GB2056076A

GB2056076A - Measuring internal pressure in pipes

Info

Publication number: GB2056076A
Application number: GB8019555A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-06-20
Filing date: 1980-06-16
Publication date: 1981-03-11
Also published as: JPS566131A; AT373393B; GB2056076B; CH647328A5; FR2459464B1; ATA436879A; JPS5942250B2; IT1131359B; FR2459464A1; DE3021919A1; IT8022879A0; DE3021919C2

Abstract

In a pick-up device for measuring internal pressure in pipes, in order to avoid the complications presented by bipolar take-off from measuring elements (6, 7) in two housing parts (2, 3), a hinge pin (4') and parts (18, 22, 22') mounted thereon are utilised to conduct the signals from the device. Elements (6,7) arranged in arcuate recesses in each housing half (2, 3) may comprise piezoelectric foils, capacitance foils, or simply an electrically conducting foil (20). The pipe itself may be used as one electrode. The take-off for the outer poles 14 of the measuring elements (6, 7) is through staggered bridge pieces (16, 17) in contact with the hinge pin (4') and the take-off for the inner poles is through the conductive elements (18, 22, 22') mounted on but insulated from the hinge pin (4'). The take-offs lead to blade terminals (18, 19) or a bipolar socket for the amplifier connection. <IMAGE>

Description

SPECIFICATION Test-data-pick-up device for measuring internal pressure in pipes This invention relates to a test-data-pick-up device for measuring internal pressure in pipes, comprising two housing parts which are articulately connected with one another by a connecting element and adapted to be clamped fast on the pipe to be tested, each housing part containing at least one measuring element with bipolar take-off for the test signals.

In test-data-pick-up devices of this kind it is known to employ measuring elements which, in order to compensate for spurious, interfering signals generated by the bending of, or oscillations in the pipe, are arranged in the device in two juxtaposed elements so as to allow electrical compensation for such interfering signals.

For each attachment and removal of a pick-up device of this kind to and from a pipeline at any time, the housing consists of two parts hinged on one side thereof to a connecting element so that it can be readily positioned over a pipe and the two parts hinged towards each other to close the housing. Subsequently the pick-up device is clamped fast on the pipe by means of screws or with the aid of a turnbuckle or snap fastener on the side thereof which is opposite the connecting element.

The relative movability of the two housing parts, whilst being necessary for operative application of the pick-up to the pipe, creates problems in respect of the manner in which the take-off terminals of the measuring elements are conducted out of the housing so that the test signals emitted by these elements can be evaluated.

It is possible, for example, to combine the terminals of all the measuring elements in each housing part and conduct the test signals from each housing part out of the device separately by means of a connector plug or a fixed, that is, permanently attached, cable. Alternatively, a connector plug or a permanently attached cable, could be provided on one of the two housing parts, the connection with the output terminals of the second housing part being made by a connecting cable of minimum length arranged on the pick-up device. It is very important to ensure that this short connecting cable cannot be damaged when the two housing parts of the device are opened and closed.

However, both these methods entail an increase in respect of weight and size of the pickup device in as much as they require either two bipolar connecting plugs or separate, electrically insulating and tension-relieving extents of the connecting cable which are led through the pickup housing. In view of the fast that the small overall size and low weight of pick-ups of the kind specified contribute greatly to a reduction of spurious interference signals, neither of these two methods is particularly suitable.

It is the aim of the present invention to arrange for the test signals to be taken from test data pick up devices of the kind specified in a simple, operatively safe, space and weight saving manner and without requiring additional connecting cables between the two parts of the housing.

The present invention consists in a test-data pick-up device for measuring internal pressure in pipes, comprising two housing parts which are articulately connected with one another by a connecting element and adapted to be clamped fast on the pipe, each housing part containing at least one measuring element with a bipolar take off of test signals, characterised in that at least one pole of each bipolar take-off is electrically connected with the connecting element which connecting element is electrically insulated relative to the other pole and that the connecting element comprises at least one terminal for the further conduction or transmission of the test signals.

