CA2613308C - A method and apparatus to detect and locate damage and breaches in roof membranes - Google Patents
A method and apparatus to detect and locate damage and breaches in roof membranes Download PDFInfo
- Publication number
- CA2613308C CA2613308C CA002613308A CA2613308A CA2613308C CA 2613308 C CA2613308 C CA 2613308C CA 002613308 A CA002613308 A CA 002613308A CA 2613308 A CA2613308 A CA 2613308A CA 2613308 C CA2613308 C CA 2613308C
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- conductor arrangement
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- 239000012528 membrane Substances 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims description 33
- 239000004020 conductor Substances 0.000 claims description 95
- 238000001514 detection method Methods 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 230000000007 visual effect Effects 0.000 claims description 7
- 230000035945 sensitivity Effects 0.000 claims description 5
- 238000005096 rolling process Methods 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 2
- 230000002093 peripheral effect Effects 0.000 abstract 1
- 239000000463 material Substances 0.000 description 6
- 230000035515 penetration Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000004888 barrier function Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 238000010408 sweeping Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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
- G01M3/16—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04D—ROOF COVERINGS; SKY-LIGHTS; GUTTERS; ROOF-WORKING TOOLS
- E04D13/00—Special arrangements or devices in connection with roof coverings; Protection against birds; Roof drainage ; Sky-lights
- E04D13/006—Provisions for detecting water leakage
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04D—ROOF COVERINGS; SKY-LIGHTS; GUTTERS; ROOF-WORKING TOOLS
- E04D15/00—Apparatus or tools for roof working
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Examining Or Testing Airtightness (AREA)
Abstract
A leak in a membrane on top of a horizontal roof deck is located by a manually operable carriage which is swept over the upper surface of the membrane on the roof deck. A measuring and switching circuit generates a voltage having a positive attached to the roof deck and a negative attached to conductive brushes on the carriage. The brushes are arranged to form an outer peripheral contact with an inner contact inside the outer contact. Thus the presence of a leak is detected by the outer set of conductive brushes at distance from the leak and by the inner conductive brush when directly over the leakage site.
Description
A METHOD AND APPARATUS TO DETECT AND LOCATE DAMAGE AND
BREACHES IN ROOF MEMBRANES
The present invention relates to a system for testing roof membranes for damage to and breaches in roof membranes by detection and location of moisture penetration. It has particular application to testing the integrity of low-slope and flat roofs of residential and commercial buildings.
BACKGROUND OF THE INVENTION
The failure to detect, find and correct minor roof deterioration in the earliest stages is considered the greatest cause of premature roof failure.
This is particularly true of roofing materials applied on low-slope or flat roofs.
Costly roofing problems are often the result of design deficiencies or faulty application of the roof system. Even when properly designed and applied, all roofing materials deteriorate from contraction and expansion of roof decks and natural aging processes.
Several methods have been used to try and locate roof leaks after they have occurred. Electric capacitance meters identify leaks using a low-frequency that measures dielectric constant changes in the roofing material as a result of moisture below the membrane. Infrared cameras allow technicians to scan roof surfaces for temperature differentials that signify moist areas through changes in thermal conductivity or evaporation. Electric field vector mapping uses a wire loop around the perimeter of the roof surface to introduce an electric potential between the structural deck and a selected roof area which is sprayed with water. The electric field potential caused by a conductive path to any roof membrane damage is then located using a sensitive voltmeter and a pair of probes.
US Patent 4,565,965 issued Jan 21st 1986 to Geesen discloses an arrangement for detecting leaks in flat roofs in which electrical pulses are transmitted through the moisture in the leak to the roof edge and then the roof is scanned by a pulse sensor and hand-held probe rods to find the leak by locating the maximum amplitude.
The method as described by Geesen requires considerable experience and careful placement of a wire loop around the perimeter of the area to be tested.
In particular, metal roof stacks and drains must be isolated by placing secondary loops around them to avoid false readings pointing towards these penetrations.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an apparatus and method for testing roof membranes for damage to and breaches in roof membranes by detection and location of moisture penetration in a flat or low slope roof construction of the type having an impermeable membrane applied over an underlying horizontal deck.
According to a first aspect of the invention there is provided a method of locating a leak site in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the method comprising:
BREACHES IN ROOF MEMBRANES
The present invention relates to a system for testing roof membranes for damage to and breaches in roof membranes by detection and location of moisture penetration. It has particular application to testing the integrity of low-slope and flat roofs of residential and commercial buildings.
