Abstract: A gas turbine cooling and sealing air supply system design for an industrial gas turbine is provided which effectively eliminates the need to dissipate bleed pressure across an orifice or similar device, thereby to optimize full load ISO performance. This flow system is realized by providing cross over valves/ejectors which allow mixing of extractions of different pressures. Control valves provided in the various extraction and cross over flow paths selectively control and determine the flow of extraction bleed air from the various stages of the compressor and between the extraction flow paths. Once the air is combined, its combined pressure and temperature is somewhere between the lower and higher pressure extraction air original pressures and temperatures. Thus, the proper pressure can be supplied to, e.g., the turbine with the least expensive, in terms of work invested, mixture of air with the lowest temperature.