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Analysis of Damaged Floor Coverings Emissions in Indoor Air Quality with Cantilever-Enhanced Photoacoustic Spectroscopy

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  1. 1. Analysis of damaged floor coverings emissions in indoor air quality with cantilever-enhanced photoacoustic spectroscopy Dr. Ismo Kauppinen, CEO, Gasera Ltd. Pittcon 2016, 8. March 2016, 10:25 pm Gasera Ltd. Tykistkatu 4, 20520 Turku, Finland
  2. 2. Indoor air quality - 2 - Most people spend approximately 80% to 90% of their time indoors Indoor air quality has a large impact on health, quality of life and work efficiency Numerous indoor air impurities are responsible for respiratory diseases , allergies, intoxication and certain types of cancer Contaminants are caused by moulds, decomposing floor covering, tobacco smoke, outgassing from furniture Indoor Air Quality
  3. 3. Air quality pollutants - 3 - Contaminant Source Carbon monoxide (CO) Incomplete combustion in fireplaces, ovens and other heating appliances, and tobacco smoking Carbon dioxide (CO2) The metabolism of building occupants and pets. Nitrogen oxides (NOx) Side product of combustion. Indoor sources: gas fires, cooking and heating appliances, smoking Indoor-generated particulate matter and dust Carpets, textiles, food, animal and plant proteins in dust, and occupants (especially in buildings with a high density of occupants) Chemicals, volatile organic compounds (VOCs) All man-made building materials emit VOCs, especially when new or damaged. Cleaning products. Formaldehyde Building materials, particle boards, household chemicals, ETS, and carpets and other household textiles. Man-made mineral fibres (MMMF) MMMF are used in insulation materials, and acoustic linings. Fibres are irritants. Mould (fragments, mouldy material, spores, microbial VOCs) Mould growth depends on moisture: wet structures, water leakages, condensation, high indoor humidity Limonene Freshners, Cleaning products, Personal care products Inorganic Ions Cooking, Smoking Metals Cooking, Smoking, Dust Elemental carbon (EC), Organic Carbon (OC) Cooking, Smoking, Dust PAHs (Polycyclic Aromatic Hydrocarbons) Building materials, Fiberboard, Chipboard, Dust, Cooking, Smoking PCBs (Polychlorinated Biphenyls) Building materials, Fiberboard, Chipboard PBDEs (Polybrominated Diphenyl Ethers) Plasticizers, flame retardants
  4. 4. - 4 - Floor coverings degrade if installed on concrete that has not been dried enough In some cases, the coverings are installed on wet concrete on purpose to avoid contractual penalties due to delays in construction projects This happens frequently Typically the problems do not appear immediately Reasons for floor coverings emissions
  5. 5. Current solution for floor coverings emissions detection techniques Field and Laboratory Emission Cell (FLEC) A hood to collect VOCs over a long time period The sample is analyzed in laboratory afterwards Time-consuming & expensive which limits the number of samples taken Laboratory analysis of the samples takes usually weeks Often the laboratory analysis result is useless because of leaking during the sampling - 5 -
  6. 6. Photoacoustic effect was discovered in 1880 by Alexander Graham Bell This theoretical potential has not been reached, since conventional microphones have been used for sensing the pressure pulses Gaseras novel cantilever sensor technology allows the use of the full potential of the photoacoustic phenomena Photoacoustic spectroscopy is based on the absorption of light leading to the local warming of the absorbing volume element. The subsequent expansion of the volume element generates a pressure wave proportional to the absorbed energy, which can be detected via a pressure detector. Photoacoustic spectroscopy PHOTOACOUSTIC GAS CELL IR SOURCE MICROPHONE IR FILTER CHOPPER A typical setup of a conventional PAS system GAS SAMPLE - 6 -
  7. 7. Key inventions Cantilever sensor Over 100 times greater physical movement can be achieved compared to conventional microphone membrane cantilever has very low string constant 1 N/m Highly linear response Optical readout system Contactless optical measurement based on laser interferometry Measures cantilever displacements smaller than picometer (10-12 m) Extremely wide dynamic measurement range - 7 -
  8. 8. Benefits of cantilever enhanced PAS - 8 - stability , reliability, easy to use Absorption is measured directly in PAS, which makes the measurement very accurate and free of drift below ppb detection limits Cantilever sensor provides high sensitivity wide linear dynamic range, miniaturization, low sample volume Sensitivity is not dependent on the optical path length multi-gas capability Many different sources can be connected to one cell suitable to wide range of process applications Possibility to heat the sample cell
  9. 9. Concept Sensitivity Patented cantilever sensor Reliability Photoacoustic principle Versatility can be combined with different types of light sources (NIR- TDL, DFB-QCL, EC-QCL, OPO, Broadband IR and filters)
  10. 10. Selection of the source
  11. 11. - 11 - Optical microphone DSP unit Laser driver TEC controller Readout interferometer Sample cell Cantilever OPO source Aspheric lensLaser beam Beam dump GasIN GasOUT Balance cell Gas exchange controller Gas exchange unit Gas valves Proposed measurement setup Typically 10 cm or less
  12. 12. - 12 - Analysis of damaged floor coverings emissions 2-ethyl-1-hexanol (2-EH) is the marker compound for the damage Photoacoustic spectrum of 2-EH in nitrogen background between 3398-3458 nm was recorded using a pulsed OPO as a source The spectral shape of measured spectrum matches well with the PNNL library spectrum Detection limit of the setup for 2-EH is 125 ppt (0.67 g/m3) for 1 min measurement time Same detection limit level than with time- consuming laboratory techniques was achieved
  13. 13. - 13 - Analysis of real samples A floor covering sample from a building with known indoor air quality issues was measured Emissions of the sample were measured with a headspace measurement Photoacoustic spectrum between 3398-3458 nm was recorded using a pulsed OPO as a source The spectral shape of 2-EH can be clearly identified in the measured floor covering sample Other features in the spectrum are due to moisture The sample strongly emits 2-EH but very little other VOCs that are absorbing in this 3398-3458 nm region High sensitivity and selectivity can be achieved
  14. 14. Thank you! - 14 - Visit us at Booth #1657