A Lung function test or Pulmonary Function test, PFT for short, is a system to evaluate the respiration system of a patient. It checks how much air a person’s lungs can hold, how quickly he or she can move air in and out of the lungs, or how well the lungs add oxygen to the blood and remove carbon dioxide from the blood. A PFT equipment consists of a Spirometer, and generates a graph which plots the flow of air going in and coming out of the lungs. The patient is given a tube, and told to take in air into the lungs fully, and exhale by blowing into the tube for as long as possible. The Spirometer’s spindle consists of multi-pole magnet and a reed switch which counts the pulses. The pulses generated are used by the PFT’s controller to generate the graph.