FREMGANGSMAATE OG ANORDNING FOR MAGNETISK AVFOELING

摘要

A method and system are described for the contactless sensing of a movable element of a mechanism such as a valve part in a subsea oil pipeline. The movable element (8) is provided with a target magnetic field source (10) which moves with the movable element; a magnetic sensor (9) is placed in proximity with the mechanism so as to give a signal dependent on the orientation of the magnetic flux produced by the target magnetic field source (10). The signal from the magnetic sensor is then processed to provide an indication of the position or orientation of the movable element. In this way there is little danger of contamination of the sensor by leakage from the valve, particularly if a cover (22) is provided, and the sensor can be removed or replaced without disturbing the valve.