Testing Dust

BS 893, Methods of Testing Dust-Extraction Plant and the Emission of Solidsfrom Chimneys, British Standards, London, 1940. 

Arrestance A measure of the ability of a filter to remove a standard test dust from the air under test conditions. 

Arrestance, average The weighted percentage ratio of the total amount of standardized test dust retained by a filter to the total amount of dust fed into the filter in order to achieve a specified final pressure drop. 

Test dust Various grades of dust used to test the collection efficiency of filters. 

For Clean Rooms (rooms of a very high standard) dust count per unit volume will be specified, but other specifications for room cleanliness are usually in terms of filtration performance against a standard test dust. Other important features are resistance to air flow and dustholding capacity, leading to the fan energy required and filter life. 

Test dusts. 0.5% material + 0.05% pyreth Standard dust. 0.75% rotenone 10 larvae per test. Averages of 12 tests Dosage of dust. 0.283 gram per square foot... 

BS893 1940 British Standard 893 (British Standards Institution, London). The method of testing dust extraction plant and the emission of solids from chimneys of electric power stations. 

Tests of the WWEP were conducted with 4 in, 8 in and 16 in diameter units at flow rates ranging from 100 to 4000 ft /min. Particle collection efficiency of these units was measured with atmospheric dust, AC fine test dust (mass mean diameter (MMD) 12 pm), artificial cotton dust (MMD = 4.0 pm) and cotton dust drawn from the processing area of a card (MMD = 3.0 pm). 

A novel device was designed to estimate the dislodgeability of dust-associated pesticide residues by skin contact (Edwards and Lioy, 1999). Called the EL Sampler , the device consists of a spring-loaded assembly that permits the sampling medium to be pressed lightly (12g/cm or 1160 Pa) onto the surface to be monitored. A 10-cm x 15-cm Empore C-18 extraction membrane was used for the sampling medium. The material was chosen after controlled experiments on particle adhesion showed it to pick up the same distribution of test dust particle sizes as the human hand. In studies in which the EL sampler was pressed onto polyethylene surfaces coated with house dust and then sprayed with a solution of pesticides in 2-propanol, the device was found to collect 35%, 31 %, 32% and 18 %, respectively, of chlorpyrifos, diazinon (0,0-diethyl 0-[6-methyl-2-(l-methylethyl)-4-pyrimidinyl] phosphorothioate), malathion and atrazine (6-chloro-A -ethyl-A -isopropyl-l,3,5-triazine-2,4-diamine). Parallel studies with human hand presses (full hand at 6.8 kg = ca. 6900 Pa) yielded collection efficiencies of 42 %, 29 %, 43 % and 21 %, respectively. 

Todd, W.F., Hagen, G.E. and Spaite, R.A. (1963), Test Dust Preparation and Evaluation, Taft Sanitary Engng. Center, US public Health Service, Cincinnati, USA, 267... 

The National Physical Laboratory has surface area and pore size distribution standards. AC fine test dust is available from General Motors for calibrating classifiers and ASME also produce standards for this purpose. 

ISO 11171 specifies calibration parameters for instruments and sensors. Repeatability and reproducibility of particle counters are ensured by a traceable standard such as provided by the National Institute of Standards and Technology (NIST). The medium test dust (MTD) reference fluid SRM-2806A is used to certify that particle counters correctly determine the count and size distribution of particles. The ISO 11171 standard specifies the maximum allowable percent differences in particle counts between test runs. Only counters that are certified as passing the ISO 11171 standard should be used for oil condition monitoring [27]. 

As for the reaction products after N2O5 is taken up on particles, Karagulian et al. (2006) reported that the yield of HNO3 is large for Arizona test dust and Kaolinite (silicate mineral including Al), but the yield is small for Saharan dust and CaCOs, and CO2 is produced with the yield of 42-50 % particularly for CaCOs. 

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