The test method

Differences between test results can be expressed by the coefficient of variation between several measurements obtained on different samples or the confidence interval. 

The total uncertainty measured between samples will in fact represent the precision of the measurements plus the contribution due to inhomogeneity U nh- 

The real difficulties remain in the determination of U. It is relatively simple to determine the method uncertainty of nondestructive analysis as repeated measurements can be performed on the same sample [39]. It is far more difficult with destructive methods and in particular in organic trace analysis. In the latter case, all the steps in the procedure rarely allow one to achieve a repeatability with a relative standard deviation of less than several percent. The methods often require a large sample intake as samples of a few milligrams are not easy to handle in extraction systems. 

The determination of the uncertainty of the measurement method necessitates the measurement of several samples in the same conditions as in the homogeneity study. This means that must be established on the material itself is in fact a sum of individual uncertainties generated by each step of the procedure  

When evaluating U the analyst has to include the Us component, which in fact consists in doing a sampling of the material and therefore includes potential heterogeneity or inhomogeneity factors. This often limits the determination of U. If the analyst works properly this should not affect too much the determination of U as the sub-sampling factor is mainly an uncertainty due to weighing. Various ways exist to 

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Since 1994 when the test method was implemented in the inspection program of many paper mills, we test now regularly the steam drums in the most paper mills in Austria (see table 1). 

Application of magnetic fluids in ultrasonic non-destructive testing [1-3] opens the real perspectives for automation of the testing methods, based on the surface waves. This report presents the results of investigations aimed at the creation of the transducer of the surface waves for the automated control. The basic attention is drawn to the analysis of the position of the front meniscus of the contact liquid when the surface waves excite through the slot gap. 

The pubHcations detailing standards (5—8) generally include both specifications and methods of analysis for the substances. The estabHshment of standards of quaHty for chemicals of any kind presupposes the abiHty to set numerical limits on physical properties, allowable impurities, and strength, and to provide the test methods by which conformity to the requirements may be demonstrated. Tests are considered appHcable only to the specific requirements for which they were written. Modification of a requirement, especially if the change is toward a higher level of purity, often necessitates revision of the test to ensure the test s vaHdity. 

The odor detection-threshold values of organic compounds, water, and mineral oil have been determined by different investigators (Table 2 and 3) and may vary by as much as 1000, depending on the test methods, because human senses are not invariable in their sensitivity. Human senses are subject to adaption, ie, reduced sensitivity after prolonged response to a stimulus, and habituation, ie, reduced attention to monotonous stimulation. The values give approximate magnitudes and are significant when the same techiriques for evaluation are used. Since 1952, the chemistry of odorous materials has been the subject of intense research (43). Many new compounds have been identified in natural products (37—40,42,44—50) and find use in flavors. 

Several countries have developed their own standard test methods for cellular plastics, and the International Organization for Standards (ISO) Technical Committee on Plastics TC-61 has been developing international standards. Information concerning the test methods for any particular country or the ISO procedures can be obtained in the United States from the American National Standards Institute. The most complete set of test procedures for cellular plastics, and the most used of any in the world, is that developed by the ASTM these procedures are pubUshed in new editions each year (128). There have been several reviews of ASTM methods and others pertinent to cellular plastics (32,59,129—131). 

Fire-rated type laminate is an HPDL capable of providing fire-rated characteristics as determined by the test methods requited by the authority having jurisdiction. 

The test methods used by industry to determine if a sample of maleic anhydride is within specifications (165) ate ASTM methods D2930, D1493, and D3366. These methods describe procedures for the determination of maleic acid content, the crystallization point, and the color properties of the maleic anhydride sample, respectively. By quantitative deterrnination of these properties, a calculation of the overall purity of the maleic anhydride sample can be made. 

Size. The precise determination of particle size, usually referred to as the particle diameter, can actually be made only for spherical particles. For any other particle shape, a precise determination is practically impossible and particle size represents an approximation only, based on an agreement between producer and consumer with respect to the testing methods (see Size measurement of particles). 

Nondestmctive tests differ from methods of laboratory analysis and testing where specimens are generally sectioned, broken, damaged, or destroyed. Nondestmctive tests can be performed on materials, components, and stmctures or systems that actually are to be used. Thus, effective use of NDE requires engineering knowledge of the stmcture, the performance characteristics, and service environment, as well as the test method. More complete information on all of the topics discussed herein are available (1 6). 

