A flow sensor module employs a fitting which defines an offset sensor bypass which is disposed at an acute angle to a linear flow path through the fitting. A dynamic pressure or flow sensor is disposed in the sensor bypass. A bonnet assembly is removably mounted to the fitting and mounts the sensor and fluidly seals the sensor in the fitting. A solid state controller has a panel which indicates a number of operational conditions including whether there is fluid flow through the flow system. The panel may have a chemical feed pump default indicator, a control valve indicator and an air trap device indicator and, in one embodiment, a manual override switch to turn on a feed pump, a control valve, an air trap device or an electrically operated device.

A flow switch assembly features a two-part base assembly having lower and upper base parts. The lower base part is made from a metallic material, adapted on piping having a fluid flow, and configured with a central orifice to receive a paddle arm that pivots on an axis and responds to fluid flow in the piping. The upper base part is made from a non-metallic material, configured with a corresponding central orifice to receive the paddle arm, and configured with a channel to receive a pivot arm to mount and allow the paddle arm to pivot on the axis to actuate an ON/OFF switch in response to fluid flow. The non-metallic material has a lower coefficient of heat transfer than the metallic material to reduce condensation build-up in the flow switch assembly when the flow switch assembly is used in cold applications and exposed to temperatures below freezing.

A flow switch assembly features a two-part base assembly having lower and upper base parts. The lower base part is made from a metallic material, adapted on piping having a fluid flow, and configured with a central orifice to receive a paddle arm that pivots on an axis and responds to fluid flow in the piping. The upper base part is made from a non-metallic material, configured with a corresponding central orifice to receive the paddle arm, and configured with a channel to receive a pivot arm to mount and allow the paddle arm to pivot on the axis to actuate an ON/OFF switch in response to fluid flow. The non-metallic material has a lower coefficient of heat transfer than the metallic material to reduce condensation build-up in the flow switch assembly when the flow switch assembly is used in cold applications and exposed to temperatures below freezing.