Deposits loose

Asbestos An lAQ investigation often includes inspection above accessible ceilings, inside shafts, and around mechanical equipment. Where material suspected of containing asbestos is not only present, but also has deposited loose debris, the investigator should take appropriate precautions. This might include disposable coveralls and a properly fitted respirator. 

If calcium or magnesium bicarbonates are present in water, the rise in temperature decomposes them, and subsequent evolution of carbon dioxide will result In a higher corrosion rate, while at the same time calcium and magnesium carbonates may deposit on the metal surface. This scale may be protective, thus slowing the corrosion rate however, it can create concentration cells if it is deposited loosely, exposing parts of the surface. 

Increased control of film composition, structure and size can be achieved by limiting the rate of reaction. This is possible using gas phase deposition where the amount of reactant is relatively low. Gas phase deposition loosely covers any hybridization strategy where at least one of the hybrid components is in the gas phase. This includes chemical vapor deposition (CVD), physical vapor deposition (PVD) and atomic layer deposition (ALD) as well as various plasma, sputtering and evaporation processes. 

The network consists of a train of molecular condensation reactions occurring in the gas phase delivering reactive intermediates that form in homogeneous reaction molecular species with low reactivity for CVD (PAH) and soot depositing loosely on the... 

In classifying deposits by structure, the adherent layer can be characterized as loose (ash and soot deposits), tacky, dense (sintered and cemented), or liquid. The properties of the adherent layer are determined by the particular stage at which the deposit formation process ends, this process consisting of the deposition of fly ash, adhesion of ash particles to the heating surface, sintering of the ash particles, and melting of the outer layer of deposits. We will be considering three types of deposits loose, tacky, and dense. 

The quantity of dense deposits m2 varies with the flow velocity in the same manner as does the quantity of loose deposits (see Fig. XII.8). The laws governing the variation in the total amount of deposits (loose plus dense), however, which is characterized by the quantity m in Eq. (XII.21), have their own special characteristics. As the air-flow velocity rises from Vi to v the quantity of deposits increases mainly because of an increase in the amount of loose deposits (Fig. XII.9). Further increases in flow velocity, still maintaining the condition that v < u < yu, tend to increase the fraction of dense deposits. When y > yJi, all of the adherent layer consists of dense deposits, the amount of these deposits first increasing and then dropping off. 

A range of collection devices has been used to separate nanoparticles from the gas (Choy 2003 Vahlas et al. 2006). Traditionally, a rotating cylindrical device cooled with liquid nitrogen has been employed for particle collection. The nanoparticles are subsequently removed from the surface of the cylinder with a scraper, usually in the form of a metallic plate. However, the simplest method of collecting nanopowders is to use a mechanical filter with a small pore size. Nanoparticles ranging from 2 to 50 mn in size may be extracted from the gas flow by thermophoretic forces from an applied permanent temperature gradient and then deposited loosely on the surface of the collection device as a powder of low density with no agglomeration. 

Since the filaments are still deposited loosely on the belt, it is necessary to bond the web structure. In general, chemical, thermal or mechanical methods are used in the... 

Gyanoacetamide. Place 150 ml. of concentrated aqueous ammonia solution (sp. gr. 0-88) in a 500 ml. wide-mouthed conical flask and add 200 g. (188 ml.) of ethyl cyanoacetate. Shake the cloudy mixture some heat is evolved and it becomes clear in about 3 minutes. Stand the loosely stoppered flask in an ice-salt mixture for 1 hour, filter rapidly with suction, and ash the solid with two 25 ml. portions of ice-cold ethanol. Dry in the air the yield of pale yellow cyanoacetamide is 110 g. (1). Recrystallise from 190 ml. of 95 per cent, ethanol a colourless product, m.p. 119-120 , is deposited with practically no loss. 

The capillary retention forces in the pores of the filter cake are affected by the size and size range of the particles forming the cake, and by the way the particles have been deposited when the cake was formed. There is no fundamental relation to allow the prediction of cake permeabiUty but, for the sake of the order-of-magnitude estimates, the pore size in the cake may be taken loosely as though it were a cylinder which would just pass between three touching, monosized spheres. If dis the diameter of the spherical particles, the cylinder radius would be 0.0825 d. The capillary pressure of 100 kPa (1 bar) corresponds to d of 17.6 pm, given that the surface tension of water at 20°C is 12.1 b mN /m (= dyn/cm). 

Although most cakes consist of polydisperse, nonspherical particle systems theoretically capable of producing more closely packed deposits, the practical cakes usually have large voids and are more loosely packed due to the lack of sufficient particle relaxation time available at the time of cake deposition hence the above-derived value of 17.6 pm becomes nearer the 10 pm limit when air pressure dewatering becomes necessary. 

The manufacture of metal in powder form is a complex and highly engineered operation. It is dominated by the variables of the powder, namely those that are closely connected with an individual powder particle, those that refer to the mass of particles which form the powder, and those that refer to the voids in the particles themselves. In a mass of loosely piled powder, >60% of the volume consists of voids. The primary methods for the manufacture of metal powders are atomization, the reduction of metal oxides, and electrolytic deposition (15,16). Typical metal powder particle shapes are shown in Figure 5. 

