GB1574011A - Leak detectors - Google Patents

Leak detectors Download PDF

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Publication number
GB1574011A
GB1574011A GB45776A GB45776A GB1574011A GB 1574011 A GB1574011 A GB 1574011A GB 45776 A GB45776 A GB 45776A GB 45776 A GB45776 A GB 45776A GB 1574011 A GB1574011 A GB 1574011A
Authority
GB
United Kingdom
Prior art keywords
sensing means
leak
electrically conductive
conductive members
leak sensing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB45776A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Atomic Energy Authority
Original Assignee
UK Atomic Energy Authority
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by UK Atomic Energy Authority filed Critical UK Atomic Energy Authority
Priority to GB45776A priority Critical patent/GB1574011A/en
Publication of GB1574011A publication Critical patent/GB1574011A/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/042—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point by using materials which expand, contract, disintegrate, or decompose in contact with a fluid
    • G01M3/045—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point by using materials which expand, contract, disintegrate, or decompose in contact with a fluid with electrical detection means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/16—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Examining Or Testing Airtightness (AREA)

Description

(54) IMPROVEMENTS IN OR RELATING TO LEAK DETECTORS (71) We, UNITED KINGDOM ATOMIC ENERGY AUTHORITY, London, a British Authority, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to leak detectors and particularly to leak sensing means for use in a leak detector.
According to the present invention leak sensing means, for use in a leak detector including an alarm circuit comprises a pair of electrically conductive members separated from each other by insulating material, the arrangement being such that when the leak sensing means is in use and when leakage occurs of a substance the leakage of which is to be detected, the insulating material is capable of being in thermal communication with substance which has leaked, and the insulating material being selected such that it can be converted to such a form, or so modified, by the temperature of a substance, that an electrical characteristic in the region between the two electrically conductive members is altered to provide an electrical signal in the alarm circuit.
The leak sensing means can be incorporated, for example, in a leak detector in which the two electrically conductive members are connected into an electrical circuit including an electrical supply and an alarm.
In one embodiment of the invention the arrangement is such that when the insulating material is converted, or modified, electrical connection is established between the two electrically conductive members.
In one particular example of this embodiment of the invention, suitable for the detection of leakage of liquid metal from a system, the insulating material is such that it is melted by the temperature of the liquid metal so that electrical connection can be established between the two electrically conductive members.
One of the electrically conductive members may be such that it can be penetrated by the liquid metal to facilitate further the establishment of electrical connection between the two electrically conductive members. To assist penetration by the liquid metal one of the electrically conductive members may be perforated.
The electrically conductive members can be, for example, in the form of thin sheets of metal (e.g. aluminium foil) separated by a layer of insulating material. The insulating material can be, for example, a plastics material (e.g. in the form of a plastic coating on the metal foil) or a substance such as a coating of polyurethane varnish applied to at least one of the electrically conductive members.
In a second embodiment of the invention, suitable for the detection of leakage of a non-conducting liquid substance, the arrangement is such that although electrical connection is not established between the two electrically conductive members, the electrical resistance between the members is altered.
Thus in accordance with this second embodiment, the leak sensing means may be, for example, incorporated as a resistance in an AC electrical circuit, such that when insulating material is converted or modified, the resistance drops and operates an alarm by putting the circuit out of balance.
Alternatively to establishing electrically conductive members, or altering the electrical resistance in the region between them (as hereinbefore disclosed) other electrical characteristics of the region between the electrically conductive members may be altered to give a signal to an alarm, e.g. capacitance and inductance.
