The manufacturing procedures for and the performance of a building air infiltration kit consisting of miniature passive perfluorocarbon tracer (PFT) permeation sources and passive adsorption tube samplers are described. With four PFT types available, homes and buildings with up to four separate zones can be evaluated fully under steady state conditions for the air infiltration and exfiltration rates from each zone as well as for the air exchange rates between zones using this inexpensive and nonobtrusive field kit. Complete details on deployment in homes and on gas chromatographic analysis of the passive samplers are presented. Examples of total air changes per hour (ACH) results in several studies showed average values between 0.25 to 0.64 h−1. A generalized correlation was used to characterize the leakiness of eleven homes in the United States and Canada, showing ACH dependency only on inside-outside temperature difference, on wind speed to the 1.5 power, and on a subjective terrain factor; the approach has application in evaluating weatherization performance. Details of multizone measurements in four homes provided insight into the role of attics, crawl spaces, and basements on the indoor air quality and weatherization needs for the living zone.
hydrometallurgical technique. A thin layer of copper was deposited on the surface of the beads, followed by a layer of nickel. Two batches, one containing approximately 0.1% and the other 0.2% copper, were each prepared and analyzed carefully by two independent methods. The two materials then were mixed in varying proportions to give a series of 10 to 20 samples. From Figure 3, the relative sampling error for these samples should be no greater than 0.1% if 10* particles are taken (the most unfavorable mixture has about 1 part of 0.1% to 2 parts of 0.2%). For 200-mesh materials, a sampling error below 0.1% is easily achieved with samples of 0.2 gram (Figure 2). If these samples were prepared from pure copper and a diluent such as pure nickel, 1010 particles (about 20 kg) would be required for each sample analyzed.In summary, the sampling of heterogeneous solids may be a major source of error if the sought-for component is present in small quantity in discrete particles. Poor precision in trace analysis may be the result of variation in sample composition. In the preparation of reference materials for trace components, the use of inert material plus pure component is not recommended. Other approaches to their preparation, particularly use of homogeneous material or of two materials close together in percentage of the sought-for component, should be used.
ACKNOWLEDGMENTThe assistance and cooperation of D. R. Weir and Sherritt-Gordon Mines, Ltd., Fort Saskatchewan, Alberta, in the preparation of the copper-in-nickel reference materials is gratefully acknowledged.
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