A rotation-related normalization of variables has been introduced, and dimensionless fundamentally based correlations have been developed, for pressure drop in a spinning cone column (SCC) in the absence of liquid flow (dry column). The pressure drop is a sum of the dynamic and the centrifugal pressure components. Under typical SCC conditions, the correlation reduces to the form of DeltaP(G)=2N(st)(k(reg)Ro(2)+k(rot)), where N-st is a number of cone sets, Ro is the Rossby number (a rotation-normalized gas flow rate), and k(reg) and k(rot) are empirical coefficients characterizing the flow regime and the centrifugal efficiency of the rotor, respectively. This "dry column approximation" fits the data extremely well (the variation accounted for by the correlation is 98% of the total variation). It can be used as a theoretical limit for pressure drop prediction in an SCC at low liquid loads. The pressure regimes are classified as the centrifugal (Ro<0.2), the intermediate (0.21). Based on these dimensionless boundaries, dimensional diagrams of SCC operating regimes are constructed for laboratory and commercial-scale columns. The generality of the results is discussed in terms of the applicability of the correlations to larger scale equipment, the determination of empirical coefficients, and the linkage with CFD analysis of SCCs.