The balances are instruments that are used to measure the mass of a body or also the weight of it. Its origins lie more than 3,500 years before Christ, in Egypt.
The scales differ from each other by the design, the principles used and the metrology criteria they use. At present, it could be considered that there are two large groups: mechanical scales and electronic scales.
In the laboratory, the balance is used to perform quality control activities and to determine specific densities or weights. Therefore, it is necessary to have optimal conditions from the environmental and structural point of view. As well as to provide the correct maintenance of this equipment, in order to ensure correct weighing.
Correct use of balances.
First, the environmental conditions required for the balance to function properly must be considered. The environmental conditions are: room temperature, exposure to sunlight, electrical surges and the presence of dirt on and in the weighing mechanism. As they could induce the equipment to give erroneous readings.
The use of environmental conditioning equipment should be studied, because sometimes these equipment produce air currents that affect weighing. For its stabilization, a reasonable time of approximately 15 minutes is required for the air flow to stop.
It is advisable not to place the scales near ovens or forklift, among others, both when stored and in use. It is important to consider that because hot or warm objects have a lower weight than when they are cold, these objects must be stabilized at room temperature before being weighed.
Balances maintenance and protection.
Regarding leveling, it is important that the scales are always level before weighing. The correct way to check is to check the level indicator. This level indicator is usually located on the top or rear of the equipment. In case the instrument does not have a level indicator, an external one can be used, placing it on the load receiving device
Cleanliness is an important factor. Both the weighing chamber and the pan must be clean, so if for any reason the balance is exposed to dust or humidity, it is essential to cover it. When weighing, it is suggested to only use clean containers. In case of spillage of any substance during weighing, it should be cleaned immediately with a clean and dry cloth. Organic solvents or chemicals should not be used to clean them as they can damage the painted surfaces and the screen.
To establish the controls of the balances, the minimum conditions must be met so that the equipment behaves regularly: they must be placed in a fixed place, on strong tables that reduce the sensitivity to movements and vibrations.
Balances should be calibrated periodically, especially the first time they are put into operation or when changing locations, and should be checked after leveling and after large changes in temperature, humidity or atmospheric pressure.
What is required to successfully install and use a balance?
- Have an environment that does not present drafts, sudden changes in temperature and is free of dust.
- Have a perfectly level counter. A high inertia platform, isolated from structures located in the vicinity, is ideal to reduce the effect of vibrations emitted by certain equipment such as centrifuges and refrigerators.
- Prevent equipment that produces high magnetic fields or vibrations.
- Avoid being under the direct influence of air conditioning systems – air currents – and sunlight.
- Have an electrical outlet in good condition, equipped with a ground pole provided with switches, that complies with the electrical regulations in force in the country or the laboratory.