Airborne spray

Rotary sampling devices called Rotorods have also been widely used for sampling airborne sprays.These devices are similar to the rotary samplers described above, but do not use Teflon or magnesium oxide slides for spray collection. Rather, droplets... 

Cascade impactors. Cascade impactors provide information on particle or droplet size spectra within airborne sprays. The air is drawn through a series of chambers that allow sequential separation of different particle sizes based on their different velocities and masses. This type of collector is not as widely used as the sampling devices discussed previously because they are relatively difficult to operate and are expensive. Further information on this and other types of sampler for spray research can be found in the literature. ... 

Vertical surfaces collect spray primarily by impaction. Plants and other entities with a vertical component will collect some material by impaction, and typically also by deposition, as discussed in the previous section. While horizontal collectors will tend to collect all or most material that falls out on to them, vertical collectors will have collection efficiencies that are more closely related to their physical characteristics, especially collector diameter. The SDTF used a-cellulose cards oriented perpendicular to the ground and strings made of cotton or Teflon in its field studies to assess spray volumes at locations above the ground. Many other researchers have used strings for assessing airborne spray volumes in drift studies. ... 

Particle size of insecticidal sprays has a bearing on the ability of airborne sprays to be transported and deposited, on foliage injury, and on the efficiency of residues in killing insects. Each problem should be carefully analyzed for the particle-size requirements. 

Two advantages of foam systems over sprays (qv) are the increased control of the area to which the product is deUvered and the decreased incidence of airborne particle release. 

The dry powder process has several additional advantages over the wet process. For example, much less waste of enamel occurs because the dry over-spray is airborne and recycled in a closed system. No-pidde ground coats have broadened the apphcation of both wet-process and dry-process systems. These enamels are appHed over cleaned-only metal. Thus the problems of disposing of pickling acid wastes containing iron sulfates and nickel wastes are eliminated (see Metal surface treatments) (7). 

Airborne partieulate matter may eomprise liquid (aerosols, mists or fogs) or solids (dust, fumes). Refer to Figure 5.2. Some eauses of dust and aerosol formation are listed in Table 4.3. In either ease dispersion, by spraying or fragmentation, will result in a eonsiderable inerease in the surfaee area of the ehemieal. This inereases the reaetivity, e.g. to render some ehemieals pyrophorie, explosive or prone to spontaneous eombustion it also inereases the ease of entry into the body. The behaviour of an airborne partiele depends upon its size (e.g. equivalent diameter), shape and density. The effeet of partiele diameter on terminal settling veloeity is shown in Table 4.4. As a result ... 

Provision and use of appropriate health surveillance, e.g. for signs of dermatitis, asthma, effects of specific solvent exposures. Full use of any spray booth, enclosure, exhaust ventilation or dilution systems, and automatic handling equipment. (The efficiency of all local exhaust ventilation and other control systems should be maintained, and checked by testing.) Where appropriate, atmospheric monitoring of airborne pollution levels. 

Utilize wet methods (spraying ground, wet drilling, ete.) when visible signs of airborne dust are generated. 

Airborne particulate matter may comprise liquid (aerosols, mists or fogs) or solids (dust, fumes). Refer to Figure 4.2. In either case dispersion, by spraying or fragmentation, will... 

The intent of this article is to provide an overview of methodology and materials for sampling airborne pesticide spray and spray collection on surfaces by sedimentation deposition and impaction after release from field sprayers. The term pesticide will be used as a general term to represent chemicals such as herbicides, insecticides, fungicides and related products. 

As a reaction to the pressure imposed on refiners operating HF processes, licensors developed safety systems to reduce the inherent risks. Among the mitigation systems are high-volume water sprays to knock down an acid cloud, a low acid inventory, and a rapid acid de-inventory system. HF modifiers, which reduce the volatility and the aerosol-forming tendency of HF, are also offered. ConocoPhillips together with Mobil developed an HF modifier technology named ReVap to reduce the volatility of the acid. It is claimed that a 60-90% reduction in airborne acid release relative to that of the unmodified acid is... 

Squirting a solution of perfume through a fine tube, near the end of which is a slight constriction, generates a fine spray of perfume comprising tiny particles of liquid. The spray remains airborne for a short time, and then settles under the influence of... 

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