A dispensing system for dispensing chemical products to a plurality of utilization points utilizes a multi-port valve to selectively deliver use dilutions from a mixing apparatus to selected utilization points. The multi-port valve utilizes a position sensor to provide positive proof-of-delivery by detecting the angular position of a rotor relative to a stator in the valve. The position sensor includes opposing annular arrangements of detectable elements and proximity detectors which rotate relative to one another about a common axis in response to rotation of the rotor such that detectable elements are oriented in proximity to a unique combination of proximity detectors at each of a plurality of predetermined angular positions. As a result, unique codes are output from the proximity detectors to positively identify positioning of the rotor at the predetermined angular positions.