WO2022165643A1

WO2022165643A1 - An apparatus for detecting dry trap in drain pipe

Info

Publication number: WO2022165643A1
Application number: PCT/CN2021/074910
Authority: WO
Inventors: Pui Tong Paul Lee; Ka Kui Cheng; Yau Dik CHEUNG; Ka Wing LAU; Chi Kwan HO; Wa Kin HAU; Kai-Yuan Chris LEE; Wai Hey Willie IP; Kei Kwan LUI
Original assignee: Lok Wing Investment & Development Co. Limited
Priority date: 2021-02-02
Filing date: 2021-02-02
Publication date: 2022-08-11

Abstract

An apparatus for detecting dry trap in a U-bend, comprising: a housing (101,201,301) configured to be secured around the U-bend; a sensor circuit within the housing (101,201,301) and having the electrically conductive first and second ends (102,202,302; 103,203,303) configured to puncture through the wall of the U-bend when the apparatus is installed, wherein the sensor circuit is configured to form an electrically closed-loop circuit when both of the first and second ends (102,202,302;103,203,303) are in contact with liquid inside the U-bend, or otherwise an opened-loop circuit. Therefore, a dry trap is detected when one or both of the first and second ends (102,202,302; 103,203,303) lose contact with liquid when the U-bend is not filled with liquid. Alternatively, the capacitive sensor (402,502,602) is used in place of the electrically conductive first and second ends (102,202,302; 103,203,303). In this case, the U-bend wall is not needed to be punctured as the capacitive sensor (402,502,602) can contactless-detect the liquid in the U-bend.

Description

AN APPARATUS FOR DETECTING DRY TRAP IN DRAIN PIPE

Inventors: Pui Tong Paul LEE, Ka Kui CHENG, Yau Dik CHEUNG, Ka Wing LAU, Chi Kwan HO, Wa Kin HAU, Kai-yuan Chris LEE, Wai Hey Willie IP, and Kei Kwan LUI

Field of the Invention:

The present invention relates generally to plumbing systems and techniques; particularly, the present invention relates to traps or U-bends that are used primarily in preventing unwanted liquid and gas flow from sewer.

Background of the Invention:

In plumbing, the U-trap, P-trap, and S-trap are some of the more popular types of traps and they normally deploy a U-bend, which appears to be a U-shaped portion of the drain pipe. The U-bend is designed to trap liquid or gas to prevent unwanted flow; most notably sewer gases and pests from entering the premises while allowing discharging liquid to pass through. In a building where multiple rooms share the same sewer pipe, the U-bend also prevents airborne bacteria, germs, and viruses from spreading from one room to another.

There are other applications for U-bends, such as in oil refining operation where U-bends are used to prevent hydrocarbons and other dangerous gases and chemical fumes from escaping through drains. Still others, like in heating systems, U-bends are used to prevent thermo-siphoning, which is the leaking of heat to unwanted locations. Almost all domestic plumbing fixtures including sinks, bathtubs, and showers are equipped with either an internal or external trap. Toilets almost always have internal traps.

Because of its shape, a U-bend retains (or “traps” ) some liquid after drainage. It is this trapped liquid that creates an air seal that prevents gases, pests, and airborne bacteria, germs, and viruses passing through the drain pipe from the connecting sewer to the drainage source in the premises. The air seal relies on this U-shaped pipe of the trap being completely filled with trapped liquid. In the absence of drainage, in time the trapped liquid evaporates, leaving the trap only partially filled. As liquid in the trap recedes below the trap seal depth, the air seal breaks, allowing gases, pests, and airborne bacteria, germs, and viruses to pass through the trap (a phenomenon called “dry trap” ) . FIG. 1A illustrates the air seal in a U-bend, and FIG. 1B illustrates the dry trap phenomenon.

Dry trap is a common problem in residential houses and buildings where residents are not staying there-within and using the plumbing at all times. This dry trap problem is the primary cause of sewer odors in long-unused bathrooms and kitchen. In addition, dry trap problem is particularly acute in where there is an epidemic of infectious airborne disease as the bacteria, germs, or viruses can spread by travelling between multiple dwelling units via a commonly connected sewer. Therefore, there is a need of a device or technique in the art for detecting dry traps for prompting for corrective actions.

