Non-invasive meter calibrating arrangement

Abstract From the Canadian patent

An arrangement for detecting cycles of operation of a positive displacement diaphragm gas meter sets up a magnetic field which is directed through the non-magnetic housing of the meter toward an internal cyclically moving ferromagnetic element of the meter. The strength of the magnetic field is varied as the ferromagnetic element moves toward and away from the source of the magnetic field. The strength of the magnetic field is detected and an output signal representative thereof is processed to define cycles of operation of the meter.