How Do I Choose the Best Electronic Balance?

People call an electronic balance a balance that uses electromagnetic force to balance the weight of an object. It is characterized by accurate and reliable weighing, fast and clear display, and has an automatic detection system, simple automatic calibration device, and overload protection.

Electronic balance

People use

Electronic balance for weighing objects.

I. Electronic balance and its classification According to the accuracy of electronic balance, it can be divided into the following categories:

Regarding the calibration method of the electronic balance (be sure to read the instructions carefully before use), we found in the verification (test)

Weighing instrument refers to the instrument that displays the mass and weighing status of the weighed object in the electronic weighing instrument, also called weighing indicator. The electronic weighing instrument was originally an analog indicating type, consisting of an error amplifier, a reversible motor, a balanced electric bridge, an excitation power supply, a dial and a pointer, etc., and worked according to the principle of an automatic balance electronic potentiometer. It has slow weighing speed, single function and low accuracy, and has been basically eliminated. The current weighing display is digital.

Composition of electronic weighing instrument

Four performance indicators of electronic balances: When using electronic balances in gas field life, the first consideration is the stability of the balance, the sensitivity of the balance, the accuracy of the balance, and the invariance of the displayed value of the balance. The so-called stability refers to the stability of the accuracy of the balance; and the sensitivity refers to the response speed of the balance readings. In this regard, electronic balances have higher sensitivity than mechanical balances; correctness refers to the accuracy of their readings; Refers to the stability of the balance reading, that is, the floating range of the balance reading. The smaller the floating range, the better the invariance.

I. Invariance of the displayed value of the electronic balance:

The invariance of the displayed value of the electronic balance refers to the degree of consistency of the measurement results obtained by the same measurement of the same object multiple times under the same conditions. For electronic balances, there is still the invariance of the displayed value of the balance, such as the control of the repeatability and reproducibility of the electronic balance, the control of the zero position of the electronic balance and the return error. Control of time drift of electronic balance display.

Second, the correctness of the electronic balance:

The accuracy of an electronic balance is the correctness of the displayed value of the balance, which indicates the ability of the displayed value of the balance to be close to the true value. From the perspective of error, the correctness of the balance reflects the degree of systematic error of the displayed value of the balance.

Third, the sensitivity of the electronic balance:

1.Place the balance on a stable workbench to avoid vibration, airflow, and sunlight

Because balance weights generally have higher accuracy and more requirements on the environment and operation, what problems should be paid attention to in daily use and how to extend the service life of electronic analytical balances.

1.1 Do not place the balance weight on the side table under the air conditioner. The electronic analytical balance that has been moved must be re-calibrated, and the weighing performance of the balance must be thoroughly checked before it can be used.

1.2 When weighing hygroscopic, volatile or corrosive items, apply the weighing bottle cap tightly and weigh as quickly as possible, taking care not to spill the weighed object (particularly corrosive items) on the weighing pan or bottom plate; When finished, the weighed object was taken away from the balance in time, and the hygiene of the weighing room was improved.

1.3 The same experiment should use the same balance for weighing to avoid errors due to weighing.

A balance made using the principle of electromagnetic force to balance gravity is called an electronic balance. As laboratory applications become more common,

Using the electronic piece counting function can quickly get the number of individual cells in a pile of objects. For example, a new batch of M3 nuts comes in a warehouse, and the number is about 5,000. To know the specific number of nuts, if it is counted manually, it will take a lot of time, and the error rate is high. If you use the counting function of the electronic balance, you can do more with less. The counting principle of the electronic balance produced by Shanghai Hengping Scientific Instrument Co., Ltd. is as follows. Take 10 nuts as

1. Turning on the problem _ No display at all after turning on: There is no 220V current in the power socket to connect to the AC socket; The AC adapter is wrong, choose a 220V ~ AC adapter (external transformer) suitable for China work; AB-S / A8-1.4v ~ 50 / 60HZ6VA; PB-S / A9.5-20VDC6W; AB / PB / GB9.5-14.5V50 / 60HZ1.5VA; (3) AC adapter burned out, replace the AC adapter;

2. Turn on the problem_ No display at all after turning on. Calibration data is lost, re-calibrate the balance; Transient interference effect;

3. Turn on the problem_ No display at all after turning on: the balance of the internal school, AB-S / A, PB-S / A; the balance of the external school, AB / PB / GB / SB; The window is not closed, improving the environment for placing the balance and closing all windproof windows. Calibration features: After the AB-S / A balance is warmed up for 1 hour, the first automatic calibration is performed; the second environment is after the balance is turned on for 2 hours; then the balance is turned on. After keeping the power on for 150 hours, automatic calibration on time can be manually triggered if necessary (internal calibration). The PB-S / A balance is automatically calibrated after it is turned on. If necessary,

Products and solutions for micro and ultra-micro balances, analytical balances, precision balances, large range precision balances, special purpose balances, comparators,

First, the instrument installation

1. Working environment: The electronic balance is a high-precision measuring instrument, so the installation position of the instrument should pay attention to:

The mounting platform is stable and flat to avoid vibration;

Avoid direct sunlight and heat, and avoid working in a humid environment;

Avoid direct air passages.

