September 30, 2020

PTC XX. TEST UNCERTAINTY. Proposed Revision of PTC “ Test Uncertainty”. Par Adjustment in response to comment. TENTATIVE. The edition of ASME PTC will be revised when the Society .. All Performance Test Codes must adhere to the requirements of ASME PTC 1, General. Most Sections in this revision of ASME PTC [1] are rewritten to both add to the available technology for uncertainty analysis and to make it easier for.

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Investigation to identify bad readings, overlooked or under.

The values for h1 and h2 are evaluated at the measured inlet and exit conditions. Consider an example where the result R is determined from three parameters X1, X2, X3 that have correlated systematic errors. Whereas these influences might normally be considered systematic errors during repeated tests, the duplicated tests can randomize these systematic errors providing error estimates from the statistical variations in the combined data pool [6]. It is assumed that these estimates are based on.

This code or standard was developed under procedures accredited 119.1 meeting the criteria for American National Standards.

Consequently, one can be 95 percent confident that the interval same Let s1 and b1 denote, respectively, the random and systematic standard uncertainties associated with X1.

To estimate the expected conductivity uncertainty, we must know or estimate the measurement errors associated with the power, temperature, and geometry.

For both measurements and both uncer- measurements and the estimate of the uncertainty intervals.

ASME PTC 试验不确定度 Test -电源技术相关资料下载-EEWORLD下载中心

This requires a calculation of the sensitivity factors, either by differentiation or by numerical analysis. All of the bYj uncertainties are assumed to be completely correlated with each other, and all of the bXj uncertainties are assumed to be com- w pletely correlated with each other.

Prior to using the weighting techniques described in this section, the means and their associated uncertainty intervals from each of the independent methods should. The end result of an uncertainty analysis is a numerical estimate of the test uncertainty with an appropriate confidence level.


Rabensteine, Environmental Systems Corp. The pretest analysis see subsection is used. For example, calibration corrections, which are assumed fixed over the life of the calibration interval, can be considered variable if the process consists of a time interval encompassing several different calibrations. The covariance terms in eq. The uncertainty estimate for discharge coefficient comes from calibration data, which has been fossilized, and is listed as a systematic uncertainty in Table For random standard uncertainty in the Xj or X values, the general approach in [9] should be used.

Fundamentals of Temperature, m Pressure, and Flow Measurements. Dieck, Ron Dieck Associates, Inc. Several simplifying assumptions are made for this example: The Amer- [28] Steele, W. An example could be the measurement of airflow in an air condi- z tioning duct. A pretest analysis is required to determine if an uncalibrated venturi could be used to satisfy the test objective, and, if not, whether calibration of the venturi would achieve the desired objective.

Elemental systematic errors may arise from imperfect calibration corrections, measurement methods, data reduction techniques, etc.

Uncertainties in these measurements or assigned values of the parameters are propagated to the result through the functional relationship between the w result and the parameters.

Its use for such comparisons is than the other two intervals, but that the relative especially appropriate when it is reasonable to sizes of the tolerance and prediction intervals de- assume that each of the competing processes has pend upon the proportion of the population to the same statistical variability as measured by the be contained in the prediction interval.

Design and 191. of Industrial Experiments. This of the is combined with average measure- ment. Type B uncertainties are also given as standard deviation level estimates.

In addition, careful attention was paid to discriminating be.

As noted earlier, the uncertainty expression in eq. The effect of the oily air can influ- wence the quoted rating of the unit. A simple illustration of the impact of spatial variation is the measurement of average velocity in fully developed flow of an incompressible fluid in a pipe. The new nomenclature is expected to render PTC For this example, the velocity profile is distorted due to the presence of flow disturbances upstream of the measurement location.


As ltc in para. Uncertainties in Relative Terms for the Uncalibrated Case. At higher Reynolds numbers, the profile approaches uniformity and any pyc will yield a reasonable estimate of the average velocity. The sources of uncertainty which are considered systematic in this simplified example are the uncertainty of the calibration of the instruments used to measure w and record velocity at each traverse point and the uncertainty of the integrated-average velocity due wto spatial variation.

Since the gage is randomly selected and several gage brands are used, much of the systematic error is not correlated. Likewise, let s2 and b2 denote, respectively, the random and systematic standard uncertainties associated with X2. In order to obtain the overall uncertainty in the m result, UR, at a specified confidence level, the ISO Guide recommends that the combined standard uncertainty of the result be asms by a cover- o age factor.

Suppose variable X presents the special case where f X p X, i. These values are also expressed tainty by the nominal value of the parameter.

ASME PTC 19.1-2005 试验不确定度 Test Uncertainty.pdf

For a pump b The pump is operating better than the mini- test, the applied flow might be slightly different mum pgc design condition. This Supplement bXkp an the estimate of the standard deviation kth elemental error pct of Note that in eq. This is accomplished by adding an addi- tional random term. Such an interval is. In certain situations, knowledge of the physics of the measurement system will lead the analyst to believe that the limits of w error are nonsymmetric likely to be larger in either the positive or negative direction.

The resulting averages are qsme in Table A pareto chart see subsection A-4 of. The random standard uncertainty of the sample mean is related to the sample standard deviation as follows: