We can define the refrigerant as the substance used for the transmission of heat in a refrigeration system . That is, through changes in temperature and pressure, heat is transferred from one place to another with processes of transformation from gas to liquid or vice versa. Gases or refrigerant fluids are used in refrigeration systems and air conditioning.

 

 

Main characteristics of refrigerant fluids

In the current market there are many types of refrigerants , the differences from one to another vary according to the characteristics they meet.

We can classify the characteristics or properties that these refrigerants must meet in two types, on the one hand, the thermodynamic characteristics and on the other, the chemical and physical ones. For example:

 

Thermodynamic characteristics

  • The freezing temperature must be lower than the temperature in the system, otherwise frostbite may occur in the evaporator.
  • Low specific volume to avoid suction and compression lines with large sizes.
  • Latent heat must be high, so that with a small amount of liquid, as much heat as possible can be absorbed.
  • High density to avoid small liquid lines.
  • To avoid leaks and lower the condensing temperature, the condensing pressure must be raised.

 

Chemical and physical characteristics

  • They should avoid being toxic, corrosive or flammable.
  • In the event of leaks, it must be easy to detect.
  • It must not affect other materials, as well as being able to mix with oil.
  • It must be a stable compound.

 

Classification of types of refrigerants

There are some regulations (RSIF, UNE-En 378 …) where the safety and environmental requirements that refrigeration systems must meet are established. Likewise, a series of categories have been created to classify correctly the types of refrigerants (BOE):

 

Classification according to its level of toxicity

In both classifications, the average concentration over time does not have adverse effects on employees who are exposed during a workday of 8h / day and 40h / week, what varies is the value according to the average concentration.

Class A (Lower toxicity): Value equal to or greater than an average concentration of 400ml / m3 [400ppm. (V / V)]

Class B (Higher degree of toxicity): Value lower than an average concentration of 400ml / m3 [400ppm. (V / V)].

 

Classification according to its flammable capacity

Group 1: Non-flammable. That is, in the tests it does not propagate the flame.

Group 2: low flammability index. Those whose lower limit or whose minimum concentration of refrigerant can spread the flame in the homogeneous mixture with air at a percentage equal to or greater than 3.5% by volume (V/V).

Group 3: Refrigerants with a high degree of flammability . Those whose lower flammability limit when mixed with air is less than 3.5% by volume (V/V).

 

These classifications are complementary, that is, an additional classification is created relative to safety according to the toxicity and flammability criteria:

L1: Refrigerants with high security. They are not flammable and their toxicity is low or null ( A1 ).

L2: Medium safety. They are corrosive or flammable refrigerants with toxic action mixed with air in a volume equal to or greater than 3.5% (A2, B1, B2, A2L) .

L3: Low safety. Flammable refrigerants mixed with air in a volume of less than 3.5% (A3, B3).

 

 

According to the new update of the regulation in Europe, a new category has to be included in the flammability and safety criteria , adding the 2L classification for those refrigerants with low flammability and low global warming potential, that is, the speed of propagation is slow (less than 10cm/s).

If you want to know more about this topic you can read it in this BOE where they deal with the subject.