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29 Cards in this Set
- Front
- Back
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Thermochemical Sensor - Thermal Conductivity type. |
Responds to anything different from the carrier gas.
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Combustion Sensor.
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Wheatstone bridge.
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Electrochemical Sensors - Conductive.
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Ions conduct electricity. Gases for electrlytes in soln. andchange conductivity of that soln.
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Electrochemical Sensors - Potentiometry.
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Gases change the pH of soln.
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Electrochemical Sensors - Coulometry.
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The amount of electricity produced = contaminant present.
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Electrochemical Sensors - Ionization.
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Make the gas conductive so electrical field can collect particles.
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Chacoal Tubes
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Adsorbs vapor molecules.
Breakthrough of 10% = junk sample. Not good for: Amines, Phenols, nitrocompounds, aldehydes, or reactive comounds. |
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Silica Gel Tubes
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Electrically polar. Attracts polar molecules like H2O, ROH, aldehydes, amines, phenols, amides, and inorganic acids.
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Diffusion Badges
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Requires 15 fpm of airflow. Not as accurate as tubes.
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Polycarbonate Filters
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Better strength than membrane. Low collection efficiency.
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Membrane Filters
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High collection efficiency. Low ash, low weight. Good for gravimetric.
Bad at high temps. |
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Mixed Fiber Filters
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Used in air cleaning. High collection efficiency. Low pressure drop.
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Glass Fiber Filters
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Not as hygroscopic as cellulose. Good for high temps. Suitable for radio frequency ashing.
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Cellulose Filters
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Cheap, strong, many sizes. High background of heavy metals.
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Mercury Sampling
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Hopcalite.
Cold Vapor AAS. |
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Fluoride Sampling
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Treated MCEF.
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Hexavalent Chromium Sampling
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PVC Filter.
IC, UV/Visible. |
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Asbestos Sampling
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25 mm Open Faced MCEF.
PCM |
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Fiber meassurement field area?
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Af = 0.00785 mm2.
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Fiber
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Greater than 3:1 aspect ratio.
Use PCM, PLC, electron microscopy, SEM, or TEM. |
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NIOSH Rule of Thumb regarding sample numbers.
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> or = 6 samples for a valid estimate of confidence interval.
> 11 samples to estimate variance. |
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NIOSH rules about blanks.
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6 media blanks in lab.
2 field blanks for every 10 samples. |
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Sample breakthrough.
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If the sample media contains >10% in the back up section, the sample is junk.
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Primary Standards
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Mariotti bottle, spirometer, frictionless piston meter.
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%Error = (Observed - expected)/Expected x 100
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<5% good flowrates.
5-10 use lower flow rate >10% resample. |
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Formaldehyde sampling
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XAD-2
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Miran
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Type of IR analyzer.
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Filters for particulate sampling:
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GFF: Oil mist, pesticides.
MCEF: Metals, asbestos, dusts. PVC: Dusts, chromium VI PTFE: PNAs, CTPVs |
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Asbestos filter area
Ac= |
Ac=385mm
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