Patent ID: 8561477

Claim:
A fluid flow sensor for use with a dispensing valve having a piston, the sensor comprising: a housing including an externally threaded portion mateable with the dispensing valve; a magnet assembly slidably positioned within the housing, wherein the magnet assembly comprises: a first magnet have a first north pole and a first south pole opposite the first north pole a second magnet having a second north pole and a second south pole opposite the second north pole; and a spacer between the first and second magnets wherein the first and second magnets are oriented such that: when the first north pole is located proximal to the spacer and the first south pole is located distal to the spacer, the second south pole is located proximal to the spacer and the second north pole is located distal to the spacer, or when or the first south pole is located proximal to the spacer and the second north pole is located distal to the spacer, the second north pole is located proximal to the spacer and the second south pole is located distal to the spacer; a piston follower coupled to the magnet assembly and comprising a shoulder portion slidably positioned within the housing; a spring positioned within the housing and operative to bias the magnet assembly and piston follower towards the piston during operation, whereby piston movement is transmitted to the magnet assembly; and a retainer portion disposed on the housing and confronting the shoulder portion whereby the magnet, piston follower, and spring are retained within the housing.