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5.1 Manufacturers of thermal insulation express the performance of their products in charts and tables showing heat gain or loss per unit surface area or unit length of pipe. This data is presented for typical insulation thicknesses, operating temperatures, surface orientations (facing up, down, horizontal, vertical), and in the case of pipes, different pipe sizes. The exterior surface temperature of the insulation is often shown to provide information on personnel protection or surface condensation. However, additional information on effects of wind velocity, jacket emittance, ambient conditions and other influential parameters may also be required to properly select an insulation system. Due to the large number of combinations of size, temperature, humidity, thickness, jacket properties, surface emittance, orientation, and ambient conditions, it is not practical to publish data for each possible case, Refs (7,8).5.2 Users of thermal insulation faced with the problem of designing large thermal insulation systems encounter substantial engineering cost to obtain the required information. This cost can be substantially reduced by the use of accurate engineering data tables, or available computer analysis tools, or both. The use of this practice by both manufacturers and users of thermal insulation will provide standardized engineering data of sufficient accuracy for predicting thermal insulation system performance. However, it is important to note that the accuracy of results is extremely dependent on the accuracy of the input data. Certain applications may need specific data to produce meaningful results.5.3 The use of analysis procedures described in this practice can also apply to designed or existing systems. In the rectangular coordinate system, Practice C680 can be applied to heat flows normal to flat, horizontal or vertical surfaces for all types of enclosures, such as boilers, furnaces, refrigerated chambers and building envelopes. In the cylindrical coordinate system, Practice C680 can be applied to radial heat flows for all types of piping circuits. In the spherical coordinate system, Practice C680 can be applied to radial heat flows to or from stored fluids such as liquefied natural gas (LNG).5.4 Practice C680 is referenced for use with Guide C1055 and Practice C1057 for burn hazard evaluation for heated surfaces. Infrared inspection, in-situ heat flux measurements, or both are often used in conjunction with Practice C680 to evaluate insulation system performance and durability of operating systems. This type of analysis is often made prior to system upgrades or replacements.5.5 All porous and non-porous solids of natural or man-made origin have temperature dependent thermal conductivities. The change in thermal conductivity with temperature is different for different materials, and for operation at a relatively small temperature difference, an average thermal conductivity may suffice. Thermal insulating materials (k < 0.85 {Btu·in}/{h·ft 2·°F}) are porous solids where the heat transfer modes include conduction in series and parallel flow through the matrix of solid and gaseous portions, radiant heat exchange between the surfaces of the pores or interstices, as well as transmission through non-opaque surfaces, and to a lesser extent, convection within and between the gaseous portions. With the existence of radiation and convection modes of heat transfer, the measured value should be called apparent thermal conductivity as described in Terminology C168. The main reason for this is that the premise for pure heat conduction is no longer valid, because the other modes of heat transfer obey different laws. Also, phase change of a gas, liquid, or solid within a solid matrix or phase change by other mechanisms will provide abrupt changes in the temperature dependence of thermal conductivity. For example, the condensation of the gaseous portions of thermal insulation in extremely cold conditions will have an extremely influential effect on the apparent thermal conductivity of the insulation. With all of this considered, the use of a single value of thermal conductivity at an arithmetic mean temperature will provide less accurate predictions, especially when bridging temperature regions where strong temperature dependence occurs.5.6 The calculation of surface temperature and heat loss or gain of an insulated system is mathematically complex, and because of the iterative nature of the method, computers best handle the calculation. Computers are readily available to most producers and consumers of thermal insulation to permit the use of this practice.5.7 Computer programs are described in this practice as a guide for calculation of the heat loss or gain and surface temperatures of insulation systems. The range of application of these programs and the reliability of the output is a primary function of the range and quality of the input data. The programs are intended for use with an “interactive” terminal. Under this system, intermediate output guides the user to make programming adjustments to the input parameters as necessary. The computer controls the terminal interactively with program-generated instructions and questions, which prompts user response. This facilitates problem solution and increases the probability of successful computer runs.5.8 The user of this practice may wish to modify the data input and report sections of the computer programs presented in this practice to fit individual needs. Also, additional calculations may be desired to include other data such as system costs or economic thickness. No conflict exists with such modifications as long as the user verifies the modifications using a series of test cases that cover the range for which the new method is to be used. For each test case, the results for heat flow and surface temperature must be identical (within resolution of the method) to those obtained using the practice described herein.5.9 This practice has been prepared to provide input and output data that conforms to the system of units commonly used by United States industry. Although modification of the input/output routines could provide an SI equivalent of the heat flow results, no such “metric” equivalent is available for some portions of this practice. To date, there is no accepted system of metric dimensions for pipe and insulation systems for cylindrical shapes. The dimensions used in Europe are the SI equivalents of American sizes (based on Practice C585), and each has a different designation in each country. Therefore, no SI version of the practice has been prepared, because a standard SI equivalent of this practice would be complex. When an international standard for piping and insulation sizing occurs, this practice can be rewritten to meet those needs. In addition, it has been demonstrated that this practice can be used to calculate heat transfer for circumstances other than insulated systems; however, these calculations are beyond the scope of this practice.1.1 This practice provides the algorithms and calculation methodologies for predicting the heat loss or gain and surface temperatures of certain thermal insulation systems that can attain one dimensional, steady- or quasi-steady-state heat transfer conditions in field operations.1.2 This practice is based on the assumption that the thermal insulation systems can be well defined in rectangular, cylindrical or spherical coordinate systems and that the insulation systems are composed of homogeneous, uniformly dimensioned materials that reduce heat flow between two different temperature conditions.1.3 Qualified personnel familiar with insulation-systems design and analysis should resolve the applicability of the methodologies to real systems. The range and quality of the physical and thermal property data of the materials comprising the thermal insulation system