ASME PTC 19.1 2013
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ASME PTC 19.1 Test Uncertainty
Published By | Publication Date | Number of Pages |
ASME | 2013 | 116 |
This Standard specifies procedures for evaluation of uncertainties in test measurements, parameters and methods, and for propagation of those uncertainties into the uncertainty of a test result. Depending on the application, uncertainty sources may be classified either by the presumed effect (systematic or random) on the measurement or test result, or by the process in which they may be quantified (Type A or Type B). The end result of an uncertainty analysis is a numerical estimate of the test uncertainty with an appropriate confidence level
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PDF Pages | PDF Title |
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5 | CONTENTS |
8 | NOTICE |
9 | FOREWORD |
10 | COMMITTEE ROSTER |
11 | CORRESPONDENCE WITH THE PTC COMMITTEE |
13 | Section 1 Introduction 1-1 GENERAL 1-2 UNCERTAINTY CLASSIFICATIONS 1-3 ADVANTAGES OF USING THIS CODE 1-4 APPLICATIONS |
14 | 1-5 DISCLAIMER |
15 | Section 2 Object and Scope 2-1 OBJECT 2-2 SCOPE |
16 | Section 3 Nomenclature and Glossary 3-1 NOMENCLATURE 3-2 GLOSSARY |
18 | Section 4 Fundamental Concepts 4-1 ASSUMPTIONS 4-2 MEASUREMENT ERROR 4-2.1 Random Error 4-2.2 Systematic Error 4-3 MEASUREMENT UNCERTAINTY 4-3.1 Random Standard Uncertainty |
19 | Figures Fig. 4-2-1 Illustration of Measurement Errors Fig. 4-2-2 Measurement Error Components |
20 | 4-3.2 Systematic Standard Uncertainty Fig. 4-3.1-1 Population Distribution |
21 | 4-3.2.1 Identifying Elemental Sources of Systematic Error. 4-3.2.2 Evaluating Elemental Systematic Standard Uncertainties. 4-3.2.2.1 Published Information. 4-3.2.2.2 Special Data |
22 | 4-3.2.2.3 Engineering Judgment. 4-3.2.3 Combining Elemental Systematic Standard Uncertainties. |
23 | 4-3.3 Combined Standard Uncertainty and Expanded Uncertainty 4-4 PRETEST AND POST-TEST UNCERTAINTY ANALYSES 4-4.1 Pretest Uncertainty Analysis 4-4.2 Post-Test Uncertainty Analysis |
24 | Fig. 4-3.3-1 Uncertainty Interval |
25 | Section 5 Defining the Measurement Process 5-1 OVERVIEW 5-2 SELECTION OF THE APPROPRIATE “TRUE VALUE” 5-3 IDENTIFICATION OF ERROR SOURCES 5-3.1 Calibration Uncertainty 5-3.2 Uncertainty Due to Test Article and/or Instrumentation Installation |
26 | 5-3.3 Data Acquisition Uncertainty 5-3.4 Data Reduction Uncertainty 5-3.5 Uncertainty Due to Methods and Other Effects 5-4 CATEGORIZATION OF UNCERTAINTIES Fig. 5-3.1-1 Generic Measurement Calibration Hierarchy |
27 | 5-4.1 Alternate Categorization Approach 5-4.2 Time Interval Effects 5-4.3 Test Objective 5-5 COMPARATIVE TESTING |
28 | Fig. 5-4.3-1 “Within” and “Between” Sources of Data Scatter |
29 | Section 6 Uncertainty of a Measurement 6-1 RANDOM STANDARD UNCERTAINTY OF THE MEAN 6-1.1 General Case 6-1.2 Using Previous Values of sX |
30 | 6-1.3 Using Elemental Random Error Sources 6-1.4 Using Estimates of Sample Standard Deviation 6-2 SYSTEMATIC STANDARD UNCERTAINTY OF A MEASUREMENT 6-3 CLASSIFICATION OF UNCERTAINTY SOURCES |
31 | 6-4 COMBINED STANDARD AND EXPANDED UNCERTAINTY OF A MEASUREMENT |
32 | Tables Table 6-4.1-1 Circulating Water-Bath Temperature Measurements (Example 6-4.1) Table 6-4.1-2 Systematic Standard Uncertainty of Average Circulating Water-Bath Temperature Measurement (Example 6-4.1) |
