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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Flow rate can be calculated by making the measurements required to define the independent variables found in eq.
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. Calibrations are also used to provide traceability to known reference standards or physical constants, or both. An additional systematic standard uncertainty may need to be assigned to the mean result to account for the possible difference between the determined mean and the true mean.
The best method to minimize the effects of many of these uncertainty sources is to perform overall system calibrations. For this example, the velocity profile is distorted due to the unxertainty of flow disturbances upstream of the measurement location.
Journal of Fluids Engineering, The general form of the expression for determining the uncertainty of a measurement is the rootsum-square of the systematic and random standard uncertainties of the measurement, with this quantity defined as the combined standard uncertainty uX .
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.
In this case, T p Investigation to identify bad readings, overlooked or under. It is interest- w ing uncerainty note that the systematic standard uncertainty in z is less than the smallest estimate of systematic standard uncertainty for any of the flowmeters.
To observe the random error associated with car-to-car variability, the experiment fx would need to be run again using a random uncertaint of different cars within the same model see Fig.
For this program the test procedure requires that the pressure gage be calibrated just prior to conducting the test.
ASME PTC 试验不确定度 Test -电源技术相关资料下载-EEWORLD下载中心
A digital thermometer was used wto measure the average temperature of a circulating a Uncertainty Due to Random Error. Users of a code or standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, is entirely their own responsibility.
In many instances, the quantity measured varies in space, making the point measurement inadequate. Because of the resulting effect of combining the elemental uncertainties in a root-sum-square manner, the larger or dominant ones will control. Furthermore, assume that the higher order terms in the Taylor series expansion for r are negligible compared to the first order terms.
This uhcertainty presents a method for determining nonsymmetric uncertainty intervals in these cases . Applied Regres- sion Analysis. However, this practice asmf the probability of rejecting bad data points. Repeated tests are those run under the same conditions to estimate a parameter or a set of parameters Xi.
Although this application of Pareto diagrams has been used to determine the relative contributions to combined standard uncertainty of systematic and random standard uncertainties, the method can ame applied just as easily to the individual estimates of the elemental errors that contribute to systematic and random standard uncertainties.
In this case, an estimate of the sample standard deviation sX would be made using engineering judgment and the best available information. A quick and easy way to numerically calculate the sensitivity coefficients of the independent m parameters is to develop a table using a spread- sheet program on the personal computer. The large sample uncertainty expression given in eq.
ASME accepts responsibility for only those interpretations of this document issued in accordance with the established ASME procedures and policies, which preclude the issuance of interpretations by individuals. This is done by first using the following relation- wship, which accounts for variable specific heats, P1p measured compressor inlet total pressure P2p measured 91.1 exit total pressure Pr1p the relative pressure determined from ideal gas property tables for air at the measured compressor inlet total temperature Pr2p the relative pressure at the exit corresponding to isentropic compression Next, the value 19.
h2s is evaluated from air property tables at a state corresponding to the value of Pr2 determined above. Ttest second is a table that summarizes the uncertainty information at the result level. The magnitude has been reduced by having averaged multiple calibrations. The uncer- water bath that is being used in an experiment. Examples of error sources include Measurement uncertainty can also exist from uncertaonty calibration corrections, uncontrolled test interactions between a the test instrumentation conditions, measurement methods, environmental and the test media or b between the test article conditions, and data reduction techniques.
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.
Standard statistical hypothesis testing may be used to evaluate the significance of the difference observed. The thermocouples from each multiprobe array were connected in parallel in a manner w which yielded a spatially averaged temperature measurement. 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.
Then the dis- o tribution of Y will be approximately normal with N expectation. At higher Reynolds numbers, the profile approaches uniformity and any measurement will yield a reasonable estimate of the average velocity. The value for h2s, however, must be evaluated at a w state corresponding to the measured exit pressure but assuming isentropic compression has occurred.
The value used is called the assigned value. In- o stead, more basic parameters, such as temperature and pressure, are either measured or assigned and.
ASME PTC 19.1-2005 试验不确定度 Test Uncertainty.pdf
A t value of 1. The same short-term and long-term effects must be applied for other variables affecting gas mileage w temperature, altitude, humidity, road conditions, ww driver variations, etc.
For example, when comparing results among various laboratories, it may be appropriate to classify an error as random rather than as systematic even though that error may tedt been constant for the duration of any single test.
Now suppose an experimental result, r, is wdefined as a function of certain measured variables, C The effects of a time interval may also be important when considering the stability and control of a test process.