This chapter concerns a sulfuric acid process and the second with optimizing indoor ventilation flow rates. Indoor air quality problems have become more serious and of greater concern now than in the past because of a number of developments that are believed to have resulted in increased levels of harmful chemicals in indoor air. The general subject of fluid flow encompasses a host of topics. One topic of importance to both environmental and chemical engineers is the optimizing of a fluid transport system. It is desired to compute the optimum values for these parameters for the economic transportation of 150 MM std ft3/day of natural gas. It appears that the optimum lies close to 400 lb/sq in. abs discharge pressure for the conditions assumed. The first step in determining the required optimum is to express the costs of additional units of the variables on the basis of dollars per operating day.