The Method 25 GC system is equipped with an FID detector, built-in air compressor, and a 10-port backflush gas sampling valve to quickly determine methane/non-methane hydrocarbons as per EPA Method 25.

In this typical methane/non-methane analysis, the non-methane hydrocarbons were backflushed after the ethane peak, but the valve timing could have been set to backflush after the methane, or after the C3, C4, C5 or C6 hydrocarbons, depending on the operator's needs.

The sample is connected to the valve inlet port on the GC valve oven, where it fills the 1mL sample loop on the gas sampling valve. The valve is then automatically rotated to inject the sample onto the column, which separates the methane (and optionally the ethane) away from the rest of the hydrocarbons. After the elution of the compound(s) of interest, the gas sampling valve is automatically returned to the starting position, which backflushes the rest of the hydrocarbons into the detector.

The PeakSimple data system controls the temperature programmable column oven and the gas sampling valve, collects the data, quantitates the non-methane hydrocarbons, and produces a printed report. The Method 25 GC comes standard with a HayeSep D column, but may be equipped with other column types as desired.