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IAQ Sampling

IAQ Sampling. Document a condition or state of the space Adequate ventilation Comfort Identify source of contamination Leakage Products. Choice of Instrument. Depends on the task For most applications a simpler, less expensive instrument will suffice. Types of IAQ Instruments.

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IAQ Sampling

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  1. IAQ Sampling • Document a condition or state of the space • Adequate ventilation • Comfort • Identify source of contamination • Leakage • Products

  2. Choice of Instrument • Depends on the task • For most applications a simpler, less expensive instrument will suffice

  3. Types of IAQ Instruments • Direct Reading or Continuous Instruments • Passive • Active • Integrated samples • Passive • Active • Grab sample

  4. Direct reading instruments • Give an instantaneous value. • Requires zeroing and calibration or point checking • Instrument chosen depends on sensitivity required • Optical instruments require periodic maintenance from manufacturer • Interferences

  5. Active vs Passive • Active instruments use a pump to draw air over the sensor. • Passive instruments rely on diffusion of air across the sensor. • Active instruments have lower sensitivity than passive instruments.

  6. Uses of Instruments • Instruments are used either to measure a contaminant or a property or condition of the space. • Particulates, gases, noise, mold, moisture are examples of contaminants • Temperature, RH, Light, Air Flow are examples of properties

  7. UFP Particle Counters Isopropyl CPC: Particle size range of 0.01 to >1.0 µm Concentration range of 0 to 100,000 particles/cm3 Water-based CPC Detects particles down to 6 nm Isopropyl P-Trak -Concentration Range 0 to 5 × 105 particles/cm3, Particle Size Range 0.02 to 1 micrometer 5x105 particles/cm3

  8. UFP Particle Counters • Identify emissions from combustion or indoor chemistry • Identify changes in ventilation conditions • Monitor clean rooms • Identify leakage from processes

  9. Alcohol CPC W-CPC

  10. Indoor Chemistry VOC’s- vapor organic compounds at typical indoor temperatures Ex: formaldehyde, benzene, chloroform, pinene Some react with OZONE

  11. Case Study - Air Cabin

  12. Nephelometers/Particle Counters personalDataRam Met One GT-526 Six Channel Particle Counter 0.3, 0.5, 0.7, 1.0, 2.0 and 5.0 um 0.001 to 400 mg/m3 DustTrak SidePak Aerosol Concentration Range 0.001 to 20 mg/m3 (calibrated to respirable fraction of ISO 12103-1, A1 test dust) Particle Size Range 0.1 to 10 micrometer (μm) Minimum Resolution 0.001 mg/m3 Measures PM1, PM2.5, Respirable, PM10 and TPM simultaneously with no need for size-selective inlet conditioners.

  13. Nephelometers • Measures light scattering • Converts to mass using an algorithm • Subject to interferences primarily from size distribution of aerosol and humidity • Newer models have place for in-line filter to correct against gravimetric value • More expensive monitors have a filtered are flow sheen to protect optics

  14. Measure several parameters with one device. CO2 –Passive - NDIR CO-Passive- electrochemical Temp RH Pressure Air flow etc Multiputpose IAQ tools Range 0 to 9,999 ft/min (0 to 50 m/s) 0 to 200°F (-18 to 93°C)

  15. NDIR Sensors • NDIR sensors are spectroscopic sensors to detect CO2 in a gaseous environment by its characteristic absorption. • The key components are an infrared source, a light tube, an interference (wavelength) filter, and an infrared detector. • The gas is pumped or diffuses into the light tube, and the electronics measures the absorption of the characteristic wavelength of light. • NDIR sensors are most common sensor for measuring carbon dioxide. • Sensitivities range from 20-50 PPM.

  16. Electrochemical sensors • Electrochemical sensors operate by reacting with the gas of interest and producing an electrical signal proportional to the gas concentration. • Sensing electrode (or working electrode), and a counter electrode separated by athin layer of electrolyte. • Gas passes through a small capillary-type opening and then diffuses through a hydrophobic barrier in to the electrolyte. • The gas reacts at the surface of the sensing electrode involving either an oxidation or reduction mechanism. These reactions are catalyzed by the electrode materials specifically developed for the gas of interest.

  17. Portable trace gas detection MIRAN SapphIRe Portable Ambient Analyzer utilizes infrared spectroscopy to accurately measure many gases with a single instrument. Wavelength coverage permits outstanding single and multi-gas monitoring as well as unknown compound identification.

  18. Other Monitors PID

  19. Ventilation Assessment • Air Flow • Ventilation Rate • HVAC Balance • Air currents • Temperature • RH • Air Tightness

  20. Balometer Vane anemometer Air Flow Hood Flow Range 30 to 2,000 cfm (15 to 1,000 l/s, 50 to 3,500 m3/hr) Accuracy ±5% reading and ±5 cfm (±2.4 l/s, ±8.5 m3/hr) Operating Temperature 32 to 140°F (0 to 60°C) 0.25 to 30 m/s (50 to 6,000 ft/min) Diameter 4 in. (100mm)

  21. Micro manometer and pitot tube Measures differential and static pressure from -15 to +15 in. H2O (-3735 to +3735 Pa)

  22. Used to measure infiltration in homes. Estimates effective leakage area Blower Door

  23. Heat Stress/Radiant Temperature Monitors

  24. Surface Temperature IR Thermometer

  25. IR Thermometer • A lens to collect the energy emitted by the target • A detector to convert the energy to an electrical signal • An emissivity adjustment to match the IRT calibration to the emitting characteristics of the object being measured • An ambient temperature compensation circuit to ensure that temperature variations within the IRT, due to ambient changes, are not transferred to the final output.

  26. Sound Level Meters

  27. Sound Level Meter • Sound level meters measure sound pressure level. • The reading given by a sound level meter does not correlate well to human-perceived loudness • A-frequency-weighting filter most common referenced in standards • Other frequency weightings of C and Z (zero) not as common.

  28. Moisture meters • measure the percentage of water in a material usually drywall, plaster or wood. • Identifies if material is unexpectedly wet or dry • Requires further inspection to identify cause

  29. Light meters Incident light meter UV light meter

  30. Small Data loggers CO2 monitor TEMP and RH logger

  31. Integrated Sampling Integrated air sampling

  32. Integrated sampling • Costly requires analytical services • Requires knowledge of suspected contaminant to identify sampling media • Requires understanding of expected concentration to identify sampling flow rate and duration • Not recommended unless a specific contaminant is suspected • Requires calibration and specialized sample handling

  33. Grab VOC Sampling Grab Sampling

  34. Passive VOC sampling

  35. Colorimetric and air current tubes

  36. Colorimetric and air current tubes • Each target analyte has a specific tube designed to change color when compound is present. • Concentrations are estimated by exposing the tube to a known volume of air usually with a bellows pump. • Air current tubes are used to track air flow patterns.

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