Simulated rain tests

The fabric s resistance to penetration and absorption of water can be measured by two different kinds of tests simulated rain tests and penetration pressure tests. 

The rain test simulates the effects of rainfaU the hydrostatic head on the spray controls the intensity of spraying. The repeUency is rated by the weight of water that penetrates the fabric and is absorbed by a blotter mounted behind the fabric at a specific intensity of spraying (AATCC Test Methods 35 and 42 INDA Standard Test 80.2-92). 

Insertion loss, weather louver The difference in simulated rain penetration between the test specimen and the calibration plate at the same test conditions. 

Briefly recalled, the WASTOXHAS approach consists in characterizing the ecotoxicological hazard potential of contaminant fluxes from waste leachate obtained under defined conditions with two different dynamic leaching procedures laboratory simulated leaching tests and field leaching tests. The approach developed below considered a specific scenario that simulates a waste deposit receiving rain or run-off water (Perrodin et al., 2002). 

Fig. 7.9. Efficiency data for two test cells (active area 4 cm2) exposed to outdoor conditions for 1 year. The efficiencies of the cells were measured from time to time with an indoor solar simulator. The dye used is Ru(NCS)2(2,2 -bipyridyl-4,4 -dicarboxylate)2 (N719). 0.6 M hexylmethylimidazolium iodide (HMII), 0.1 M Lil, 0.05 M I2, 0.5 M tert-butylpyridin (TBP) in propionitril was used as the electrolyte. Surlyn 1702 (Dupont) was used as the sealant. The cells were placed under a window to protect them from rain. Test location INAP, Gelsenkirchen, Germany...

Four samples of treated fabric are subjected to simulated rain for 10 min. The fabrics (placed on inclined cups and sealed at the edges) are in constant motion and the side of the fabric not exposed to the rain is subjected to a rubbing action. The repellency of the fabric is determined by the appearance of the wetted side, the amount of water absorbed by the fabric and the amount of water passing through the fabric. This test requires an elaborate special apparatus. 

AATCC Test Method 35 -2000 " is designed to simulate a rain event. A special apparatus is used to hold the 20 x 20 cm fabric sample in a vertical position backed by a weighed piece of blotter paper. The fabric face is sprayed with water under constant hydrostatic pressure for 5 min and the blotter paper reweighed. The increase in weight of the backing paper is a measure of the resistance of the fabric to penetration by the simulated rain. 

The laboratory column is filled (loose packed) with the test material and distilled water is pumped through the column to simulate rain or runoff percolation through the highway subsurface (flow rates of 5-50 cm/day) The contaminants are leached from the test material into the water under laminar flow conditions... 

Accelerated UV tests provide an alternative and generally much more rapid means of measuring the effects of light on polymers under consistent and reproducible conditions. The UV light is generally provided by xenon arc lamps and some modern UV exposure cabinet provide a very rapid assessment of polymeric materials (Figure 3.4) and correlate well with environmental exposure. Any element of the environment can be incorporated into a weatherometer . For example, relative humidity may be varied and an alternating water spray can be incorporated to simulate rain. As has already been noted this surface treatment may... 

In the second series of tests, field-grown soybeans (Glycine max (L.) Merr. Beeson) were exposed to simulated rain at pH 2.8,... 

The Bundesmann rain tester was developed in 1935 and is similar to the rain test suggested by AATCC Test Method 35, but the method of estimating the water penetration through the fabric is different. Bundesmann rain tester measures the water collected in the cups covered with test fabric and subjected to simulated rainfall, whereas the AATCC Test Method 35 measures the change in the weight of blotter paper placed under the fabric subjected to simulated rain. 

Environmental test rooms Environmental test rooms which permit various combinations of temperature, fogging, humidity levels, and shower effects to simulate rain can reproduce in an accelerated mode many of the factors present in an actual exposure. For the most part, these tests use small cut or machined specimens, but assemblies of simulated components and complete systems can also be tested as shown in Fig. 11.35. 

The AATCC 35-1994 rain test developed by Slowinske and Pope [156] simulates exposure to rain of variable intensity (Fig. 12.7). A sample of the fabric backed by a weighed paper blotter is sprayed with water for 5 min. The blotter is weighed to determine the amount of water that has leaked through the fabric. The hydrostatic pressure of water and, consequently, the intensity of the impact of its drops on the fabric is varied in increments of 0.3 m (1 ft) from 0.6 m to 2.4 m (2 ft to 4 ft). The rain test has ranked fabrics in the same order as exposure to a 3-in. rain, but some discrepancies became evident in the correlation with l-in./h rain. 

