EPA Method 2H Determination of Stack Gas Velocity Taking Into Account Velocity Decay Near the Stack Wall
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ID： |
325EBAF88B5641C1BF7C127846204466 |
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文件大小(MB)： |
0.42 |
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页数： |
28 |
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文件格式： |
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日期： |
2011-9-29 |
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文本摘录（文本识别可能有误，但文件阅览显示及打印正常，pdf文件可进行文字搜索定位）：
Method 2H—Determination of Stack Gas Velocity Taking Into Account Velocity Decay Near,the Stack Wall,1.0 Scope and Application,1.1 This method is applicable in conjunction with Methods 2, 2F, and 2G (40 CFR Part 60,Appendix A) to account for velocity decay near the wall in circular stacks and ducts.,1.2 This method is not applicable for testing stacks and ducts less than 3.3 ft (1.0 m) in diameter.,1.3 Data Quality Objectives. Adherence to the requirements of this method will enhance the,quality of the data obtained from air pollutant sampling methods.,2.0 Summary of Method,2.1 A wall effects adjustment factor is determined. It is used to adjust the average stack gas,velocity obtained under Method 2, 2F, or 2G of this appendix to take into account velocity decay,near the stack or duct wall.,2.2 The method contains two possible procedures: a calculational approach which derives an,adjustment factor from velocity measurements and a default procedure which assigns a generic,adjustment factor based on the construction of the stack or duct.,2.2.1 The calculational procedure derives a wall effects adjustment factor from velocity,measurements taken using Method 2, 2F, or 2G at 16 (or more) traverse points specified under,Method 1 of this appendix and a total of eight (or more) wall effects traverse points specified,under this method. The calculational procedure based on velocity measurements is not applicable,for horizontal circular ducts where build-up of particulate matter or other material in the bottom,of the duct is present.,2.2.2 A default wall effects adjustment factor of 0.9900 for brick and mortar stacks and 0.9950,for all other types of stacks and ducts may be used without taking wall effects measurements in a,stack or duct.,2.3 When the calculational procedure is conducted as part of a relative accuracy test audit,(RATA) or other multiple-run test procedure, the wall effects adjustment factor derived from a,single traverse (i.e., single RATA run) may be applied to all runs of the same RATA without,repeating the wall effects measurements. Alternatively, wall effects adjustment factors may be,derived for several traverses and an average wall effects adjustment factor applied to all runs of,the same RATA.,3.0 Definitions.,3.1 Complete wall effects traverse means a traverse in which measurements are taken at drem(see,section 3.3) and at 1-in. intervals in each of the four Method 1 equal-area sectors closest to the,wall, beginning not farther than 4 in. (10.2 cm) from the wall and extending either (1) across the,entire width of the Method 1 equal-area sector or (2) for stacks or ducts where this width exceeds,12 in. (30.5 cm) (i.e., stacks or ducts greater than or equal to 15.6 ft [4.8 m] in diameter), to a,distance of not less than 12 in. (30.5 cm) from the wall. Note: Because this method specifies that,measurements must be taken at whole number multiples of 1 in. from a stack or duct wall, for,clarity numerical quantities in this method are expressed in English units followed by metric,units in parentheses. To enhance readability, hyphenated terms such as “1-in. intervals” or “1-in.,incremented,” are expressed in English units only.,3.2 d lastDepending on context, d lastmeans either (1) the distance from the wall of the last 1-,in. incremented wall effects traverse point or (2) the traverse point located at that distance (see,Figure 2H–2).,3.3 d remDepending on context, d remmeans either (1) the distance from the wall of the,centroid of the area between d lastand the interior edge of the Method 1 equal-area sector closest,to the wall or (2) the traverse point located at that distance (see Figure 2H–2).,3.4 “May,” “Must,” “Shall,” “Should,” and the imperative form of verbs.,3.4.1 “May” is used to indicate that a provision of this method is optional.,3.4.2 “Must,” “Shall,” and the imperative form of verbs (such as “record” or “enter”) are used,to indicate that a provision of this method is mandatory.,3.4.3 “Should” is used to indicate that a provision of this method is not mandatory but is highly,recommended as good practice.,3.5 Method 1 refers to 40 CFR part 60, appendix A, “Method 1—Sample and velocity traverses,for stationary sources.”,3.6 Method 1 exterior equal-area sector and Method 1 equal-area sector closest to the wall,mean any one of the four equal-area sectors that are closest to the wall for a circular stack or duct,laid out in accordance with section 2.3.1 of Method 1 (see Figure 2H–1).,3.7 Method 1 interior equal-area sector means any of the equal-area sectors other than the,Method 1 exterior equal-area sectors (as defined in section 3.6) for a circular stack ……
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