Overall, the test methods pubhshed by INDA (Table 4) continue to be the general tests used to characterize fabrics however, specific market apphcations often generate special test procedures to fiilfill unique needs. 

Method vahdation is the demonstration, accompanied by a high degree of assurance, that the test method consistently performs as expected. Vahdation of test methods is especially important when the intended method differs from a compendial or other referenced method and yet is expected to provide equivalent or perhaps better test results. When the reference method is to be used unchanged, no vahdation is necessary. Thus a primary benefit of using compendial methods as written is not needing to do a method vahdation. 

Method Transfer. Method transfer involves the implementation of a method developed at another laboratory. Typically the method is prepared in an analytical R D department and then transferred to quahty control at the plant. Method transfer demonstrates that the test method, as mn at the plant, provides results equivalent to that reported in R D. A vaUdated method containing documentation eases the transfer process by providing the recipient lab with detailed method instmctions, accuracy and precision, limits of detection, quantitation, and linearity. 

The test methods appHcable to refractories are available (34). These methods are summarized ia Table 16. 

Test Methods. The test methods used for water or oil repeUency are quite varied, in accordance with paper or paperboard type and end use. Two tests commonly used to measure water repeUency, the Hercules Size Test and the COBB Test, as weU as others have been summarized (55,69,70). 

Benzaldehyde is sold as technical grade or as meeting the specifications of the NationalVormulary (NF) (7), the Vood Chemicals Codex (FCC) (8), or the British Pharmacopeia (BP) (9) (Tables 4 and 5). The test methods used for the analysis of benzaldehyde are standard methods, with the exception of the assay method. 

The test methods for zinc oxide impression pastes are outlined in ADA specification no. 16 and Federal specification U-1-500. 

Correlation of all aspects of the test method with the practical system of interest is always important. The test used for dairy cleaning is an excellent example (116). Milk is used to tag the soil with radioactive Ca by an exchange with radioactive CaCl2. This treatment is apphed to stainless steel planchets by suspending the planchets in milk under actual pasteurizing conditions. 

Robert Koch, in Germany in 1881, did scientific laboratory tests on 70 different chemicals, at different concentrations and in different solvents, to assess thek abiUty to kill spores of anthrax bacteria (7). Refinement of the testing methods were made in 1897, 1903, and 1908 (8). They continued to be improved, standardized, and pubUshed under the auspices of organizations like the Association of Official Analytical Chemists (AOAC) (now called AO AC International). 

In many commercial brochures, chemical resistance is indicated as excellent, good, fair, or poor. Although the test method is usually outlined, wide interpretation is possible. Immersion tests are usually described in this manner. Hydrolytic stabiUty is tested by salt-spray cycling or autoclave cycling. 

Even if the process were at steady state, tensile strength, a key property would still reflect some variation. Steady state, or stable operation of any process, has associated with it a characteristic variation. Superimposed on this is the testing method, which is itself a process with its own characteristic variation. The observed variation is a composite of these two variations. 

The types of sedimentation encountered in process technology will be greatly affected not only by the obvious factors—particle size, hquid viscosity, sohd and solution densities—but also by the characteristics of the particles within the shiny. These properties, as well as the process requirements, will help determine both the type of equipment which will achieve the desired ends most effectively and the testing methods to be used to select the equipment. 

The test methods indicated are the approved referee methods. Other acceptable methods are indicated in Section 2 and 5.1. 

The test method and test results will generally be the same as for a switchgear assembly, discussed in Section 14.3.7. 

Maximum Pressure and Rate of Pressure Rise and KJ These explosibility parameters are used in assessing whether equipment will contain the maximum pressure developed during deflagration, or to design deflagration relief vents and other explosion prevention systems (see NEPA 68 and 69). The test method is given in ASTM E 1226. 

In the case of crystalline polymers such as types E and F the situation is somewhat more complicated. There is some change in modulus around the which decreases with increasing crystallinity and a catastrophic change around the. Furthermore there are many polymers that soften progressively between the Tg and the due to the wide melting range of the crystalline structures, and the value determined for the softening point can depend very considerably on the test method used. 

Because of the diversity of the sources for this book the Izod data frequently referred to are expressed in a variety of units according to the test method used and no attempt has been made to convert the data to the use of a common unit. 

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