Summary of the Invention:

It is the objective of the present invention to provide an apparatus for detecting dry trap that is low cost and simple to use and install on existing installed and pre-installed U-bends. The apparatus for detecting dry trap may also be adapted to be an integrated solution with traps under various embodiments of the present invention.

In accordance with a first embodiment of the present invention, an apparatus for detecting dry trap is provided, comprising: a housing, wherein the housing is dimensioned to transversely wrap around a U-bend pipe or tube when the apparatus is installed; and a sensor circuit secured within the housing having an electrically conductive first end and an electrically conductive second end exposed from the housing. When the apparatus is installed, the first end and the second end are located directly opposite to each other with the first end located at the top exterior of the trap upper dip point of the U-bend pipe or tube and the second end located across at the bottom exterior of the trap lower dip point of the U-bend pipe or tube. Further, both ends are configured to puncture or extend via holes through the wall of the U-bend pipe or tube at their respective locations into the interior of the U-bend pipe or tube such that both ends are in contact with liquid when it is completely filling the U-bend pipe or tube interior. The sensor circuit is configured to form an electrically closed-loop circuit when both its first and second ends are in contact with electrically conductive liquid, or otherwise an electrically opened-loop circuit.

The apparatus further comprises a signal processing and data communication circuitry that is electrically connected to the sensor circuit, and is configured to continuously monitor and detect the electrically closed-loop and opened-loop conditions of the sensor circuit. The signal processing and data communication circuitry is further configured to periodically generate and transmit to an external receiver via wire or wireless communication a data signal corresponding to the detected electrically closed-loop or opened-loop condition of the sensor circuit, and/or transmit the data signal when the sensor circuit condition changes closed-loop to opened-loop, which indicates an occurrence of dry trap.

The signal processing and data communication circuitry may be housed within the housing or external to the housing. The apparatus further comprises an electrical power source, such as a battery, or a connection to an electricity outlet. The external receiver may further process the data signal and send warning data messages to a user interfacing device, such as a mobile phone, trigger an alarm, and/or actuate a water supply source to the plumbing system that drains through the U-bend so to refill the U-bend.

In various embodiments described herein, the shape of the housing resembles approximately the letter “C” , with an opening for transversely fitting on to a U-bend that is already installed in a plumbing system. In other embodiments, the housing may take a ring shape. In other embodiments, the housing may take any shape as long as it is capable of securing around the U-bend pipe or tube. In these embodiments, the housing may also include moveable parts connected by hinges, hooks, screws and bolts, straps, and/or other connection mechanisms so to allow the apparatus to be transversely fitted and secured on to a U-bend pipe or tube without first having the U-bend disconnected from the plumbing system.

In accordance to a second embodiment of the present invention, an apparatus similar to that provided by the first embodiment is provided. The difference in the second embodiment is that when the apparatus is installed, the housing, which includes the first end and the second end of the sensor circuit, are placed at a location on the U-bend pipe or tube exterior that is further above the trap dip. The placement of the first end and the second end of the sensor circuit is ideally to be within the trap seal depth of the particular U-bend such that when liquid there-within recedes past the level corresponding to the capacitive sensor’s placement location and before the air seal breakage point is reached, the sensor circuit’s first end and second end lose their contacts with the liquid, turning the sensor circuit to an electrically opened-loop condition. The signal processing and data communication circuitry then generates and transmits to the external receiver a data signal corresponding to the detected electrically opened-loop, which can be regarded as a warning of an imminent occurrence of dry trap.

In accordance to a third embodiment of the present invention, an apparatus similar to that provided by the first embodiment is provided. The difference in the third embodiment is that when the apparatus is installed, the first end and the second end are not necessary located directly opposite to each other and aligned perpendicularly. In this third embodiment, the first end is placed at a location on the U-bend pipe or tube exterior that is further above the trap dip while the second end remains to be at the bottom exterior of the trap lower dip point of the U-bend pipe or tube.

