MeDOAS
The MeDOAS (Mobile extractive Differential Optical Absorption Spectroscopy) instrument system is designed to measure gas concentrations of BTEX and other gases in the extracted air using internal UV-light. The system consists of a Main Unit with a multi-pass Optical Reflection Cell mounted in a temperature-controlled enclosure and a separate Spectrometer Unit. The system also includes vibration dampers, valves, hoses, air pump and mounting beams. IT-infrastructure including GPS-receiver, computer and monitor can also be provided on request.
Note: the MeDOAS system can be mounted on a mobile platform (vehicle) or in a stationary indoor space. A gas inlet for air extraction is needed.
Note: Local wind measurements are helpful for the data interpretation.
| Specification of standard configuration | |
| Units (version) | MeDOAS Main Unit (v4) Spec. Unit -L (v2) |
| Measurement Principle | Active, Extractive Multi-Reflection Cell |
| Measured Quantity (Unit) | Concentration in Optical Cell (ppb) |
| Light Source | Internal UV-lamp (Xe) |
| Calibration Source | Internal Pb Hollow Cathode Lamp |
| Optical Path Length | 100-118m |
| Flow Rate | 120 l/min |
| Spectrometer Model | Czerny Turner Grating Spectrograph |
| Detector Type | CCD, Peltier Cooled |
| Spectral Range | UV, 250-275 nm |
| Spectral Resolution | 0.15 nm |
| Standard Species & Detection Limits (ppb) | Benzene (1) Toluene (2) Etylbenzene (4) p-Xylene (1) |
| Additional Species | Ozone, Sulphur Dioxide, Furfural, Paracresol, Phenol, Naphtalene, Styrene, Trimethyl Benzene |
| Sampling Time | 4 - 10 s |
| Dimensions W x H x D | 450 x 400 x 1750 mm - Main Unit 612 x 405 x 322 mm - Spec. Unit -L |
| Weight (kg) | 112 kg - Main Unit 36 kg - Spec Unit |
| Housing | Powder Coated Aluminium (RAL9003) |
| Operational Environment | Temperature: 5-35 deg C
Relative Humidity: 0-90% (non-condensing) |
| Intern Temp. Regulation | Heating Plates |
| Vibration Suppression | Pneumatic Mounts |
| Supply Voltage | 100-240V AC, 50/60 Hz |
| Nominal Power | 520 W (with no inlet heater) |
| Data Interface | USB-B |
| Software | FluxMeasure, FluxCtrl, FluxReport |
| Main Accessories | Measurement Computer, Optical Fiber, GPS Receiver, Inlet Heater, Particle Filter (Cyclone), Spare Parts & Tool Kit |
