Wet spraying

Classically, aerosols are particles or droplets that range from about 0.15 to 5 p.m ia size and are suspended or dispersed ia a gaseous medium such as air. However, the term aerosol, as used ia this discussion, identifies a large number of products which are pressure-dispensed as a Hquid or semisohd stream, a mist, a fairly dry to wet spray, a powder, or even a foam. This definition of aerosol focuses on the container and the method of dispensiag, rather than on the form of the product. 

An emulsion system in which the propellant is in the external or continuous phase is shown in Figure 2b. As the Hquefied propellant vaporizes, it escapes direcdy into the atmosphere, leaving behind droplets of the formulation which are emitted as a wet spray. This system is typical of many water-based aerosols or w/o emulsions. 

Pollutant Loading Typical inlet concentrations to a wire-pipe ESP are 1 to 10 grams per cubic meter (g/m ) (0.5 to 5 gr/fl ). It is common to pretreat a waste stream, usually with a wet spray or scrubber, to bring the stream temperature and... 

Insulation dry mixed in factory with inorganic fillers and binders for application by wet spraying. Usually mineral... 

Primarily used in fire-protection applications as dense boards or wet sprays. 

Vitreous enamel is normally applied to the prepared metal or over a ground-coat by spraying or dipping. Alternative wet techniques are used, of which the most common has been electrostatic wet spraying. Electrophoretic deposition from the slurry has been found to be highly suitable for some components. 

Water rinses are used in surface preparation operations such as acid pickling, alkaline cleaning, and nickel deposition to remove any process solution film left from the previous bath. A water rinse may also follow the neutralization step. Another common water use is in the ball milling process, which uses water as the vehicle for the enamel ingredients, as a cooling medium, and for cleaning the equipment. Coating application processes normally use wet spray booths to capture oversprayed enamel particles. Water wash spray booths use a water curtain into which the enamel particles are blown and captured. 

Wellman-Lord The most widely used regenerable flue-gas desulfurization process. The sulfur dioxide is absorbed in sodium sulfite solution in a wet spray scrubber, forming sodium bisulfite ... 

We will now discuss some examples where NIR spectroscopic imaging has been used to evaluate some materials of commercial interest. This will include examples from a variety of home/commercial product areas including fabric wetting, spray deposition, food composition and surfactant deposition on nonwoven materials. These examples will demonstrate both qualitative and quantitative uses of NIR spectral imaging for determining chemical distributions in nonhomogeneous materials. 

The adsorption of surfactants at the liquid/air interface, which results in surface tension reduction, is important for many applications in industry such as wetting, spraying, impaction, and adhesion of droplets. Adsorption at the liquid/liquid interface is important in emulsification and subsequent stabilization of the emulsion. Adsorption at the solid/liquid interface is important in wetting phenomena, preparation of solid/liquid dispersions, and stabilization of suspensions. Below a brief description of the various adsorption phenomena is given. 

Generally low exposure No wetting spray Little dust... 

Dimethyl ether may be used as an aerosol propellant for topical aerosol formulations in combination with hydrocarbons and other propellants. Generally, it cannot be used alone as a propellant owing to its high vapor pressure. Dimethyl ether is a good solvent and has the unique property of high water solubility, compared to other propellants. It has frequently been used with aqueous aerosols. A coarse, wet, spray is formed when dimethyl ether is used as a propellant. 

To control fungal diseases, thin plants to increase air movement. If weather is wet, spray sulfur in the evening. Plant cultivars, such as Provider and Tendercrop , that tolerate all 3 diseases. Under some conditions, a baking-soda-and-soap spray (1 teaspoon baking soda, 1 teaspoon liquid dish soap, 1 quart water) may prevent further infection. 

Leaves with spots, blotches, or brown areas. Causes Powdery mildew angular leaf spot scab Alternaria leaf blight other fungal and bacterial diseases. Various diseases attack squash. Reduce problems by keeping foliage dry when watering and by not touching plants when wet. Spray infected plants with a dilute solution of copper spray to reduce the spread of the disease. 

Tab. 4 Tafel slopes of the methanol oxidation on technical Pt/Ru anodes. The anodes are prepared by wet spraying. Methanol concentration 1 M, potential range used forthe calculation of the b factors 0.25-0.4 V (RHE) (A. Havranek and K. Wippermann, unpublished results)...

Electrostatic precipitator Batch process load electrodes, then clean via wet spray or mechanical rapping. For particle conductivity between 10 and 0.01 reciprocal ohm m. Prefer negatively charged configuration. May need to adjust conditions to get particle conductivity into acceptable range. For particles >10 pm, use 38-m plate area per m /s gas flow 1 pm, use 100-m plate area per m /s gas flow 0.4 pm, use 120-m plate area per mVs gas flow. 

Figure 11-68. Mobile Environmental Laboratory built in Drexel University carrying preeise exhaust gas eharaeterization faeility as well as 10 kW wet (spray) pulsed corona discharge for treatment of large-volume low-concentration exhaust gases containing VOCs.

A mobile plasma laboratory for VOC removal from the exhaust streams typical for paper mills and wood processing plants (see Table 11 ) has been built at Drexel University (Fig. 11-68, see Gutsol et al., 2005) based on 10 kW wet (spray) pulsed corona discharge. A photograph of the discharge from one of the six windows is presented in Fig. 11-69 all... 

External antistatic agents are applied to the surface of the molded article from aqueous or alcoholic solution by wetting, spraying, or soaking the plastic object in solution, followed by drying at room temperature or under hot blown air. Their concentration varies between 0.1 and 2% by weight. Almost all... 

Sprayed concrete, shotcrete (dry sprayed) or gunite (wet sprayed) are methods of rapidly applying concrete to soffits or vertical surfaces. It can be used over patches and to overlay metal mesh anodes for cathodic protection as described in Section 7.6. It is sometimes applied as a temporary cosmetic repair in the Northern USA and Canada when concrete has spalled or is in danger of spalling. As it does nothing to slow the corrosion rate it is comparable in effectiveness to patch repairing, and may suffer from the same incipient anode problem. 

Wet mix spraying of mortars is becoming more popular as proprietary mixes have been developed. The consistency of the mix is easier to control in wet mix application if segregation does not occur in the mixer before spraying. Application rates are higher and it is often possible to finish the surface of a wet sprayed mix. This is far more difficult with dry missed shotcrete. 

This is a wet sprayed mortar containing nickel plated carbon fibres to achieve conductivity (Figure 7.14). It requires a primary anode, usually the titanium mesh ribbon. This is a proprietary anode and there are no variations. 

Electrostatic precipitator Batch process load electrodes then clean via wet spray or mechanical rapping. For particle conductivity between 10" and 0.01 m. Prefer negatively charged configuration. May need to adjust conditions to get particle conductivity into acceptable range. 

Coat n. Paint, varnish or lacxjuer applied to a surface in a single application (one layer) to form a properly distributed film when dry. A coating system sexually consists of a number of coats separately apphed in a predetermined order at suitable intervals to allow for drying or curing. It is possible with certain types of material to build up coating systems of adequate thickness and opacity by a more or less continuous process of application, e.g., wet-on-wet spraying. In this case, no part o the system can be defined as a separate coat in the above sense. 

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