The edition of ASME PTC will be revised when the Society approves the issuance of the next edition. There will be no Addenda issued to ASME PTC. ASME PTC Test Uncertainty [ASME] on *FREE* shipping on qualifying offers. The scope of this Code is to specify procedures for . (Revision of ASME PTC ). Test Uncertainty. Performance Test Codes. AN AMERICAN NATIONAL STANDARD. Two Park Avenue • New York, NY.
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Other confidence levels may be used, if required. The second test is then run in the same facility with the design change and hopefully with instruments, setups, and calibrations identical to those used in the first test.
The final data reduction equation becomes: Special tests had previously been conducted to determine if taking additional traverse points 20 along each of the 4 radii would result in a significant change in the measurement of the overall average velocity in the pipe, as computed using eq. If there is not valid engineering justifica- tion to remove the suspected outliers and if removal of the outliers will significantly change the test result and its associated uncertainty, the validity of the test should be questioned.
The use of tolerance o in this instance is different from that of PTC 1. For example, the velocity at the center of the pipe is twice the average velocity.
This of the is combined with average measure- ment. Experimental Methods for Engineers, 6th edition. The uncertainty for the comparative analysis can be computed using the method from subsection The removal of these outliers should be documented within the. Once the random variation of the test variables is understood, then this information can be used to streamline the test procedure by reducing the number of measurements taken in the later phases of the test.
The former w describes an error source whose effect is systematic or constant for the duration of a test. This Supplement utilizes two major classifications for errors and uncertainties. When the uncertainty intervals com- pletely overlap, as in Case 2, one can uncetrainty reasonably confident that there has been a trst accounting of all major uncertainty components.
Whereas these influences might normally be considered systematic errors during repeated tests, the duplicated kncertainty can randomize these systematic errors providing error estimates from the statistical variations in the combined data pool .
Type A uncertainties are the calculated standard deviations obtained from tedt sets. The random standard uncertainty for the curve- fx fit will be determined using standard least squares analysis [9, 14, 16], where the assumption is made that there is no random standard uncertainty in the X values and the random standard uncertainty z in the Y values is constant over the range of the curve-fit.
Therefore, it is important to select the power setting such that measurements are at least at the midscale of the power supply range.
The example looks at each case in both absolute and relative i.
In these w cases, some of the systematic errors are said to be correlated and these nonindependent errors must be considered in the determination of the fx systematic standard uncertainty of the result . The American Society of Mechanical Engineers; In addition, careful attention was paid to discriminating be.
For 191. standard uncertainty in the Xj or X values, the general approach in  should be used.
This avoids the need to develop weighting factors fx for each sample area. The table has been developed in accordance with the step-bystep procedure of Section 9. In successive measurements of the parameter, the values of these elemental random error sources change resulting in the random scatter evident in the successive measurements. Type B uncertainties are those that are estimated w or approximated rather than being calculated from data. For example, if experience indicates that timeto-time and test apparatus-to-apparatus variations are significant, a test design that averages multiple test ltc on one rig or for only one day may produce optimistic random uncertainty estimates compared to testing several rigs, each monitored several times over a period of several days.
The effect of the oily air can influ- wence the quoted rating of the unit.
Variability in independent test results obtained under different test conditions, varying experimental setups, or configuration changes allow for additional between-test random errors. T1p measured compressor inlet total temper- The adiabatic efficiency of the air compressor ature was initially calculated using the following simpli- T2p measured compressor exit total temper- fied engineering relationship: The fuel consumption of an automotive engine changes 191 altitude and speed.
Steele, Vice Chair G.
The results are plotted in Fig. Usually these estimates are made us- o ing engineering judgment and are therefore ISO Type B estimates.
Suppose a thermocouple is being used to measure the temperature of a gas stream, but the user of the thermocouple believes there may be a tendency for the thermocouple to provide a temperature reading that is lower than the actual gas temperature due to a radiative heat transfer mechanism.
The time interval must be clearly specified to classify an error, and it may not always be the same interval unceertainty the test duration. The value of 2 in the equation is based on the assumption that the uncertaintyy of possible systematic errors is normally distributed.
When a data set of interest from the test m meter involves multiple calibrations, the calibration process random standard uncertainty will cause scatter in the individual test meter data samples and thus should remain classified as calibration o random standard uncertainty in the uncertainty analysis.
Journal of Thermophysics and Heat Transfer, 7: The end result of an uncertainty analysis is a numerical estimate of the test uncertainty with an appropriate confidence level. The uncertainty is calculated using the method in subsections through Rabensteine, Environmental Systems Corp.