limit the calculation accuracy. Persons using this practice must have a knowledge of the practical application of heat transfer theory relating to thermal insulation materials and systems.1.4 The computer program that can be generated from the algorithms and computational methodologies defined in this practice is described in Section 7 of this practice. The computer program is intended for flat slab, pipe and hollow sphere insulation systems.1.5 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 and are not considered 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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5.1 Heat Gain to Space—This test method determines the heat gain to the space from a hood/appliance system.NOTE 2: To maintain a constant temperature in the conditioned space, this heat gain must be matched by space cooling. The space sensible cooling load, in tons, then equals the heat gain in Btu/h divided by the conversion factor of 12 000 Btu/h (3.412 W) per ton of cooling. Appliance heat gain data can be used for sizing air conditioning systems. Details of load calculation procedures can be found in ASHRAE, see Ref (1) and Ref (2)5. The calculation of associated cooling loads from heat gains to the test space at various flow rates can be used along with other information by heating, ventilation, air conditioning (HVAC), and exhaust system designers to achieve energy-conservative, integrated kitchen ventilation system designs.5.2 Parametric Studies: 5.2.1 This test method also can be used to conduct parametric studies of alternative configurations of hoods, appliances, and replacement air systems. In general, these studies are conducted by holding constant all configuration and operational variables except the variable of interest. This test method, therefore, can be used to evaluate the following:5.2.1.1 The overall system performance with various appliances, while holding the hood and replacement air system characteristics constant.5.2.2 Entire hoods or characteristics of a single hood, such as end panels, can be varied with appliances and replacement air constant.5.2.3 Replacement air characteristics, such as makeup air location, direction, and volume, can be varied with constant appliance and hood variables.1.1 This test method covers the determination of appliance heat gain to space derived from the measurement and calculation of appliance energy consumption, energy exhausted, and energy to food, based on a system energy balance, parametric evaluation of operational or design variations in appliances, hoods, or replacement air configurations.1.2 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 and are not considered standard.1.3 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.1.4 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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5.1 Manufacturers of radiant barriers express the performance of their products in terms of the total hemispherical emittance. The purpose of a radiant barrier is to decrease the radiation heat transfer across the attic air space, and hence, to decrease the heat loss or gain through the ceiling below the attic. The amount of decrease in heat flow will depend upon a number of factors, such as weather conditions, amount of mass or reflective insulation in the attic, solar absorptance of the roof, geometry of the attic and roof, and amount and type of attic ventilation. Because of the infinite combinations of these factors, it is not practical to publish data for each possible case.5.2 The calculation of heat loss or gain of a system containing radiant barriers is mathematically complex, and because of the iterative nature of the method, it is best handled by computers.5.3 Computers are now widely available to most producers and consumers of radiant barriers to permit the use of this practice.5.4 The user of this practice may wish to modify the data input to represent accurately the structure. The computer program also may be modified to meet individual needs. Also, additional calculations may be desired, for example, to sum the hourly heat flows in some fashion to obtain estimates of seasonal or annual energy usages. This might be done using the hourly data as inputs to a whole-house model, and by choosing house balance points to use as cutoff points in the summations.1.1 This practice covers the estimation of heat gain or loss through ceilings under attics containing radiant barriers by use of a computer program. The computer program included as an adjunct to this practice provides a calculational procedure for estimating the heat loss or gain through the ceiling under an attic containing a truss or rafter mounted radiant barrier. The program also is applicable to the estimation of heat loss or gain through ceilings under an attic without a radiant barrier. This procedure utilizes hour-by-hour weather data to estimate the hour-by-hour ceiling heat flows. The interior of the house below the ceiling is assumed to be maintained at a constant temperature. At present, the procedure is applicable to sloped-roof attics with rectangular floor plans having an unshaded gabled roof and a horizontal ceiling. It is not applicable to structures with flat roofs, vaulted ceilings, or cathedral ceilings. The calculational accuracy also is limited by the quality of physical property data for the construction materials, principally the insulation and the radiant barrier, and by the quality of the weather data.1.2 Under some circumstances, interactions between radiant barriers and HVAC ducts in attics can have a significant effect on the thermal performance of a building. Ducts are included in an extension of the computer model given in the appendix.1.3 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.1.4 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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The current gain of a transistor is basic to its operation and is its single most important parameter. Ionizing radiation, that is, gamma radiation due to a nuclear burst, will degrade the current gain due to lifetime damage in the bulk material. Degradation of gain will be greatest immediately following a burst of ionizing radiation and the gain will rapidly recover to a quasi steady-state value. Defect annealing may continue for weeks but usually the current gain recovery is small or negligible. This method provides a procedure that does not require special-purpose test equipment. This method is suitable for use for specification acceptance, service evaluation, or manufacturing control.1.1 This test method covers the measurement of common-emitter d-c current gain (forward, hFE, or inverted, hFEI) of bipolar transistors, for which the collector-emitter leakage current, ICEO, is less than 10% of the collector current, IC, at which the measurement is to be made, and for which the shunt leakage current in the base circuit is less than 10% of the base current required. 1.2 This test method is suitable for measurement of common-emitter d-c current gain at a single given value of test transistor collector current or over a given range of collector currents (for example, over the range of the transistor to be tested). 1.2.1 The nominal ranges of collector current over which the three test circuits are intended to be used are as follows: 1.2.1.1 Circuit 1, less than 100 [mu]A, 1.2.1.2 Circuit 2, from 100 [mu]A to 100 mA, and 1.2.1.3 Circuit 3, greater than 100 mA. 1.3 This test method incorporates tests to determine if the power dissipated in the transistor is low enough that the temperature of the junction is approximately the same as the ambient temperature. 1.4 The values stated in International System of Units (SI) 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 the safety problems, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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