The placement of the first end is ideally to be within the trap seal depth of the particular U-bend such that when liquid there-within recedes past a certain level before the air seal breakage point is reached, the first end loses its contact with the liquid, turning the sensor circuit to an electrically opened-loop condition. The signal processing and data communication circuitry then generates and transmits to the external receiver a data signal corresponding to the detected electrically opened-loop, which can be regarded as a warning of an imminent occurrence of dry trap.

In accordance to a fourth embodiment of the present invention, an apparatus for detecting dry trap is provided, comprising: a housing, which can be similar to that in the afore-described first embodiment; and a capacitive sensor secured by or within the housing. When the apparatus is installed, the capacitive sensor is located at the top exterior of the trap upper dip point of the U-bend pipe or tube, wherein the U-bend pipe or tube is made of PVC, ceramic, or other non-conductive material. Further, the housing is configured to place the capacitive sensor on or close to the exterior wall surface of the U-bend pipe or tube. The capacitive sensor is supplied with an electrical charge from an electrical power source such that an absolute positive voltage is presented on the exterior side of the section of the U-bend pipe or tube where the capacitive sensor is located. When liquid is filling the U-bend pipe or tube interior completely and contacting the interior side of the section of the U-bend pipe or tube where the capacitive sensor is located, an electrical ground is presented on the interior side of the section so to cause a change in the parasitic capacitance of the capacitive sensor. On the other hand, as liquid recedes when a dry trap begins to occur, the electrical ground on the interior side is suspended, causing a change in the parasitic capacitance of the capacitive sensor.

The changes in the parasitic capacitance of the capacitive sensor, thus can be used to indicate the fullness, or level, of liquid filling the U-bend pipe or tube interior. The apparatus further comprises a signal processing and data communication circuitry that is electrically connected to the capacitive sensor, and is configured to continuously monitor and detect, or receive the changes in parasitic capacitance of the capacitive sensor. The signal processing and data communication circuitry is further configured to periodically generate and transmit to an external receiver via wire or wireless communication a data signal corresponding to the detected changes in parasitic capacitance of the capacitive sensor, which indicates an occurrence of dry trap. The signal processing and data communication circuitry may be housed within the housing or external to the housing.

The apparatus further comprises an electrical power source, such as a battery, or a connection to a electricity outlet. The external receiver may further process the data signal and send warning data messages to a user interfacing device, such as a mobile phone, an electronic kiosk, or a computer terminal, trigger an alarm, and/or actuate a water supply source to the plumbing system that drains through the U-bend so to refill the U-bend.

In accordance to a fifth embodiment of the present invention, an apparatus similar to that provided by the fourth embodiment is provided. The difference in the fifth embodiment is that when the apparatus is installed, the capacitive sensor is not necessary located at the top exterior of trap upper dip point of the U-bend pipe or tube. In this fifth embodiment, the capacitive sensor is placed at a location on the U-bend pipe or tube exterior that is further above the trap dip. The placement of the capacitive sensor is ideally to be within the trap seal depth of the particular U-bend such that when liquid there-within recedes past the level corresponding to the capacitive sensor’s placement location and before the air seal breakage point is reached, the electrical ground on the corresponding U-bend pipe or tube interior side at the capacitive sensor’s placement location is suspended, causing a change in the parasitic capacitance of the capacitive sensor. The signal processing and data communication circuitry then generates and transmits to the external receiver a data signal corresponding to the detected changes in parasitic capacitance of the capacitive sensor, which can be regarded as a warning of an imminent occurrence of dry trap.

In accordance to a sixth embodiment of the present invention, an apparatus for detecting dry trap is provided, comprising: a housing, which may be in a ring shape or “C” shape; and a capacitive sensor. The capacitive sensor may comprise one or more sensor pads or substrate in strip form secured within and around the housing. When the apparatus is installed, the housing transversely wraps or rings around the exterior of the U-bend pipe or tube with the capacitive sensor placed on or closely to the exterior wall surface of the U-bend pipe or tube, wherein the U-bend pipe or tube is made of PVC, ceramic, or other non-conductive material.

