Dust adherence

Dusts are the simplest means of insecticide dispersal and are appHed by introducing the finely divided carrier, with particles of 0.5 ndash 3.0 p.m in diameter, into a moving air stream. In comparison with sprays, dusts adhere poody to surfaces and cause serious drift problems away from the treatment area. 

With aridity increasing, various plant species of forage crops become gradually less numerous to finally disappear. In Dry Steppe ecosystems xerophylic half-shrubs and salt-tolerant plants replace the grasses. However, the ash content is higher in these species. This is attributed not only to a higher concentration of major ash elements in the plant tissue, but also to the exposure to finely dispersed dust adhered to the plants exterior (Table 9). 

Mg)2(Al,Si)40io(OH)2] was prepared by sifting glauconite sand to obtain a fraction of uniform size (<40 and >70 mesh size). The sand was washed repeatedly in distilled water to remove dust adhering to the particles and was packed in a stainless-steel tube to form a column 15 cm long by 1.0 cm diameter with 53 percent porosity. 

Semiconductor devices must be prevented from being spoiled with dust by all means because dust adherence of the dust coming from the air or treating chemicals to the surface of the devices causes reduction of yield and deterioration of performance. 

Closer inspection of the face reveals that the dust adhered to the tacky PVC face both disfigures and changes the appearance of the model. 

For Pis, both types are available. It has been pointed out that positive types are advantageous over negative types. With positive types, pinholes are unlikely to be formed. With negative types, if dust adheres, that portion is not exposed and therefore is etched out, thus forming a hole. 

Particulate emission control equipment applicable to dryers in soda ash plants includes cyclones, wet scrubbers, ESPs, and baghouses. Venturi scrubbers are used to control emissions from rotary steam tube dryers. Cyclones in series with venturi scrubbers are used to control emissions from fluid-bed steam tube dryers. Both venturi scrubbers and ESPs have been used to control emissions from gas-fired dryers. However, the use of ESPs or baghouses can result in operation problems because of the high humidity of the dryer exit gas and the fact that the collected soda ash particles are quite soluble and hygroscopic. This wet, sticky dust adheres to the electrodes and hoppers of the ESP or blinds and cakes the fabrics in the baghouse. Controlled emission factors of total PM from rotary soda ash dryers and fluid-bed soda ash dryers are 0.25 and 0.019 kg/mg of product, respectively [85]. 

Another technique that can be used to remove a layer of dust adhering to a surface is the use of freely falling solid spherical balls to strike the surface [88]. The ball size, the height from which it falls, and the repetition frequency are held the same in all experiments so that the particle-layer detachment conditions are kept constant. 

Hydrophobic vinyl polymers such as chlorinated PVC films or polyvinyl-butyral may be used as a removable layer other materials used for this purpose are cellulose esters with added antistatic agents [231]. Such layers act as a unique sort of screen or shield for the main coating. Atmospheric dust adheres to this layer and is then removed along with the layer. 

If we denote by x and Xq the amount of carryoff (entrainment) of adherent particles by dusty and clean streams, in mg/(m sec), and by c the concentration of dust in the air stream, in mg/m, then the quantity (jc - Xq)/c characterizes the entrainment of adherent dust due to the kinetic energy of the particles in the impinging stream, referred to unit concentration of dust (with mass constant). As the diameter of the particles suspended in the stream is increased from 5 to 17.5 /xm, the value of (x - Xq)Ic in the case of particles of magnetite dust adhering to the surface is found to drop from 0.9 to 0.1 since along with the... 

Quantity of dust adhering to precipitator electrode, g/cm Coefficient of removal... 

The frontal part of the tubes is subjected to the impact of large particles, so that no dust adheres to this part except at low flow velocities. 

Hafner J, Riiegger M, Kralicek P, Eisner P (1995) Airborne irritant contact dermatitis from metal dust adhering to semisynthetic working suits. Contact Dermatitis 32 285-288 Henriksen H (1982) Selection of materials for protective gloves. Polymer membranes for protection against contact with epoxy preparations. Danish Directorate of Labour Inspection Services, Copenhagen... 

Dustproofing. Oil is commonly used for dustproofing coal. When coal is sprayed with oil, the film causes some dust particles to adhere to the larger pieces of coal and others to agglomerate into larger lumps not easily airborne. Calcium chloride absorbs moisture from the air, providing a wet surface to which the dust adheres. 

A film may be applied to a white tile or a glass sheet and placed in a suitably dusty environment. Two effects can be noted - the amount of dust adhering to the surface and the amount of dirt held by the polymer after washing. The attraction exerted by a polymer on dust particles depends partly on the static charges that build up on the surface. In many cases the likelihood of incorporation of dirt into a polymer will be related with the glass transition temperature of the polymer. 

Fig. V.4. Differential particle size distribution curves. 1) In the original dust 2,3) in dust adhering to plates moving at 1.4 and 2.8 m/sec, respectively.

The way in which Ks depends on the state of the painted surface is shown in Fig. VI.5. As a result of holding the sample in air (curve 3), atmospheric dust adheres to their surfaces the original surface is thus screened, and the value of Ks may raise by a factor of 2-2,5. Spherical glass particles cannot be removed at all from oily surfaces in an air flow (curve 1),... 

In the second case the triboadhesive method maybe used, for example, in separating asbestos fiber (the falling-out product) from mineral dust adhering to the surface of the drum (captured or held product) [423]. 

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