BACKGROUND OF THE INVENTION
The failure to detect, find and correct minor roof deterioration in the earliest stages is considered the greatest cause of premature roof failure.
This is particularly true of roofing materials applied on low-slope or flat roofs.
Costly roofing problems are often the result of design deficiencies or faulty application of the roof system. Even when properly designed and applied, all roofing materials deteriorate from contraction and expansion of roof decks and natural aging processes.
Several methods have been used to try and locate roof leaks after they have occurred. Electric capacitance meters identify leaks using a low-frequency that measures dielectric constant changes in the roofing material as a result of moisture below the membrane. Infrared cameras allow technicians to scan roof surfaces for temperature differentials that signify moist areas through changes in thermal conductivity or evaporation. Electric field vector mapping uses a wire loop around the perimeter of the roof surface to introduce an electric potential between the structural deck and a selected roof area which is sprayed with water. The electric field potential caused by a conductive path to any roof membrane damage is then located using a sensitive voltmeter and a pair of probes.
US Patent 4,565,965 issued Jan 21st 1986 to Geesen discloses an arrangement for detecting leaks in flat roofs in which electrical pulses are transmitted through the moisture in the leak to the roof edge and then the roof is scanned by a pulse sensor and hand-held probe rods to find the leak by locating the maximum amplitude.
The method as described by Geesen requires considerable experience and careful placement of a wire loop around the perimeter of the area to be tested.
In particular, metal roof stacks and drains must be isolated by placing secondary loops around them to avoid false readings pointing towards these penetrations.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an apparatus and method for testing roof membranes for damage to and breaches in roof membranes by detection and location of moisture penetration in a flat or low slope roof construction of the type having an impermeable membrane applied over an underlying horizontal deck.
According to a first aspect of the invention there is provided a method of locating a leak site in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the method comprising:
providing a first conductor arrangement for engaging the roof above the membrane;
providing a return conductor arrangement for electrical connection to the support deck;
generating an electrical potential between the first and return conductor arrangements;
mounting the first conductor arrangement on a carriage which can be moved over the roof so as to scan the first conductor arrangement over selected areas of the roof while the first conductor arrangement remains in contact with the roof as the carriage is moved;
sensing the current flowing from the roof support deck to the first conductor arrangement;
and detecting the changes in current as the first conductor arrangement is scanned over the selected areas of the roof to locate the leak in the ] 5 membrane.
Preferably the carriage is mounted on roller wheels for carrying the carriage in rolling movement over the roof_ However a sliding action without wheels is possible or other transport devices such as rollers may be used.
Preferably the carriage includes a handle such that the carriage can be manually rolled across the roof. However the device may be propelled by other arrangements including robotically.
providing a return conductor arrangement for electrical connection to the support deck;
generating an electrical potential between the first and return conductor arrangements;
mounting the first conductor arrangement on a carriage which can be moved over the roof so as to scan the first conductor arrangement over selected areas of the roof while the first conductor arrangement remains in contact with the roof as the carriage is moved;
sensing the current flowing from the roof support deck to the first conductor arrangement;
and detecting the changes in current as the first conductor arrangement is scanned over the selected areas of the roof to locate the leak in the ] 5 membrane.
Preferably the carriage is mounted on roller wheels for carrying the carriage in rolling movement over the roof_ However a sliding action without wheels is possible or other transport devices such as rollers may be used.
Preferably the carriage includes a handle such that the carriage can be manually rolled across the roof. However the device may be propelled by other arrangements including robotically.
Preferably the first conductor arrangement comprises at least one conductive component arranged for engaging the roof and for sliding over the roof while in contact therewith. This may be a conductive brush with conductive flexible bristles but other flexible conductive members may be used.
Such a member may include a vertically floating support to maintain intimate contact with the roof while accommodating variances in the roof surface.
Preferably the first conductor arrangement includes first and second conductor members which are electrically isolated each other. Preferably the circuit includes first and second circuit sections arranged to independently sense the i0 current flowing from the roof support deck to the first and second conductor members and to detect the changes in current as the first conductor arrangement is scanned over the selected areas of the roof to locate the leak in the membrane.
Preferably the circuit includes two independent leakage current detection components sharing a common power supply source.