33 | Section 7 Uncertainty of a Result 7-1 PROPAGATION OF MEASUREMENT UNCERTAINTIES INTO A RESULT 7-1.1 Single and Repeated Tests 7-2 SENSITIVITY 7-2.1 Analytically |
34 | 7-2.2 Numerically 7-3 RANDOM STANDARD UNCERTAINTY OF A RESULT 7-3.1 Single Test 7-3.2 Repeated Tests 7-3.3 Multiple Tests: Combined Tests 7-4 SYSTEMATIC STANDARD UNCERTAINTY OF A RESULT |
35 | 7-5 COMBINED STANDARD UNCERTAINTY AND EXPANDED UNCERTAINTY OF A RESULT |
36 | Section 8 Additional Uncertainty Considerations 8-1 CORRELATED ERRORS 8-1.1 Correlated Systematic Errors |
37 | Table 8-1 Burst Pressures |
39 | 8-1.2 Correlated Random Errors |
40 | 8-2 NONSYMMETRIC SYSTEMATIC UNCERTAINTY 8-2.1 Nonsymmetric Systematic Uncertainty Interval for a True Value |
41 | Fig. 8-2.1-1 Gaussian Distribution for Nonsymmetric Systematic Errors Fig. 8-2.1-2 Rectangular Distribution for Nonsymmetric Systematic Errors Fig. 8-2.1-3 Triangular Distribution for Nonsymmetric Systematic Errors Table 8-2.1-1 Expressions for q for the Gaussian, Rectangular, and Triangular Distributions in Figs. 8-2.1-1 Through 8-2.1-3 |
42 | Table 8-2.1-2 Systematic Standard Uncertainties, bXns, for the Gaussian, Rectangular, and Triangular Distributions in Figs. 8-2.1-1 Through 8-2.1-3 |
43 | 8-2.2 Nonsymmetric Systematic Uncertainty Interval for a Derived Result Fig. 8-2.1-4 Triangular Distribution of Temperatures |
44 | 8-3 FOSSILIZATION OF CALIBRATIONS |
45 | 8-4 SPATIAL VARIATIONS 14 |
46 | 8-5 ANALYSIS OF REDUNDANT MEANS Fig. 8-5-1 Three Cases of Redundant Means |
47 | 8-6 REGRESSION UNCERTAINTY 8-6.1 Linear Regression Analysis 8-6.2 Least-Squares 8-6.3 Random Standard Uncertainty for Y Determined From Regression Equation 8-6.4 Systematic Standard Uncertainty for Y Determined From Regression Equation |
48 | 8-6.4.1 Systematic Standard Uncertainty in Yj Data. 8-6.4.2 Systematic Standard Uncertainty in Xj Data With No Systematic Standard Uncertainty in Xnew. 8-6.4.3 Systematic Standard Uncertainty in Xj Data With Correlated Systematic Standard Uncertainty in Xnew. 8-6.4.4 Systematic Standard Uncertainty in Xj Data With Uncorrelated Systematic Standard Uncertainty in Xnew. 8-6.4.5 Systematic Standard Uncertainty for Y. |
49 | 8-6.5 Uncertainty for Y From Regression Equation 8-7 SIMPLIFIED UNCERTAINTY ANALYSIS FOR CALIBRATIONS 8-7.1 Assumptions Applicable to Both Example Cases 8-7.2 In-Spec Calibration Uncertainty 8-7.2.1 Additional Assumptions 8-7.2.2 In-Spec Uncertainty Calculation. Table 8-6.4.5-1 Systematic Standard Uncertainty Components for Yˆ Determined From Regression Equation |
50 | 8-7.3 Calibration Constant or Curve Uncertainty Calculation 8-7.3.1 Additional Assumptions. 8-7.3.2 8-7.3.3 8-7.3.3.1 8-7.3.3.2 8-7.3.3.3 8-7.3.4 8-7.3.4.1 8-7.3.4.2 8-7.3.5 |
51 | 8-7.4 Reporting Calibration Measurement Uncertainty |
52 | Section 9 Step-by-Step Calculation Procedure 9-1 GENERAL CONSIDERATIONS 9-2 CALCULATION PROCEDURE |
53 | Table 9-2-1 Table of Data, Independent Parameters Table 9-2-2 Summary of Data, Calculated Result |
54 | Section 10 Examples EXAMPLES AS ILLUSTRATIONS OF TERMS AND METHODS 10-1 COMBINED CYCLE PERFORMANCE UNCERTAINTY 10-1.1 Purpose 10-1.2 Defined Measurement Process 10-1.2.1 Description of Test Instrumentation. |
