Test And Study On Measurement Uncertainty And Reliability Of Pump

Water pumps, one kind of important electromechanical product, are widely used in various fields, from industry, agriculture to household applications. Although with different run-condition and standards, all of the production has some common demands, such as quality and reliability. The study on their quality evaluation, i.e. the study on their sampling plan, property test and its measurement uncertainty, reliability theories and reliability test, are very important to the estimate of their quality and reliability.The two kinds of mistakes existing in sampling inspection are analyzed and the characteristics of two kinds of sampling inspection are discussed in the dissertation. Under the condition of the inevitable mistakes, the viewpoint that the risk faced by manufacture side should be controlled chiefly is come up with. To solve the problems existing in current sampling inspection when non-conforming items are used as quality index, Sampling procedures and tables for pump products are designed on the small probability principle of statistics.Based on the theory of error, the article analyses the present situation of measuring technology of pump. Point out that high precision measurement can be realized by the methods and channels, such as using high precision meters, and adjusting them in working position, applying 16 bit A/D transformer, introducing computer to process data, etc. The measurement precision of pump efficiency can be limited to the range from 0.3% to 0.5%. In view of the measurement accuracy of turbine flowmeter relevant to the flow state of fluid that is related to fluid viscosity and the downstream length of flowmeter,experiment on the relationship between the measurement accuracy of flowmeter and the flow state fluid is performed. The relationship between the flow rate measurement accuracy and fluid viscosity as well as the downstream length of flowmeter is identified through the experiment. In this paper, the processing methods for pump property data are discussed. A new processing method is put forward that orthogonal polynomial is used to fit the characteristic curves of pump with random data to avoid the ill-conditioned system of equations that probably appears in ordinary polynomial fitting. The Forsythe Recurrence Method is adopted to generate the orthogonal polynomial, and the degree of the polynomial is determined by significance test rather than by experience.The sources of measurement uncertainty in the common pump property tests are discussed and evaluation methods of measurement uncertainty for different indexes are detailedly analyzed in the paper.An simplified measurement uncertainty gray assessment method is given after analyzing the uncertainty assessment mentods. Meanwhile, the evaluation procedure is given.Deficiencies are found in the applicability and error analysis of current measurement system analysis method on the metrological property analysis. The function of metrological transformation—the most important characteristic of measurement system is not considered in current reliability analysis,which makes metrological property analysis and reliability analysis of the measurement system totally separated from each other.Based on it,a new idea of applying measurement uncertainty to measurement system analysis is presented to connect metrological roperty analysis with reliability analysis.Research works is done on the theory and method of equality design for measurement system based on the analysis of invalidation theory of measurement system.Because that water pump is one kind of long-life, repairable, complex item, its reliability test plans are different from those of others. In this paper, the distribution of the pumps'failure rate is verified, and the three failure periods of submerged motorpump are found through reliability tests, and the reliability indexes and failures'criterions are put forward, and the reliability test methods and their test programs are introduced.