| 摘要 |
<p>The present invention provides a method for locating the longitudinal axis of a branch pipe (2) from a main pipe (1) which method comprises mounting a magnetic field emitter (10) in the branch pipe (2) so that it radiates magnetic lines of force along the branch pipe (2) and into the main pipe (1), and locating the axis of the branch pipe by detecting the primary line of the magnetic flux emitted from the emitter (10) by means of a location device (20, 22) moveable within the main pipe. The method of the invention is of special use in drains which have linings (4). A device for use in the method of the invention is also provided.</p> |
