Precalibrated flow meter with airflow compensator

An air flow compensator which comprises:

• a fluid flow passage having an inlet end and an outlet end;
• a proximity sensor positioned adjacent the outlet end of the fluid flow passage;
• a main slide element having a magnetic element in one end, the main slide element moveable between a first position in which the magnetic element is spaced away from the proximity sensor and a second position in which the magnetic element is near the proximity sensor;
• a secondary slide element positioned on the main slide element for movement therewith and for independent movement along the main slide element, the secondary slide element being positioned within the fluid flow passage so as to determine the amount of fluid that can flow therethrough;
• a first spring element that biases the secondary slide toward the inlet end of the fluid flow passage;
• and
• a second spring element that biases the main slide element toward the inlet end of the fluid flow passage.