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4.1 This guide is intended to describe heat management program elements that foundries use to prevent or manage heat strain and heat-related illness. Specifically, the guide:4.1.1 Provides an objective framework for recognizing heat stress and heat strain, and4.1.2 Facilitates use of best practices to manage heat exposures to minimize heat strain and prevent heat-related illness.1.1 This guide is intended to establish best practices for recognizing and managing occupational heat stress and heat strain in foundry environments.1.2 Objectives of the foundry heat stress and heat strain management guide are as follows:1.2.1 Provide an objective framework for recognizing heat stress and heat strain, and1.2.2 Facilitate use of best practices to manage heat exposures to minimize heat strain and prevent heat-related illness.1.3 In this guide, procedures necessary to manage heat stress and heat strain in foundries are described.1.4 Key elements of this guide include definitions of heat stress and heat strain, plus techniques for recognizing, communicating, managing, and controlling heat stress and heat strain to prevent heat-related illnesses.1.5 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only.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.

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定价： 843元 加购物车

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This specification applies to heat meters used to measure heat in heat exchange circuits in which energy is absorbed (cooling) or given up (heating) by a flowing liquid. For this specification, the necessary elements of a heat meter consist of a sensor to measure flow of the heat-conveying liquid, a pair of temperature sensors that measure the temperature differential across the heat exchange circuit, and a device that receives input from the flow and temperature sensors and calculates energy. This specification does not cover electrical safety or mechanical safety (including pressure safety).This specification defines heat meters as complete or combined instruments. A complete instrument refers to a heat meter that does not have separable subassemblies, while a combined meter is a heat meter that has separable subassemblies. It specifies the allowable flow rate maximum permissible error (MPE) by accuracy class and turndown; the combined allowable error percentages for the temperature sensor pair and the heat calculator for measured difference temperatures in –17°C [2°F] increments; maximum lead cross section and length requirements; types of instruments; metrological characteristics of flow sensors of heat meters and complete instruments; data exchange and communications protocols; heat meter testing methods; operating conditions during testing; type approval tests and measurements; surge transients for signal and dc lines; surge transients for ac power lines; carrier frequencies; field strength; initial verification tests; test temperature ranges; product marking and inscriptions; and installation and operation instructions.1.1 This specification defines general specifications for heat meters. Heat meters are instruments that measure heat in heat exchange circuits in which energy is absorbed (cooling) or given up (heating) by a flowing liquid.1.2 For this specification, the necessary elements of a heat meter consist of a sensor to measure flow of the heat-conveying liquid, a pair of temperature sensors that measure the temperature differential across the heat exchange circuit, and a device that receives input from the flow and temperature sensors and calculates energy.1.3 Electrical safety is not a part of this specification.1.4 Mechanical safety (including pressure safety) is not a part of this specification.1.5 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 nonconformance 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.

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4.1 General—The heat of ablation provides a measure of the ability of a material to serve as a heat protection element in a severe thermal environment. The parameter is a function of both the material and the environment to which it is subjected. It is therefore required that laboratory measurements of heat of ablation simulate the service environment as closely as possible. Some of the parameters affecting the heat of ablation are pressure, gas composition, heat transfer rate, mode of heat transfer, and gas enthalpy. As laboratory duplication of all parameters is usually difficult, the user of the data should consider the differences between the service and the test environments. Screening tests of various materials under simulated use conditions may be quite valuable even if all the service environmental parameters are not available. These tests are useful in material selection studies, materials development work, and many other areas. 4.2 Steady-State Conditions—The nature of the definition of heat of ablation requires steady-state conditions. Variances from steady-state may be required in certain circumstances; however, it must be realized that transient phenomena make the values obtained functions of the test duration and therefore make material comparisons difficult. 4.2.1 Temperature Requirements—In a steady-state condition, the temperature propagation into the material will move at the same velocity as the gas-ablation surface interface. A constant distance is maintained between the ablation surface and the isotherm representing the temperature front. Under steady-state ablation the mass loss and length change are linearly related. where: t   =   test time, s, ρo   =   virgin material density, kg/m3, δL   =   change in length or ablation depth, m, ρc   =   char density, kg/m3, and δc   =   char depth, m. This relationship may be used to verify the existence of steady-state ablation in the tests of charring ablators. 4.2.2 Exposure Time Requirements—The exposure time required to achieve steady-state may be determined experimentally by the use of multiple models by plotting the total mass loss as a function of the exposure time. The point at which the curve departs significantly from linearity is the minimum exposure time required for steady-state ablation to be established. Cases exist, however, in the area of very high heating rates and high shear where this type of test for steady-state may not be possible. 1.1 This test method covers determination of the heat of ablation of materials subjected to thermal environments requiring the use of ablation as an energy dissipation process. Three concepts of the parameter are described and defined: cold wall, effective, and thermochemical heat of ablation. 1.2 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. 1.3 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.

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