The installation of the apparatus on to the U-bend is such that the placement of the capacitive sensor is ideally to be within the trap seal depth of the particular U-bend such that when liquid there-within recedes past the level corresponding to the capacitive sensor’s placement location and before the air seal breakage point is reached, the electrical ground on the corresponding U-bend pipe or tube interior side at the capacitive sensor’s placement location carried by the liquid there-within is suspended, causing a change in the parasitic capacitance of the capacitive sensor. A signal processing and data communication circuitry then generates and transmits to the external receiver a data signal corresponding to the detected changes in parasitic capacitance of the capacitive sensor, which can be regarded as a warning of an imminent occurrence of dry trap.

Brief Description of the Drawings:

Embodiments of the present invention are described in more detail hereinafter with reference to the drawings, in which:

FIG. 1A depicts a diagram illustrating an air seal of a U-bend;

FIG. 1B depicts a diagram illustrating the dry trap phenomenon;

FIG. 2 depicts a diagram illustrating an apparatus for detecting dry trap in accordance to a first embodiment of the present invention;

FIG. 3 depicts a diagram illustrating an apparatus for detecting dry trap in accordance to a second embodiment of the present invention;

FIG. 4 depicts a diagram illustrating an apparatus for detecting dry trap in accordance to a third embodiment of the present invention;

FIG. 5 depicts a diagram illustrating an apparatus for detecting dry trap in accordance to a fourth embodiment of the present invention;

FIG. 6 depicts a diagram illustrating an apparatus for detecting dry trap in accordance to a fifth embodiment of the present invention; and

FIG. 7 depicts a diagram illustrating an apparatus for detecting dry trap in accordance to a sixth embodiment of the present invention.

Detailed Description of Preferred Embodiments:

In the following description, apparatuses of detecting dry traps and the likes are set forth as preferred examples. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions may be made without departing from the scope and spirit of the invention. Specific details may be omitted so as not to obscure the invention; however, the disclosure is written to enable one skilled in the art to practice the teachings herein without undue experimentation.

Referring to FIG. 2, in accordance with a first embodiment of the present invention, an apparatus for detecting dry trap is provided. The apparatus comprises: a housing 101, wherein the housing 101 is dimensioned to transversely wrap around a U-bend pipe or tube 110 when the apparatus is installed; and a sensor circuit (not shown in the figure) secured within the housing having an electrically conductive first end 102 and an electrically conductive second end 103 exposed from the housing. When the apparatus is installed, the first end 102 and the second end 103 are located directly opposite to each other with the first end 102 located at the top exterior of the trap upper dip point 111 of the U-bend pipe or tube 110 and the second end 103 located across at the bottom exterior of the trap lower dip point 112 of the U-bend pipe or tube 100. Further, both ends are configured to puncture or extend via holes through the wall of the U-bend pipe or tube 100 at their respective locations into the interior of the U-bend pipe or tube such that both ends are in contact with liquid when it is filling the U-bend pipe or tube interior to at least the top of the trap seal depth of the U-bend. The sensor circuit is configured to form an electrically closed-loop circuit when both its first and second ends are in contact with electrically conductive liquid, or otherwise an electrically opened-loop circuit.

The apparatus further comprises a signal processing and data communication circuitry 104 that is electrically connected to the sensor circuit, and is configured to continuously monitor and detect the electrically closed-loop and opened-loop conditions of the sensor circuit. The signal processing and data communication circuitry 104 is further configured to periodically generate and transmit to an external receiver 105 via wire or wireless communication a data signal corresponding to the detected electrically closed-loop or opened-loop condition of the sensor circuit, and/or transmit the data signal when the sensor circuit condition is detected being changed from electrically closed-loop to opened-loop, which indicates an occurrence of dry trap.

The signal processing and data communication circuitry 104 may be housed within the housing 101 or external to the housing 101. The apparatus further comprises an electrical power source 106, such as a battery, or a connection to a electricity outlet. The external receiver 105 may further process the data signal and send warning data messages to a user interfacing device, such as a mobile phone, an electronic kiosk, and a computer terminal, trigger an alarm, and/or actuate a water supply source to the plumbing system that drains through the U-bend so to refill the U-bend.

