Measuring and testing – With fluid pressure – Leakage
Patent
1998-11-10
2000-09-05
Larkin, Daniel S.
Measuring and testing
With fluid pressure
Leakage
73 405R, 324220, 324240, 324243, G01N 2782, G01R 3312
Patent
active
061125806
DESCRIPTION:
BRIEF SUMMARY
The invention concerns an apparatus for status detection, in particular leak detection, in pipelines.
In district heating installations leak signalling including leakage location is effected by means of metallic conductors which are embedded in the thermal insulation of the pipelines (DE 579 184, 637 703, 1 814 857; and 2 337 983). When a leak occurs, the location of the defect can then be found out by resistance measurement or also transit time measurement. The metallic conductors of copper or Ni/Cr are already incorporated into the thermal insulation, which generally consists of polyurethane, in the foaming operation for the production thereof, in the manufacture of the individual pipe portions (`lengths`), in which respect uniform spacings in relation to the medium-bearing pipe are to be observed in order to obtain comparable measurements. During the construction phase, not only the medium-bearing pipes and the protective or outer pipes, but also the leakage signalling conductors have to be connected together, in the region of the pipe-connection locations (sleeves or sockets).
In the case of so-called post-insulation of the connecting sleeves or sockets by the application of polyurethane foam, comparatively high temperatures and comparatively large forces occur within the foam, which in the extreme case result in the electrical connections being torn away between the signalling conductors. Then the entire pipeline region between such torn-away electrical connections ceases to be accessible for monitoring and locating operations.
In the case of pipelines which are designed for temperatures above 130 or 140.degree. C., an insulation which consists of glass fiber cloth and which is applied directly to the medium-bearing pipe is generally used, in addition to the heat-insulating layer of polyurethane. When a leak occurs, the hot water which has passed therethrough can then very rapidly be propagated in the longitudinal direction so that in a few minutes pipeline portions of several hundred meters in length are flooded. Leak signalling in such a situation then only indicates that the entire pipeline length involved has to be renewed.
Accordingly, the object of the present invention is to provide an apparatus for leak detection and location, which avoids the problems with leak signalling conductors in the thermal insulation and which permits leakage points or regions to be reliably and accurately located.
As a sensor unit with an induction coil operates in a passive mode, there is no need for any installed power source, for example in the form of a battery. In addition, a plurality of sensor units which are distributed over a pipe run length do not have to be connected together by way of lines which run in the thermal insulation so that there are no problems in connection with such signalling conductors.
The interrogation unit only has to irradiate a magnetic field into the pipe by means of its exciter coil; the frequency thereof can advantageously be matched to the resonance frequency of the induction coil in the sensor unit or can also be a multiple thereof. To produce a predetermined resonance frequency, a possibly adjustable capacitor can be connected in parallel relationship with the induction coil in the sensor unit. Due to the resonance between the magnetic field which is radiated by the interrogation unit, and the induction coil in the sensor unit, energy is taken from the radiated magnetic field. That fact can be detected in the transmitter and used to locate the sensor unit.
A substantially higher degree of sensitivity, with additional advantages, can be achieved if, in accordance with a development of the invention, the sensor unit has an electronic evaluation unit connected to the induction coil, with a memory and an associated writing and reading circuit. The switching arrangement is then connected to the evaluation unit and the interrogation unit has a programmable control unit. Then, both transmission energy for the sensor unit and also interrogation and programming signals are transmitted by
REFERENCES:
patent: 4377733 (1983-03-01), Yamaguchi et al.
patent: 4843319 (1989-06-01), Lara
patent: 4843320 (1989-06-01), Spies
patent: 5030911 (1991-07-01), Lam
Patent Abstracts of Japan, Publication No. 62237337 dated Oct. 17, 1987, Application Date: Apr. 8, 1986 as No. 61080458 entitled Sodium Leakage Detector.
Larkin Daniel S.
Michael Hesky GmbH
LandOfFree
Device for detecting leaks in pipelines does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for detecting leaks in pipelines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for detecting leaks in pipelines will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2200425