Balance & Scale Care & Use
A balance has special use and care procedures just like other measuring equipment. Items to be measured should be at room temperature before weighing. A hot item will give a reading less than the actual weight due to convection currents that make the item more buoyant. And, if your balance is enclosed, warm air in the case weighs less than air of the same volume at room temperature.
Another important part of using a balance is cleaning. Scales are exposed to many chemicals that can react with the metal in the pan and corrode the surface. This will affect the accuracy of the scale.
Also, keep in mind that a potentially dangerous situation could occur if a dusting of chemicals is left on the balance pan. In many lab and classroom situations, more than one person uses a single scale for weighing. It would be impossible for each person to know what everyone else has been weighing. There is a chance that incompatible chemicals could be brought into contact if left standing or that someone could be exposed to a dangerous chemical that has not been cleaned from the balance. To avoid damaging the scale or putting others in danger, the balance should be kept extremely clean. A camel's hair brush can be used to remove any dust that can spill over during weighing.
is another care issue when it comes to scales. A scale cannot be accurate indefinitely; they must be rechecked for accuracy. There are weight sets available that allow users to calibrate the scale themselves or the scales can be calibrated by hiring a professional to calibrate them on site.
The correct weight set needs to be chosen when calibrating a scale. The classes of weight sets start from a Class One which provides the greatest precision, then to Class Two, Three, Four and F and finally go down to a Class M, which is for weights of average precision. Weight sets have class tolerance factors, and as a general rule, the tolerance factor should be greater than the readability of the scale.Class 1
provides the greatest precision and is used for calibrating high precision analytical balances. Class 2
is used for calibrating high precision top-loading balances. The remaining classes utilize weights of decreasing precision. In fact, calibration weights themselves often need to be re-certified depending on the degree of accuracy required from the weighing instrument. Many government and industry specifications require proof of accuracy. The weights can change due to scratches, wear, accumulation of dirt and atmospheric corrosion, thus reducing the accuracy of the set.