Liquid flow switches, volumetric are devices with a switch output used for measuring the flow or quantity of a moving fluid in terms of a unit of volume per unit time, such as liters per minute.  The basis of good flow switch selection is a clear understanding of the requirements of the particular application.  Measuring the flow of liquids is a critical need in many industrial plants. In some operations, the ability to conduct accurate flow measurements is so important that it can make the difference between making a profit and taking a loss.  In other cases, inaccurate flow measurements or failure to take measurements can cause serious (or even disastrous) results.