Correct use and maintenance of electronic balances

First, the electronic balance and its classification:

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 ultra-micro electronic balance ultra-micro balance zui large weighing is 2 to 5g , the scale index value is less than ( zui large ) weighing 10-6, such as Mettler 's UMT2 type electron balance is an ultra-micro electronic balance.

2 , the microbalance of the microbalance weighing is generally 3 to 50g The index value is less than ( 10 u large ) weighing 10-5 , such as Mettler 's AT21 type electronic balance and Sartorius ' S4 type electronic balance.

3 , semi-micro balance semi-micro balance weighing is generally 20 to 100g The index value is less than ( 10 u large ) weighing 10-5 , such as Mettler 's AE50 type electronic balance and Sartorius 's M25D type electronic equality .

4 , constant electronic balance such a balance of Zui large weighing is generally 100 to 200g The index value is less than (10 u large ) weighing 10-5 , such as Mettler 's AE200 type electronic balance and Sartorius 's A120S , A200S type electronic days average are constant electronic balances.

5 , The analytical balance is an electronic analytical balance, which is a general term for constant balances, semi-micro balances, microbalances and ultra-micro balances.

6 , Electronic balances such as precision electronic balances are collectively referred to as electronic balances with an accuracy level of II.

two, Purchase and use precautions:

1 , How to choose an electronic balance The electronic balance should be considered from the absolute accuracy of the electronic balance ( division value e) to meet 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 graduation value d is 1mg , the calibration scale index value e is 10mg, zui large weighing is 200g The Mettler electronic balance is used to weigh 7mg of objects, so that it can not produce accurate results : in the " JJG98-90 non-automatic balance test verification procedures", zui large allowable error and verification scale graduation value "e" For the same order of magnitude, the zai's large allowable error of this balance is 1e , obviously it is impossible to weigh 7mg of objects ; the weighing of 15mg is not a good choice for such a balance, because the relative error of the test results will be large, should Select a higher level of balance, some manufacturers have specified the value of small weighing of zui at the factory. Therefore, we must consider the accuracy level when purchasing and using an electronic balance.

 

The requirements of the range of symmetry range. In addition to the accuracy of the electronic balance, it should also be noted whether the large scale of Zui meets the needs of the range. Usually take the large load of zui plus a little insurance factor, that is, the common load can be relaxed later, not the bigger the better.

2 , About the calibration of the electronic balance ( be sure to read the instructions carefully before use ) In the verification ( test ) , we found that the error in the first measurement of the balance is large . The reason is that a considerable part of the instrument is not in the long time interval. Calibration is 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: When the CAL key when the display appears Tap CAL-, i.e. let go, the display will appear where CAL-100 " 100” Is a flashing code, indicating that the calibration weight is required 100g Standard weight. At this point, I will be ready. " 100g "The 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 , take the calibration weight, the display should appear 0.000g If the occurrence is not zero, then clear it again and repeat the above calibration operation. ( Note: in order to get accurate calibration results, repeat the above calibration )

 

Some people think that the heavier the object weighed within the range of the electronic balance, the greater the damage to the balance. This understanding is not entirely correct. The general safety weapon zui large safety load is the large static load that it can withstand without causing permanent changes 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.

Second, 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 as required by the instructions.

4. When weighing volatile and corrosive items, place them in a closed container to avoid corrosion and damage to the electronic balance.

5 , Self-school or regular external schools are often used for electronic balances to ensure that they are in good condition.

6 , If the electronic balance fails, it should be repaired in time, and it is not allowed to work with " illness " .

7 , The operating balance should not be overloaded to avoid damaging the balance.

8 , If you do not use an electronic balance for a long time, you should temporarily collect it as well.

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