Preferably the first conductor member is an inner member and the second member is a perimeter outer member such that both the first inner member and the second outer member engage the roof with the outer member peripherally surrounding the inner member. The outer member can be formed from four brushes in the form of an outer rectangle and the inner conductor may be one or more inner brushes contained within the outer periphery.
Preferably the circuit includes variable sensitivity of the changes and an output display for providing a visual indication of the changes to an operator.
According to a second aspect of the invention there is provided a method of locating a(eakage site in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the method comprising:
Such a member may include a vertically floating support to maintain intimate contact with the roof while accommodating variances in the roof surface.
Preferably the first conductor arrangement includes first and second conductor members which are electrically isolated each other. Preferably the circuit includes first and second circuit sections arranged to independently sense the i0 current flowing from the roof support deck to the first and second conductor members and to detect the changes in current as the first conductor arrangement is scanned over the selected areas of the roof to locate the leak in the membrane.
Preferably the circuit includes two independent leakage current detection components sharing a common power supply source.
Preferably the first conductor member is an inner member and the second member is a perimeter outer member such that both the first inner member and the second outer member engage the roof with the outer member peripherally surrounding the inner member. The outer member can be formed from four brushes in the form of an outer rectangle and the inner conductor may be one or more inner brushes contained within the outer periphery.
Preferably the circuit includes variable sensitivity of the changes and an output display for providing a visual indication of the changes to an operator.
According to a second aspect of the invention there is provided a method of locating a(eakage site in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the method comprising:
5 providing a first conductor arrangement for engaging the roof above the membrane;
providing a return conductor arrangement for electrical connection to the roof support deck;
wherein the first conductor arrangement includes first and second conductor members which are electrically isolated from each other;
wherein the first conductor member is an inner member and the second member is an outer shielding member at least partly surrounding the first inner member;
generating an electrical potential between the first conductor member of the first conductor arrangement and the roof support deck;
generating an electrical potential between the second conductor member of the first conductor arrangement and the roof support deck;
scanning the first conductor arrangement over selected areas of the roof such that both the first inner member and the second outer member engage the roof as the first conductor arrangement is scanned;
independently sensing the current flowing from the roof support deck to the first and second conductor members of the first conductor arrangement;
providing a return conductor arrangement for electrical connection to the roof support deck;
wherein the first conductor arrangement includes first and second conductor members which are electrically isolated from each other;
wherein the first conductor member is an inner member and the second member is an outer shielding member at least partly surrounding the first inner member;
generating an electrical potential between the first conductor member of the first conductor arrangement and the roof support deck;
generating an electrical potential between the second conductor member of the first conductor arrangement and the roof support deck;
scanning the first conductor arrangement over selected areas of the roof such that both the first inner member and the second outer member engage the roof as the first conductor arrangement is scanned;
independently sensing the current flowing from the roof support deck to the first and second conductor members of the first conductor arrangement;
and locating the leakage site by:
detecting changes in the sensed current received by the second outer conductor member at a distance from the a leakage site with the second outer conductor member shielding the first inner conductor member to reduce communication of current thereto from the leakage site;
and detecting the changes in the sensed current received by the first inner conductor member when the first inner conductor member is over the leakage site and the second outer shielding conductor member acts as a shield around the leakage site.
Preferably the circuit includes variable sensitivity of the changes and an output display for providing a visual indication of the changes to an operator so that the operator can detect the presence of a leak in the area of the device and an audible alert for indicating when the inner conductor member is over the leakage site.
According to a third aspect of the invention there is provided an apparatus for locating a leak in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the apparatus comprising:
a conductor arrangement for engaging the roof above the membrane including first and second conductor members which are electrically isolated each other;
detecting changes in the sensed current received by the second outer conductor member at a distance from the a leakage site with the second outer conductor member shielding the first inner conductor member to reduce communication of current thereto from the leakage site;
and detecting the changes in the sensed current received by the first inner conductor member when the first inner conductor member is over the leakage site and the second outer shielding conductor member acts as a shield around the leakage site.
Preferably the circuit includes variable sensitivity of the changes and an output display for providing a visual indication of the changes to an operator so that the operator can detect the presence of a leak in the area of the device and an audible alert for indicating when the inner conductor member is over the leakage site.