2. Balance installation: Operate strictly in accordance with the instrument manual.

Second, the use of balance

1. Level adjustment: Before turning on the balance, you should observe whether the blisters in the spirit level at the rear of the balance are located in the center of the ring.

2. Warm-up: When the balance is turned on for the first time or after a long-term power failure, it needs a warm-up time of at least 30 minutes. Therefore, under normal circumstances, laboratory electronic balances, do not cut off the power often.

3. Weighing:

Press the ON / OFF key to turn on the display;

Wait for the instrument to self-test. When the display shows zero, the self-test process ends and the balance can be weighed;

Place the weighing paper, and press the Tare button on both sides of the display screen to peel. When the display shows zero, add the reagent to be weighed on the weighing paper.

After weighing, press the ON / OFF key to turn off the display.

Third, matters needing attention

1. In order to use the balance correctly, please familiarize yourself with several states of the balance:

O in the upper right corner of the monitor: it means the monitor is off;

The lower left corner of the display shows O: indicating that the instrument is in standby state and can be weighed;

A diamond symbol appears in the upper left corner of the display: the instrument's microprocessor is performing a function and no other tasks are accepted at this time.

2. The balance has been strictly calibrated during installation, so the balance cannot be moved easily, otherwise the calibration work needs to be performed again.

3. It is strictly prohibited to directly weigh without using weighing paper! After each weighing, please clean the balance to avoid contamination of the balance, affecting the accuracy of the weighing, and affecting the work of others

4. Tips for using electronic balance

a. Before weighing, check whether the balance is normal, whether it is in a horizontal position, and whether the inside and outside of the glass frame are clean.

b. The weighing object cannot exceed the load of the balance, and hot objects cannot be weighed.
Corrosive or hygroscopic objects must be weighed in a closed container.

c. All weighings in the same chemical test should use the same balance from beginning to end, using different balances will cause errors.

d. Each balance is equipped with a fixed weight. Do not misuse the weights of other balances.
Keep the weights clean and dry. Use the tweezers to pick up the weights. Do not hold them with your hands. Put them back in the weight box after use.

e. After weighing, check whether the balance beam is lifted, whether the weight has been returned, whether the index plate has turned to "0", whether the power is cut off, and whether the side door is closed. Finally, cover the balance and fill in the use record.

f. Keep the inside of the balance clean frequently, if necessary, wipe it with a soft brush or silk cloth or wipe it with absolute ethanol.

g. A desiccant should be placed in the balance. Weighing must not exceed the maximum load of the balance.

Before 2013, most electronic balances already had program adjustment functions, so that the functions of electronic balances were more complete and their ability to adapt to the environment was stronger. Under normal circumstances, the electronic balance manufacturer has set up normal procedures for the user before the electronic balance leaves the factory. Only when the conditions or needs of the user have changed, it is necessary to call or change the relevant procedures of the electronic balance.

The internal procedure of calling the electronic balance should be completed in the following steps:

1. Turn off the balance switch.

2. Press the tare key and the on / off key of the electronic balance at the same time, and immediately release the on / off key of the electronic balance. Continue to hold down the tare key of the electronic balance.

3. When "CH5" appears on the display of the electronic balance, release the tare key of the electronic balance.

4. At this time, on the display of the electronic balance, the page numbers of the programs set in the electronic balance appear in sequence, such as L1, L2, and L0.

5. When a page number other than zero appears, press the tare key of the electronic balance as required. The page number and the line number appear on the display as two digits, such as L11, L12 to L10, and the line number appears cyclically.

6. When the shape code other than zero appears on the display of the electronic balance , you can press the Tare key as needed. The three-digit number appears on the display of the electronic balance. The last digit is the code, such as L111, L112 to L110 After that, it starts to cycle.

7. According to the above method, the program of the electronic balance can be arbitrarily selected (mainly for observation, if necessary, the locking device of the program switch of the electronic balance should be opened).

It should be noted that if "Lxxx" appears on the display to indicate that the program can only be read and cannot be changed, the L symbol indicates that the electronic balance program is locked. If "Cxxx" appears, the electronic balance program switch is on and the program can be modified.

1. When the horizontal bubble is above the horizontal circle, it indicates that the upper position of the electronic balance is higher. We need to rotate the two upper corners of the electronic balance to move the bubble downward.

2. When the horizontal bubble is below the horizontal circle, it indicates that the lower position of the electronic balance is high. We need to rotate the two corners of the lower part of the electronic balance to move the bubble upward.

3. When the horizontal bubble is on the left side of the horizontal circle, it indicates that the left side of the electronic balance is high. We need to rotate the two angles on the left side of the electronic balance to move the bubble to the right.

