商品明細

US EPA Designated Equivalent Method*

Ecotech presents the latest addition to the Serinus range: The Serinus 60 NO2 analyser with Cavity Attenuated Phase Shift (CAPS) spectroscopy technology. This technology allows direct measurement of nitrogen dioxide (NO2), rather than an indirect calculation from a chemiluminescence analyser. Using a modulated blue LED light source, the detector measures the phase shift attributable to the level of NO2 in the measurement cell over an average path length of several kilometres.

Serinus 60 Theory of Operation
The measurement of nitrogen dioxide (NO2) utilises Cavity Attenuated Phase Shift (CAPS) spectroscopy technology. sample air is filtered to remove particulates and dried before entering the precision stainless steel 264 mm measurement cell.

The measurement cell contains two high reflectivity mirrors located at either end to provide an average optical path length of several kilometres. A modulated blue light source emits a narrow band wavelength of 450 nm which is used as a photon source for the cavity attenuation process. The LED is pulsed into the optical cavity and the photon ‘leakage’, as a result of the optical cavity, is determined through the output voltage measured by the vacuum photodiode detector. The detector is used in conjunction with a narrow band-pass interference filter (450 nm).

During LED modulation the photon leakage of the cavity combined with photon absorption from gas molecules within the cavity produces a shift in the phase of the response signal measured by the detector.

By measuring the shift in phase angle without NO2 in the sample (background) a baseline phase shift can be measured. During operation, NO2 gas molecules within the cavity will increase photon decay and this will be reflected as a change in phase of the detector signal. This change in phase is proportional to the NO2 concentration. Using this principle it is possible to reliably measure NO2 concentrations of well under 1 ppb up to 1000 ppb. Due to the continuous measurement of the sample, the analyser has a fast response time of less than 30 seconds.