CFC Numbering Scheme
Rule of 90
- Add 90 to the CFC number.
- Resulting digits give the number of atoms, respectively, of carbon,
hydrogen, and flourine.
Examples
- CFC-11: 11 + 90 = 101 --> CCl3F
- CFC-12: 12 + 90 = 102 --> CCl2F2
- HFC-134a 134 + 90 = 224 --> H2C2F4 (CF3-CFH2)
("a" refers to how the atoms are arranged)