The classification of balances has a narrow sense and a broad sense. The balance in the narrow sense refers to the double-disk equal-arm mechanical balance. It is a weighing instrument that uses the equal-arm lever balance principle to compare the measured object with the corresponding weight to determine the quality of the measured object. The generalized balance includes three types: double-disc equal-arm mechanical balance, single-disc unequal-arm mechanical balance, and electronic balance.
Double-disc equal-arm mechanical balances are generally classified into three types: ordinary sign balance, differential sign balance and shelf balance. It can also be divided into 4 types: verification balance, analytical balance, precision balance such as 0.01 gram scale and ordinary balance.
The verification balance is a balance specially used by the measurement department, the commodity inspection department or other relevant departments or factories to check or calibrate the weight.
Analytical balances are high-accuracy balances used for chemical analysis and accurate measurement of substances. In most cases, the minimum division value of this type of balance is less than 10-5 of the maximum weighing. Analytical balances can be divided into constant balances (weighing and minimum division values are 100 ï½ 200g and 0.01 ï½ 1mg), semi-micro balances (30 ï½ 100g and 1 ï½ 10g), and micro balances according to the measurement range and the minimum division value 3 ~ 30g and 0.1 ~ 1g) and ultra-micro balance (3 ~ 5g and below 0.1g).
Precision scale is widely used in the precise measurement of various substances, the minimum scale value is usually 10-5 ~ 10-4 of the maximum weighing.
How to use the balance:
1. It should be placed in a level place. The game code should be reset to zero.
2. Adjust the balance nuts (nuts at both ends of the balance) to adjust the zero point until the pointer is aligned with the central scale line.
3. The left tray puts the weighing object, and the right tray puts the weight (left object right code). According to the properties of the weighing object, it should be placed on glassware or clean paper. The mass of the glassware or paper should be weighed on the same balance beforehand, and then the substance to be weighed should be weighed.
4. The added weight is increased from the estimated maximum value of the weighing object and gradually reduced. The tray balance can only be weighed down to 0.1 grams. Add or subtract weights and move the slider on the ruler until the pointer is aligned with the center scale line again.
5. Objects that are too cold or too hot cannot be weighed on a balance. It should be placed in a desiccator to room temperature before weighing (or weighing in a special vessel).
6. The mass of the object = the weight of the weight + the degree displayed by the travel code
7. The weights must be taken lightly with tweezers. The removed weights should be placed in the weight box. After weighing, the weight should be moved back to zero.
8. When weighing dry solid medicines, put a piece of paper of the same quality on each of the two trays, and then weigh the medicine on the paper.
9. Drugs that are easy to deliquesce must be weighed in glassware (such as small beakers and watch glass). 10. If the code is rusty, the measurement result is too small; if the weight is worn, the measurement result is too large.
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