How Designated of a Refrigerants?

Designation of refrigerants:

A large number of refrigerants have been developed over the years for a wide variety of applications, a numbering system has been adopted to designate various refrigerants. From the number one can get some useful information about the type of refrigerant, its chemical composition, molecular weight etc.

All the refrigerants are designated by R followed by a unique number.

                     (i) Fully saturated, Halogenated compounds:  

These refrigerants are derivatives of alkenes (C_nH_2n+2) such as methane (CH₄), ethane (C₂H₆).

These refrigerants are designated by R XYZ, where

• X+1 indicates the number of Carbon (C) atoms
• Y-1 indicates number of Hydrogen (H) atoms, and
• Z indicates number of Fluorine (F) atoms

*** The balance indicates the number of Chlorine atoms. Only 2 digits indicate that the value of X is zero.

Ex: R 22

• X = 0 ⇒ No. of Carbon atoms = 0+1 = 1 ⇒ derivative of methane (CH₄)

• Y = 2 ⇒ No. of Hydrogen atoms = 2-1 = 1

• Z = 2 ⇒ No. of Fluorine atoms = 2 

The balance = 4 – no. of (H+F) atoms = 4-1-2 = 1 ⇒ No. of Chlorine atoms = 1

 

∴The chemical formula of R 22 = CHClF₂

Similarly it can be shown that the chemical formula of:

• R12 = CCl₂F₂
• R134a = C₂H₂F₄ (derivative of ethane)

(Letter a stands for isomer, e.g. molecules having same chemical composition but different atomic arrangement, e.g. R134 and R134a)

                     (ii) Inorganic refrigerants: 

These are designated by number 7 followed by the molecular weight of the refrigerant (rounded-off).

Ammonia	Molecular weight is 17	Designation is R 717
Carbon dioxide	Molecular weight is 44	Designation is R 744
Water	Molecular weight is 18	Designation is R 718

 

                    (iii) Mixtures:  

Azeotropic mixtures are designated by 500 series, where as zeotropic refrigerants (e.g. non-azeotropic mixtures) are designated by 400 series.

Azeotropic mixtures:

• R 500: Mixture of R 12 (73.8 %) and R 152a (26.2%)
• R 502: Mixture of R 22 (48.8 %) and R 115 (51.2%)
• R 503: Mixture of R 23 (40.1 %) and R 13 (59.9%)
• R 507A: Mixture of R 125 (50%) and R 143a (50%)

Zeotropic mixtures:

• R 404A: Mixture of R 125 (44%), R 143a (52%) and R 134a (4%)
• R 407A: Mixture of R 32 (20%), R 125 (40%) and R 134a (40%)
• R 407B: Mixture of R 32 (10%), R 125 (70%) and R 134a (20%)
• R 410A: Mixture of R 32 (50%) and R 125 (50%)

                   (iv) Hydrocarbons:

• R 290: Propane (C₃H₈)
• R 600: n-butane (C₄H₁₀)
• R 600a : iso-butane (C₄H₁₀)

Unsaturated Hydrocarbons:

• R1150: Ethylene (C₂H₄)
• R1270: Propylene (C₃H₆)