A leak detector incorporating a leak sensing means in accordance with the present invention will now be described, by way of example, with reference to the single figure of the drawing accompanying the Provisional Specification which is a diagrammatic representation of a leak detector for use in detecting the leakage of a hot substance.
Referring now to the figure, there is provided a leak sensing means comprising two electrically conductive members in the form of thin (0.003 in. thickness )aluminium sheets 1 and 2, separated from each other by an insulating material in the form of a thin coating of polyurethane varnish 3.
The sheet 1 is electrically connected by conductor 4 to one terminal of an electrical supply 5 and a sheet 2 is electrically connected by conductor 6 to an alarm bell 7 which is in turn connected to a second terminal of the electrical supply 5 by conductor 8.
In operation, the leak sensing means, comprising the sheets 1 and 2 and the coating of polyurethane varnish 3, is arranged so that sheet 1 is above sheet 2 and placed under a system containing a hot substance (e.g. liquid sodium) the leakage of which is to be detected.
In the event of a leak occurring in the system the hot substance falls onto the upper sheet 1, the heat causes the polyurethane varnish 3 to melt and to allow the two sheets 1 and 2 to come into contact.
An electrical circuit incorporating the electrical supply 5 and an alarm bell 7 is thereby completed and the alarm bell 7 is sounded giving warning of a leak in the system.
It will be appreciated that leak sensing means in accordance with the present invention finds application in the detection of leaks in regions of a system not accessible during operation. Such systems include apparatus containing liquid metals, for ex ample, experimental rigs.
In the case of apparatus containing liquid sodium (e.g. experimental liquid sodium rigs) aluminium is preferred for the electrically conductive members since, in the event of a leak, liquid sodium would attack the aluminium with the result that penetration to the insulating layer would be assisted.
It will be appreciated that the present invention can provide leak sensing means which can be shaped according to dimensional requirements dictated by the system to be monitored for leaks. Thus, in one form, leak sensing means comprising a composite sheet consisting of two sheets of metal foil separated by an insulating layer, could be manufactured in lengths or rolls, cut to a given shape to suit particular requirements and placed as desired under the system to be monitored.
WHAT WE CLAIM IS: 1. Leak sensing means, for use in a leak detector including an alarm circuit, comprising a pair of electrically conductive members separated from each other by insulating material, the arrangement being such that when the leak sensing means is in use and when leakage occurs of a substance the leakage of which is to be detected, the insulating material is capable of being in thermal communication with the substance which has leaked, and the insulating material being selected such that it can be converted to such a form, or so modified by the tem perature of the substance, that an electrical characteristic in the region between the two electrically conductive members is altered to provide an electrical signal in the alarm circuit.
2. Leak sensing means as claimed in claim 1 wherein the arrangement is such that when the insulating material is converted, or modified, electrical connection is established between the two electrically conductive members.
3. Leak sensing means as claimed in claim 2, and suitable for the detection of leakage of liquid metal from a system, wherein the insulating material is such that it is melted by the temperature of the liquid metal so that electrical connection can be established between the two electrically conductive members.
4. Leak sensing means as claimed in claim 3 wherein one of the electrically conductive members is such that it can be penetrated by the liquid metal to facilitate further the establishment of electrical connection between the two electrically conductive members.
5. Leak sensing means as claimed in claim 4 wherein to assist penetration by the liquid metal one of the electrically conductive members is perforated.
6. Leak sensing means as claimed in any one of claims 1 to 5 wherein the electrically conductive members are in the form of thin sheets of metal.
7. Leak sensing means as claimed in claim 6 wherein the thin sheets of metal are of aluminium foil.
8. Leak sensing means as claimed in any one of claims 1 to 7 wherein the insulating material is a layer of plastics material.
9. Leak sensing means as claimed in any one of claims 1 to 7 wherein the insulating material is a coating of polyurethane varnish applied to one of the electrically conductive members.
10. Leak sensing means as claimed in claim 1, and suitable for the detection of leakage of a non-conducting liquid substance wherein the arrangement is such that although electrical connection is not estab
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (15)

