Verification of the measuring instrument consists in the fact thatmetrological and other characteristics of certain items are checked and their similarity to passport data is checked. Such actions are carried out by specially appointed persons in the intended room, while specialized equipment is used. These actions have received the name - calibration of scales.
State verification has the right to conductspecialists of Federal agencies agencies that deal with technical coordination and belong to state agents. In the event that the measuring instruments meet all the requirements, it is considered that they have been verified. If, as a result of verification, some malfunctions were detected, then instead of the passport a certificate is issued that the device is unsuitable for use. Such scales require repair or calibration. If the verification was successful, then the owner retains the appropriate certificate, and the impression of the stamp remains on the attested scales.
In total there are three stages. The first stage consists in checking without applying a load. At this stage, it is checked how correctly the balance is installed, and how they react to an attempt to unbalance them. At the second stage, the verification is carried out using a weight that weighs approximately 1/10 of the load from the largest weighing limit. The weight is usually placed in the center and at the sides, the readings should equal the mass of the weight. The third stage determines the accuracy with which the scales operate, taking into account the maximum load. In this case, the weight is set only in the center, the sensitivity of the weight is not checked at the same time.
Verification of the balance is carried out in two ways. The first one is statistical. It involves measuring the forces applied to the sensors to be checked and the pattern exposed. That is, this method is applied to both model and verified scales. The disadvantage of this method of verification is that the results may be unreliable. Another drawback of this method is that the instrument to be tested is not operated. A dynamic method of checking conveyor devices or continuous instruments is weighing a control sample. The disadvantage of this method is that this process is very laborious, while the result of verification will be inaccurate. The products to be weighed must be in a bunker, which is physically impossible to perform. There should also be samples of weights, which is not always possible. With this method, the balance will not be operated according to the staffing schedule.
Verification of electronic scales includesseveral stages of work: the study and testing of the device, the identification of metrological parameters, the measurement of the volatility of weights that are not subjected to stress. This also includes the recognition of the error of the readings of the instrument being checked, the sensitivity of the balance. If the balance has not passed the appropriate verification, then they are not allowed to operate.
Verification of weights (the frequency of this procedure -once a year) is conducted in accordance with the legislative documents "On metrology and metrological activities". All scales in service are subject to periodic verification.
In the documents for the operation of the balance are registeredconditions that must be strictly observed. When verification of the balance is carried out, the temperature, humidity and atmospheric pressure must clearly correspond to the working parameter. During the external inspection, it is usually established that there are no cracks and corrosion, all control objects should be in place, according to the operating documents. If it is a crane device, then in the passport there must be a certificate of its test for the strength of the crane hook. At the time of testing the balance, it is necessary to determine how well they are working, whether the control device is overloaded. During the determination of metrological boundaries, the inconsistency of the balance indication is checked in the absence of any loads. Metrological boundaries are calculated by estimating the weights of the 4th digit. If the results of the verification were positive, then it is noted in the passport and a stamp is made on the scales, which indicates the suitability of the balance for operation. If the result of verification is negative, then the balance is not applied.