Nevertheless, Slowinske and Pope concluded that the rain test correlated with the exposure to rain (simulated in a rain room) better than any other test. 

However, for multiple-impact studies and for evaluating the resistance of materials, the usual approach is to attach the specimen(s) to periphery of a rotating disc or arm, such that in their circular path they repeatedly pass through and impact against liquid jets, sprays, or simulated rain diq)s. An example of such a device is shown in Fig. 9. The velocity of the specimen then determines the impact velocity. Such test facilities range from small laboratory apparatuses with specimen velocities of up to about 2(X) m/s (655 fl/s) to... 

Accelerated Tests. Weather resistance in an accelerated test is defined as the resistance of plastics towards changes caused by simulated open-air weathering (simulation of global radiation by means of filtered xenon arc radiation and periodic rain). After the weathering (measured by the product of intensity and duration), defined properties of the test sample are compared with those of an identical unweathered sample. Properties should be considered which are of practical importance, such as color or surface properties. For standards, see Table 1 ( Weathering in apparatus ). Apparatus test chamber, rain and air humidification equipment, air flow equipment, radiation measuring equipment. 

These waste simulation trials based on laboratory column experiments still needed to be validated using a field approach. Two field leaching tests were thus built on an experimental site (CERED, Vernon, France) to simulate real conditions of a waste deposit site receiving rain or run-off water (Perrodin et al., 2002). The first... 

A more severe simulation of a rain event is provided by ISO 9865. This test method is similar to AATCC Test Method 35 except that the water is sprayed for 10 min and the undersides of the fabric samples are rubbed while the spraying takes place. A rather elaborate apparatus is required. The appearance of the fabric face, the amount of water absorbed by the fabric and the amount of water passing through the fabric are all factors in determining the repellency rating of the fabric. 

The research available to date presents a partial view of the impacts of acid rain on woody plants. Many of the impacts are still only potential impacts, as simulation studies versus field studies present a conflicting view. However, one thing appears quite clear - more research is needed. As many researchers have found, the effect of acid rain is not going to be one of simple cause and effect, but rather one of a multiple factor interaction. Thus, future work should be statistically designed to test the inter-action(s) rather than main effects. Work needs to be done over both the short and long term to assess injury. Basic physiological work across disciplines with the standardization of techniques used (e.g. one set type of simulator for all researchers to produce simulated acid rain) must be employed in order for different experimental results to be comparable. If we can discover how plants will react to given combinations of stresses, only then will we be able to propose an appropriate course of action. 

The process is understood to have been applied successfully to many sites in Europe. The treatment undoubtedly improves the characteristics of the soil and sludge and immobilises the organic matter to a degree. However, there is concern as to whether the treated material meets the requirements of the appropriate leaching tests [32.35, 32.36]. The latter simulates the effects of acidic rain, which is much more aggressive than normal groundwater. 

Foliage of herbaceous species such as bracken fern, soybean, pinto bean, and sunflower are very sensitive to simulated acid rain. Foliage of Tradescantia and poplar exhibited less visual injury compared with these four species while pin oak exhibited the least amount of visible injury among these species. From these experimental results, it may be suggested that foliage of broadleaved herbaceous plants is more sensitive than foliage of woody broadleaved plants. More plant species should be tested to see if this relationship is correct. 

Studies with simulated acidic rain found growth of the bacterial plant pathogen Pseudomonas phaseolicola totally inhibited by a solution of pH 3.2.When these solutions were used for inoculation of Phaseolus vulgaris Red Kidney test plants, no infection or disease development was observed. Control plants inoculated with solutions at pH 5.6 developed normal disease patterns. Additional studies with other host-parasite pairs are summarized in Table II. 

It has been reported previously that simulated acidic rain and multiple exposures to ozone decreased the foliar dry weight of red kidney beans in laboratory tests (Shriner, 1978). The stimulatory effects of nitrate in simulated acidic rain on the growth of trees also has been demonstrated (Tveite and Abrahamsen, 1978 Wood and Bormann, 1977). Exposure to ozone shifted the partitioning of photosynthate in parsley but, in this case, root growth was depressed relative to the growth of aboveground parts (Oshima et al., 1978). 

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