CEM - Abstract

Abstract Information :

As a part of Euramet funded project, Heroes, intercomparison measurements at low HCl concentration levels were performed with continuous P-AMS FTIR and wet chemical method EN1911 in April 2021 in Finland. In addition of the comparison between FTIR and wet chemical method, three different filter materials (stainless steel, PTFE and ceramic) were tested as a heated probe filter in FTIR sampling line in order to assess if the filter material has an effect on the measured HCl concentrations. European standardization organization CEN has produced Technical Specification CEN/TS 17337 “Stationary source emissions. Determination of mass concentration of multiple gaseous species. Fourier transform infrared spectroscopy” and the quality assurance procedures for P-AMS FTIR were made according to this TS document. This presentation will focus on the observations related to the use of TS document in the laboratory and field measurements when measuring low HCl concentrations.

Two FTIR’s (Fourier Transform Infrared) Gasmet Dx4000 were used in the measurements, with portable sampling units, heated sampling probes and filters. In addition, Hovacal vaporization unit and Gasmet portable syringe vaporizing unit were used for injecting and vaporizing HCl solution according to wet gas injection approach. Before field test campaign sampling line passivations and response time checks were made in the laboratory. Passivation and response time checks of the lines were made using Hovacal which produced 8 mg/m3 (dry, NTP 0°C) HCl concentration and 1.35 vol-% (wet, NTP 0°C) water vapour. According to pre-tests in laboratory, all equipment fulfilled the criteria set in CEN/TS 17337.

During field measurements the check gas approach of CEN/TS document was followed. Test gas of carbon dioxide with concentration of 20 vol-% was used to test the analyser performance. In the field the HCl concentration of 8 mg/m3 (dry, NTP 0°C) and 1.35 vol-% (wet, NTP 0°C) water vapor was produced using Gasmet syringe vaporizing unit. The results and measurement uncertainties were assessed according to CEN/TS document.

FTIR technique is widely used all over the world and CEN/TS 17337 provides good guidance for the users of FTIR technique. It, for example, has instructions for the measurement uncertainty calculations which are missing still even in some EN standards. In our presentation we tell about some minor practical issues (for example used terminology) which could be clarified in CEN/TS 17337. However, these modifications do not diminish the value of CEN/TS 17337.