Teach you how to properly calibrate electronic balance scales
Shanghai Jiujin Weighing Apparatus Factory ---
Teach you how to properly calibrate electronic balance scales
Electronic balance scale excellent performance, accurate weighing - Explorer quasi-micro balance zui a large range of 220g, readability of 0.01mg. zui with newly developed high-speed integrated sensor with a built-in 2 groups and the correction weights AutoCal automatic calibration system, to facilitate linearization professional testing and calibration, the cumulative error is reduced, ensuring accurate weighing; Explorer quasi Microprotein We can provide a variety of balance models ranging from 52g to 220g and readability from 0.1mg to 0.01mg. The combination of high-speed integrated sensors and 13 weighing applications combines comprehensive product performance and application.
  
1. How to classify electronic scales and determine their tolerances
At present, there are many manufacturers producing electronic balances. Some manufacturers fail to specify their performance indicators in the product description in detail, or the labels are not standardized, not uniform, some give grades, and some do not. For example, some electronic balances clarify the actual scale index value d, but do not indicate its verification scale value e, which for the user will mistakenly think that d = e, that the electronic balance can distinguish the small value of zui is it The exact value that can be weighed by itself. For the metrological verification personnel, it is very important to determine the calibration scale value e of the electronic balance, because e is the basis for assessing the accuracy level and the large allowable error of the Zui: in the measurement verification, if the parameters of the parameters are The large indication error is not more than 1d, we determine e = d; if the error value of each parameter index zui is less than 10d, we determine e = l0d. Sometimes it depends on the specific situation, such as when d: 0.2mg, e = 5d; d: 0.5mg, e = 2d. In summary, the division of the scale value of the verification scale should be in the following form: l × l0k or 2 × 10k or 5 × 10k  k is a positive integer, a negative integer or zero). We classify the situation except e=d as ≠d, where e=l0dzui is common. The following is a summary of the classification of the electronic balance and its large allowable error based on the verification index value e.
Second, the main content of electronic balance measurement performance verification
In daily cycle verification and routine product quality inspection, it is generally necessary to check the following items: balance sensitivity, discriminative force verification; zui large allowable error (weighing linear error) of each load point of the balance; balance repeatability Verification; the balance of the balance or the verification of the four-corner error; the verification of the balance function.
Third, the balance level and Zui large allowable error
The author thinks that it is used as a standard electronic balance for the transmission of magnitude. Judging its error standard should be judged according to the error standard of “verificationâ€.
1. Verification of sensitivity and discriminating power of electronic balance
The sensitivity of an electronic balance generally refers to the indexing sensitivity, which should be exactly equal to the verification scale value of the corresponding load of the balance. For electronic balances with digital indications and automatic or semi-automatic calibration devices, the sensitivity of the balance can be exempted. When the electronic balance verifies the index value e≥1mg, the discriminating power can be determined as follows: on an electronic balance that is in equilibrium at no load or loading, an equivalent of 1.4 times the numerical scale graduation value is added. When the load (1.4d) is gently applied to the balance pan (or removed from it), the original balance value must be changed.
2. Verification of the large allowable error of Zui at each load point of the electronic balance
First, warm up and then calibrate the electronic balance according to the operating procedures of the manual (this step is critical). After the calibration is completed, the zero position is displayed. Starting from the zero load, it gradually loads upwards until it is added to the balance of the zui, and then gradually unloads until it is zero. During the verification process, the verification operator selects the load point according to the specific circumstances of the balance (this is not explicitly given in the verification procedure), but the following load points should be verified: (1) No load. (2) Full load. (3) Zui small weighing Min (I level balance: 100e; level II balance: 50e; level III balance: 20e; level IV balance: 20e). (4) Those loads corresponding to the "inflection point" of the balance error value, such as Class I balance: 50000e, 200000e; Class II balance: 5000e, 20000e; Level III balance: 500e, 2000e, etc. The error calculation is divided into two cases:
(1) When e≠d, the formula for calculating the indication error shall be E=I-L (E: the indication error of the balance, I: the indication value of the balance, and the balance of the balance on the L balance);
(2) When e=d, the calculation formula of the indication error should be E=I-L+(1î“”2)d-â–³L (d: the actual scale division value of the electronic balance, AL: on the balance scale The value added to the load).
In either case, the error at each of the resulting load points is required to be less than the allowable error specified in the procedure.
3. Electronic balance repeatability test
The electronic balance repeatability test should be carried out under no-load and loading conditions. There are two kinds of loads to be loaded: one is full load and the other is half load. It is required to read and record the equilibrium positions of the loading and the unloading in the verification, and note that the load should be returned to zero every time the load is added. The difference between the results of multiple measurements of the same load is required to not exceed the value of the large allowable error of the balance at the load.
4. Electronic balance eccentricity verification (four-angle error verification)
For a standard balance, the test load is equal to the large amount of zui of the balance, and its four-corner error is equal to the large value of zui and the small value of zui. For working balances, the test load is equal to one-third of the large load of the balance, and the four-corner error is equal to the larger of the difference between the indication of each point and the indication of the center point.
5. Checking the balance function of the electronic balance
For newly purchased electronic balances, check the balance function. Generally, two load points are selected, namely: (1î“”3) Max, (2î“”3) Max. The difference between the two results obtained under the same load shall not exceed the value of the large allowable error of zui at the time of the load.
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