The KOBOLD S-Series flow switches operate on the well-known variable-area principle, but without the use of the open conical measuring tube. Instead, these flow switches use a cylindrical control tube with a conical groove along its axis, which makes for a very compact design. This metal flow switch can be used for continuous monitoring of liquids and gases to ensure that excessive or insufficient flow does not result in damage to equipment. Applications for these variable-area flow switches can be found wherever it is necessary to economically, yet reliably monitor flow conditions.