If the presence of flow in a piping system must be monitored, a calorimetric flow switch ? often known as a flow monitor ? is often used. But so how exactly does a calorimetric flow switch actually work? The following post explains this in more detail.
Calorimetric flow switches, which are often also referred to as thermal flow monitors, use the physical laws of heat transport in flows. Soar is basically made between two technical solutions: continuous and regulated heating.
Schematic illustration of a measuring probe for a calorimetric flow switch
Continuous heating
A flow switch that is using the calorimetric measuring principle consists of a measuring probe with two temperature sensors integrated into it (see illustration). One of the sensors is heated continuously using a heating element (wire-wound) with a continuing heating power and measures the temperature at the heating element. The next sensor determines the temperature of the medium in the pipe. Consequently, Highly Effective occurs between the two sensors, which is registered by the electronics. The bigger the flow velocity of the medium in the offing, the smaller this temperature difference is. The foundation for this may be the cooling aftereffect of flowing media. The molecules in the medium, which are flowing at night probe tip, collect ?packages of heat? and transport them away. The more molecules flow past, the greater the cooling effect. The number of molecules passing by increases continuously with increasing flow velocity.
Regulated heating
The measuring probe is basically identical in design: There are two temperature sensors in the medium, among which may be heated. In this technical solution, the heating power is regulated so the temperature difference between the two temperature sensors is kept constant throughout. Consequently, because the flow velocity increases, the heating power should be increased to keep the size of the temperature difference constant. The applied heating power is thus a primary measure of the flow velocity in the medium.
Note
Do you have further questions on the measuring principle behind the calorimetric flow switch or do you want help with selecting this type of product? In its portfolio, WIKA has a calorimetric flow switch for monitoring the flow of liquid media (model FSD-3). Your contact person will be happy to assist you to.