Abstract: Sulfur oxides (SO.sub.x) are scrubbed from combustion effluents with economies in capital and operating costs by virtue of an arrangement of spray header piping and nozzles which permits ease of access for service with reduced spacing (e.g., 0.5 to 1.25 meters) between spray levels. At least two spray levels in a spray zone include a plurality of spray header pipes arranged parallel to the other spray header pipes within a spray level and vertically parallel to spray header pipes in at least one adjacent spray level. Each of the spray levels includes a plurality of spray nozzles extending from said spray headers. A majority of nozzles in a reference spray level are positioned such that lines drawn between them form a pattern of squares with the nozzles located at the corners of the squares. And, a majority of nozzles in an adjacent spray level are positioned over the centers of squares defined by four nozzles in the reference spray level.