According to a third aspect of the invention there is provided an apparatus for locating a leak in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the apparatus comprising:
a conductor arrangement for engaging the roof above the membrane including first and second conductor members which are electrically isolated each other;
a carriage carrying the first and second conductor members which can be moved over the roof so as to scan the members over selected areas of the roof;
wherein the first conductor member is an inner member and the second member is an outer shielding member at least paEtly surrounding the first inner member with both the first inner member and the second outer member engaging the roof;
and a circuit arranged to sense current flowing from the roof support deck to each of the first and second members, the circuit including two independent current detection components respectively for the first and second conductor members;
the circuit being arranged to detect changes in current as the conductor members are moved over the roof.
The device is used in a method in which a power supply potential is applied between the roof deck and the two sets of conductive brushes so that any ] 5 leakage path through the roof membrane to the roof deck will be detected by the first set of conductive brushes at distance from the leak and by the second set of conductive brushes when directly over the leakage site. Usually the selected area to be tested is wetted while reading the outer perimeter display and then sweeping the platform in a covering pattern over the wetted area if the outer perimeter brush detection circuit indicates a leak. The sweeping process is halted and the area directly under the platform examined when the inner brush circuit indicates a leakage by a visual and/or audible response.
wherein the first conductor member is an inner member and the second member is an outer shielding member at least paEtly surrounding the first inner member with both the first inner member and the second outer member engaging the roof;
and a circuit arranged to sense current flowing from the roof support deck to each of the first and second members, the circuit including two independent current detection components respectively for the first and second conductor members;
the circuit being arranged to detect changes in current as the conductor members are moved over the roof.
The device is used in a method in which a power supply potential is applied between the roof deck and the two sets of conductive brushes so that any ] 5 leakage path through the roof membrane to the roof deck will be detected by the first set of conductive brushes at distance from the leak and by the second set of conductive brushes when directly over the leakage site. Usually the selected area to be tested is wetted while reading the outer perimeter display and then sweeping the platform in a covering pattern over the wetted area if the outer perimeter brush detection circuit indicates a leak. The sweeping process is halted and the area directly under the platform examined when the inner brush circuit indicates a leakage by a visual and/or audible response.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:
Figure 1 is an isometric view of a roof membrane on a roof deck including a basic illustration of the sensor brushes and measurement circuits.
Figure 2 is a circuit schematic.
Figures 3A, 3B and 3C show respectively a top plan view, a bottom plan view and a front view of a carriage and sensing system for use in the general method of Figure 1.
DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENT
Referring now to the drawings, the overall arrangement of the subject roof membrane moisture detection system can best be seen with reference to Figure 1. A roof membrane 2 is illustrated which is applied as a direct covering layer over a concrete roof deck 1. The deck is typically of concrete but can be of any suitable material to provide the necessary structural strength and can be steel or wood. The membrane is an impervious material such as plastics and is sealed at any joints to provide a continuous water barrier over the roof deck. This barrier is intended to provide the leak prevention and any penetration therein caused by a puncture or faulty seal or by wear can allow the moisture to penetrate to the deck where it can cause damage or can continue into the structure to cause damage to internal structures.
One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:
Figure 1 is an isometric view of a roof membrane on a roof deck including a basic illustration of the sensor brushes and measurement circuits.
Figure 2 is a circuit schematic.
Figures 3A, 3B and 3C show respectively a top plan view, a bottom plan view and a front view of a carriage and sensing system for use in the general method of Figure 1.
DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENT
Referring now to the drawings, the overall arrangement of the subject roof membrane moisture detection system can best be seen with reference to Figure 1. A roof membrane 2 is illustrated which is applied as a direct covering layer over a concrete roof deck 1. The deck is typically of concrete but can be of any suitable material to provide the necessary structural strength and can be steel or wood. The membrane is an impervious material such as plastics and is sealed at any joints to provide a continuous water barrier over the roof deck. This barrier is intended to provide the leak prevention and any penetration therein caused by a puncture or faulty seal or by wear can allow the moisture to penetrate to the deck where it can cause damage or can continue into the structure to cause damage to internal structures.
The membrane may be covered by a layer of an aggregate material for heat insulation and protection. If used, the aggregate may be loose or may contain a binder such as asphalt. The arrangement described herein can be used with various roof constructions they can range from directly adhered membranes with no ballast (aggregate) to fully built up roofs with gardens.
