Fluid discharge event detector

Abstract

A fluid discharge event detection apparatus measures a change in capacitance to detect the presence of a fluid in a sensing conduit where the presence of fluid indicates a discharge event. The apparatus includes a first conduit, the sensing conduit and a control valve, coupled between the first conduit and the sensing conduit. The control valve is configured to activate and fluidly couple the first conduit and the sensing conduit to one another when the control valve detects at least one predetermined condition of a fluid within the first conduit. A sensor, configured to measure a capacitance value, is disposed about the sensing conduit. A controller, coupled to the sensor, is configured to detect a change in the sensing conduit capacitance value and assert an alarm condition upon detection of the change in the sensing conduit capacitance value.

Claims

1. A hot water heater assembly with a fluid discharge event detection apparatus, comprising: a hot water heater having a tank; a first conduit connected to the tank; a temperature and pressure relief valve having an inlet coupled to the first conduit, the temperature and pressure relief valve also having an outlet; a sensing conduit coupled to the outlet of the temperature and pressure relief valve, wherein the temperature and pressure relief valve is configured to open and fluidly couple the first conduit and the sensing conduit to one another, wherein the temperature and pressure relief valve is normally closed and mechanically opens to discharge water through the outlet based upon predetermined temperature and pressure conditions being exceeded; a sensor, disposed and positioned around an exterior of the sensing conduit and entirely outside of an interior of the sensing conduit so that water flow is not diverted, obstructed or restricted and the sensor is never in contact with the water, the sensor being configured to output a signal proportional to a capacitance of the sensing conduit; and a controller, coupled to the sensor, configured to periodically: measure a capacitance value of the sensing conduit as a function of the sensor output signal; detect a change in the measured sensing conduit capacitance value; and assert an alarm condition upon detection of the change in the measured sensing conduit capacitance value, wherein the alarm condition is configured to indicate a no flow condition when the sensing conduit is dry, a some flow condition when the sensing conduit is under 25% wet, or a full flow condition when the sensing conduit is more than 25% wet based on the measured capacitance value of the sensing conduit.

2. The hot water heater assembly of claim 1, wherein the controller is further configured to: detect a rate of change of the measured capacitance value of the sensing conduit; and distinguish between an excess temperature condition and an excess pressure condition as a function of the detected rate of change of the measured capacitance value of the sensing conduit.

3. The hot water heater assembly of claim 2, wherein the detected rate of change of the measured capacitance value of the sensing conduit is a function of a flow rate of fluid within the sensing conduit.

4. The hot water heater assembly of claim 1, wherein the temperature and pressure relief valve is configured to activate when at least one of: a pressure within the first conduit that is not within a predetermined range of pressure values is detected; and a temperature within the first conduit that is not within a predetermined range of temperature values is detected.

5. The hot water heater assembly of claim 1, wherein the sensing conduit consists of electrically non-conductive material.

6. The hot water heater assembly of claim 1, wherein the sensed conduit capacitance value is a function of an amount of fluid within the sensing conduit with no flow being an inner surface area of the sensing conduit being dry, some flow being the inner surface area being less than one quarter wet, and full flow being the inner surface area being mostly wet.

7. An apparatus for detecting a fluid discharge event of at least one portion of: a hot water heater assembly; a boiler; a backflow relief valve; or a fire sprinkler, the apparatus comprising: a sensing conduit having a first end configured to couple to a discharge conduit of the at least one portion; a sensor, disposed and positioned around an exterior of the sensing conduit and entirely outside of an interior of the sensing conduit, configured to output a signal proportional to a capacitance of the sensing conduit; and a controller, coupled to the sensor, configured to periodically: measure a capacitance value of the sensing conduit as a function of the sensor output signal; generate readings of some flow or continuous flow based on the measured capacitance value of the sensing conduit; detect a change in the measured sensing conduit capacitance value; and assert condition based upon detection of the change in the measured sensing conduit capacitance value, wherein the condition selectively indicates some flow or continuous flow based on the measured capacitance value of the sensing conduit, wherein some flow corresponds to the sensing conduit being under 25% wet and continuous flow corresponds to the sensing conduit being more than 25% wet.

8. The detecting apparatus of claim 7, wherein the controller is further configured to: detect a rate of change of the measured capacitance value of the sensing conduit; and distinguish between an excess temperature condition and an excess pressure condition of a source of the fluid within the sensing conduit as a function of the detected rate of change of the measured capacitance value of the sensing conduit.

9. The detecting apparatus of claim 8, wherein the detected rate of change of the measured capacitance value of the sensing conduit is a function of a flow rate of the fluid within the sensing conduit and the controller is further configured to selectively indicate the condition as no flow.

10. The detecting apparatus of claim 7, wherein the temperature and pressure relief valve is configured to activate and fluidly couple the discharge conduit and the sensing conduit to one another when the temperature and pressure relief valve detects at least one predetermined condition of a fluid within the discharge conduit.

