An Agilent 6890N gas chromatograph (GC) based analytical system was installed in Hegyhátsál in 26-27 January, 2006. Air samples are taken from 96m elevation. Using ECD and FID sensors the mixing ratio of CH₄, CO, N₂O and SF₆ are monitored continuously.

System description:

Auxiliary system components:

Hydrogen generator: Parker Balston: Mod.: 9090
Air compressor: Jun-Air Mod.: OF-302-25B x 2
Zero Air generator: Parker Balston Mod.: 75-83-220
N₂ generator: Parker Balston Mod.: 76-92-220
We had problems with the latter model, since there was no catalyst for hydrocarbon (especially methane) removal. To establish the optimal condition for the N₂ generator we dried the compressed air with an adsorption dryer, Mod.: HL-S0120, but this did not decrease the methane concentration in the generated nitrogen. To solve the problem, we use compressed nitrogen, with purity of 99.99990% (6.0).

Sampling system:

Filter
Pump: KNF Neuberger, Mod.: N86ATE (special version)
Rotameter1
Miniature pneumatic supply - constant pressure and stream splitter
Rotameter2
Dryer at about -90 deg.C
Valco 10 position sampling valve with microelectronic controller

Summary of the system:

Instrument principle: GC
Manufacturer: Agilent
Type: 6890N
Acquired: 2003
Sample flow: approx. 150 ml/min
Reference flow: approx. 150 ml/min
Sample period: 10 mins
Flush time: 0.5 mins
Calibration freq: 12 hours
Target freq: 0.3 hours
Column A: Unibeads+mol.sieve 5A 1/8 inch,4+6 feet
Column B: Hayesep Q 1/8inch 4+6 feet
Measurements stored 6 per hr
Levels: 96 meter AGL

The GC system in operation at the measurement site

Schematic diagram of the Agilent 6890N setup (Figure by courtesy of Cyril Messager, LSCE)