The basic operation is shown in Figure 1. A typical concrete deck I
over which the non-conducting water proof membrane 2 is applied is illustrated. A
defect in the membrane 3 allows water 4 to intrude and forms a conductive path to the roof deck. The conductive outer 7 brushes and inner 8 brush are placed on the top surface of the membrane 2 with the outer perimeter conductive brushes 7 surrounding the inner brush 8. The brush sets are positioned so as to be in intimate contact with the wetted surface 4 of the test area. The outer sweep detection circuit 5 and inner sweep detection circuit 6 which share a common power supply are connected to the outer brush set 7 and inner brush set 8 respectively with the common positive side of both connected to a grounding point 9 on the deck.
A DC potential is applied between the roof deck 1 and the wetted area 4. At the membrane damage site 4 there is a conductive path through the membrane and a leakage current 10 travels through the damage point and back to the outer conductive brush 7. The return current picked up by the outer brushes is measured and displayed on the outer sweep circuit 5. As the outer brush perimeter surrounds the inner brush sensor, very little of the return current reaches the inner brush 8. The sweep system is then moved forward over the membrane towards the defect and when the outer brush passes over the damage site, the inner brush picks up the return current and provides a visual and audible alarm. The damage site is thereby located.
A detailed schematic of the detector circuit is shown in Figure 2. The 5 roof deck connection 9 is connected to the ground terminal 13 which ties the connecting cable from roof deck to the positive supply 17 of the circuit. The connecting lead from the inner brush 8 is connected to the negative summing input of a first stage Amplifier 14. Diodes DI and D2 provide input protection. The gain of the first stage is set by Resistors R2 and R3 while Capacitor Cl filters out any 10 unwanted noise. The output of Amplifier 14 is tied to the input of a second Amplifier through Resistor R4. Resistors R4, R5 set the gain of the second stage Amplifier to unity. The positive summing input of Amplifier 15 is tied to common through Resistor R6.
A voltage to frequency converter 21 has an input which is connected to 15 the output of Amplifier 15. The output of the voltage to frequency converter is applied to the input of audio Amplifier 23 through volume control 22. The audio output of Amplifier 23 is connected to a speaker 24. The output of Amplifier 15 is applied to voltage divider defined by Resistors R7 and R8 which scales the signal level and applies it to the input of a display driver 19. The display driver 19 is connected to and drives an LED level display 20 of the inner brush.
The entire first and second stage input circuit 18 is duplicated in a second sensing system schematically indicated at 27. The connecting lead from the outer brushes 8 is connected to the input of the second amplifier circuit 27 as indicated at 25. The output of the circuit 27 is applied to display driver 28 which drives a LED level display 29 of the outer brush.
The mechanical arrangement of the apparatus is illustrated in Figure 3.
A horizontal platform or carriage 30 with a flat top wall and a depending side wall 35 forming four sides of a rectangular carriage. The carriage is carried on four swivel wheels or casters 31 attached to the top plate by mountings 36. The carriage supports an outer brush assemblies defined by two parallel front and rear brushes 32 and two parallel side brushes 37, thus defining a rectangular outer area just inside the outside wall of the carriage. Inside the outer rectangular area is provided a single transverse brush defining an inner brush 33. Vertically floating brackets 34 position the outer brushes and allow vertical movement of the brushes as the platform travels over the membrane surface. Similar brackets 38 carry the inner brush. The brushes are formed as a strip from conductive bristles carried on a base so that the base can float upwardly and downwardly from pressure of the roof against the tips of the bristles so that a constant electrical contact is maintained with the roof.
A simple manually graspable handle assembly 40 is attached to brackets 39 on the top plate of the carriage. The sweep circuits are mounted in a housing 41 and attached to the handle 40 assembly at a position below a top hand rail of the handle assembly.
The basic operation is shown in Figure 1. A typical concrete deck I
over which the non-conducting water proof membrane 2 is applied is illustrated. A
defect in the membrane 3 allows water 4 to intrude and forms a conductive path to the roof deck. The conductive outer 7 brushes and inner 8 brush are placed on the top surface of the membrane 2 with the outer perimeter conductive brushes 7 surrounding the inner brush 8. The brush sets are positioned so as to be in intimate contact with the wetted surface 4 of the test area. The outer sweep detection circuit 5 and inner sweep detection circuit 6 which share a common power supply are connected to the outer brush set 7 and inner brush set 8 respectively with the common positive side of both connected to a grounding point 9 on the deck.
