GB2573992A

GB2573992A - Leak detector

Info

Publication number: GB2573992A
Application number: GB1806013.7A
Authority: GB
Inventors: Kerr Noel; Wilson Richard
Original assignee: Disonics Ltd
Current assignee: Disonics Ltd
Priority date: 2018-04-11
Filing date: 2018-04-11
Publication date: 2019-11-27
Also published as: GB201806013D0

Abstract

A leak detector comprises two wedge units with piezoelectric transducers 7 mounted on the wedge units. The leak detectors is mounted on a suspect pipe (17, fig 4) with the bases 3 of the wedge units touching the pipe: the piezoelectric transducers 7 are pulsed alternately and a time difference between a pulse travelling one way along the pipe compared to the other way along the pipe is taken as indicative of a leak.

Description

LEAK DETECTOR

Technical Field [0001] This invention relates to a detector for detecting leaks in domestic and communal water systems.

Background Art [0002] Known leak detectors for domestic and communal water systems rely on a probe in the water supply to detect a flow in the supply when there should be none. Installing such detectors in an existing system requires turning of the water supply, and installing the probe unit in the supply. Other methods involve monitoring existing water meters for flow when there should be none, however this may only indicate a leak somewhere in a large domestic system but will not isolate the area of the leakage or listening to pipes, perhaps using stethoscopes to hear water flowing - this latter is unreliable because sound passes through pipes and a detected sound could be the sound of water flowing properly in another part of the system.

Disclosure of Invention [0003] According to the present invention a leak detector for a pipe in domestic or communal water system comprises a pair of wedge units having parallel sides, base, top, two ends, one of which is inclined at an acute angle with respect to the base, said inclined end having a piezoelectric transducer mounted in which the wedge units are mounted on the pipe so that the piezoelectric transducers are aligned with each other in the direction of water flow in the said pipe, with the inclined ends of the wedge units facing away from each other so that one inclined end is directed upstream of any flow in the pipe and the other inclined end is directed downstream of any flow in the pipe said wedge units being mounted in slots in a printed circuit board, said circuit board having mounted thereon an analysis system to analyse transmitted and received acoustic pulses of the piezoelectric transducers, the upper part of the wedge units and the piezoelectric transducers being mounted in a pot in a potting compound with the bases of the wedge units being attached to the pipe.

[0004] In one arrangement the wedge units comprise a thermoplastic preferably polyether ether ketone.

[0005] Other features of the invention are described in the examples of the invention described below with reference to the accompanying drawings.

Brief Description of Drawings [0006] Figure 1A shows side view a wedge unit used in the present invention with a piezoelectric transducer in place;

[0007] Figure 1B shows an end of the wedge unit of figure 1A looking in the direction of the arrow;

[0008] Figure 2 shows the leak detector assembled in a pot.

Description of Examples of the Invention [0009] In figures 1A and 1B a wedge unit 1 for use in a leak detector comprises what was originally a rectangular a block of polyether ether ketone (PEEK) with parallel sides 2, a base 3, a top 4 and ends 5 and 6. One end 5 is perpendicular to the base; the other end 6 is cut or machined to incline at an acute angle 8 to the base 3. The nose of the angle 8 is cut off and the base 3 is extended at either end to form lips 9 to enable the wedge unit 1to be mounted in a printed circuit board as described below with reference to figures 2 and 3.

[0010] A rectangular piezoelectric transducer 7, having connecting leads 10, is glued, using Araldite® or similar proprietary adhesive to the inclined end 6.

[0011] In figure 2, two wedge units 1, with the piezoelectric transducers 7 in place, are mounted in longitudinal slots 13 in a rectangular printed circuit board 11. The wedges are aligned longitudinally. The circuit board 11 has mounted thereon a circuit and components 12 for analysing signals from the piezoelectric transducers 7. External connections 14 from the circuit board 11 to a display 20 (in figure 4) are provided. As can be seen the lips 9 of the bases 3 engage the circuit board below the slots 13, so that bases 3 of the wedge units remain exposed.

[0012] The circuit board 12 has holes 15, to receive screws which enable the board to be mounted on the base of a rectangular stainless steel box 16 with the bases 3 of the wedge units exposed as seen in figure 3. The top of the box 16 can be removed to enable the interior of the box to be filled with potting compound of conventional form. The finished leak detection unit 21 may then be attached to a pipe 17 (see figure 4) where a leak may be suspected. The leak detection unit 21 is mounted so that one wedge unit 1 will be upstream of the other whatever the direction of flow of water 18 in the pipe 17. The bases 3 of the wedge units 1 contact the outside of the pipe 17. The transducers 7 which are mounded on inclined ends of the wedge units are indicated. The unit 21 is clamped to the pipe by metal bands 22. The external connections 14 from the circuit board are connected to a display 20.

[0013] As water! 8 passes through the pipe 17, one of the piezoelectric transducers 7A in box 16 is pulsed. The acoustic wave 19 is refracted on entry into water in the pipe and towards the other transducer7B in the pot

16. Depending on the specific configuration and pipe diameter this wave may or may not be reflected from the opposite side of the pipe towards the second transducer 7B or it may pass directly to the second transducer 7B. The pulse is detected by the second transducer 7B, and the time between transmission and detection calculated. The second piezoelectric transducer 7B is then pulsed, and this travels to the first piezoelectric transducer 7A in a similar way where it is detected. If the two time measurements are different, there is water flowing in the pipe, and if this is not intended then a leak is suspected. The alternate pulsing can be undertaken a number of times to be sure of accuracy. The difference between the times taken for the acoustic pulse to travel from the first piezoelectric transducer 7A to the second 7B and vice-versa is an indication of the extent of the leak, the greater the difference the larger the leak.

[0014] In the illustrated example contact between the wedge units 1 and the outside of any pipe 17 can be enhanced by applying a thin layer of silicon grease between the base of the wedge and the outside surface of the pipe.

[0015] There are a number of suitable commercial piezoelectric transducers which can be used with this invention. In the illustrated examples, the transducer used was from PI Ceramics GmbH of Lederhose, Thuringia, Germany - model PIC255.

Claims

1. A leak detector for a pipe in domestic or communal water system comprising a pair of wedge units having parallel sides, base, top, two ends, one of which is inclined at an acute angle with respect to the base, said inclined end having a piezoelectric transducer mounted in which the wedge units are mounted on the pipe so that the piezoelectric transducers are aligned with each other in the direction of water flow in the said pipe, with the inclined ends of the wedge units facing away from each other so that one inclined end is directed upstream of any flow in the pipe and the other inclined end is directed downstream of any flow in the pipe said wedge units being mounted in slots in a printed circuit board, said circuit board having mounted thereon an analysis system to analyse transmitted and received acoustic pulses of the piezoelectric transducers, the upper part of the wedge units and the piezoelectric transducers being mounted in a pot in a potting compound with the bases of the wedge units being attached to the pipe.

2. A leak detector according to claim 1 in which the wedge units comprise polyether ether ketone.