California Code of Regulations
Title 19 - Public Safety
Division 1 - State Fire Marshal
Chapter 3 - Fire Extinguishers
Article 23 - Table for Conversion of Classification of Older Extinguishers to Approximate Present Classification
Section 616 - Method Classification

Under the present method of classification it is possible for units of the same size to have different classifications. For example, 15-pound carbon dioxide extinguishers may have a classification of 4-B:C, 6-B:C, or 8-B:C, according to the fire extinguishing potential of the individual units. Therefore, an exact conversion from the old method to new method of classification is not possible.