The vapor phase of carbon dioxide shall not be less than 99.5 percent carbon dioxide. The water content of the liquid phase shall not be more than 0.01 percent by weight [-30°F (-34.4°C) dew point]. Oil content of the carbon dioxide shall not exceed 10 ppm by weight.

Note: Carbon Dioxide obtained from dry ice converters will generally be unsatisfactory unless it is properly processed to remove excess water and oil. The preferred source of carbon dioxide for recharging extinguishers is from a low-pressure supply, either directly or via dry cylinders used as an intermediary means.