Which valve will be better for air piping, butterfly or ball valve?
Butterfly valves allow for more volume but are weaker under pressure. They cost less than ball valves and don’t seal flow as well. Ball valves(generally) have a smaller throat than the piping so constricts the volume more, but they operate better under higher pressures. Some high pressure requirements use ball valves with the same diameter as the piping so as not to restrict or drop pressure. They seal better against the flow, but are more expensive than butterfly valves. So, look at your applications.