Analytical balances are used in laboratory tests where highly precise and accurate weighing is necessary. Unlike usual scales that are not substantially affected by environmental factors analytical balances are highly sensitive to ambient conditions like the strength of the local gravitational field, pressure, temperature, ventilation, condensation due to humidity, air current, etc. They can be used to determine the mass of test samples as small as 0.01 milligrams and even smaller samples.
The entire weighing apparatus is enclosed in a dust-free and protective weighing chamber. This transparent chamber minimizes potential loss of the sample and supports accurate weighing of substances in small amounts. Care must be taken to ensure that the sample to be weighed attains room temperature. Temperature differences, through convection, result in the formation of air currents that decrease the accuracy of the analytical balance. Various types of analytical balances are available depending on the requirements and experimental needs of the lab. Weighing balances determine the weight and mass of test substances and samples. Top-loading balances are commonly found in all labs, medical establishments and research divisions. They are used to weight samples that weigh no more than two hundred grams. The resolution of weighing isn’t that high and these balances more or less belong to the category of semi-analytical balances. Their readability is up to 0.001 grams. Analytical balances are very accurate and give better reading. They are also better suited to cope with a wide range of environmental conditions with steady readings. It is imperative that lab personnel must refer to the operating manual that has detailed instructions regarding the use of an analytical balance as well as guideline on its care, maintenance and troubleshooting.
Most analytical balances are now available with an auto calibration option. This should not be a point of concern for unsupported models because manual calibration is extremely easy and doesn't take a lot of time. Once the balance is calibrated using the available test weights, the sample to be weighed must be placed in the tared weighing platform or container before closing the doors of the weighing chamber. Liquids and pulverized samples must be handled carefully using a spatula and forceps. The weighing pan must be free of dust and fingerprints for accurate weighing. The most important thing that must be kept in mind is that the analytical balances must always show a stable reading of zero prior to weighing.
Micro and ultra micro balances have a weighing limit of six grams and a seven decimal readability. These balances also feature a wide array of units to display the mass of objects that are to be weighed. These include ounces, grains, kilograms, grams, newtons and pounds.
This article was written by Dr. Bob Sandor, a Director at Tovatech, a leading North American supplier of analytical balances. When not busy running his company, he explores his fascination with the many aspects of various scientific & industrial devices. For more information on this article visit the Tovatech site from any of the above links.
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