CHARACTERISTICS OF REFRIGERANTS
Pure R-12 (CC 1425F425) is colorless. It is odorless in concentrations of less than 20 percent by volume in air. In higher concentrations, its odor resembles that of carbon tetrachloride. It has a boiling point of -21°F at atmospheric pressure. At ordinary temperatures under a pressure of approximately 70 psig to 75 psig, R-12 is liquid. Because of R-12’s low boiling point at atmospheric pressure, you must always protect your eyes from contact with liquid R-12; the liquid will freeze the tissues of the eyes. Always wear goggles if you is to be be exposed to R-12. R-22 (CHC1F425) and R-11(CC1435F) are colorless, nonexclusive, nonpoisonous refrigerants with many properties similar to those of R-12. Because of the similarities between R-22, R-11, and R-12, only R-12 is discussed. Mixtures of R-12 vapor and air, in all proportions, will not irritate your eyes, nose, throat, or lungs. The refrigerant will not contaminate or poison foods or other supplies with which it may come in contact. The vapor’s nonpoisonous. However, if R-12 concentration becomes excessive, it can cause you to become unconscious or cause death because of lack of oxygen to the brain.R-12 is nonflammable and nonexclusive in either liquid or vapor state. R-12 will not corrode the metals commonly used in refrigerating systems.R-12 is a stable compound capable of undergoing the physical changes required of it in refrigeration service without decomposing. It is an excellent solvent and has the ability to loosen and remove all particles of dirt, scale, and oil with which it comes in contact within a refrigerating system.
CHARACTERISTICS OF GOOD REFRIGERANTS:
1. Latent heat of evaporation must be higher, lesser the mass required per unit capacity.
2. It must be volatile, capable of being evaporated, low boiling point.
3. Safety operating condition, non explosive.
4. Non-toxic and easy to detect simple test.
5. It must have reasonable evaporating and condensing pressure.
6. Compression ratio must lower thus low power consumption required and high volume efficiency.
7. Critical temperature should be well above condensing temperature.