The scale is a laboratory instrument It measures the mass of a body or chemical, using as a means of comparison the force of gravity acting on the body.
It must be taken into account that weight is the force that the gravitational field exerts on the mass of a body; such force being the product of mass by the local acceleration of gravity. The local term is included to emphasize that acceleration depends on factors such as geographical latitude, height above sea level and density of land, where the measurement is made. This force is measured at Newton. Did you know what? The scale has other names, including scales and weights.
What is the scale used ford?
The scale is used to measure the mass of a body or substance or also the weight of them, since there is a well defined relationship between mass and weight. In the laboratory, the scale is used for quality control activities -with devices such as pipettes-, to prepare mixtures of components in predefined proportions and to determine specific densities or weights.
Some types of scales
Scales differ from each other by design , the principles used and the metrology criteria used. At present, two major groups could be considered: mechanical scales and electronic scales.
What are the mechanical balances? More common?
- Spring scale. Its operation is based on a mechanical spring property, which is that the force exerted by a spring is proportional to the constant of spring elasticity [k] multiplied by the elongation of the spring [x] [F = -kx].
- Sliding weight balance. It has two known masses that can be moved on scales – one with a macro graduation and the other with a micro graduation – by placing a substance of unknown mass on the tray, its weight is determined by sliding the masses on the above scales until the equilibrium position is obtained. At that time the reading is taken by adding up the amounts indicated by the position of the masses on the scales mentioned.
- Analytical balance. It works by comparing known weight masses with the mass of a substance of unknown weight. It is built on a symmetrical bar or lever that is supported by a blade-like support at a central point called a fulcrum. At its ends there are stirrups or bushings that are also supported by blades that allow them to swing smoothly. From there are suspended two dishes. In one are placed the masses or certified weights and in the other those that need to be analyzed. The entire assembly has a locking or locking system that allows the main lever to rest in a stable way when not in use or when changing the counterweights is required. It has an external box that protects the balance from interference, such as air currents, that may occur in the place where it is installed. At present, an analytical balance is considered to be one that can weigh ten thousandths of a gram (0.0001 g) or one hundred thousandths of a gram (0.00001 g); they have a capacity that usually reaches up to 200 grams.
4 . Top plate balance. This type of balance has a load plate placed on top, which is supported by a column that is held upright by two pairs of guides that have flexible couplings.
- Replacement balance. It’s a unique saucer scale. An unknown mass is placed on the weighing plate and balanced by removing masses of known magnitude from the counterweight side using a mechanical cam system until a steady position is reached.
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