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定价： 481元 / 折扣价： 409 元

定价： 384元 / 折扣价： 327 元 加购物车

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3.1 Standard nomenclature shall be used to facilitate communication between designers, suppliers, and users of HVAC ventilation ductwork components.3.2 Standard design parameters shall be used to define ventilation ductwork shapes.3.3 Standard variables for design parameters (see 2.2) are useful in writing CAD/CAM software for automatic fabrication of ventilation ductwork shapes.1.1 This practice covers the identification of design configurations and descriptive nomenclature for sheetmetal HVAC ductwork shapes frequently used in shipbuilding. This practice also covers parametric dimensions of these shapes. (See Table 1.)1.2 This practice does not cover the location of seams or joints within a shape or the method of joining shapes together.1.3 Since this practice is not measurement sensitive, it is applicable whether inch-pound or SI metric dimensions are used.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 / 折扣价： 550 元 加购物车

定价： 260元 / 折扣价： 221 元 加购物车

5.1 The pinhole test provides one method of identifying the dispersive characteristics of clay soils that are to be or have been used in earth construction. The piping failures of a number of homogeneous earth dams, erosion along channel or canal banks, and rainfall erosion of earthen structures have been attributed to the colloidal erosion along cracks or other flow channels formed in masses of dispersive clay (2).5.2 This test method models the action of water flowing along a crack in an earth embankment. Other indirect tests, such as the double hydrometer test (Test Method D4221), the crumb test (3, 4), that relates the turbidity of a cloud of suspended clay colloids as an indicator of the clay dispersivity, and chemical tests that relate the percentage of sodium to total soluble salt content of the soil are also used as indicator tests of clay dispersibility (2). The comparison of results from the pinhole test and other indirect tests on hundreds of samples indicates that the results of the pinhole test have the best correlation with the erosional performance of clay soils in nature.5.3 Method A and Method C of the pinhole test require the evaluation of cloudiness of effluent, final size of the pinhole, and computation of flow rates through the pinhole in order to classify the dispersive characteristics of the soil. Method B requires only the evaluation of the cloudiness of effluent and final size of the pinhole to classify the dispersive characteristics of the soil. The computation of flow rates through the pinhole in Method A serves primarily as a guide to the proper equipment and specimen performance under sequential pressures applied during the test. All methods produce similar results and any method can be used to identify dispersive clays.5.4 The use of Method A or Method C results in the accumulation of data relative to sequential flow rates through the pinhole and consequent enlargement or erosion of the hole. The pinhole erosion test was developed for the purpose of identifying dispersive soils and is not intended to be a geometrically scaled model of a prototype structure. Since the theory of similitude was not used in the design of the pinhole test, quantitative data are not obtained. The quantity of flow through the pinhole, amount of soil erosion, or the rate of soil erosion should not be extrapolated to actual field conditions (3). However, such data may be useful in performing qualitative evaluations of the consequences of such erosion in terms of dam failure, loss of life and property. They also may be used in considering the cost effectiveness of defensive design measures necessary to minimize the effects of failure due to dispersive clays. For example, the amount of colloidal erosion that will occur in a soil classed as ND2 (very slightly dispersive) will be very small for a relatively long period of time. Such erosion may not be significant in evaluating the cost-benefit relationships in projects where public safety is not involved or where normal maintenance procedures will handle the problem. In such cases, classifying the soil as ND (nondispersive) using Method B of the pinhole test should be adequate.5.5 Pinhole tests that result in classifying soil as slightly dispersive (ND3 by Method A or Method C or SD by Method B) indicate high uncertainty about the existence of significant problems to be considered in the design or stability of a structure. In such cases, it is advisable to resample and test a number of other soils from the same area to generate an adequate statistical sample for problem evaluation. The original slightly dispersive sample may come from an area on the edge of a more highly dispersive soil.5.6 In a few physiographic areas or geoclimatic conditions, or both, neither the pinhole test nor the other indicator tests provide consistent identification of dispersive clays (5, 6, 7). In such cases, the results of the tests (8, 9) should be evaluated in terms of cost effectiveness and design judgment (7).5.7 For some projects, it may be desirable to perform the pinhole test using eroding fluids other than distilled water (8, 10). In such cases, Method A, Method B, or Method C may be used to identify the dispersive characteristics of the soil and compare the results with those obtained using distilled water.NOTE 1: Notwithstanding the statement on precision and bias contained in these test methods: The precision of these test methods is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies which meet the criteria of Practice D3740 are generally considered capable of competent and objective testing. Users of these test methods are cautioned that compliance with Practice D3740 does not in itself assure reliable testing. Reliable testing depends on several factors; Practice D3740 provides a means of evaluating some of those factors.1.1 This test method presents a direct, measurement of the dispersibility and consequent colloidal erodibility of clay soils by causing water to flow through a small hole punched in a specimen. The results of the tests are qualitative and provide general guidance regarding dispersibility and erodibility. This test method is complemented by Test Method D4221.1.2 This test method and the criteria for evaluating test data are based upon results of several hundred tests on samples collected from embankments, channels, and other areas where clay soils have eroded or resisted erosion in nature (1).21.3 Three alternative procedures for classifying the dispersibility of clay soils are provided as follows:1.3.1 Method A and Method C, adapted from Ref (1), classify soils into six categories of dispersiveness as: dispersibility (D1, D2), slight to moderately dispersive (ND4, ND3), and nondispersive (ND2, ND1).1.3.2 Method B classifies soils into three categories of dispersiveness as: dispersibility (D), slightly dispersive (SD), and nondispersive (ND).1.4 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.1.5 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 / 折扣价： 550 元 加购物车

