Environmental test chamber studies

Abstract Adsorption and desorption of indoor air pollutants to and from indoor surfaces are important phenomena. Often called sink effects, these processes can have a major impact on the concentration of pollutants in indoor environments and on the exposure of human occupants to indoor air pollutants, Basic theories are used to describe the processes using fundamental equations. These equations lead to models describing sink effects in indoor environments. Experimental studies have been performed to determine the important parameters of the sink models. Studies conducted in dynamic, flow-through environmental test chambers have quantified adsorption and desorption rates for many combinations of indoor air pollutants and interior surfaces. Sink effects have been incorporated into indoor air quality (lAQ) models to predict how adsorption and desorption processes affect... 

Studies conducted in dynamic, flow-through environmental test chambers have quantified adsorption and desorption rates for only a small number of the available combinations of indoor air pollutants and interior surfaces. 

This work does not address the fundamental question of mirror corrosion mechanisms. Rather, our study was limited to visual observations of weathering effects upon commercial products exposed to extreme conditions in an environmental test chamber. The principal parameters investigated were 1) the materials ability to protect silvered mirrors from moisture and 2) the effect of mechanical stress (coefficients of expansion mismatches) due to temperature-humidity cycling. 

Physieal-meehanieal eharacteristies of fibrous materials were determined with PM-3-1 tensile testing machine according to TU 25.061065-72. Kinetics of UV-aging was studied with Feutron 1001 environmental test chamber (Germany). Irradiation of samples was carried out with a 375 W high pressure Hg-lamp, at a distance of 30 cm. 

Figure 2-15. Environmental test chamber to study tensile properties at different temperatures. (Courtesy of Instron Corporation.)...

Dix and Lavan conducted studies to measure the effectiveness of draperies and other indoor shading devices on the coefficient of thermal transmission, U, under winter and summer conditions (89)- With the aid of two environmentally controlled chambers and thermistors located near a test window, they determined that a medium-colored drapery with a white plastic backing reduced conductive heat loss in the winter by 6-1%, and conductive and radiant (solar) heat gains in the slimmer by 33%. Because shades inside casements were more effective than draperies in reducing heat loss under winter conditions, they concluded that the ability of the material to block air flow was more important than other properties of the material used (8 ). 

In addition to the technical developments the scientific applications of chambers are being expanded, for example, the current understanding of secondary organic aerosol formation has been developed principally from environmental chamber studies and chambers have been used even more recently to investigate photolysis processes under real atmospheric conditions. Such new scientific applications are often linked to new technical analytical and other technical developments and environmental chambers offer a perfect platform for testing environmental monitors. 

While the majority of studies have focused on LSD, some evidence suggests that hallucinogens derived from the phenylethylamine nucleus affect locomotion in a manner that is interpretable only by considering the environmental context. For example, the substituted amphetamine DOM produces a dose-dependent (0.5-10 mg/kg) reduction in locomotor activity when rats are tested in a novel open field, while a slight but significant increase in activity is observed in a familiar environment (171). This report corroborates the separate findings of DOM-induced hyperactivity in rats or mice in a familiar chamber (29,196) and hypoactivity in mice in an unfamiliar setting (92). Mescaline (10 mg/kg) has also been reported to increase locomotion in rats in a familiar environment (196). 

Pollutants emitted by various sources entered an air parcel moving with the wind in the model proposed by Eschenroeder and Martinez. Finite-difference solutions to the species-mass-balance equations described the pollutant chemical kinetics and the upward spread through a series of vertical cells. The initial chemical mechanism consisted of 7 species participating in 13 reactions based on sm< -chamber observations. Atmospheric dispersion data from the literature were introduced to provide vertical-diffusion coefficients. Initial validity tests were conducted for a static air mass over central Los Angeles on October 23, 1968, and during an episode late in 1%8 while a special mobile laboratory was set up by Scott Research Laboratories. Curves were plotted to illustrate sensitivity to rate and emission values, and the feasibility of this prediction technique was demonstrated. Some problems of the future were ultimately identified by this work, and the method developed has been applied to several environmental impact studies (see, for example, Wayne et al. ). 

Monitoring and Evaluation. Program model Simpson, 1995), predictions are 27% higher than the mean whereas the lowest, the CB4-TNO version of the carbon bond 4 mechanism, predicts ozone concentrations 35% below the mean. Other studies in which the carbon bond 4 mechanism was tested against environmental chamber data have also found that it underpredicts 03 formation (e.g., Simonaitis et al., 1997). The sensitivity of predicted 03 by CB4 to the chemistry, particularly radical-radical reactions, has been discussed by Kasibhatla et al. (1997). 

Empirical work conducted during the 2003 mesocosm study tested whether P. pouchetii solitary cells or colonies would be resuspended from fjord sediment incubated with filtered water in controlled environmental chambers. 

To be fully utilized, this chamber should also serve as a resource for collaborative studies where environmental chamber measurements imder highly controlled conditions would be useful. We encourage collaboration with other researchers who have instrumentation that we lack that would be useful for various studies, such as our collaboration with William Brune of Penn State University, whose HO and HO2 radical measurement instrumentation was used with the surrogate - NOx experiments carried out for the observational based methods study. This facility would also be useful as a test bed for evaluating analytical instrumentation for use in ambient monitoring, since it can produce realistic but highly characterized simulated pollution conditions for instrument evaluation and inter-comparisons. 

Although the entire MCM has been tested in atmospheric models, and through intercomparison with the results of chamber-validated mechanisms (e.g. Derwent et al, 1998 Jenkin et al, 2002), it has only been partially tested using environmental chamber data. It has been used in a number of studies involving die European Photoreactor (EUPHORE) in Valencia (EUPHORE, 2002), providing the basis for validation of the mechanisms for selected VOC. MCM v3 chemistry has thus already been tested for the photo-oxidation of a-pinene-NOx mixtures at comparatively low NOx concentrations (Saunders et al, 2003). The aromatic mechanisms in MCM v3 and MCM v3.1 have also been evaluated against a set of smog-chamber experiments the evaluation was focused on four representative species of the... 

Various tests and analytical methods are used for the characterisation and evaluation of the properties of vegetable oil-based polymer composites. Mechanical tests for properties such as tensile, flexural, compressive, impact, hardness and wear are carried out by a universal testing machine (UTM), and by equipment for testing impact, hardness, abrasion loss, and so on. Weather and chemical resistance tests are performed in UV/ozone, an artificial environmental chamber and in different chemical media. Water uptake and biodegradability tests are carried out by standard ASTM methods. Biodegradability and biocompatibility may be studied by the same procedure as described in Chapter 2. However, in practice only a few such studies have been performed for vegetable oil-based composites. 

Load frames for tensile testing are available in a range from less than 1 kN to over 300 kN. Environmental chambers that fit around the sample can be used to study low- or high-temperature behaviour, and are typically available to control temperatures in the range - 70-250°C. 

The required moisture conditioning time depends on specimen thickness, difiusion coefficient, and temperature. While it can be calculated, it is best measured. Fig. 1 shows the free moisture swelling strain as a function of time for FM 300K at 50 °C. The specimen was equilibrated for two weeks at 17% RH at which time the silica gel was then replaced with new gel pre-conditioned to 92% RH. After 24 hours the specimen had reached about 95% of its final moisture content Still, in the present study all (0.3 mm thick) specimens were conditioned in environmental chambers for two weeks prior to testing. In comparison, Ishida and Allen [4] and Ishida [5] reported that about 100 days... 

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