kellukemittari

The kellukemittari, also known as a "bell thermometer" or "float thermometer," is a type of laboratory instrument used for measuring the specific gravity or density of liquids. It typically consists of a glass bulb containing a weight, often made of lead or mercury, at its lower end, and a long, thin stem with a calibrated scale etched onto it. The bulb is designed to be buoyant in the liquid being tested.

The principle of operation relies on Archimedes' principle, which states that a body submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the body. When the kellukemittari is placed in a liquid, it sinks until the buoyant force acting on it equals its own weight. The depth to which it sinks is inversely proportional to the density of the liquid.

A denser liquid will provide a greater buoyant force for a given volume displaced, causing the kellukemittari to float higher. Conversely, a less dense liquid will exert less buoyant force, and the kellukemittari will sink deeper. The calibrated scale on the stem allows for direct reading of the specific gravity or density at the point where the liquid surface intersects the scale.

Kellukemittarit are often used in various applications, including quality control in industries such as brewing, winemaking, and chemical manufacturing. They are relatively simple to use and provide a quick, albeit less precise, method for determining liquid densities compared to more sophisticated instruments like hydrometers or pycnometers. Different kellukemittarit are designed for specific density ranges and temperatures, requiring careful selection for accurate measurements.