11. The detecting apparatus of claim 10, wherein the at least one predetermined condition of fluid within the discharge conduit of the temperature and pressure relief valve is one of: a pressure within the sensing conduit that is not within a predetermined range of pressure values; and a temperature within the sensing conduit that is not within a predetermined range of temperature values.

12. The detecting apparatus of claim 7, wherein the sensed conduit capacitance is a function of an amount of fluid within the sensing conduit.

13. A method of detecting a fluid discharge event in a hot water heater assembly, comprising: coupling a first end of a sensing conduit to a discharge conduit of a temperature and pressure relief valve coupled to a tank of the hot water heater assembly; disposing and positioning a sensor around an exterior of sensing conduit and entirely outside of an interior of the sensing conduit, the sensor configured to output a signal proportional to a capacitance of the sensing conduit; periodically measuring, as a function of the sensor output signal, a capacitance value of the sensing conduit; generating readings of no flow when the sensing conduit is dry, some flow when the sensing conduit is under 25% wet, or continuous flow when the sensing conduit is more that 25% wet based on the measured capacitance value of the sensing conduit; detecting a change in the measured sensing conduit capacitance value; asserting an alarm condition selected from no flow, some flow, and continuous flow upon detection of the change in the measured sensing conduit capacitance value; and diagnosing: a temperature related failure based on the change being a ramp input; and a pressure related failure based on the change being a step input.

14. The method of claim 13, further comprising: detecting a rate of change of the measured capacitance value of the sensing conduit; and distinguishing between an excess temperature condition and an excess pressure condition of a source of the fluid within the sensing conduit as a function of the detected rate of change of the measured capacitance value of the sensing conduit.

15. The method of claim 14, wherein the detected rate of change of the measured capacitance value of the sensing conduit is a function of a flow rate of the fluid within the sensing conduit.

16. The method of claim 13, wherein the measured sensing conduit capacitance value is a function of an amount of fluid within the sensing conduit.

17. The method of claim 13, further comprising: coupling a fluid within the discharge conduit to ground.

18. The hot water heater assembly of claim 1, wherein the sensor is positioned within a wall portion of the sensing conduit.

19. The hot water heater assembly of claim 1, wherein the sensor is a circular ring, or a portion of a circular ring.

20. The hot water heater assembly of claim 1, wherein the controller is further configured to continuously measure the capacitance value of the sensing conduit as a function of the sensor output signal.

21. The hot water heater assembly of claim 5, wherein the sensor comprises electrically conductive material.

22. The detecting apparatus of claim 7, wherein the sensor is positioned within a wall portion of the sensing conduit.

23. The detecting apparatus of claim 7, wherein the sensor is a circular ring, or a portion of a circular ring.

24. The detecting apparatus of claim 7, wherein the controller is further configured to continuously measure the capacitance value of the sensing conduit as a function of the sensor output signal.

25. The detecting apparatus of claim 7, wherein: the sensing conduit consists of electrically non-conductive material; and the sensor comprises electrically conductive material.

26. The method of claim 13, further comprising: positioning the sensor within a wall portion of the sensing conduit.

27. The method of claim 13, further comprising: providing the sensor as a circular ring, or a portion of a circular ring.

28. The method of claim 13, further comprising: continuously measuring the capacitance value of the sensing conduit as a function of the sensor output signal.

29. The method of claim 13, further comprising: providing the sensing conduit consisting of electrically non-conductive material; and providing the sensor comprising electrically conductive material.

30. The hot water heater assembly of claim 1, further comprising a feedback mechanism to control: a temperature response based on the change being a ramp input; and control a pressure response based on the change being a step input.

31. A backflow relief valve comprising: a fluid discharge event detection apparatus including: a first conduit connected to an upstream fluid network; a second conduit connected to a downstream fluid network; a sensing conduit intermediate the first and second conduit; a first check valve for controlling flow in the first conduit; a second check valve for controlling flow in the second conduit, wherein the first and second check valves normally only allow flow in an upstream direction and mechanically open for reverse flow based upon predetermined pressure conditions being exceeded; a sensor, disposed and positioned around an exterior of the sensing conduit and entirely outside of an interior of the sensing conduit, configured to output a signal proportional to a capacitance of the sensing conduit; and a controller, coupled to the sensor, configured to periodically: measure a capacitance value of the sensing conduit as a function of the sensor output signal; detect a change in the capacitance value; and assert a status condition based upon detection of the change in the capacitance value, wherein the status condition is configured to indicate: no flow when the sensing conduit is dry; some flow when the sensing conduit is under 25% wet; and continuous flow when the sensing conduit is more than 25% wet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The various features and advantages of the present invention may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:

(2) FIG. 1 is a fluid discharge detection assembly in accordance with an aspect of the present disclosure coupled to a known water heater;

(3) FIG. 2 is a block diagram of a fluid discharge detection assembly in accordance with an aspect of the present disclosure;

