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Idea Transcript
Air Pollution Sampling
Categories of sampling Source sampling Ambient sampling Industrial hygiene sampling Residential and indoor sampling Process or QC sampling
Sampling = monitoring? Sampling - a proper technique use to acquire a representative sample of possible contaminated air or gaseous for later evaluation or analysis of the quantity of pollutants present Monitoring – methods and equipment designed to give real time or near realtime information on air or gaseous characteristics example concentrations.
Who sets standard method?? Environmental Protection Agency American Society for Testing and Materials American Society for Mechanical Engineers American Council of Governmental Industrial Hygienist American Society of Heating, Refrigiration and Air Conditioning Engineers OSHDepartment SIRIM
Continuous Monitor BAM - PMs TEOM - PMs UVF – SO2 UVA - Ozone IR - CO Chemiluminescence – NOx OFTEN NOT HIGHLY SENSITIVE!!!
Sampling + collect + instrument
Following collections – concentrate – instrumental analysis.. Gravimetric GC – Gas chromatography GC/MS – GC with Mass spect. FID – Flame ionisation detection PID – photoionisation detection ECD – Electron Capture Detection AA – Atomic Absorption Spec. IC – ion chromatograph EM – Elect. microscope
Air + Gas Measuring Devices 3 Broad Categories measure volume directly measure rate of gas flow measure velocity of gas
Direct volume measurement Q = V/t v= volume, t=time spirometer displacement bottle soap bubble meter mercury sealed piston roots meter Wet test meter (WTM) dry gas meter (DGM)
Gas Flow Rate Measurements Orifice meter venturi meter rotameter mass flow meter
Velocity measuring devices Principle: measure average velocity then multiply cross sectional area of pipe or duct the gas is flowing through. Example:pitot tube electronic velocity meter
Calibrations
A process of comparison of a device in response to that of a device that is know to be ‘correct’
Calibration frequency Instrument characteristics - sensitivity and experience with its stability under similar use patterns Instrument use - rough handling, moving, heavy usage, and changing environment Instrument users - multiple users of various skills increase needs for calibration.
FLOW MOVING & CONTROLLING DEVICE Constant flow rate is very important as measuring unit is usually in volumetric unit. Critical or limiting orifice electronic and mass flow sensor differential pressure flow controllers
? Instrument use this? PM10 samplers personal pumps large variety of ambient air monitoring and sampling instruments
Air Sampling Method Gaseous pollutants Particulate Matter
Gaseous pollutants sampling methods Impingers (Absorber) Adsorbers Cryogenic systems whole air samplers