Accuracy class is the main characteristic of all measuring instruments, in particular, scales. Determines the boundaries of permissible errors (basic and additional), is indicated in state standards for a certain type of product. Also, this parameter is necessarily present in the technical characteristics of devices with reference output parameters for both electronic and mechanical measuring instruments.
Until 2001, GOST 24104-1988 was used, according to which there were 4 classes of accuracy of scales: 1st, 2nd, 3rd, 4th. They were determined by the error of the product and the LEL.
On July 1, 2001, the new GOST 24104-2001 began to operate, in which the accuracy class was developed according to the international recommendations of OIML, and is 3 classes of accuracy of scales: I-special, II-high and III-medium.
If we compare the GOSTs of 1988 and 2001, the 1st special class includes 1 and 2 classes of GOST 24104-1988, the 2nd high and IIIrd average - the standards of weights of the 3rd and 4th classes GOST 24104-1988.
Scale Accuracy and Uncertainty Parameters
The Largest Weighing Limit (LEL) indicates the upper limit of the weighing limit. This parameter specifies the maximum weight that can be weighed on the scales at one time.
The Smallest Weighing Limit (LWL) defines the lower limit of the weighing limit. Here you define the minimum weight that can be read on the balance in one go.
The scale division value (d) is equal to the difference in weight division between the readings on the scale of the mechanical scale. On electronic devices, this value denotes the mass of the scale readout.
Verification scale mark (e) is a conditional value, expressed as a unit of mass, used in the classification of weighing equipment and standardization of requirements.
The number of verifying divisions of the balance (n) is the LEL / e value.
The price of the verification scale determines the maximum permissible error of the balance. Therefore, in the manufacture of weighing devices, one should strive to achieve the ratio d = e, since the lower the error on the weighing equipment, the higher the accuracy of the balance measurement.
Weighing intervals by accuracy class for balances
The absolute error of the balance by the absolute value of the measurement range should fluctuate within the permissible error, according to GOST 24104-2001.
Other factors that affect the accuracy of the balance
In fact, there are a large number of factors that affect the accuracy of the weighing equipment and, accordingly, the measurement error. Frankly speaking, it is impossible to measure the weight (mass) absolutely accurately. These factors, first of all, include atmospheric effects (for example, fluctuations in temperature and humidity of the environment), human factor, etc. So, the error in measuring the weight of electronic equipment can arise from the radiation of a mobile phone or from mechanical scales - from the natural wear and tear of rubbing parts. Therefore, in the manufacture of scales and weighing equipment, it is necessary to minimize the error in measuring the mass (weight) and extend the uninterrupted operation of the mechanism.
