Balances, Uncategorized

Good Weighing Practice – Tips on operating analytical balances

The current line of analytical balances including modern micro and semi-micro balances eliminate the need for special rooms to carry out weighing. Weighing test samples, which is a crucial part of the procedure of analytical experimentation, is now directly integrated with the industrial production. Advances in technology have simplified the task of operating an analytical balance. The weighing time is also greatly reduced and these advantages have made analytical balances extremely helpful and useful in medical establishments as well as research and development labs.

Atmospheric factors like changes in the environmental temperature and pressure, strong air vibrations and air currents, static buoyancy, gravitation and moisture due to condensation decrease the accuracy and efficiency of weighing. Semi-micro, micro, and analytical balances are extremely sensitive to these physical effects. Laboratory protocol must be followed at all times, even if a weighing room is not used exclusively for the weighing process. Moisture uptake and slow evaporation further affect analytical balances. Electrostatics and electromagnetic fields are other circumstances that cannot be controlled or suppressed by the device. These factors directly act on the sample that is being weighed as well as the weighing pan.

bm series micro analytical balance


To get the utmost weighing efficiency and reduce the margin of error to the minimum, the following things must always be considered. 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 balance should also be free from air vibrations caused by the the air conditioning unit. The temperature of the weighing room must be constant and the relative humidity should fall between 45 to 60 percent. It is not advisable to operate outside this range as it can damage the unit. Constant monitoring and timely adjustments are mandatory 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 lighting devices and direct sunlight. Fluorescent bulbs can be used instead of light tubes. The internal components of the analytical balance can be permanently and irreversibly damaged by heat.

Once plugged in to the electric power supply, the analytical balance should not be switched off. Precision, semi-micro, and 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 leveling and adjustment must be done to increase the sensitivity, accuracy and efficiency of the device.Regular calibration is recommended.

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