In various embodiments described herein, the shape of the housing resembles approximately the letter “C” , with an opening for transversely fitting on to a U-bend that is already installed in a plumbing system. In other embodiments, the housing may take a ring shape. In other embodiments, the housing may take any shape as long as it is capable of securing around the U-bend pipe or tube. In these embodiments, the housing may also include moveable parts connected by hinges, hooks, screws and bolts, straps, and/or other connection mechanisms so to allow the apparatus to be fitted and secured on to a U-bend pipe or tube without first having the U-bend disconnected from the plumbing system.

Referring to FIG. 3, in accordance to a second embodiment of the present invention, an apparatus similar to that provided by the first embodiment is provided. The difference in the second embodiment is that when the apparatus is installed, the housing 201, which includes the first end 202 and the second end 203 of the sensor circuit, are placed at a location on the U-bend pipe or tube 210 exterior that is further above the trap dip 213. The placement of the first end 202 and the second end 203 of the sensor circuit is ideally to be within the trap seal depth of the particular U-bend such that when liquid there-within recedes past the level corresponding to the capacitive sensor’s placement location and before the air seal breakage point 214 is reached, the sensor circuit’s first end 202 and second end 203 lose their contacts with the liquid, turning the sensor circuit to an electrically opened-loop condition. The signal processing and data communication circuitry 204 then generates and transmits to the external receiver 205 a data signal corresponding to the detected electrically opened-loop, which can be regarded as a warning of an imminent occurrence of dry trap.

Referring to FIG. 4, in accordance to a third embodiment of the present invention, an apparatus similar to that provided by the first embodiment is provided. The difference in the third embodiment is that when the apparatus is installed, the first end 302 and the second end 303 are not necessary located directly opposite to each other and aligned perpendicularly. In this third embodiment, the first end 302 is placed at a location on the U-bend pipe or tube 310 exterior that is further above the trap dip 313 while the second end 303 remains to be at the bottom exterior of the trap lower dip point 312 of the U-bend pipe or tube 310.

The placement of the first end 302 is ideally to be within the trap seal depth of the particular U-bend such that when liquid there-within recedes past a certain level before the air seal breakage point 314 is reached, the first end loses its contact with the liquid, turning the sensor circuit to an electrically opened-loop condition. The signal processing and data communication circuitry 304 then generates and transmits to the external receiver 305 a data signal corresponding to the detected electrically opened-loop, which can be regarded as a warning of an imminent occurrence of dry trap.

Referring to FIG. 5, in accordance to a fourth embodiment of the present invention, an apparatus for detecting dry trap is provided. The apparatus comprises: a housing 401, which can be similar to that in the afore-described first embodiment; and a capacitive sensor 402 secured by or within the housing. When the apparatus is installed, the capacitive sensor 402 is located at the top exterior of the trap upper dip point 411 of the U-bend pipe or tube 410, wherein the U-bend pipe or tube 410 is made of PVC, ceramic, or other non-conductive material. Further, the housing 401 is configured to place the capacitive sensor 402 on or close to the exterior wall surface of the U-bend pipe or tube 410. The capacitive sensor 402 is supplied with an electrical charge from an electrical power source 406 such that an absolute positive voltage is presented on the exterior side of the section of the U-bend pipe or tube 410 where the capacitive sensor 402 is located. This turns the corresponding interior side of the section of the U-bend pipe or tube 410 into a capacitive sensing area. When liquid is filling the U-bend pipe or tube 410 interior completely and contacting the capacitive sensing area, an electrical ground is presented on the capacitive sensing area. On the other hand, as liquid recedes when a dry trap begins to occur, the electrical ground on the capacitive sensing area is suspended, causing a change in the parasitic capacitance of the capacitive sensor 402.

