Selected Test Methods

ASTM D 3574 - Test K covers dry-heat aging of flexible cellular materials. This test consists in exposing foam samples in an air-circulating oven at 140°C for 22 hours. The specimens are then removed and conditioned for not less than 12 hours at 23°C and 50 percent RH. As with the Steam Autoclave Tests (Jj and J2) physical tests are carried out before and after agiqg. According to Shah (1) tensile properties are usually studied after dry-heat aging. 

ASTM C 522 covers the measurement of airflow resistance and the related measurements of specific airflow resistance and airflow resistivity of porous materials that can be used for the absorption and attenuation of sound. The method describes how to measure a steady flow of air through a test specimen, how to measure the air-pressure difference across the specimen, and how to measure the volume velocity of airflow through the specimen. The airflow resistance, R, the specific airflow resistance, r, and the airflow resistivity, rQ, may be calculated from the measurements. The apparatus includes a suction generator or positive air supply arranged to draw or force air at a uniform rate through the specimen. A flowmeter is used to measure the volume velocity of airflow through the specimen, and a differential-pressure-measuring device measures the static-pressure difference between the two faces of the specimen with respect to atmosphere. 

ASTM C 384 is another method used for acoustical materials. This method is an impedance-tube method. In the test a flexible-foam specimen is placed in a cavity over a vacuum chamber. A specified constant-air-pressure differential is then created. The air-flow value is the rate of flow of air required to maintain this pressure differential. The test is carried out 1) with air flow parallel to foam rise, and 2) with air flow perpendicular to foam rise. Air-flow values are proportional to porosity in flexible foams. 

ASTM D 3574 - Test G is another method used for air flow of flexible foams. The test measures the ease with which air passes through a cellular structure. The test consists in placing a flexible-foam core specimen in a cavity over a chamber and creating a specified constant air-pressure differential. The rate of flow of air require to maintain this pressure differential (125 Pa) is the air-flow value. The results are reported in cubic decimeters per second (dm /sec). Tests are usually carried out in two directions parallel to foam rise and perpendicular to foam rise. 

ASTM Test Methods D 2842 on water absorption and D 2856 on open-cell content require knowledge of surface cell volume, which uses cell-size values in the calculation. 

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TABLE 25-31 Regulatory Citations for Selected Test Methods... 

Johnson, I. (2000) Criteria-based procedure for selecting test methods for effluent testing and its application to Toxkit microbiotests, in G. Persoone, C. Janssen and W.M. De Coen (eds.), New Microbiotests for Routine Toxicity Screening and Biomonitoring, Kluwer Academic / Plenum Publishers, New York, pp. 73-94. 

In ASTM F78-98 Standard Practice for Selecting Generic Biological Tests Methods for Materials and Devices , the selection test methods to evaluate medical devices is described. Regarding hemocompatibility tests for blood compatibility, hemolysis, and complement activation are described. Under blood compatibility, hemolysis and thrombosis are described as the most obvious examples of incompatibility with blood. It is suggested that thrombogenicity (formation of thromboemboli or platelet activation) be tested under dynamic conditions that simulate in the use procedures for the device. Complement activation is of concern in some cases and should be tested in vitro by assessing the status of various complement components. However, complement activation will probably not represent the only portion of the inflammatory response stimulated by medical devices. 

A wide range of plastics test methods are available and routinely used to characterize plastics and rubber. Even a basic introduction to the common tests used is beyond the scope of this chapter. The following introductory discussion is on several selected test methods that will allow the reader to better understand the test data presented in other chapters. With most of these tests, there are an extensive theoretical foundation and numerous practical details on how to carry them out as well as the relevant standards that have been left out. With most tests described here, the experience of the operator in sample preparation, carrying out the tests, and analysis of data is critical to obtain rqtroducible results. 

The second part on biodegradation is very similar to EN 13432, e.g., with regard to selected test methods, six-month period, irrelevant components below 1%, no need for testing natural materials. Differences are the required pass level (60% for homopolymers, 90% for heteropolymers both in absolute terms), the acceptable total for irrelevant components (3%) and the requirement to test components between 1% and 10% separately. 