A DC potential is applied between the roof deck 1 and the wetted area 4. At the membrane damage site 4 there is a conductive path through the membrane and a leakage current 10 travels through the damage point and back to the outer conductive brush 7. The return current picked up by the outer brushes is measured and displayed on the outer sweep circuit 5. As the outer brush perimeter surrounds the inner brush sensor, very little of the return current reaches the inner brush 8. The sweep system is then moved forward over the membrane towards the defect and when the outer brush passes over the damage site, the inner brush picks up the return current and provides a visual and audible alarm. The damage site is thereby located.
A detailed schematic of the detector circuit is shown in Figure 2. The 5 roof deck connection 9 is connected to the ground terminal 13 which ties the connecting cable from roof deck to the positive supply 17 of the circuit. The connecting lead from the inner brush 8 is connected to the negative summing input of a first stage Amplifier 14. Diodes DI and D2 provide input protection. The gain of the first stage is set by Resistors R2 and R3 while Capacitor Cl filters out any 10 unwanted noise. The output of Amplifier 14 is tied to the input of a second Amplifier through Resistor R4. Resistors R4, R5 set the gain of the second stage Amplifier to unity. The positive summing input of Amplifier 15 is tied to common through Resistor R6.
A voltage to frequency converter 21 has an input which is connected to 15 the output of Amplifier 15. The output of the voltage to frequency converter is applied to the input of audio Amplifier 23 through volume control 22. The audio output of Amplifier 23 is connected to a speaker 24. The output of Amplifier 15 is applied to voltage divider defined by Resistors R7 and R8 which scales the signal level and applies it to the input of a display driver 19. The display driver 19 is connected to and drives an LED level display 20 of the inner brush.
The entire first and second stage input circuit 18 is duplicated in a second sensing system schematically indicated at 27. The connecting lead from the outer brushes 8 is connected to the input of the second amplifier circuit 27 as indicated at 25. The output of the circuit 27 is applied to display driver 28 which drives a LED level display 29 of the outer brush.
The mechanical arrangement of the apparatus is illustrated in Figure 3.
A horizontal platform or carriage 30 with a flat top wall and a depending side wall 35 forming four sides of a rectangular carriage. The carriage is carried on four swivel wheels or casters 31 attached to the top plate by mountings 36. The carriage supports an outer brush assemblies defined by two parallel front and rear brushes 32 and two parallel side brushes 37, thus defining a rectangular outer area just inside the outside wall of the carriage. Inside the outer rectangular area is provided a single transverse brush defining an inner brush 33. Vertically floating brackets 34 position the outer brushes and allow vertical movement of the brushes as the platform travels over the membrane surface. Similar brackets 38 carry the inner brush. The brushes are formed as a strip from conductive bristles carried on a base so that the base can float upwardly and downwardly from pressure of the roof against the tips of the bristles so that a constant electrical contact is maintained with the roof.
A simple manually graspable handle assembly 40 is attached to brackets 39 on the top plate of the carriage. The sweep circuits are mounted in a housing 41 and attached to the handle 40 assembly at a position below a top hand rail of the handle assembly.
Claims (27)
1. A method of locating a leak site in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the method comprising:
providing a first conductor arrangement for engaging the roof above the membrane;
providing a return conductor arrangement for electrical connection to the support deck;
generating an electrical potential between the first and return conductor arrangements;
mounting the first conductor arrangement on a carriage which can be moved over the roof so as to scan the first conductor arrangement over selected areas of the roof while the first conductor arrangement remains in contact with the roof as the carriage is moved;
sensing the current flowing from the roof support deck to the first conductor arrangement;
and detecting the changes in current as the first conductor arrangement is scanned over the selected areas of the roof to locate the leak in the membrane.
providing a first conductor arrangement for engaging the roof above the membrane;
providing a return conductor arrangement for electrical connection to the support deck;
generating an electrical potential between the first and return conductor arrangements;
mounting the first conductor arrangement on a carriage which can be moved over the roof so as to scan the first conductor arrangement over selected areas of the roof while the first conductor arrangement remains in contact with the roof as the carriage is moved;
sensing the current flowing from the roof support deck to the first conductor arrangement;
and detecting the changes in current as the first conductor arrangement is scanned over the selected areas of the roof to locate the leak in the membrane.
2. The method according to Claim 1 wherein the carriage is mounted on roller wheels for carrying the carriage in rolling movement over the roof.
3. The method according to Claim 1 or 2 wherein the carriage includes a handle such that the carriage can be manually rolled across the roof.
4. The method according to any one of Claims 1 to 3 wherein the first conductor arrangement comprises at least one conductive component arranged for engaging the roof and for sliding over the roof while in contact therewith.
