real-gas

Real-gas compressibility (Z-factor) for O₂/N₂/He mixes.

Virial fit per component, Z(P) = 1 + a·P + b·P² + c·P³ (P in bar absolute), mixed linearly by mole fraction. Coefficients from atdotde/realblender as used by Subsurface and GasPlanner scuba-physics (MIT © 2018 JirkaPok — see THIRD_PARTY_NOTICES.md). Valid 0–500 bar absolute. The source does not state its reference temperature; treat results as room-temperature approximations.