Dirt retention

The filter elements should remove particles of five microns, must be water-resistant, have a high flow rate capability with low pressure drop, possess high dirt-retention capacity, and be rupture-resistant. The clean pressure drop should not exceed five psig at 100 °F (38 °C). The elements must have a minimum collapse differential pressure of 50 psig. Pleated-paper elements are preferred—provided they meet these requirements. Usually, the pleated-paper element will yield the five psig clean drop when used in a filter that was sized to use depth-type elements. This result is due to the greater surface area of the pleated element, more than twice the area of a conventional stacked disc-type or other depth-type elements. 

Optical KLenents. Problems which are common to many solar-related optical elements Include dirt retention, cleaning, surface abrasion, and photodegradation. A common feature of some of these problems Is that the deleterious effects occur at an Interface. Ultraviolet radiation, atmospheric components, mechanical stress, etc., can have a profound effect on performance by changing surface characteristics. The lifetimes of UV stabilizers can be limited by exudation permeability can cause harmful reactions at Interfaces and mechanical properties can be Influenced by surface crazing. In other applications mechanical behavior of the bulk polymer Is critical and virtually all applications require that the polymer system withstand multiple environmental stresses simultaneously. 

Uses Surf, additive, slip agent, antiblocking agent, surf. tens, reducer, substrate wetting agent tor topcoats Features Reactive sol. resist. weather resist. less dirt retention Properties Colorless liq. aromatic odor sp.gr. 0.92 dens. 7.65 Ib/gal vapor pressure 4 mm Hg flash pt. (Seta) > 25 C ref. index 1.485 25% NV... 

Dirt retention can be a problem with exterior gloss latex paints. Latex paints must be designed to coalesce at relatively low application temperatures. 

Dirt retention Dirt retention is the tendency of a dry film to attract and hold soiling material on or in its surface. ... 

EXAMINATION Chalking Dirt Retention Substrate Swell... 

Figure 4.17 New nanobinder Col.9 combines in one product the advantages of conventional coating types in terms of low dirt pick-up, chalking and rack resistance, and colour retention. (Reproduced from Col.9.com)...

Dirt, soils, and clays Retention of particulates and colloids in turbid water supplies concn of fines in kaolin processing Polysaccharides and oligosaccharides Concn of starch effluents concn of pectin extracts... 

In on-line experiments with a plant effluent containing 2% detergents, 1% oil and 0.8% suspended solids (metal, dirt, etc.), tubular modules equipped with UF membranes of different pore-sizes and a microfiltration membrane have been tested. (The experiments were carried out in the gear and axle production of Daimler Benz AG.) As expected, the MF membrane produced the highest flux for detergents. Because of th relatively low retention capacity for oil, however, the use of MF membranes is limited to a maximum oil concentration of about 10% in the concentrate. In this case, the oil concentration of the permeate is about 50 mg/ , contrary to the UF membranes, where the oil concentration of the permeate is independent of the oil concentration of the concentrate up to the phase inversion concentration of about 41%. 

Solution adhesive is obtained from solid rubber obtained by coagulation of latex as acquired from the tree. The coagulation is effected by dilute aqueous solution of organic acids. The solid rubber can be graded in terms of dirt content, ash content, nitrogen content, and volatile matter. It can also be categorized by plasticity retention index and Mooney viscosity. To maintain uniformity it is necessary to choose solid natural rubber of known characteristics. 

PVC plastisol based coating compositions are desirable coating vehicles from the standpoint of fabrication, thick film capability, and have the ability to be formulated with high solids, but generally exhibit poor durability, color retention, chalk resistance and dirt resistance ... 

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