Balancing of air distribution and ventilation systems has for many years been accepted as perhaps more of an art than a science. Techniques for balancing have been outlined by such organizations as SMACNA (Sheet Metal and Air-Conditioning Contractors Association) and the AABC (Associated Air Balance Council) which formulate step by step procedures. Two of the most highly recognized balancing procedures are the proportional balance and the traverse procedure. With proper application similar results can be obtained from either method. It is beyond the scope of this paper to discuss the relative merit of these two procedures. The exact procedure to achieve proportional balancing is described. The method discussed in this paper offers an approach to system balancing through design using slide gate dampers. Obviously, not every system can be applicable to this type design. These data have been developed in the lab and field tested, and, thus, when properly applied can be expected to achieve desirable results.