4.1 For a fabricated panel to be properly used, it must be adequately identified and packaged. It must be handled and stored in such a way that its physical property values are not degraded. Failure to follow good practice may result in the unnecessary failure of the fabricated panel in a properly designed application.4.2 This guide is not intended to replace project-specific storage, handling, identification, packaging, or installation requirements or quality assurance programs.1.1 This guide covers guidelines for the identification, packaging, handling, storage, and deployment of fabricated geomembrane panels. This guide is not to be considered as all encompassing since each project involving fabricated panels presents its own challenges and special conditions.1.2 This guide is intended to aid fabricators, suppliers, purchasers, and users of fabricated panels in the identification, packaging, handling, storage, and deployment of fabricated geomembrane panels.1.3 This guide is written for factory-fabricated geomembrane panels only. Other geosynthetics use Guide D4873/D4873M as their guide.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车

4.1 This practice is useful for assessing the source for an oil spill. Other less complex analytical procedures (Test Methods D3328, D3414, D3650, and D5037) may provide all of the necessary information for ascertaining an oil spill source; however, the use of a more complex analytical strategy may be necessary in certain difficult cases, particularly for significantly weathered oils. This practice provides the user with a means to this end.4.1.1 This practice presumes that a “screening” of possible suspect sources has already occurred using less intensive techniques. As a result, this practice focuses directly on the generation of data using preselected targeted compound classes. These targets are both petrogenic and pyrogenic and can constitute both major and minor fractions of petroleum oils; they were chosen in order to develop a practice that is universally applicable to petroleum oil identification in general and is also easy to handle and apply. This practice can accommodate light oils and cracked products (exclusive of gasoline) on the one hand, as well as residual oils on the other.4.1.2 This practice provides analytical characterizations of petroleum oils for comparison purposes. Certain classes of source-specific chemical compounds are targeted in this qualitative comparison; these target compounds are both unique descriptors of an oil and chemically resistant to environmental degradation. Spilled oil can be assessed in this way as being similar or different from potential source samples by the direct visual comparison of specific extracted ion chromatograms (EICs). In addition, other, more weathering-sensitive chemical compound classes can also be examined in order to crudely assess the degree of weathering undergone by an oil spill sample.4.2 This practice simply provides a means of making qualitative comparisons between petroleum samples; quantitation of the various chemical components is not addressed.1.1 This practice covers the use of gas chromatography and mass spectrometry to analyze and compare petroleum oil spills and suspected sources.1.2 The probable source for a spill can be ascertained by the examination of certain unique compound classes that also demonstrate the most weathering stability. To a greater or lesser degree, certain chemical classes can be anticipated to chemically alter in proportion to the weathering exposure time and severity, and subsequent analytical changes can be predicted. This practice recommends various classes to be analyzed and also provides a guide to expected weathering-induced analytical changes.1.3 This practice is applicable for moderately to severely degraded petroleum oils in the distillate range from diesel through Bunker C; it is also applicable for all crude oils with comparable distillation ranges. This practice may have limited applicability for some kerosenes, but it is not useful for gasolines.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 / 折扣价： 550 元 加购物车

This practice explains the procedure for identifying standard grades and types of flat-rolled electrical steels in ASTM electrical steel specifications. This practice applies to flat-rolled magnetically soft irons and steel such as low-carbon steels and alloys of iron with silicon, aluminum, and so forth produced to a specified thickness and maximum value of core loss. These designations are intended to replace the old AISI M designations which are no longer supported. The practice also has a cross-reference between thickness and electrical sheet gage number.1.1 This practice covers the procedure for designating (within ASTM specifications) standard grades of flat-rolled electrical steels made to specified maximum values of specific core loss. This practice applies to magnetically soft irons and steel (low-carbon steels and alloys of iron with silicon, aluminum, and other alloying elements) where a core loss measurement at a stated peak value of alternating induction and a stated frequency, such as 1.5 T (15 kG) and 60 Hz, is normally used to grade the material. This practice also applies when some other property is specified (or a different induction or frequency, or both) as the limiting characteristic, provided the material also meets all the requirements of the ASTM specification.1.2 Individual specifications that are in conformity with this practice are Specifications A677, A683, A726, A876, and A1086.1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to customary (cgs-emu and inch-pound) units which are provided for information only and are not considered standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车