55 | Fig. 10-1.1-1 Train Thermal Performance Test |
56 | 10-1.3 Analysis 10-1.3.1 Calculation of Net Electrical Output and Net Heat Rate for Reference Conditions. 10-1.4 Sensitivities |
57 | 10-1.5 Uncertainty of the Measurements 10-1.5.1 Electrical Output. 10-1.5.2 Ambient Inlet Temperature. |
58 | 10-1.5.3 Ambient Pressure. 10-1.5.4 Relative Humidity. 10-1.5.5 Fuel Flow. |
59 | 10-1.5.6 Lower Heating Value. 10-1.5.7 Fuel Analysis. 10-1.6 Uncertainty of Result |
60 | Table 10-1.6-1 Combined Cycle Net Facility Electrical Output Uncertainty Including the Correlated Uncertainties |
61 | Table 10-1.6-2 Combined Cycle Net Facility Heat Rate Uncertainty Including the Correlated Uncertainties |
62 | Table 10-1.6-3 Combined Cycle Net Facility Electrical Output Uncertainty Excluding the Correlated Uncertainties |
63 | Table 10-1.6-4 Combined Cycle Net Facility Heat Rate Uncertainty Excluding the Correlated Uncertainties |
64 | 10-2 TAYLOR SERIES PROPAGATION FOR RANDOM ERRORS THAT ARE NOT INDEPENDENT 10-2.1 Purpose 10-2.2 The Test Data Table 10-2.2-1 Test Pressure Data for an Orifice Measuring Flow in a Pipe |
65 | 10-2.3 Approach A: Assuming No Correlation 10-2.3.1 Approach A Computation. 10-2.4 Approach B: Assuming Correlation Exists 10-2.5 Approach C: Computation of Deltas and Their Standard Deviation |
66 | 10-3 FLOW MEASUREMENT USING PITOT TUBES 10-3.1 Define the Measurement Process Table 10-2.5-1 Individual Delta Pressure Measurements |
67 | 10-3.2 Data Summary 10-3.3 Velocity Results Fig. 10-3.1-1 Four Circumferential and Ten Radial Traverse Locations |
68 | 10-3.4 List Elemental Uncertainty Sources 10-3.5 Calculate Random Standard Uncertainty Table 10-3.2-1 Average Values at Each Traverse Circumferential and Radial Location Table 10-3.3-1 Standard Deviations at Each Traverse Circumferential and Radial Location Table 10-3.3-2 Summarized Average Circumferential Velocities and Grand Average Velocity |
69 | 10-3.6 Propagate Random Standard Uncertainty 10-3.7 Calculate Systematic Standard Uncertainties 10-3.7.1 Calibration. Table 10-3.6-1 Random Standard Uncertainty for Both Average Circumferential Velocities and Grand Average Velocity |
70 | 10-3.7.2 Spatial Variation. Table 10-3.7.1-1 Systematic Standard Uncertainty for Average Circumferential Velocities Table 10-3.7.1-2 Systematic Standard Uncertainty Due to Instrumentation Sources for Grand Average Circumferential Velocities |
71 | 10-3.8 Propagate Systematic Standard Uncertainties 10-3.9 Uncertainty of Result 10-4 POST-TEST UNCERTAINTY ANALYSIS EXAMPLE: HRSG HIGH PRESSURE STEAM FLOW 10-4.1 Purpose |
72 | 10-4.2 Definition of Measurement Process 10-4.3 Analysis 10-4.3.1 Data Reduction Equation. 10-4.3.2 Identification of Parameters. 10-4.3.3 Sensitivities. Table 10-3.9-1 Components of Uncertainty in the Grand Average Pipe Velocity |
73 | Table 10-4.3.2-1 Identification of Parameters |
74 | 10-4.4 Random Standard Uncertainty 10-4.5 Systematic Standard Uncertainty 10-5 HUMIDITY MEASUREMENT 10-5.1 Introduction |
75 | Table 10-4.3.3-1 Calculated Sensitivities of Each Parameter |
76 | Table 10-4.4-1 Random Standard Uncertainty Estimated for Each Parameter |
77 | Table 10-4.5-1 Systematic Standard Uncertainty Estimated for Each Parameter Table 10-4.5-2 Identified Elemental Uncertainty Components and Values That Are Assumed to Be the Same for Each Parameter |