Mica schist deposits range in consistency from loosely consoHdated soil to fairly hard ore and vary in color from brown to almost white. These ore bodies are noted for thek micaceous appearance, which results from a 40—90% mica content. Mica sizes vary from <44 fim to - 1.5 cm. 

Catalysts for dielectric surfaces are more complex than the simple salts used on metals. The original catalysts were separate solutions of acidic staimous chloride [7772-99-8J, used to wet the surface and deposit an adherent reducing agent, and acidic palladium chloride [7647-10-17, which was reduced to metallic palladium by the tin. This two-step catalyst system is now essentially obsolete. One-step catalysts consist of a stabilized, pre-reacted solution of the palladium and staimous chlorides. The one-step catalyst is more stable, more active, and more economical than the two-step catalyst (21,23). A separate acceleration or activation solution removes loose palladium and excess tin before the catalyzed part is placed in the electroless bath, prolonging bath life and stability. 

In a third process, a loose liner is fastened to a carbon steel shell by welds spaced so as to prevent collapse of the hner. A fourth method is weld overlay, which involves depositing multiple layers of alloy weld metal to cover the steel surface. 

Manganese-rich deposits usually take one of three forms A loosely adherent, friable, brown, or black deposit may occur (Fig. 4.5). A thin, dark, brittle, glassy manganese layer sometimes forms on heat transfer surfaces (Fig. 4.6). Nodular manganese deposits also occur (Fig. 4.7). Both nodular and glassy layers tend to occur on copper alloys. 

Internal surfaces were covered by loosely adherent corrosion product and deposit. Much of the corrosion product was cuprous oxide. Substantial amounts of iron, silicon, aluminum, zinc, and nickel were also found. Not unexpectedly, chlorine concentrations up to 2% by weight were present sulfur concentrations of about 1% were also found. 

One gram of 6,7-dihydro-5H-dibenz[c,e] azepine hydrochloride was dissolved in water, made alkaline with concentrated ammonia, and the resultant base extracted twice with benzene. The benzene layers were combined, dried with anhydrous potassium carbonate, and mixed with 0.261 g of allyl bromide at 25°-30°C. The reaction solution became turbid within a few minutes and showed a considerable crystalline deposit after standing 3 A days. The mixture was warmed VA hours on the steam bath in a loosely-stoppered flask, then cooled and filtered. The filtrate was washed twice with water and the benzene layer evaporated at diminished pressure. The liquid residue was dissolved in alcohol, shaken with charcoal and filtered. Addition to the filtrate of 0.3 gram of 85% phosphoric acid in alcohol gave a clear solution which, when seeded and rubbed, yielded 6-allyl-6,7-dihydro-5H-dlbenz[c,e] azepine phosphate, MP about 211°-215°C with decomposition. 

Marl. This is loose or crumbly deposit that contains a substantial amount of calcium carbonate. 

Lead is not generally attacked rapidly by salt solutions (especially the salts of the acids to which it is resistant). The action of nitrates and salts such as potassium and sodium chloride may be rapid. In potassium chloride the corrosion rate increases with concentration to a maximum in 0.05m solution, decreases with a higher concentration, and increases again in 2m solution. Only loosely adherent deposits are formed. In potassium bromide adherent deposits are formed, and the corrosion rate increases with concentration. The attack in potassium iodide is slow in concentrations up to 0.1m but in concentrated solutions rapid attack occurs, probably owing to the formation of soluble KPblj. In dilute potassium nitrate solutions (0.001 m and below) the corrosion product is yellow and is probably a mixture of Pb(OH)2 and PbO, which is poorly adherent. At higher concentrations the corrosion product is more adherent and corrosion is somewhat reduced Details of the corrosion behaviour of lead in various solutions of salts are given in Figure 4.16. 

The relation between free phosphoric acid content and total phosphate content in a processing bath, whether based on iron, manganese or zinc, is very important this relation is generally referred to as the acid ratio. An excess of free acid will retard the dissociation of the primary and secondary phosphates and hinder the deposition of the tertiary phosphate coating sometimes excessive loss of metal takes place and the coating is loose and powdery. When the free acid content is too low, dissociation of phosphates (equations 15.2, 15.3 and 15.4) takes place in the solution as well as at the metal/solution interface and leads to precipitation of insoluble phosphates as sludge. The free acid content is usually determined by titrating with sodium... 

Rinse in water to remove the acid, brush very lightly with a soft bristle brush to remove any loose film, and rinse again. If film remains, immerse for 1 min in concentrated nitric acid and repeat previous steps. Nitric acid may be used alone if there are no deposits. (See comments on this method when used for corroded specimens in the paper by Mercer, A. D., Butler, G. and Warren, G. M., Br. Corros. J., 12, 122 (1977).)... 

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