IFW is a mechanical switch for the detection and confirmation of liquid flow. The flow body houses a diaphragm responsive to flow rate. A connected rod and lever mechanism triggers a micro switch at a manually adjustable set point. An optiional light, either neon (VAC) or LED (VDC), can indicate operation. Compatible liquids must be non-corrosive to the brass and copper alloy wetted parts and NBR or optional FKM diaphram. Wiring method can be normally open or closed with a range of voltages. A terminal box and CE compliance are also optional.