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; verification of the balance or quadrilateral error of the balance; verification of the balance function of the balance.
1, an electronic balance sensitivity, discrimination of the assay
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≥ 1 mg, the discriminating power can be determined as follows: on an electronic balance that is in equilibrium at no load or loading, an applied load equivalent to 1.4 times the numerical scale graduation value is applied. (1.4 d ) , when it is gently placed on the scale ( or removed from it ) , the original balance value must be changed.
2 , the 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 very important ) . After the calibration is completed, the zero position is displayed. Starting from zero load, it gradually loads upwards monotonically 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 conditions of the balance ( this is not explicitly given in the verification procedure ) , but the following load points shall be verified:
(1) No load.
(2) Full load.
(3) zui small weighing Min ( Class I balance: 100 e; Class II balance: 50 e; Level III balance: 20 e; Level IV balance: 20 e ) .
(4) Those loads corresponding to the “inflection point†of the balance error value, such as Class I balance: 50000 e, 20000 e; Class II balance: 5000 e, 2000 e; Level III balance: 500 e, 2000 e, 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: balance indication error, I: balance indication value, L balance is called load on the disc ) ;
(2) When e=d, the calculation formula of the indication error should be E=I-L+ (1 2) d-â–³L ( d: the actual scale division value of the electronic balance, AL: the indication value on the scale of the balance Round up the added 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 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 once for each additional load. It is required that the difference between the results of multiple measurements of the same load shall not exceed the absolute value of the large allowable error of the zui at the time of 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 , the inspection of the balance function of the electronic balance
For newly purchased electronic balances, check the balance function. Generally, two load points are selected, namely: (1 3 ) Max, ( 2 3 ) Max. The difference between the two results obtained under the same load shall not exceed the absolute value of the large allowable error of zui at the time of the load.
Shenzhen Sunson Tech Co., Ltd , https://www.sunsonkiosk.com