**WARNING** start of CLMS field may overlap end of DESC **. example, with reference to the single figure of the drawing accompanying the Provisional Specification which is a diagrammatic representation of a leak detector for use in detecting the leakage of a hot substance. Referring now to the figure, there is provided a leak sensing means comprising two electrically conductive members in the form of thin (0.003 in. thickness )aluminium sheets 1 and 2, separated from each other by an insulating material in the form of a thin coating of polyurethane varnish 3. The sheet 1 is electrically connected by conductor 4 to one terminal of an electrical supply 5 and a sheet 2 is electrically connected by conductor 6 to an alarm bell 7 which is in turn connected to a second terminal of the electrical supply 5 by conductor 8. In operation, the leak sensing means, comprising the sheets 1 and 2 and the coating of polyurethane varnish 3, is arranged so that sheet 1 is above sheet 2 and placed under a system containing a hot substance (e.g. liquid sodium) the leakage of which is to be detected. In the event of a leak occurring in the system the hot substance falls onto the upper sheet 1, the heat causes the polyurethane varnish 3 to melt and to allow the two sheets 1 and 2 to come into contact. An electrical circuit incorporating the electrical supply 5 and an alarm bell 7 is thereby completed and the alarm bell 7 is sounded giving warning of a leak in the system. It will be appreciated that leak sensing means in accordance with the present invention finds application in the detection of leaks in regions of a system not accessible during operation. Such systems include apparatus containing liquid metals, for ex ample, experimental rigs. In the case of apparatus containing liquid sodium (e.g. experimental liquid sodium rigs) aluminium is preferred for the electrically conductive members since, in the event of a leak, liquid sodium would attack the aluminium with the result that penetration to the insulating layer would be assisted. It will be appreciated that the present invention can provide leak sensing means which can be shaped according to dimensional requirements dictated by the system to be monitored for leaks. Thus, in one form, leak sensing means comprising a composite sheet consisting of two sheets of metal foil separated by an insulating layer, could be manufactured in lengths or rolls, cut to a given shape to suit particular requirements and placed as desired under the system to be monitored. WHAT WE CLAIM IS:
1. Leak sensing means, for use in a leak detector including an alarm circuit, comprising a pair of electrically conductive members separated from each other by insulating material, the arrangement being such that when the leak sensing means is in use and when leakage occurs of a substance the leakage of which is to be detected, the insulating material is capable of being in thermal communication with the substance which has leaked, and the insulating material being selected such that it can be converted to such a form, or so modified by the tem perature of the substance, that an electrical characteristic in the region between the two electrically conductive members is altered to provide an electrical signal in the alarm circuit.
2. Leak sensing means as claimed in claim 1 wherein the arrangement is such that when the insulating material is converted, or modified, electrical connection is established between the two electrically conductive members.
3. Leak sensing means as claimed in claim 2, and suitable for the detection of leakage of liquid metal from a system, wherein the insulating material is such that it is melted by the temperature of the liquid metal so that electrical connection can be established between the two electrically conductive members.
4. Leak sensing means as claimed in claim 3 wherein one of the electrically conductive members is such that it can be penetrated by the liquid metal to facilitate further the establishment of electrical connection between the two electrically conductive members.
5. Leak sensing means as claimed in claim 4 wherein to assist penetration by the liquid metal one of the electrically conductive members is perforated.
6. Leak sensing means as claimed in any one of claims 1 to 5 wherein the electrically conductive members are in the form of thin sheets of metal.
7. Leak sensing means as claimed in claim 6 wherein the thin sheets of metal are of aluminium foil.
8. Leak sensing means as claimed in any one of claims 1 to 7 wherein the insulating material is a layer of plastics material.
9. Leak sensing means as claimed in any one of claims 1 to 7 wherein the insulating material is a coating of polyurethane varnish applied to one of the electrically conductive members.
10. Leak sensing means as claimed in claim 1, and suitable for the detection of leakage of a non-conducting liquid substance wherein the arrangement is such that although electrical connection is not estab
lished between the two electrically conductive members, the electrical resistance between the members is altered.
11. Leak sensing means as claimed in claim 10, for incorporation as a resistance in an AC electrical circuit wherein the arrangement is such that when insulating material is converted or modified, the resistance drops and operates an alarm by putting the circuit out of balance.
12. Leak sensing means as claimed in claim 1 wherein the electrical characteristic in the region between the electrically conductive members which is altered is capacitance or inductance.
13. A leak detector incorporating a leak sensing means as claimed in any one of claims 1 to 12, the electrically conductive members being connected into an electrical circuit including an electrical supply and an alarm.
14. A leak sensing means, for use in a leak detector including an alarm circuit, substantially as hereinbefore described with reference to the single figure of the drawing accompanying the Provisional Specification.
15. A leak detector substantially as hereinbefore described with reference to the single figure of the drawing accompanying the Provisional Specification.
* r
GB45776A 1977-01-06 1977-01-06 Leak detectors Expired GB1574011A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB45776A GB1574011A (en) 1977-01-06 1977-01-06 Leak detectors

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB45776A GB1574011A (en) 1977-01-06 1977-01-06 Leak detectors

Publications (1)

Publication Number Publication Date
GB1574011A true GB1574011A (en) 1980-09-03

Family

ID=9704687

Family Applications (1)

Application Number Title Priority Date Filing Date
GB45776A Expired GB1574011A (en) 1977-01-06 1977-01-06 Leak detectors

Country Status (1)

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GB (1) GB1574011A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2619890A1 (en) * 1987-08-25 1989-03-03 Electricite De France System for detecting a leak in a high-temperature fluid pipe
FR2770021A1 (en) * 1997-10-22 1999-04-23 Doryokuro Kakunenryo MULTI-SHEATH SODIUM LEAK DETECTION APPARATUS

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2619890A1 (en) * 1987-08-25 1989-03-03 Electricite De France System for detecting a leak in a high-temperature fluid pipe
FR2770021A1 (en) * 1997-10-22 1999-04-23 Doryokuro Kakunenryo MULTI-SHEATH SODIUM LEAK DETECTION APPARATUS

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PCNP Patent ceased through non-payment of renewal fee