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.
|Published (Last):||24 May 2015|
|PDF File Size:||20.72 Mb|
|ePub File Size:||2.29 Mb|
|Price:||Free* [*Free Regsitration Required]|
If any of the elemental systematic uncertainties are nonsymmetrical, then the method given in subsection should be used to determine the systematic standard uncertainty of the measurement. For random standard uncertainty in the Xj or X values, the general approach in  should be used.
This example uncetrainty differences in the analysis for both the uncalibrated and uncertainyy cases. Attempting to identify all elemental sources of systematic error requires a thorough understanding of the test objectives and test process.
The systematic standard uncertainty from their curve fits is not, bm4 p 4. Requirements of military and commercial contracts have led 191 the establishment of extensive hierarchies of standards laboratories. From a sample of more than 30 readings using the thermocouple, the user finds that X p An eloquent treatment of these terms is given by Gerald Hahn  in his paper, which is.
If the published information is presented as a multiple of a standard deviation, then the elemental systematic standard uncertainty is estimated as the multiple of the standard deviation divided by the multiplier.
The posttest analysis see teet validates the pretest fx analysis, provides data for validity checks, and provides a statistical basis for comparing test results.
Circumferential variations may also be present. Fundamentals of Temperature, m Pressure, and Flow Measurements.
ASME PTC – Test Uncertainty
When a statistic is calculated from the sample, the degrees of freedom associated with the statistic is reduced by one for w every estimated parameter used in calculating the statistic. Thus, an engineer who is concerned with the performance of a mass-produced item, such as a transistor or a lamp, would generally be interested in a tolerance interval to enclose a high proportion of the sampled population.
The use of back-to-back tests is an excellent method to reduce the systematic standard uncertainty when comparing two or more designs. The latter describes the limits harmony with international guidelines and standards. In addition, the systematic uncertainties of the throat and pipe diameters are eliminated set to zero in Table In addition, the objective of the test may affect the categorization as discussed in para.
This case would occur if the same instruments are used to measure Xnew as were used to measure Xj. For small samples, bad data points are hard to identify.
A forward differencing scheme is used with a value of Qx equal w to 0. Special tests had uncertainry 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. This of the is combined with average measure- ment.
ASME PTC 19.1-2005 试验不确定度 Test Uncertainty.pdf
While this Supplement is in harmony with the ISO GUM, this Supplement emphasizes the effects of errors rather uncertxinty the basis of the information utilized in the estimation of their limits. Once all elemental sources of systematic error are identified, elemental system- atic standard uncertainties for each source are evaluated.
Type B uncertainties do not have data to calculate a standard deviation and must be estimated by other means. One measurement will not give the true average value directly. This can be essential to establishing agreement on any deviations from applicable test code requirements and can help reduce the risk that disagreements regarding the testing method will surface after conducting the test.
The random standard uncertainty of the sample mean is related to the sample standard deviation as follows: It is assumed that these estimates are based on large degrees of freedom and that the population of possible error values associated with each elemental systematic error source is normally distributed. Therefore, it is important to select the power setting such that measurements are at least at the midscale of the power supply range. Because of the resulting effect of combining the elemental uncertainties in a root-sum-square manner, the uncrtainty or dominant ones will control.
Also a tolerance interval to include at least 90 percent of the population twst a probability of 0. In this case, the user of the thermocouple believes that the true gas temperature falls between unvertainty average measured with the thermocouple, X p The term sc in eq.
With high-speed computing capabilities, Monte Carlo methods have become popular for 119.1 the test result uncertainty using the test input variable values and their associated uncertainties. X and sX are statistics. Historic data are invaluable for calculated.
Typically, w these error distributions are assumed Gaussian normally distributed or rectangular uniformly distributed. Program 2 correlated systematic uncertainties: X curve is a mean value for the data set, the curve should be a good representation of the data if the simple linear fit is appropriate. This paragraph presents a method for determining nonsymmetric uncertainty intervals in these cases .
For this program the test procedure requires that the pressure gage be calibrated just prior to conducting the test. The covariance terms in eq. The uncertainty in power required to otc a constant heat flux will depend on the type of material being tested. This is in contrast to the situation at high Reynolds numbers, where the flow is turbulent. The effect of the propa- gation can be approximated by the Taylor series method see Nonmandatory Appendix C.
Sometimes, z multiple calibrations are performed but the results are averaged into a single set of calibration constants for use in processing all data samples e. Ni will be 1 for a single data point or w assigned value of a parameter. All of the bYj uncertainties are assumed etst be completely correlated with each other, and all of the bXj uncertainties are assumed to be com- w pletely correlated with each other.
An example of an averaged output is an averaging pressure probe often used to measure average velocity at a cross section of pipe. The test design should be tailored to the specific situation. From the definition of mass flow rate, the ssme can be replaced with the volumetric flowrate Q through the expression Q p AV, where A is the cross-sectional area of the tube.
Uncertainties in Absolute Terms Example The suspected outliers should then be subjected to an engineering analysis. Note that these values were obtained of a test result, uR. Dieck, Ron Dieck Associates, Inc.