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.
Cal. Code Regs. Tit. 19, § 616