

R22 is nonflammable and nonexplosive. When exposed to open fire, R22 decomposes into toxic gas called CoCl2. Therefore, adequate ventilation for the refrigerating system is required when repairing refrigeration compressor with open fire. While

repairing, ventilate the operation environment. R22 is capable of long time operation in steel or copper container under the temperature from 135 to 150°C, and will start to decompose above such temperature. When reacting with frozen oil, it frees the carbon from the oil without effect to the acid and the water components, to form carbon deposit and when co-existing with iron, it decomposes at 500°C.

The standard boiling point of R22 is -40.8°C. R22 is a medium temperature refrigerant. When water is used as the cooling medium, the condensation pressure should not exceed 1.53 MPa, and when wind is used as the cooling medium, the condensation pressure should not exceed 2.16 MPa (tropical air conditioning excluded).

The solubility of water in R22 is 10 times greater than that in R12, and the lower the temperature, the higher the water content, therefore it is required that the water content in R22 should not exceed 40 to 60mg/L (ppm).

R22 has micro-solubility in lubricating oil. They dissolve inside the pump case of compressor and condenser, and when they separate in evaporator, the solubility changes with the temperature. The permeability of R22 is higher than that of R12, therefore its sealing is more demanding, and the refrigerating capacity of unit volume is about 40% larger than R12. R22 has good electrical performance and excellent insulation performance, although in the liquid phase, the dielectric constant is high and the insulation resistance is low. High dielectric constant means that the insulation resistance decreases due to the trace impurities. When it mixes with lubricating oil, the insulation capacity will decrease sharply. Special attention should be paid to the impurities of the electrical insulating material plant when using the range 2 in the closed system.