Method and apparatus for detecting fissures in canalizations

摘要

Longitudinal cracks and anomalies may be detected by using four trolleys (11,12,13,14) which are supported at 90 degree intervals around a central structure. Each trolley has wheels (711-715) which are set at an angle to the longitudinal axis such that the trolley pursues a helicoidal path along the inner wall of the conduit. The trolleys have permanent magnets which impose a magnetic field on the conduit wall through trolley brushes, and the strength of the magnetic field is measured by. Hall detectors (82) located in very close proximity to the conduit wall and then processed electronically with other data by electronic processor.