15 Questions about Laboratory Analytical Balance(Part 2)


Question 10. What is the minimum weighing amount of a ten-thousand-cent scale balance?

The error of the instruments used in analytical chemistry quantitative experiments is controlled within 0.5%, which is within five thousandths. The indication error of the one-ten-thousandth balance is 0.1mg, calculated as five thousandths, the minimum sample weight is 2g, which is 0.2g.

Question 11: Should I re-calibrate the balance after cleaning?

It's just cleaning and sanitation, no calibration is needed. In addition, the balance should not be calibrated frequently. Calibration will only be done when the error of the balance exceeds the allowable error. If the calibration procedure is frequently started, it indicates that the stability of the balance is a problem...

Electronic Balance

Electronic Balance

Question 12: 6 reasons why the electronic balance cannot start normally

Many old balances cannot be opened before use. There are 6 reasons for this phenomenon:

Reason 1:

1. If the calibration data is lost, please recalibrate the balance;

2. It may be affected by instantaneous interference;

Reason 2:

1. The environment where the balance is placed is too bad, improve the environment;

2. The body temperature of the hand left in the weighing room minimizes this human factor;

3. The temperature of the weighed object is not isothermal with the balance, and the sample is placed next to the balance to isothermal;

4. The sample has properties such as water absorption, water release, static electricity, magnetism...etc. ,

Reason 3:

The water absorption and release of the desiccant form airflows in different directions, causing changes in air buoyancy, resulting in unstable weighing. The desiccant in the weighing room should be removed to maintain a stable weighing environment;

Reason 4:

1. No weighing pan installed: After power off, install the correct weighing pan before turning on the balance;

2. Wrong weighing: use the correct weighing that conforms to the balance

3. The weighing pan and the wind-proof ring collide: due to improper installation, please find out the cause of the collision and reinstall it correctly.

Reason 5:

1. There is no 220V current connected to the AC power socket on the power socket of the balance;

2. If the AC adapter fails, choose a 220V~ AC adapter (external transformer) suitable for our country's work;

3. If the AC adapter is broken, replace it with a new one;

Reason 6:

1. The environment where the balance is placed is too bad: Environmental factors include: vibration, airflow, temperature, and external magnetic field. The above environment must be improved and the windshield window of the weighing room must be closed for the balance to work normally.

2. The parameter settings in the balance menu are not good: After entering the menu, use the "RESET" function to exit the menu correctly and return to the factory settings.

Question 13: How to test the performance of 0.01g lab electronic balance?

Regarding the purchase of electronic balances, how can I buy a balance with a relatively high cost performance? The following specifically introduces the detection methods of a good balance.

1. Stability: Stability can be divided into long-term stability and instantaneous stability. Long-term stability means that the electronic balance does not change much in the ambient temperature. Instantaneous stability means that the value displayed after the balance is placed on the measured object is displayed immediately and remains unchanged. change. After the power is turned on, the difference in the weight of the same supplementary test object at different time periods will be maintained for a long time. The smaller the difference of the above parameters, the more stable the performance of the electronic balance.

2. Linear accuracy: Linearity is also a very important indicator for measuring electronic balances, which mainly refers to the deviation between the displayed value and the absolute value within the entire weighing range. For electronic balances with poor quality, even after full-scale calibration, it is difficult to obtain accurate weighing values within the weighing range of the electronic balance.

3. Repeatability: Repeatability is another important indicator for measuring electronic balances. If the repeatability is not good, the collected data is unreliable. Repeatability mainly refers to the fluctuation of the value of the electronic balance, which is repeatedly weighed many times. Minimum, maximum and deviation.

4. Sensitivity: refers to the resolution and the time limit of the resolution. Resolution refers to the verification division value e or display resolution d. The smaller the value, the better (super sensitivity). Reflecting the time limit, the shorter the time for the electronic balance to increase a sensitivity value after increasing a sensitivity value, the better. We believe that electronic balances have fast response and high sensitivity.

PS: The meaning of e and d in electronic balance

e is "verification index value" d is "actual index value"

Simply put, the "actual scale value" d represents the readability of the balance, and the "verified scale value" e refers to the accuracy of the balance.

5. Service life: the length of service life. Service life refers to the expected period of use by the enterprise.