First, the electronic balance and its classification KOKEN Co., Ltd , https://www.hnb-maker.com
The balance that uses the electromagnetic force to balance the weight of the object is called an electronic balance. It is characterized by accurate and reliable weighing, fast and clear display, automatic detection system, simple automatic calibration device and overload protection.
According to the accuracy of the electronic balance can be divided into the following categories:
1. The maximum weighing of ultra-micro electronic balance ultra-micro balance is 2 to 5g, and the scale index value is less than (maximum) weighing 10-6. For example, Mettler's UMT2 type electron balance is an ultra-micro electronic balance.
2. Weighing of microbalances Microbalances are generally between 3 and 50 g, and their indexing values ​​are less than 10-5 of the (maximum) weighing, such as Mettler's AT21 electronic balance and Sartorius' S4 electronic balance.
3, semi-micro balance semi-micro balance weighing is generally 20 to 100g, its index value is less than (maximum) weighing 10-5, such as Mettler's AE50-type electronic balance and Sartorius's M25D-type electronic equality class.
4. Constant electronic balance The maximum weighing of such a balance is generally 100 to 200g, and its division value is less than (maximum) weighing 10-5, such as Mettler's AE200 electronic balance and Sartorius' A120S, A200S type electronic average. Belongs to a constant electronic balance.
5. Analytical balance In fact, the electronic analytical balance is the general term for constant balance, semi-micro balance, micro balance and ultra-micro balance.
6. Electronic balances such as precision electronic balances are collectively referred to as electronic balances with an accuracy level of II.
Second, purchase and use precautions
1. (1) How to choose an electronic balance The electronic balance should be selected from the absolute accuracy of the electronic balance (division value e) to consider whether it meets the accuracy requirements of weighing. If you choose a balance with a precision of 0.1mg or a balance with a precision of 0.01mg, you should not say that you want a balance of one ten thousandth or one hundred thousandth of a precision. Because some foreign manufacturers use the relative accuracy to measure the balance, otherwise they buy it. The balance cannot meet the needs of the user. For example, in the actual work encountered such a situation, with an actual scale division value d of 1mg, the scale of the scale index e is 10mg, the maximum weighing of 200g Mettler electronic balance, used to weigh 7mg of objects, This can not produce accurate results: in the "JJG98-90 non-automatic balance test verification procedures", the maximum allowable error and the calibration scale index value "e" is the same order of magnitude, the maximum allowable error of this balance is 1e, Obviously, we can't weigh 7mg objects; weighing 15mg is not the best choice for such balances, because the relative error of the test results will be very large, we should choose a higher level of balance, some manufacturers have been at the factory The value of the minimum weighing is specified. Therefore, we must consider the accuracy level when purchasing and using an electronic balance. (2) Requirements of the range of symmetry range In addition to the accuracy of the electronic balance, it should be noted whether the maximum weighing needs to meet the range. Usually take the maximum load plus a small insurance factor, that is, the common load can be relaxed, not the bigger the better.
2. About the calibration of the electronic balance (be sure to read the manual carefully before use) In the verification (test), we found that the error is large when the balance is first tested. The reason is that a considerable part of the instrument is at a longer interval. No calibration has been performed and the balance is considered to be directly weighed by zero display. (It should be pointed out that the electronic balance starts to display zero point. It cannot be said that the accuracy of the balance weighing data meets the test standard, and only the balance zero stability is qualified. Because it is necessary to consider the other technology when measuring whether a balance is qualified or not. Compliance of indicators). Due to long storage times, positional movements, environmental changes or for accurate measurements, the balance should generally be calibrated prior to use. The calibration method is divided into internal calibration and external calibration. Germany's Saudi Lisi, Swiss-made METTLER, Shanghai-made "JA" and other series of electronic days have a calibration device. If you do not read the instructions carefully before use, it is easy to ignore the “calibration†operation, resulting in a large weighing error. The following is an example of the Shanghai Tianping Instrument Factory JA1203 electronic balance as an example to explain how to externally calibrate the balance. Method: Press the CAL button when the CAL- appears on the display, the display will appear CAL-100, where “100†is the flashing code, indicating that the calibration weight requires a standard weight of 100g. At this point, the "100g" calibration weight is placed on the weighing plate, and the display will appear in the "----" waiting state. After a long time, the display will appear 100.000g, and the calibration weight will be taken. The display should show 0.000g. If the occurrence is not zero, then clear it again and repeat the above calibration operation. (Note: It is best to repeat the above calibration in order to get accurate calibration results.) Some people think that the heavier the object weighed within the electronic balance range, the greater the damage to the balance. This understanding is not entirely correct. The maximum safe load of a general weighing instrument is the maximum static load that it can withstand without causing a permanent change in its metering performance. Since the electronic balance adopts the principle of automatic compensation circuit of electromagnetic force, when the weighing pan is loaded (be careful not to exceed the weighing range), the electromagnetic force will push the weighing pan back to the original equilibrium position, so that the electromagnetic force and the gravity of the object to be weighed Balance, as long as the weighing size within the allowable range has little effect on the balance, it will not affect the accuracy of the electronic balance due to long-term weighing.
Third, the maintenance and maintenance of the electronic balance
1. Place the balance on a stable work surface to avoid vibration, airflow and sunlight.
2. Adjust the level bubble to the middle position before use.
3. The electronic balance should be preheated according to the requirements of the manual.
4. When weighing volatile and corrosive items, place them in a closed container to avoid corrosion and damage to the electronic balance.
5, often self-school or regular external school electronic balance to ensure that it is in the best state.
6. If the electronic balance fails, it should be repaired in time, and it is not allowed to work with “illnessâ€.
7. The operating balance should not be overloaded to avoid damage to the balance.
8. If you do not use the electronic balance for a long time, you should temporarily collect it as well.