The other pole of the above defined pick-up device is, where applicable, in direct connection with the pipe under test.

By a connection of the poles of each measuring element with the corresponding poles of the measuring element opposite thereto in the other housing part a convenient and easy way is created of achieving electrical compensation for the interfering signals within the pick-up device itself, thus replacing the two separate, in each case, bipolar means of conduction of the test signals out of the two housing parts with a single combined bipolar output lead for the fully compensated test signals from the pick-up.

According to a further feature of the invention the electrical connection between one pole of each take-off and the connecting element consists of contact bridge pieces which, on the one hand embrace the connecting element for the two housing parts in cup or shell-like manner and, on the other hand, are so arranged in the housing as to make safe and reliable contact with the corresponding pole of the measuring element.

Such an arrangement ensures a simple electrical connection without entailing additional assembly costs.

According to a further feature of this invention at least one of the parts of the connecting element which is connected with one of the terminal poles may comprise connector means, for example a blade terminal. Owing to the provision of this connector on the connecting element any additional outlay for conducting the test signals out of the pick-up housing can be kept very low.

In a further feature of the invention one part of the connecting element between the two housing parts may be an electrically conducting pin, supported in both housing parts and providing the hinge or articulation means between the housing parts. This very simple and basic form of hinged joint between the two housing parts also affords a simple and secure transmission of test signals.

According to another feature of the invention the connecting element may comprise a connector part which is in electrical connection with the other pole of each signal take-off and which is electrically insulated relative to the pin.

In this case one pole of the signal take-off is electrically connected to the pin, but the connecting element comprises a connector part which is electrically insulated relative to the pin and through which the desired combined single output lead from the other pole of the pick-up is made. This arrangement makes it possible to take full advantage of an essential feature of this invention, namely that any interference signals are electrically compensated for within the pick-up device itself so that the test signals from both housing parts can be conducted jointly out of the device even if the latter is applied to painted, varnished or otherwise electricallynon-conducting pipes.

According to a further embodiment of the invention the other pole of each measuring element take-off may be electrically connected to the connector part by means of scissor-like movable contact blades. This ensures durable and reliable contacting of the other take-off pole relative to the connector part even after frequently repeated opening and closing of the pick-up housing.

According to another feature of this invention the connector part may be designed as the first contact and the end of the pin may be designed as the second contact of a bipolar connector sleeve, or socket. This has the advantage that the amplifier cable requires only a single plug and the co-action with the connector socket according to this invention ensures a simple and secure electric connection between measuring element and amplifier.

Furthermore, according to this invention both housing parts of the pick-up device may be made of an electrically insulating material, especially a plastics material, and are preferably made as injection mouldings. This not only eliminates all problems regarding relative insulation of the various terminals in the housing but makes for easy and inexpensive production of the pick-up device. The comparatively low application forces required for the reliable functioning of test-data pick-up devices of the kind specified can be easily met by plastics injection mouldings of this type.

According to a further feature of this invention the contact bridge pieces which make the electrical connection between the terminals of one pole on the measuring element and the pin may be integrated in the housing parts, preferably as integral parts of the injection moulding. Such an arrangement also contributes to simplified production as well as ensuring the rigid location of the contact bridge pieces in the housing which in turn enables a secure and reliable transmission of the test signals from the measuring elements to the pin.

The invention is hereinafter more particularly described with reference to the embodiments shown by way of example in the accompanying drawings wherein: Figure 1 is a side view of a test-data-pick-up device having a unipolar take-off of the test signals through the pin of the connecting element the other pole being through the pipe itself, Figure 2 shows the pick-up according to Figure 1 in open position and partly in section, Figure 3 is a side view of a pick-up with bipolar take-off for the test signals through the pin of the connecting element, Figure 4 shows the pick-up of Figure 3 in open position and partly in section, Figure 5 is a side view of a pick-up with bipolar take-off through the connecting element which latter comprises a bipolar connector sleeve or socket, and Figure 6 shows the pick-up according to Figure 5 in open position.

