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Published byAmi Campbell Modified over 9 years ago
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Measurement of total mass concentration
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1. Sampling probe - Isokinetic or sampling from still air 2. Flow rate - Rotameter or digital flowmeter 3. Filter - Nearly 100% efficiency for all size. - 13, 25, 37, 47 mm (circular). - 200 mm x 250 mm (Hi volume sampler).
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4. Filter holder - Open-face: uniorm distribution of particles for analysis in microscope. - Closed-face: simple, for mass concentration measurement. Open-faceClosed-face
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5. Balance - Analytical balance, 0.01 to 0.1 mg sensitivity. - Electrobalance, 0.1 to 10 g sensitivity. - Sample should be kept in the room with balance for 1 - 24 hr until equilibrium. 6. Vacuum pump - Personal pump; low flow rate 1-4 l/min.
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- Larger pumps; 100 l/min. Diaphragm pumpBlower pump for Hi-volume sampler
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Calculation for mass concentration is concentration is total mass collected is flow rate is sampling time Minimum sampling volume is sampling volume is sensitivity of balance is standard concentration
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Personal sampler
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- Used in ocupational hygiene to evaluate workers’ exposure to aerosol. - Measuring in the breathing zone; with 30-cm radius of workers’ mouth. - Light weight, battery powered pump and plastic filter holder. - Additional size selective option available; e.g. PM-10. SKC personal sample.
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SKC personal sampler taken apart.
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High Volume sampler - Using 2- or 3-stage centrifugal blower to pull air in. - High flow rate: up to 1700 l/min (60 CFM). - Variable speed motor is used to keep constant flow rate that may be affected by temperature and pressure change, or pressure drop due to dust loading on filter. - Used 200 mm x 250 mm (8 in x 10 in) glass fiber filter. - A roof with 50% for sampling of 30 micron particle at wind speed of 8 km/hr.
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PM-10 & PM-2.5 - Standard in analysis of atmospheric dust issued by the U. S. Environmental Protection Agency (EPA). - Suspended particle smaller than 10 micron in diameter. - Respirable; smaller particle travels deeper in respiratory tract. - Impactor or cyclone can be used to cut off particles greater than 10 micron. - 24-hr average for 3 samplings in 3 years must not exceed 150 g/m 3. - Annual average for 24-hr sampling must not exceed 50 g/m 3. PM- 10
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- Suspended particle smaller than 2.5 micron in diameter. - For study of small aerosol particles thae affect visibility. - Particles smaller than 2.5 microns usually composed of SO 4 2-, NO 3 -, NH 4 +, and C. - Toxic metals; Ni, Cd or Cr. - Organic compounds; Polyaromatic Hydrocarbons (PAH). PM- 2.5
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Personal sampler for respirable dust - Using cyclone for size selection. - Flow rate of 1.9 l/min
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PM-10 High Volume Sampler - For sampling of suspended particles smaller than 10 micron.
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PM-10/PM-2.5 Dichotomous Sampler - Classifying particles in 2 size range; 10 micron and 2.5 micron. - Using virtual impactor.
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