A flow meter includes a magnet actuated switch, and an impeller configured to be insertable into a standard NPT ¼″ pipe fitting. Rotation of the impeller in response to a fluid flow actuates the magnet actuated switch with a frequency that is proportional to a flow rate of the fluid flow. The impeller has a cylindrical shaft and a plurality of extensions that extend from the cylindrical shaft that form a spiral shaped cross section. Each extension has an inner curved surface and an outer curved surface, and the inner curved surface is concave shaped to catch the flow of the fluid, and the outer curved surface is convex shaped to provide reduced counter resistance to the rotation of the impeller. A pipe section assembly includes a pipe section including a standard NPT ¼″ pipe fitting and the flow meter vertically inserted into the pipe fitting.