4. When the horizontal bubble is on the right side of the horizontal circle, it indicates that the right side of the electronic balance is high. We need to rotate the two right corners of the electronic balance to move the bubble to the left.

Tip: Sometimes the horizontal bubble comes out of the oblique angle position, which requires us to use several corners back and forth.

1.Inaccurate weighing failure analysis

Observe whether the internal code value is stable, whether there is friction in various parts of the sensor, whether the stabilized voltage power supply is stable, whether the op amp circuit is normal, and use a weight to test whether the four-foot weighing scale is even. Follow the instructions in the manual to further perform partial analysis or weight correction of the meter.

2.Failure analysis that cannot return to zero after the weight is removed

Check whether the output signal value of the sensor is within the standard (A / D total amplification code / used internal code range / base code range). If the signal value is not within the standard, adjust the adjustable resistance of the sensor to adjust the signal value to the standard. If it ca nt be compensated, please check the sensor for problems. Under the condition that the sensor output is normal (the scale body is stable), the meter will be locked. Generally, there is a problem with the amplifier circuit and A / D conversion circuit. Finally solve the problem.

3.Failure to boot

First determine the problem caused by non-fuse, power switch, power cord and voltage switch, and check the transformer for AC voltage input and AC power output. If the meter has a battery, remove the battery and start it with AC power to see if it is caused by insufficient battery voltage. Secondly, check whether the rectifier circuit, voltage regulator circuit and display drive circuit are abnormal. If these are all right, check whether the processor and the auxiliary circuit are burned out.

4, display garbled

Remove the original display circuit and replace it with a normal display circuit to see if it is normal. If the display is normal, there is a problem with the display circuit. If it is not normal, you should check the drive circuit for failure, and finally check whether the pins of the processor display output are within a reasonable output range.

5.Keys are not easy to use

First replace the new key for testing. If the new key functions normally, it can be determined that the key is not in good contact, and the circuit between the key and the CPU is disconnected or soldered. Check whether there is any bad contact on the key support. Measure the short circuit and open circuit of the keys and the diodes and resistors on the CPU circuit.

6, can not be called full load

It is almost the same as the case where it is impossible to return to zero. Most of them may be changed due to the small signal input range. Detect according to the method that cannot be returned to zero. If no problem can be found, first check whether the power supply and A / D circuit are normal, and then check the sensor output.

7, pointer jump

When the beam is lifted, if the distance between the blade of the fulcrum knife and the pad is different from front to back, the pointer will jump when the balance is turned on. The screw in front of the left arm of the horizontal bracket can be loosened, and then the small pillar can be adjusted by hand Height until the pointer no longer jumps.

1. Place the balance on a stable workbench 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 instructions.

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

5. The self-calibration or regular external calibration of the electronic balance is often carried out to ensure that it is in the best condition.

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

7. Do not overload the operating balance to avoid damaging the balance.

8. If the electronic balance is not used for a long time, it should be stored temporarily.

Precautions

I. The heart of an electronic balance A gravity electromagnetic sensor reed (usually a total of 618) is thin and thin, which is easily damaged, and the higher the accuracy of the balance, the thinner the gravity sensing reed is, so in use Special care should be taken to protect it. Do not load the balance with objects weighing more than its weighing range. Never press the weighing pan by hand or drop the balance to the ground to avoid damaging the balance or changing the performance of the gravity sensor. Also weigh an object For especially heavy objects] generally do not take more than 30 seconds to remove the weighing pan and its tray when moving and transporting.

Second, the electronic balance is actually an instrument for measuring the gravitational force of the earth on the objects exposed on the weighing plate, that is, gravity, and due to the difference in the diameter and latitude of the earth, the gravity acceleration (9-9. 8m2 / s) is not the same everywhere The local weighing accuracy depends on whether the correct calibration and the accuracy of the anvil are performed. If you find that the balance has been calibrated in Guangzhou, there is a certain error in the local weighing. This does not mean that the balance has any failure. According to the method described in the manual of each model of electronic balance , the standard anvil code approved by the metrology department can be used for accurate weighing.

Third, the calibration mechanism of electronic balance is generally divided into three categories:

Fully automatic calibration: standard anvil and motor servo mechanism are integrated, and the calibration can be completed within tens of seconds by pressing a function key ;

Semi-automatic calibration: built-in standard anvil code but no servo mechanism, after entering the calibration procedure, you need to manually load and unload the calibration code;

Manual calibration: There is no standard anvil in the balance and the servo mechanism needs to manually enter the calibration program and add a standard anvil for calibration. Generally, the balance with lower accuracy uses manual calibration.

4. The electronic balance is a precision electronic measuring instrument that is highly sensitive to the environment. Care should be taken when using it. The installation surface should be free of obvious vibrations and should not be left open in the air conditioner. If these conditions cannot be met, some improvement measures should be taken such as changing the use Install windproof ink on the site and pay attention to adjust the bottom screw to center the bubble of the level indicator. Failure to adjust the balance level is also one of the reasons for weighing errors.