Eluorspar assay may be completed by fluoride determination alone, because the mineralogical grouping rarely iacludes fluorine minerals other than fluorite. Calcium can be determined as oxalate or by ion-selective electrodes (67). SiUca can be determined ia the residue from solution ia perchloric acid—boric acid mixture by measuriag the loss ia weight on Aiming off with hydrofluoric acid. Another method for determining siUca ia fluorspar is the ASTM Standard Test Method E463-72. 

The most effective specification is that which accomplishes the desired result with the fewest requirements. Properties and performance should be emphasized rather than how the objectives ate to be achieved. Excessive demonstration of emdition on the part of the writer or failure to recognize the usually considerable processing expertise held by the vendor results in a lengthy and overly detailed document that generally is counterproductive. Redundancy may lead to technical inconsistency. A requirement that cannot be assessed by a prescribed test method or quantitative inspection technique never should be included in the specifications. Wherever possible, tests should be easy to perform and highly correctable with service performance. Tests that indicate service life are especially useful. Standard test references, eg, ASTM methods, ate the most desirable, and those that ate needed should be selected carefully and the numbers of such references should be minimized. To eliminate unnecessary review activity by the would-be complier, the description of a standard test should not be paraphrased or condensed unless the original test is referenced. 

The American Society of Mechanical Engineers (ASME) United Engineering Center 345 East 47th Street New York, NY 10017 The ASME Boiler and Pressure Vessel Code, under the cognisance of the ASME PoHcy Board, Codes, and Standards, considers the interdependence of design procedures, material selection, fabrication procedures, inspection, and test methods that affect the safety of boilers, pressure vessels, and nuclear-plant components, whose failures could endanger the operators or the pubHc (see Nuclearreactors). It does not cover other aspects of these topics that affect operation, maintenance, or nonha2ardous deterioration. 

OU repeUency is measured by observing a fabric s resistance to wetting by a selected series of numbered test Uquid hydrocarbons with a range of surface tensions. The fabric rating is based on the Uquid that does not wet the fabric surface in a specified time (AATCC Test Method 118 and INDA... 

Reference 38 is a good guide to the selection of plate thickness test methods. Test methods may vary with the purity and electrochemical activity of the deposit. Metals deposited from commercial plating solutions are seldom pure. For example, zinc deposits from the three commonly used baths, ie, cyanide, chloride, and zincate, vary significantly in purity and activity (39). Standard ASTM test methods for determining plate thickness are... 

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. 

When maldug any economic analysis, care should be taken to be certain that the efficiency ratings of all motors being considered are on the same basis. While this should not be a problem for motors rated 1 to 500 horsepower as covered by the NEMA Standards for efficiency marldug, it is common practice for several different test methods to be used when measuring the efficiency of motors rated over 500 horsepower. A particular test method may need to be selected by the test facility on the basis of available test equipment and power supply. All test methods that may be used to test any one motor will not necessarily give the same result for efficiency. 

One of perspective development trends of methods of heavy metals contents reification in natural waters is the creation of selective and express test-method with a possibility of detection at a level and above than maximum allowable concentrations (MAC) of metals - toxiferous. 

The sensitive and selective soi ption-spectroscopic and visual test-methods for detenuination of Pb(II), Zn(II), 0,0 and F" in water and food-stuffs were proposed in comparative with known DRS and VT methods. 

Following this procedure urea can be determined with a linear calibration graph from 0.143 p.g-ml To 1.43 p.g-ml and a detection limit of 0.04 p.g-ml based on 3o criterion. Results show precision, as well as a satisfactory analytical recovery. The selectivity of the kinetic method itself is improved due to the great specificity that urease has for urea. There were no significant interferences in urea determination among the various substances tested. Method was applied for the determination of urea in semm. 

The information obtained during the background search and from the source inspection will enable selection of the test procedure to be used. The choice will be based on the answers to several questions (1) What are the legal requirements For specific sources there may be only one acceptable method. (2) What range of accuracy is desirable Should the sample be collected by a procedure that is 5% accurate, or should a statistical technique be used on data from eight tests at 10% accuracy Costs of different test methods will certainly be a consideration here. (3) Which sampling and analytical methods are available that will give the required accuracy for the estimated concentration An Orsat gas analyzer with a sensitivity limit of 0.02% would not be chosen to sample carbon monoxide... 

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