The changes in the parasitic capacitance of the capacitive sensor 402, thus can be used to indicate the fullness, or level, of liquid filling the U-bend pipe or tube 410 interior. The apparatus further comprises a signal processing and data communication circuitry 404 that is electrically connected to the capacitive sensor 402, and is configured to continuously monitor and detect, or receive the changes in parasitic capacitance of the capacitive sensor 402. The signal processing and data communication circuitry 404 is further configured to periodically generate and transmit to an external receiver 405 via wire or wireless communication a data signal corresponding to the detected changes in parasitic capacitance of the capacitive sensor 402, which indicates an occurrence of dry trap. The signal processing and data communication circuitry 404 may be housed within the housing 401 or external to the housing 401.

The apparatus further comprises an electrical power source 406, such as a battery, or a connection to a electricity outlet. The external receiver 405 may further process the data signal and send warning data messages to a user interfacing device, such as a mobile phone, an electronic kiosk, and a computer terminal, trigger an alarm, and/or actuate a water supply source to the plumbing system that drains through the U-bend so to refill the U-bend.

Referring to FIG. 6, in accordance to a fifth embodiment of the present invention, an apparatus similar to that provided by the fourth embodiment is provided. The difference in the fifth embodiment is that when the apparatus is installed, the capacitive sensor 502 is not necessary located at the top exterior of trap upper dip point 511 of the U-bend pipe or tube 510. In this fifth embodiment, the capacitive sensor 502 is placed at a location on the U-bend pipe or tube 510 exterior that is further above the trap dip 513. The placement of the capacitive sensor 502 is ideally to be within the trap seal depth of the particular U-bend such that when liquid there- within recedes past the level corresponding to the capacitive sensor’s placement location and before the air seal breakage point is reached, the electrical ground on the corresponding U-bend pipe or tube 510 interior side at the capacitive sensor’s placement location is suspended, causing a change in the parasitic capacitance of the capacitive sensor 502. The signal processing and data communication circuitry 504 then generates and transmits to the external receiver 505 a data signal corresponding to the detected changes in parasitic capacitance of the capacitive sensor 502, which can be regarded as a warning of an imminent occurrence of dry trap.

Referring to FIG. 7, in accordance to a sixth embodiment of the present invention, an apparatus for detecting dry trap is provided. The apparatus comprises: a housing 601, which may be in a ring shape or “C” shape; and a capacitive sensor 602. The capacitive sensor 602 may comprise one or more sensor pads or substrate in a strip form secured within and around the housing 601. When the apparatus is installed, the housing 601 transversely wraps around the exterior of the U-bend pipe or tube 610 with the capacitive sensor 602 placed on or closely to the exterior wall surface of the U-bend pipe or tube 610, wherein the U-bend pipe or tube 610 is made of PVC, ceramic, or non-conductive material.

The installation of the apparatus on to the U-bend is such that the placement of the capacitive sensor 602 is ideally to be within the trap seal depth of the particular U-bend such that when liquid there-within recedes past the level corresponding to the capacitive sensor’s placement location and before the air seal breakage point is reached, the electrical ground on the corresponding U-bend pipe or tube 610 interior side at the capacitive sensor’s placement location carried by the liquid there-within is suspended, causing a change in the parasitic capacitance of the capacitive sensor 602. The signal processing and data communication circuitry 604 then generates and transmits to the external receiver 605 a data signal corresponding to the detected changes in parasitic capacitance of the capacitive sensor 602, which can be regarded as a warning of an imminent occurrence of dry trap.

The signal processing and data communication circuitries, and external receivers of the various embodiments disclosed herein may be implemented using computing devices, computer processors, or electronic circuitries including but not limited to digital signal processors (DSP) , application specific integrated circuits (ASIC) , field programmable gate arrays (FPGA) , and other programmable logic devices configured or programmed according to the teachings of the present disclosure. Computer instructions or software codes running in the general purpose or specialized computing devices, computer processors, or programmable logic devices can readily be prepared by practitioners skilled in the software or electronic art based on the teachings of the present disclosure.

The foregoing description of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to the practitioner skilled in the art.

The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalence.

