Manufactured based on proven design of Mid-West, USA, these are rugged in construction, and simple to install. The flow sensor is a multi-ported averaging pitot tube which spans the entire flow profile and produces differential pressure which has square root relationship with flow rate. Based on pipe or duct size the Delta Tube is constructed so that strategically located sensing ports continually sample the impact and static pressures produced by the Delta tube’s obstruction of the flow stream profile. Within the probe the impact pressures sensed by the upstream are continually averaged in an isolated plenum chamber. Similarly the static pressures sensed by the downstream ports are averaged in a second isolated plenum chamber. All conventional secondary instruments can be used for direct measurement, or transmission of the differential pressure produced by the Delta Tube which is proportional to square of flow rate.