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    Home > How to reduce the weighing error of electronic balance

    How to reduce the weighing error of electronic balance

    • Last Update: 2012-04-28
    • Source: Internet
    • Author: User
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    In the verification (test) of electronic balance, we found that the measurement error of the balance is large The reason is that quite a number of instruments have not been calibrated in a long time interval, and it is considered that the balance can be directly weighed if it shows zero position We should master the correct calculation method, so as to record the experimental data There are two cases: * when e ≠ D, the calculation formula of indication error shall be e = I-L (E: indication error of balance, I: indication value of balance, load on L balance scale); the second one is when e = D, the calculation formula of indication error shall be e = I-L (1? 2) d - △ L (D: actual scale division value of electronic balance Al: the load added on the electronic balance scale for the rounding of the indication) In either case, the error of each load point is required to be less than the allowable error specified in the regulations Electronic balance repeatability verification: the electronic balance repeatability verification shall be carried out under no-load and loading conditions There are two kinds of loading: one is full load, the other is half load It is required to read and record the balance position of loading and no-load respectively in the verification, and pay attention to return to zero once for each loading It is required that the difference between multiple measurement results of the same load shall not exceed the value of Zui large allowable error of the balance at that load Bias load verification of electronic balance (quadrangular error verification): for standard balance, the test load is equal to the Zui large scale of the balance, and the quadrangular error is equal to the Zui large scale minus the Zui small scale For the working balance, the test load is equal to one-third of the large load of the balance Zui, and the quadrangular error is equal to the larger Zui of the difference between the indication of each point and the indication of the center point Check the balance function of electronic balance: for the newly purchased balance, check its balance function Generally, select two load points, namely: (1? 3) max, (2? 3) max The difference between the two results under the same load shall not exceed the value of Zui large allowable error under the load What should be paid attention to in the verification of electronic balance: how to choose standard weight? The selected standard weight can be grade weight or equal weight, but its error (mass tolerance for grade weight and verification accuracy for equal weight) shall not be greater than 1? 3 of Zui big allowable error of the tested balance under this load Secondly, the range of standard weight can cover the Zui range of electronic balance (it should be pointed out that the display of zero point when the electronic balance is turned on does not mean that the data accuracy of balance weighing meets the test standard, but only that the balance zero position stability is qualified Because it is necessary to consider the conformity of other technical indexes to measure whether a balance is qualified or not Due to the long storage time, position movement, environmental change or to obtain measurement, the balance should be calibrated before use There are two calibration methods: internal calibration and external calibration Most of the electronic days produced by manufacturers have calibration devices on average If you do not read the manual carefully before use, it is easy to ignore the "calibration" operation, resulting in large weighing error The exemption problems of electronic balance: (1) when D ≤ 1mg, the balance can be exempted from the discrimination; (2) when e ≠ D, the balance can be exempted from the discrimination; (3) for electronic balance with digital indication and automatic or semi-automatic calibration device, the sensitivity of the balance can be exempted The verification certificate shall be standardized: after the verification of electronic balance, the verification certificate or verification result notice shall be issued according to the actual verification result The author thinks that it is a very serious and legal responsibility to issue the certificate Firstly, the format should be standardized, and the content should cover all the information of "4.1" in gjb2725-96 The calibration (verification) or test results should be accurate and objective.
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