Kapillarrohre

Kapillarrohre, also known as capillary tubes, are very narrow tubes, typically with a diameter of less than one millimeter. The name "capillary" comes from the Latin word "capillaris," meaning "hair-like," referring to their extremely small size. This narrow bore is the defining characteristic of these tubes and is responsible for their unique physical properties.

The behavior of fluids within kapillarrohre is governed by capillary action, a phenomenon resulting from the interplay of adhesive and cohesive forces. Adhesion refers to the attraction between the fluid molecules and the tube walls, while cohesion describes the attraction between the fluid molecules themselves. If the adhesive forces are stronger than the cohesive forces, the liquid will "wet" the surface and be drawn up into the tube against gravity. The height to which the liquid rises is inversely proportional to the diameter of the tube; the narrower the tube, the higher the liquid will climb. Conversely, if cohesive forces dominate, the liquid may be depressed within the tube.

Kapillarrohre have a wide range of applications across various scientific and industrial fields. In laboratories, they are used for precise measurement of small liquid volumes, in chromatography for sample introduction, and in thermometers to contain and indicate temperature changes via the expansion or contraction of a liquid column. In biology and medicine, they are essential for collecting and transporting blood samples, and in certain diagnostic tests. Industrially, kapillarrohre are utilized in refrigeration systems for refrigerant flow control, in the design of certain types of heat exchangers, and in microfluidic devices for manipulating tiny amounts of fluids. Their ability to control fluid movement and facilitate heat transfer in confined spaces makes them invaluable components in many technologies.