API TR 2575 pdf download Measurement of Thermally Cracked Gas 1 Scope This technical report presents a method to compute the density, compressibility factor, and supercompressibility factorfor thermally cracked gas (TCG) for custody transfer using orifice meters. It provides equations，parameters,computation flow diagrams, and example spreadsheet calculations. This technical report applies to TCG mixtures after treatment. See Table 2 for more...