5. The method according to Claim 4 wherein the conductive component comprises a conductive brush.
6. The method according to Claim 1 wherein the first conductor arrangement includes first and second conductor members which are electrically isolated from each other, wherein an electrical potential is arranged to be applied between the first conductor member of the first conductor arrangement and the roof support deck and between the second conductor member of the first conductor arrangement and the roof support deck and wherein the current flowing from the roof support deck to the first and second conductor members is independently sensed to detect the changes in current as the first conductor arrangement is scanned over the selected areas of the roof to locate the leak site in the membrane.
7. The method according to Claim 6 wherein there is provided a measuring and switching circuit which includes two independent leakage current detection components sharing a common power supply source.
8. The method according to Claim 6 or 7 wherein the first conductor member is an inner member and the second member is an outer shielding member surrounding the first inner member with both the first inner member and the second outer member engaging the roof.
9. The method according to any one of Claims 1 to 8 wherein the first conductor arrangement includes a vertically floating support to maintain intimate contact with the roof while accommodating variances in the roof surface.
10. The method according to any one of Claims 1 to 9 wherein the circuit includes variable sensitivity of the changes and an output display for providing a visual indication of the changes to an operator.
11. The method according to any one of Claims 1 to 10 wherein the circuit includes an audible alert.
12. A method of locating a leakage site in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the method comprising:
providing a first conductor arrangement for engaging the roof above the membrane;
providing a return conductor arrangement for electrical connection to the roof support deck;
wherein the first conductor arrangement includes first and second conductor members which are electrically isolated from each other;
wherein the first conductor member is an inner member and the second member is an outer shielding member at least partly surrounding the first inner member;
generating an electrical potential between the first conductor member of the first conductor arrangement and the roof support deck;
generating an electrical potential between the second conductor member of the first conductor arrangement and the roof support deck;
scanning the first conductor arrangement over selected areas of the roof such that both the first inner member and the second outer member engage the roof as the first conductor arrangement is scanned;
independently sensing the current flowing from the roof support deck to the first and second conductor members of the first conductor arrangement;
and locating the leakage site by:
detecting changes in the sensed current received by the second outer conductor member at a distance from the a leakage site with the second outer conductor member shielding the first inner conductor member to reduce communication of current thereto from the leakage site;
and detecting the changes in the sensed current received by the first inner conductor member when the first inner conductor member is over the leakage site and the second outer shielding conductor member acts as a shield around the leakage site.
providing a first conductor arrangement for engaging the roof above the membrane;
providing a return conductor arrangement for electrical connection to the roof support deck;
wherein the first conductor arrangement includes first and second conductor members which are electrically isolated from each other;
wherein the first conductor member is an inner member and the second member is an outer shielding member at least partly surrounding the first inner member;
generating an electrical potential between the first conductor member of the first conductor arrangement and the roof support deck;
generating an electrical potential between the second conductor member of the first conductor arrangement and the roof support deck;
scanning the first conductor arrangement over selected areas of the roof such that both the first inner member and the second outer member engage the roof as the first conductor arrangement is scanned;
independently sensing the current flowing from the roof support deck to the first and second conductor members of the first conductor arrangement;
and locating the leakage site by:
detecting changes in the sensed current received by the second outer conductor member at a distance from the a leakage site with the second outer conductor member shielding the first inner conductor member to reduce communication of current thereto from the leakage site;
and detecting the changes in the sensed current received by the first inner conductor member when the first inner conductor member is over the leakage site and the second outer shielding conductor member acts as a shield around the leakage site.
13. The method according to Claim 12 wherein the first conductor arrangement is mounted on a carriage which can be moved over the roof so as to scan the first conductor arrangement over selected areas of the roof while the first and second conductor members remain in contact with the roof as the carriage is moved.
14. The method according to Claim 13 wherein the carriage is mounted on roller wheels for carrying the carriage in rolling movement over the roof and wherein the carriage includes a handle such that the carriage can be manually rolled across the roof.
15. The method according to any one of Claims 12 to 14 wherein the first and second conductor members each are arranged for engaging the roof and for sliding over the roof while in contact therewith.
16. The method according to any one of Claims 12 to 15 wherein the conductor members each comprise a conductive brush.
17. The method according to any one of Claims 12 to 16 wherein the conductor members each include a vertically floating support to maintain intimate contact with the roof while accommodating variances in the roof surface.
