Shimadzu's Natural Gas Systems are specially-modified GC-8As designed for the measurement of natural gas components. Determining the composition of natural gas is important because its heating value (and price) is determined by its BTU per cubic foot.

Shimadzu's two systems conform to ASTM D1945 and D3588. Natural Gas System #1 separates C 1 - C5 paraffins and isoparaffins, O₂, N₂, CO and C6+ by backflush. System #2 analyzes the same components, but it produces a single air peak rather than separating O₂ and N₂. After analysis, the mole% of each component is automatically calculated, along with the BTUs per cubic foot, compressibility, specific gravity, and relative density.

Each system is reliable and easy to operate. The PRG-102A event programmer switches the valves automatically, while the optional Chromatopac data processor controls the system operation and performs the required calculations automatically. Calibration is based on a Certified Calorific Natural Gas Standard.