Claims

An apparatus for detecting dry trap in a U-bend, comprising:

a housing configured to transversely wrap around the U-bend pipe when the apparatus is installed on to the U-bend; and

a sensor circuit secured in the housing and having an electrically conductive first end and an electrically conductive second end exposed from the housing;

wherein the first end and the second end are configured to puncture or extend via holes through the wall of the U-bend pipe when the apparatus is installed on to the U-bend;

wherein the sensor circuit is further configured to form an electrically closed-loop circuit when both the first end and the second end are in contact with liquid inside the U-bend pipe, or otherwise an electrically opened-loop circuit; and

wherein one or both of the first end and the second end loses contact with liquid when the U-bend pipe is not filled with liquid to at least top of a trap seal depth of the U-bend.
The apparatus of claim 1, further comprising:

a signal processing and data communication circuitry electrically connected to the sensor circuit and configured to detect the opened-loop circuit and closed-loop circuit condition of the sensor circuit and generate a data signal when the opened-loop circuit condition of the sensor circuit is detected, the data signal indicating a dry trap is occurring or about to occur.
The apparatus of claim 1,

wherein the housing is configured such that the first end of the sensor circuit is placed at the U-bend’s trap upper dip point and the second end of the sensor circuit is placed at the U-bend’s trap lower dip point; and

wherein when the opened-loop circuit condition of the sensor circuit is detected, a dry trap is occurring.
The apparatus of claim 1,

wherein the housing is configured such that both the first end and the second end of the sensor circuit are placed at locations within the U-bend’s trap seal depth; and

wherein when the opened-loop circuit condition of the sensor circuit is detected, a dry trap is about to occur.
The apparatus of claim 1,

wherein the housing is configured such that the first end of the sensor circuit is placed at a location within the U-bend’s trap seal depth and the second end of the sensor circuit is placed at the U-bend’s trap lower dip point; and

wherein when the opened-loop circuit condition of the sensor circuit is detected, a dry trap is about to occur.
An apparatus for detecting dry trap in a U-bend, comprising:

a housing configured to be secured on the U-bend pipe exterior when the apparatus is installed on to the U-bend; and

a capacitive sensor secured in the housing and positioned on or close to the U-bend pipe exterior wall surface when the apparatus is installed on to the U-bend;

wherein the capacitive sensor is supplied with an electrical charge from an electrical power source such that an absolute positive voltage is presented on the U- bend pipe exterior area where the capacitive sensor is located, and turning a corresponding U-bend pipe exterior area into a capacitive sensing area;

wherein when liquid inside the U-bend pipe contacts the capacitive sensing area, an electrical ground is presented on the capacitive sensing area;

wherein a parasitic capacitance of the capacitive sensor changes each time when the electrical ground is presented on and suspended from the capacitive sensing area; and

wherein the capacitive sensing area is not in contact with liquid when the U-bend pipe is not filled with liquid to at least top of a trap seal depth of the U-bend.
The apparatus of claim 6, further comprising:

a signal processing and data communication circuitry electrically connected to the capacitive sensor and configured to detect the changes in the parasitic capacitance of the capacitive sensor and generate a data signal when it is detected that the electrical ground is suspended from the capacitive sensing area, the data signal indicating a dry trap is occurring or about to occur.
The apparatus of claim 6,

wherein the housing is configured such that the capacitive sensor is placed at the U-bend’s trap upper dip point; and

wherein when it is detected that the electrical ground is suspended from the capacitive sensing area, a dry trap is occurring.
The apparatus of claim 6,

wherein the housing is configured such that the capacitive sensor is placed at a location within the U-bend’s trap seal depth; and

wherein when it is detected that the electrical ground is suspended from the capacitive sensing area, a dry trap is about to occur.
The apparatus of claim 9, wherein the capacitive sensor comprises one or more sensor pads secured or substrate in a strip form within and around the housing.
A trap comprising a U-bend and the apparatus of claim 1.
A trap comprising a U-bend and the apparatus of claim 6.
A plumbing system comprising a trap;

wherein the trap is one of U-trap, P-trap, and S-trap; and

wherein the trap comprises a U-bend and the apparatus of claim 1.
A plumbing system comprising a trap;

wherein the trap is one of U-trap, P-trap, and S-trap; and

wherein the trap comprises a U-bend and the apparatus of claim 6.