There are several types of scales and balances for different needs. A precision balance scale is used for exact mass measurement. Its accuracy is not affected by gravity, unlike spring scales. One such precision scale is the analytical balance or a chemical balance, which is a high-precision beam balance used in quantitative chemical analysis.
Pocket scales are small portable scales used by jewelers and chemists to weigh fine items and powders in circumstances where a laboratory scale is not available.
Gram scales measure the weight of an item in grams instead of ounces, pounds or kilos. A beam balance is composed of a level with two equal arms and a pan suspended from each arm while an ordinary balance is a scale for weighing that is affected by gravitational pull.
An analytical balance is very sensitive. It can measure the mass of a single grain of substance. It should be used in a draft-free environment and placed on a solid bench or table that is free of vibrations.
When you need exact weight measurements, then you need a precision balance scale. Let us see the steps in using a precision balance scale in a laboratory setting.
- Before you weigh anything on an analytical balance, it has to be tared or recalibrated to read 0.0000 g. Press and release the Tare button to recalibrate.
- Make sure that you do not bump the balance once you have done your recalibration.
- Chemicals and other substances to be weighed should be placed on paper or dishes.
- Use tongs, tweezers and gloves to avoid adding fingerprints.
- Allow hot substances to completely cool before you take measurements.
- You will use an analytical balance if you need high degree accuracy and precision when you measure mass as the scale is not affected by gravity.
- The weighing pan used in high precision balance should be at least .01 mg. It is located in an enclosure that is transparent and has doors to prevent dust from collecting inside as well as to block the air currents inside the laboratory (from air conditioning) from affecting its operation.
- If you are using a direct method to measure weight, the substance should be added to the tared container that will hold it and not directly on the pan.
- The temperature of the samples you are going to weigh should equal room temperature so that a natural convection that can form air currents within the enclosure that can affect the process of weighing.
- Maintain constant load in the balance beam. You can do this by subtracting mass on the side of the beam where sample has been added. Do not subtract fixed weights; rather, you should use a small spring force.
There are many types of precision balance scale available today, with different price ranges. There are micro balances and ultra-micro balances that are used to weigh the smallest of samples. There are also electronic precision scales available today that provide ease of operation and accurate readings with a turn of a dial or the push of a button but these types can still be susceptible to the environment where it is used. As with other precision instruments, handle it with extreme care to ensure long years of use.