This Code provides procedures for the conduct and reporting of performance tests of flue gas desulfurization systems (FGDS). The application of this Code is limited to the process and equipment employed to remove sulfur dioxides from flue gas or other sulfur-dioxide-laden gas streams. The methodology described may be adapted for assessment of removal of other emissions if agreed to by the parties to the test. This Code does not apply to removal of sulfur oxides from gases during the combustion process. Types of systems covered: (a) Dry FGD System. An FGD system process in which a flue gas containing sulfur oxides passes through an alkaline material but is not saturated with moisture; the gas leaves the reactor at a temperature above the adiabatic saturation, thus producing a dry by-product or dry waste product. (b) Wet FGD System. An FGD system process in which a flue gas containing sulfur oxides passes through an alkaline material and is saturated with moisture, thus producing a wet by-product or wet waste product. (c) Regenerable FGD System. An FGD system process that regenerates and recycles the sorption medium.