First, the construction principle and characteristics of electronic balance
Principle: Weigh directly according to the principle of electromagnetic force balance.
Features: stable performance, easy operation, fast weighing and high sensitivity. Automatic correction, peeling and quality electrical signal output.
Second, the use of electronic balance
1 Level adjustment: The blisters should be at the center of the level.
2 Turn on the power and warm up for 30 minutes.
3 Turn the switch ON to make the display light and display the weighing mode 0.0000g
4 Weighing: Press the TAR button to display after zero. Place the weighing object in the center of the tray. After the reading is stable, the number is the mass of the object.
5 Peeling weighing: Press the TAR button to clear, put the empty container in the center of the disc, press the TAR button to display zero, that is, peeling. Put the weighing object into an empty container. After the reading is stable, the reading shown by the balance is the mass of the object.
Third, the weighing method
1 Direct weighing method
Used to directly weigh the mass of a solid object. Such as a small beaker.
Requirements: The object is clean and dry, not easy to deliquesce, sublimate, and not corrosive.
Method: After the zero point of the balance is adjusted, close the balance and cover the object with a clean paper strip (you can also wear special gloves) and place it in the center of the left disk of the balance. Adjust the weight to balance the balance, and the resulting reading is the mass of the object.
2 fixed mass weighing method
Used to weigh the specified mass of the sample. For example, weigh the reference material to prepare a standard solution of a certain concentration and volume.
Requirement: The sample does not absorb water, is stable in air, and has fine particles (powder).
Method: First weigh the quality of the container and close the balance. Then add a fixed mass of the weight to the right pan, then slowly add the sample to the container holding the sample with a horn spoon, and weigh it with a semi-open balance. When the applied sample differs from the specified mass by less than 10 mg, fully open the balance and carefully place the burr containing the sample to the top of the container of the left weighing plate about 2-3 cm. The other end of the spoon is placed on the palm. Use the thumb, middle finger and palm to hold the horn spoon, and use the index finger to flick the handle and slowly shake the sample into the container until the balance is balanced. This must be done with great care.
3 Decrement weighing method / difference method
Used to weigh samples of a certain mass range. It is suitable for weighing a plurality of substances which are easily absorbed, easily oxidized or easily reacted with CO2.
method:
1Clamp the dried weighing bottle with a small piece of paper and rough the quality on the scale.
2 Add a little more than the required amount to the weighing bottle with a horn spoon and thickly weigh it on the scale.
3 Place the weighing bottle in the center of the left plate of the balance, add the appropriate weight or ring code on the right plate to balance it, and weigh the accurate mass of the weighing bottle and the sample (accurate to 0.1mg), and record the reading. , set to m1g. Turn off the balance and subtract the minimum value to be weighed from the right weight or ring code. The weighing bottle is taken up to the top of the receptacle, and the right hand grips the cap handle with a piece of paper to open the cap. Tilt the bottle down slowly and gently tap the bottle with the cap to allow the sample to slowly fall into the container (do not sprinkle the sample outside the container). When it is estimated that the poured sample is close to the required mass (estimated from the volume), slowly raise the weighing bottle and gently tap the bottle with the lid to make the sample attached to the upper part of the bottle Into the bottle, cover the bottle cap, put the weighing bottle back on the left plate of the balance and weigh it. If the left side is heavy, you need to re-tap. If the left side is light, you can't knock it again. Accurately weigh the mass, and set the mass to m2g. Then the mass poured into the receptacle is (m1-m2)g. Repeat the above operation to weigh multiple samples.
Fourth, 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-calibration or regular external schooling of electronic balances is often carried out to ensure that they are in the best 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.