78 | Table 10-4.5-3 Combined Standard Uncertainty and Expanded Uncertainty of the Result |
79 | 10-5.2 Definition of the Measurement Process Fig. 10-5.1-1 Schematic of Moisture Absorption and Removal System |
80 | 10-5.3 Analysis 10-5.3.1 Data Analysis Equation. 10-5.3.2 Parameters. 10-5.3.3 Sensitivities. Table 10-5.2-1 Measured Values and Statistical Properties |
81 | 10-5.4 Estimation of the Systematic and Random Standard Uncertainties |
82 | Fig. 10-5.3.3-1 Example for Estimating Sensitivity From a Chart Table 10-5.4-1 Estimated Values, Standard Uncertainties, and Calculated Sensitivities |
83 | 10-5.5 Estimation of the Combined Standard Uncertainty and the Expanded Uncertainty 10-6 PERIODIC COMPARATIVE TESTING 10-6.1 Problem Definition |
84 | Fig. 10-6.1-1 Installed Arrangement Table 10-5.5-1 Standard Uncertainties, Combined Standard Uncertainty, and Expanded Uncertainty of the Result Table 10-6.1-1 Pump Design Data (Tc = 20°C) Table 10-6.1-2 Summary of Test Results |
85 | Fig. 10-6.1-2 Pump Design Curve With Factory and Field Test Data Shown Fig. 10-6.1-3 Comparison of Test Results With Independent Control Conditions |
86 | 10-6.2 Comparison With Independent Control 10-6.3 Comparative Uncertainties |
88 | Table 10-6.2-1 Uncertainty Propagation for Comparison With Independent Control Table 10-6.2-2 Summary Uncertainties Table 10-6.2-3 Summary of Results for Each Test |
89 | Fig. 10-6.2-1 Comparison of Test Results Using the Initial Field Test as the Control Table 10-6.3-1 Uncertainty Propagation for Comparative Uncertainty Analysis |
90 | Table 10-6.3-2 Correlated Terms for Comparative Uncertainty Analysis |
91 | Section 11 References |
93 | Section 12 Additional References |
95 | Nonmandatory Appendix A Statistical Considerations A-1 UNDERSTANDING STATISTICAL INTERVALS A-1.1 Confidence Interval for the Population Mean A-1.2 Tolerance Interval to Contain a Specific Proportion of the Population |
96 | A-1.3 Prediction Interval to Contain All of a Specified Number of Future Observations A-1.4 How to Select the Right Interval |
97 | A-1.5 Where to Get More Information |
98 | A-1.6 References A-2 WEIGHTING METHOD |
99 | A-3 OUTLIER TREATMENT A-3.1 General A-3.2 Thompson tau Technique Modified1 A-3.3 Example |
102 | A-4 PARETO DIAGRAMS A-4.1 General A-4.2 Example |
105 | Nonmandatory Appendix B Guidelines for Degree of Freedom and Confidence Intervals B-1 GENERAL UNCERTAINTY ANALYSIS MODEL |
106 | B-2 LARGE SAMPLE UNCERTAINTY ANALYSIS APPROXIMATION |
107 | Nonmandatory Appendix C Propagation of Uncertainty Through Taylor Series C-1 INTRODUCTION C-2 DEFINITIONS C-3 PRELIMINARY CONSIDERATIONS |
108 | C-4 PROPAGATION OF UNCERTAINTY/ERROR THROUGH TAYLOR SERIES C-4.1 The First Order Approximation C-4.2 Assessing the Validity of the First Order Approximation |
110 | C-4.3 The Limitation of the Present Approach C-5 PROPAGATION OF SYSTEMATIC AND RANDOM COMPONENTS OF UNCERTAINTY C-6 THE PROBABILITY DENSITY FUNCTION OF A RESULT |
111 | Nonmandatory Appendix D The Central Limit Theorem |
112 | Nonmandatory Appendix E General Regression Uncertainty E-1 INTRODUCTION E-2 LEAST-SQUARES E-3 SYSTEMATIC UNCERTAINTY |
113 | E-4 GENERAL APPROACH TO LINEAR REGRESSION UNCERTAINTY E-5 HIGHER ORDER REGRESSION EQUATIONS E-6 REFERENCE |