18. The method according to any one of Claims 12 to 17 wherein the current is independently sensed by a circuit which includes variable sensitivity of the changes and an output display for providing a visual indication of the changes to an operator.
19. The method according to any one of Claims 12 to 18 wherein the current is independently sensed by a circuit which includes an audible alert for indicating when the inner conductor member is over the leakage site.
20. The method according to any one of Claims 12 to 19 wherein the potential applied across the conductive detectors and the roof deck when selected and across the conductive detectors and the roof deck when not selected is substantially the same.
21. Apparatus for locating a leak in a roof, where the roof comprises a generally horizontal roof support deck with a water impermeable membrane applied onto the upper surface of the support deck, the apparatus comprising:
a conductor arrangement for engaging the roof above the membrane including first and second conductor members which are electrically isolated each other;
a carriage carrying the first and second conductor members which can be moved over the roof so as to scan the members over selected areas of the roof;
wherein the first conductor member is an inner member and the second member is an outer shielding member at least partly surrounding the first inner member with both the first inner member and the second outer member engaging the roof;
and a circuit arranged to sense current flowing from the roof support deck to each of the first and second members, the circuit including two independent current detection components respectively for the first and second conductor members;
the circuit being arranged to detect changes in current as the conductor members are moved over the roof.
a conductor arrangement for engaging the roof above the membrane including first and second conductor members which are electrically isolated each other;
a carriage carrying the first and second conductor members which can be moved over the roof so as to scan the members over selected areas of the roof;
wherein the first conductor member is an inner member and the second member is an outer shielding member at least partly surrounding the first inner member with both the first inner member and the second outer member engaging the roof;
and a circuit arranged to sense current flowing from the roof support deck to each of the first and second members, the circuit including two independent current detection components respectively for the first and second conductor members;
the circuit being arranged to detect changes in current as the conductor members are moved over the roof.
22. The apparatus according to Claim 21 wherein the carriage is mounted on roller wheels for carrying the carriage in rolling movement over the roof.
23. The apparatus according to Claim 21 or 22 wherein the carriage includes a handle such that the carriage can be manually rolled across the roof.
24. The apparatus according to any one of Claims 21 to 23 wherein the conductor members each comprise a conductive brush.
25. The apparatus according to any one of Claims 21 to 24 wherein the conductor members each include a vertically floating support to maintain intimate contact with the roof while accommodating variances in the roof surface.
26. The apparatus according to any one of Claims 21 to 25 wherein the circuit includes variable sensitivity of the changes and an output display for providing a visual indication of the changes to an operator.
27. The apparatus according to any one of Claims 21 to 26 wherein the circuit includes an audible alert for indicating when the inner conductor member is over the leakage site.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002613308A CA2613308C (en) | 2007-12-03 | 2007-12-03 | A method and apparatus to detect and locate damage and breaches in roof membranes |
| AU2008288640A AU2008288640A1 (en) | 2007-08-17 | 2008-08-13 | A method and apparatus to detect and locate roof leaks |
| EP08783367A EP2179259A4 (en) | 2007-08-17 | 2008-08-13 | A method and apparatus to detect and locate roof leaks |
| PCT/CA2008/001457 WO2009023956A1 (en) | 2007-08-17 | 2008-08-13 | A method and apparatus to detect and locate roof leaks |
| US12/646,265 US8319508B2 (en) | 2007-08-17 | 2009-12-23 | Method and apparatus to detect and locate roof leaks |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002613308A CA2613308C (en) | 2007-12-03 | 2007-12-03 | A method and apparatus to detect and locate damage and breaches in roof membranes |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2613308A1 CA2613308A1 (en) | 2008-03-18 |
| CA2613308C true CA2613308C (en) | 2009-01-06 |
Family
ID=39190477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002613308A Expired - Fee Related CA2613308C (en) | 2007-08-17 | 2007-12-03 | A method and apparatus to detect and locate damage and breaches in roof membranes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2613308C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9790688B2 (en) | 2009-03-09 | 2017-10-17 | Smt Research Ltd. | Apparatus, system and method for detecting defects in building structures |
-
2007
- 2007-12-03 CA CA002613308A patent/CA2613308C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9790688B2 (en) | 2009-03-09 | 2017-10-17 | Smt Research Ltd. | Apparatus, system and method for detecting defects in building structures |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2613308A1 (en) | 2008-03-18 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20151203 |