Pyxis GC BTEX analyser for ambient air

Pollutants in ambient air, such as BTEX levels, originate from various sources such as transportation, diverse (petrochemical) industries, or the use of petrochemical raw materials and solvents. BTEX components (Benzene, Toluene, Ethylbenzene, and Xylene) are or have been widely used. The Pyxis BTEX analyser precisely monitors these concentrations in outdoor air. By applying modern technology, a very compact and “carrier gas-free” gas chromatograph has been developed that continuously samples and delivers a measurement result every 10 minutes. The Pyxis operates as described in EN 14662-3.

Air flows

Ambient air is continuously drawn in. This air is divided into three flows:

• Dilution air for control with known concentration;
• Air as carrier gas;
• Sample gas.

Optionally, an auto-check can be performed at programmed intervals using a small calibration cylinder. The measurement signal is then corrected, mainly due to detector drift. If the signal degradation is too high, a warning is generated. A portion of the sampling stream is additionally filtered and used as carrier gas. The sample gas goes directly into the adsorption trap for component enrichment. After a period, desorption occurs, and the sample with carrier gas flows through the GC column and is detected by a PID sensor. Every 10 minutes, a chromatogram is produced, and the concentrations of Benzene, Toluene, Ethylbenzene, and Xylene are determined.

MicroGC

In fact, the Pyxis is a MicroGC: a miniaturised gas chromatograph. The "preconcentrator" and GC column are manufactured using MEMS technology (Microelectromechanical Systems). These components are therefore extremely compact. For detection, a MiniPID sensor is used.

Mini-PC

The system is programmed and configured via a mini-PC. All components are housed in a weather-resistant enclosure where the temperature is maintained at a constant 45 °C. Optionally, the unit can be equipped with a battery/UPS that allows for 6 additional hours of operation after a power outage.

Specifications