The housing 1 of the pick-up comprises two housing parts 2 and 3 which, for easy application to a pipe, not shown, are articulately connected on one side thereof by means of the connecting element 4 which latter comprises a hinge pin 4', whilst on the other side they are provided with a suitable tensioning or fastener device allowing a force in direction of arrows 5 to be applied and thus to clamp the two housing parts 2, 3 fast on the pipe to be tested.The measuring elements 6, 7 are so arranged in housing parts 2 and 3 as to extend each in a substantially semi-circular arc around the pipe when the device is clamped fast thereon and when the tensioning or clamping device is operative, that is in the presence of a clamping force in the direction of arrows 5, they are pressed against the pipe by the elastic supporting elements 8 and 9 thus ensuring frictional transmission of pipe surface deformations to the measuring elements 6 and 7.

The semi-circular recesses 10, 11, 12 and 13 in the two housing parts 2 and 3 are so designed as to have a firm grip on the pipe when the pick-up is clamped fast on the pipe so that the application force applied by the elastic elements 8 and 9 to the measuring elements 6 and 7 relative to the pipe is independent of the clamping force which is effective in the direction of arrows 5. This also ensures that the pick-up device as a whole sits firmly on the pipe and pipe vibrations are distributed throughout the housing 1 so that in use they do not affect or distort the test signal.

The measuring elements 6 and 7 may be, for -example, piezoelectric foils wherein, in accordance with the familiar piezo principle, tension compression variations generate electric charges at the foil surface which are taken off in bipolar form through electrically conducting contact layers applied by vapour deposition to both sides of the foil, and appropriately further processed.

Alternatively, capacitive measuring foils may be used in which case the foil would consist of at least two electrode layers separated by an elastic insulating layer, which together form a condenser.

The pipe itself may also be used as an electrode.

Any circumferential variation of the pipe entails a variation in electrode spacing so that the capacitance of the condenser is correspondingly varied and this allows the conversion of a pressure variation into a test signal.

Ç According to Figure 2, the outer poles 14, that is the electrically conducting contact layers of the measuring elements 6 and 7 which in the fitted position of the pick-up device are further away from the pipe, are electrically connected via contact bridge pieces 1 6, 1 7 with the pin 4'. The end of the pin 4' which protrudes from the housing 1 carries a blade terminal 1 9 designed for the connection thereto of the amplifier connection cable, not shown.

The two housing parts 2 and 3 are plastics injection mouldings. This makes it an easy matter to make the external electrical connection of the inner poles 1 5 of each bipolar take-off, that is those poles which are nearer to the pipe when the device is in situ, directly through the pipe on which the device is clamped fast because the pin 4', which is electrically connected with the outer poles 14, is electrically insulated relative to the pipe by the plastics housing 1.

In the embodiment of Figure 3 and 4, in order to obtain a simple and secure take-off for the test signals in pick-up devices which are designed for application to painted or otherwise electrically non-conducting pipe surfaces, the inner pole 1 5 of each of the two measuring elements 6 and 7 is provided with an electrically conducting protective foil 20, which may consist of copper-beryllium.

Each of these protective foils 20 is connected by means of a soidered terminal 21 to a contact strip 22, 22'. An insulating sleeve 23 which is fitted at the end of the pin 4' carries the contact strips 22, 22' which are thereby pivoted together like a pair of scissors. The contact strips 22, 22' are external of the housing 1 as well as a connector part 18, which in this arrangement is in the form of a blade terminal.In this manner the insulating sleeve provides for the electrical insulation of the contact strips 22, 22' and the connector part 1 8 relative to the pin, these parts being electrically connected to the inner poles 1 5. The pin 4, as already described in connection with Figures 1 and 2, is electrically connected via contact bridge pieces 1 6 and 17 to the outer pole 14 of each of the measuring elements 6 and 7 and also carries a blade terminal 1 9 at its end opposite the insulating sleeve 23.

