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Manufacture of Pyrotechnic Compositions
Published in Ajoy K. Bose, Military Pyrotechnics, 2021
A small quantity of the material may be sieved through a single mesh by hand and the material passed through the sieve may be taken in a bowl for retention. The results of sieving mainly depend upon comparative size of the ingredient particle and hole size in the sieve, the orientation of the particles, sieving duration and extent of sieve movement. Sieving gives a quick mass distribution of particles of varied sizes but some of its drawbacks are:It works with only dry ingredient particles.It does not segregate the particles based upon density, porosity or surface features.The ingredient particles may be spherical, elongated or flat and as such would behave differently when shaken or vibrated.It is possible for a few elongated particles to jump and pass through the sieve through its nose. There are chances that a few particles may agglomerate due to electrostatic charges and humidity and may give wrong particle size.There is a lower limit of sieve hole size
Aggregates
Published in M. Rashad Islam, Civil Engineering Materials, 2020
A gradation test (Figure 2.14) is performed on a sample of aggregate in a laboratory. A typical sieve analysis involves a nested column of sieves with a wire mesh cloth (screen). A representative weighed sample is poured into the top sieve, which has the largest screen openings. The column is typically placed in a mechanical shaker. The shaker shakes the column for a fixed amount of time. After the shaking is complete, the material on each sieve is weighed. The weight of the sample on each sieve is then divided by the total weight of the batch to calculate the percentage retained on each sieve. Then, the ‘Cumulative % Retained’ is calculated by summing up the ‘% Retained’ in the corresponding sieve plus that on the larger sieves. The ‘Percent Finer’ for a certain sieve is calculated as 100 minus the ‘Cumulative % Retained’ for that sieve. The results of sieve analysis are provided in a graphical form to identify the type of gradation of the aggregate. A common practice is to present a ‘Percent Finer versus Particle Diameter’ curve.
Soil classification
Published in Ivan Gratchev, Dong-Sheng Jeng, Erwin Oh, Soil Mechanics Through Project-Based Learning, 2018
Ivan Gratchev, Dong-Sheng Jeng, Erwin Oh
The amount of each fraction can be found by means of relatively simple sieve tests and, when necessary, hydrometer tests. The sieve test is commonly used in practice and numerous videos of this laboratory experiment are freely available on the Internet. In this test, an oven-dried soil sample is sieved through a stack of sieves. Each sieve has a mesh of a certain size so that it does not allow particles smaller than the hole in the mesh to pass through it. The sieves are arranged in order where the largest one is on top and the finest sieve is at the bottom. A pan is placed below the bottom sieve to collect the soil that passes the finest sieve. By measuring the mass of soil retained in each mesh and expressing it as a percentage of the total, the grain size distribution curve is obtained.
Assessing the physical, mechanical properties, and γ-ray attenuation of heavy density concrete for radiation shielding purposes
Published in Geosystem Engineering, 2019
Ahmed S. Ouda, Hakim S. Abdelgader
A sieve analysis is a procedure used to assess the particle size distribution of a granular material. The size of aggregate particles differs from aggregate to another, and for the same aggregate, the size is also different. The particle size distribution of fine and coarse aggregates has been assigned by sieving analysis. This method is used to determine the compliance of the aggregate gradation with specific requirements of ASTM C136 (2014). Sieve analyses of coarse and fine aggregates are given in Table 4.
Extraction of dust collected in HVAC filters for quantitative filter forensics
Published in Aerosol Science and Technology, 2020
Alireza Mahdavi, Jeffrey A. Siegel
To extract dust, we placed the diagonal end of the flanged tailpiece (Figure S5) on the filter and vacuumed the filter by moving the tailpiece head along the filter pleats for the entire filter length. In each extraction cycle, we vacuumed filters until the dust sock got full enough to diminish suction flow (generally for less than five minutes). The duration of vacuuming in Phase 1 (artificially loaded filters) varied as we were still refining the extraction technique. Naturally loaded filters (Phase 2) were vacuumed for a fixed duration of 5 min to eliminate any variations caused by extraction duration. When the sieve was blocked, we cleared it using a brush or spatula for the cases of the artificially and naturally loaded filters, respectively. Upon completion of extraction, we disassembled the sampler and recovered any collected dust left in the dust sock and on the inner wall of the coupler by reversing the dust sock and tapping/shaking the coupler and storing the dust into a container in both phases (referred to as after-sieve dust). With the ASHRAE-loaded filters in Phase 1 and all the filters in Phase 2, we also recovered the dust captured by the sieve by picking dust via tweezers or gently shaking the sieve and stored it in a separate container (i.e., pre-sieve dust). The containers used to store the dust were Petri dishes in Phase 1 and amber vials in Phase 2. To overcome the limited retention capacity of the sampler, we often completed more extraction cycles for the same filter to increase dust recovery from a filter (Table S1). The number of extraction cycles in Phase 2 was generally higher because of the importance of this natural dust for future filter forensics analyses. We generally stored the dust recovered from different extractions of the same filter in the same storage containers, as we found a negligible influence of adding dust fractions from the same filter on the particle size distribution of the cumulatively added dust (Figure S6).