The current line of analytical balances including sophisticated micro and semi-micro balances provide additional features to carry out laboratory weighing. Weighing test samples, which is an integral aspect of the procedure of analytical experimentation, is equally important in the industrial production. Advances in technology have eliminated the complexity of operating an analytical balance. The weighing time is also greatly reduced and these made analytical balances extremely valuable to medical establishments and research and development labs.

Atmospheric factors like changes in the environmental temperature and pressure, strong air vibrations and air currents, gravitation, static buoyancy and moisture due to condensation alter the efficiency and accuracy of weighing. Semi-micro, micro, and analytical balances are extremely sensitive to these physical effects. Laboratory protocol must be followed at all times, especially if a weighing room is not used solely for the weighing process. Slow evaporation and moisture uptake further affect analytical balances. Electromagnetic fields and electrostatics are other factors that cannot be suppressed or controlled by the device. These forces affect the weighed sample and the weighing pan.

To attain the maximum weighing efficiency and reduce the margin of error to the minimum, a few important things must be kept in mind. The analytical balance must be placed on an anti-magnetic lab table or lab bench, and the area should be exclusive for the balance alone. It must offer protection against electrostatic charges. The lab bench should be secured either on the wall or to the floor. This prevents the transfer of vibrations from the floor to the wall. The weighing bench must be upright when working to minimize air vibrations.

The area above the legs of the bench is usually the most stable as it is has relatively fewer vibrations when compared with other parts of the bench. A good idea would be to place the analytical balance exactly over this area of the table. The temperature of the weighing room must be constant and the RH (relative humidity) should be in the range of forty five to sixty percent. It is not advisable to operate outside this range as it can damage the unit. Timely adjustments and constant monitoring should be practiced in the weighing room. Installing a sliding door to access the weighing room is helpful as it reduces the vibrations to a great extent. The balance must be away from direct sunlight or lighting devices. Fluorescent bulbs can be used instead of light tubes. Analytical balances are affected by heat as it can permanently and irreversibly damage the internal components of the weighing apparatus.

Once plugged in to the electric power supply, the analytical balance should not be switched off. Precision, micro, and semi-micro balances need adequate time to warm up. Precision balances need around three hours, while semi-micro and micro balances need six and twelve hours respectively. Balance adjustment and leveling must be done to increase the accuracy, sensitivity and efficiency of the device.

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.