Which gas is often reclaimed in an automatic purger?

The gas commonly reclaimed in an automatic purger is aqua ammonia. Aqua ammonia is typically involved in various industrial processes, particularly in refrigeration systems where it acts as a refrigerant.

Automatic purgers are used to remove certain gases or contaminants from systems, and aqua ammonia can be effectively recovered and reused in processes where it is needed. This reclamation is crucial for maintaining system efficiency and reducing waste.

Chlorofluorocarbons (CFCs) and Freon, while also used as refrigerants, are typically phased out due to their environmental impact, particularly their contribution to ozone depletion. Carbon dioxide is not generally reclaimed in the same context as aqua ammonia and is often used in other applications, such as beverage carbonation or as a fire suppression agent.

Thus, aqua ammonia stands out as the correct option because it is not only reclaimable but also continues to serve a vital role in refrigeration and other systems.