In the arrangement shown in Figures 5 and 6 the connecting element is designed at one end as a bipolar connecting socket 24 for an amplifier connecting cable, not shown. The connector part 1 8 which is electrically insulated by the sleeve 25 and insulating washer 28 relative to pin 4' is provided with an annular washer 30 next to the housing 1 and arranged as a first contact 26 whilst the end of the pin 4' is arranged as the second contact 27 of the bipolar connector socket 24. In this embodiment also the connection between the outer poles 14 of the measuring elements 6 and 7 and the pin 4' is made by contact bridge pieces 1 6 and 17'. The electrically conducting protective foils 20 which are in contact with the inner poles 1 5 of the measuring elements 6 and 7 are provided with extended terminal portions 29 which are arranged in the two housing parts 2 and 3 in such a way as to be electrically connected with the first contact 26 of the bipolar connector socket 24.

It will be appreciated that owing to the electrical connection of the corresponding poles of the measuring elements which are opposite each other when the device is clamped fast on the pipe, compensation for interfering signals generated by distortions and oscillations of the pipe is also fully accomplished within the pick-up device according to the embodiments shown in Figures 3 to 6, that is to say prior to the final take-off of the test signals from the device and their further transmission can be arranged in a very simple and convenient manner.

Claims

1. A test-data pick-up device for measuring internal pressure in pipes, comprising two housing parts which are articulately connected with one another by a connecting element and adapted to be clamped fast on the pipe, each housing part containing at least one measuring element with a bipolar take-off of test signals, characterised in that at least one pole of each bipolar take-off is electrically connected with the connecting element which connecting element is electrically insulated relative to the other pole and that the connecting element comprises at least one terminal for the further conduction or transmission of the test signals.

2. A test-data pick-up device as claimed in claim 1, in which the other pole of said bipolar take-off is adapted to be in direct electrical conductive connection with the pipe.

3. A pick-up device according to claim 1 or claim 2, in which the electrical connection between one pole of each bipolar take-off and the connecting element is made by means of contact bridge pieces.

4. A pick-up device according to any of claims 1 to 3, in which the connecting element comprises one or more parts which, or at least one of which, is connected to one of the poles of the take-off and comprises terminal means.

5. A test-data pick-up device as claimed in claim 4 in which the terminal means is a substantially flat connecting plate.

6. A pick-up device according to any of the preceding claims in which the connecting element comprises an electrically conducting pin supported in oth housing parts and providing the articulated connection or hinged joint of the housing parts.

7. A pick-up device according to claim 6, in which the connecting element comprises a connector part which is electrically connected with the other pole of each take-off and electrically insulated relative to the pin.

8. A pick-up device according to claim 7, in which the other pole of each take-off is electrically connected with the connector part by means of movable scissor-like contact blades.

9. A pick-up device according to claim 7, in which the connector part serves as the first contact and the end of the pin as the second contact of a bipolar connector socket.

10. A pick-up device according to any one of claims 1 to 9, in which the two housing parts are made from an electrically insulating material.

11. A test-data pick-up device as claimed in claim 10 in which the insulating material is a plastics material.

12. A test-data pick-up device as claimed in claim 10 or claim 1 in which the two housing parts are injection mouldings.

13. A pick-up device according to claim 3 or any of claims 4 to 12 as appendant to claim 3 in which the contact bridge pieces are integral with the housing parts.

14. A pick-up device as claimed in claim 13 in which the contact bridge pieces are integrally moulded into the housing parts.

1 5. A pick-up device substantially as hereinbefore described with reference to, and as illustrated by Figures 1 and 2 of the accompanying drawings.

16. A pick-up device substantially as hereinbefore described with reference to and as illustrated by Figures 3 and 4 of the accompanying drawings.

1 7. A pick-up device substantially as hereinbefore described with reference to and as illustrated by Figures 5 and 6 of the accompanying drawings.