(4) FIG. 3 shows an exemplary embodiment of a fluid discharge detection assembly in accordance with an aspect of the present disclosure;

(5) FIG. 4 is a conceptual representation of the operation of the fluid discharge detection assembly in accordance with an aspect of the present disclosure;

(6) FIG. 5 is a graph representing capacitance values versus time detected during a cyclic fluid discharge event occurring when a T&P valve releases fluid;

(7) FIG. 6 is a graph representing capacitance values versus time detected during another cyclic fluid discharge event occurring when a T&P valve releases fluid;

(8) FIG. 7A is a fluid discharge event detection apparatus in accordance with an aspect of the present disclosure;

(9) FIG. 7B is a partial cutaway view of the fluid discharge event detection apparatus of FIG. 7A;

(10) FIG. 7C is another view of the fluid discharge event detection apparatus in FIGS. 7A and 7B;

(11) FIGS. 8A-8D show an additional exemplary embodiment of a fluid discharge event detection apparatus in accordance with an aspect of the present disclosure for attachment to either a T&P relief valve or a discharge pipe;

(12) FIGS. 9A-9D show another exemplary embodiment of a fluid discharge event detection apparatus constructed in accordance with an aspect of the present disclosure for attachment to either a T&P relief valve or a discharge pipe; and

(13) FIG. 10 is a cross-sectional view of a T&P valve.

DETAILED DESCRIPTION

(14) This application claims priority from U.S. Provisional Patent Application Ser. No. 62/755,857, entitled “Detector For Sensing Fluid Leak Without Obstructing Flow,” filed Nov. 5, 2018, the entire contents of which is hereby incorporated by reference for all purposes.

(15) Aspects of the present disclosure, as described below, use capacitance measurement technology to detect a fluid discharge and/or fluid flow without obstructing the flowpath and can be applied in T&P relief or other applications where fluid is discharged in order to provide relief. The advantages, and other features of the technology disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain embodiments taken in conjunction with the drawings which set forth representative embodiments of the present technology and wherein like reference numerals identify similar structural elements. Directional indications such as upward, downward, right, left and the like are used with respect to the figures and not meant in a limiting manner.

(16) In brief, the subject technology relates to any assembly that may leak fluid, for example, water, whether by design or expected failure, so that upon leakage or improper flow, notification of the flowing or dripping condition without obstructing the flow path is performed. For example, such a device may be a backflow prevention device like a vented backflow preventer, a water shutoff assembly for a flood detection device, a water heater and the like.

(17) One non-limiting example of an aspect of the present disclosure will be discussed with respect to FIG. 1. As shown in FIG. 1, a hot water heater 100, as is known, includes a cold water inlet 105 that feeds cold water to a tank 110. The water is heated in the tank 110 and provided via a hot water outlet 115. A T&P relief valve 120 connects to the tank 110 and, as known, operates to release fluid and, thereby, prevents pressure from building up. When the relief valve 120 releases water, the released water is carried away in a discharge pipe 125, oftentimes, to a drain in the floor.

(18) In accordance with an aspect of the present disclosure, a fluid detection assembly 130 is coupled to the discharge pipe 125. The fluid detection assembly 130 is configured to detect water that may be flowing or present within the discharge pipe 125 where the presence of water is indicative of an over temperature or over pressure condition, as will be described below in more detail.

(19) In an alternative aspect of the present disclosure, as will be discussed below, the fluid detection assembly 130 and the relief valve 120 can be incorporated into a single unit. Advantageously, in any arrangement, no portion of the fluid detection assembly 130, or any portion or component thereof, is placed in the flow path of the discharge pipe 125 in order to avoid the possibility of obstructing fluid flow.

(20) Referring now to FIG. 10, the T&P relief valve 120 includes a body 140 having a first conduit 142 that connects to the water heater 110, and a second conduit 144 that connects to the discharge pipe 125. A valve member 146 is biased into a closed position by a compression spring 150 to prevent flow between the first conduit 142 and the second conduit 144. An expandable thermal actuator 160 is secured in the first conduit 142 so that a first end 162 engages the valve member 146 and a second end 164 extends into the water heater 110. The T&P relief valve 120 also includes a handle 152 connected to the valve member 146. When the pressure within the water heater 110 exceeds a predetermined level, the pressure at the first conduit 142 overcomes the compression spring 150 to move the valve member 146 and allow water to escape through the second conduit 144. Likewise, when temperature within the water heater 110 exceeds a predetermined level, the thermal actuator 160 expands and overcomes the compression spring 150 to move the valve member 146 and allow water to escape through the second conduit 144. The handle 152 can be used to manually test the T&P relief valve 120 by moving the valve member 146 to open the valve.

(21) Referring now to FIG. 2, the fluid detection assembly 130 includes a sensor electrode 205 operative to generate a signal indicative of the presence of water or fluid in the discharge pipe 125. The sensor electrode 205 will be described in more detail below. The fluid detection assembly 130 also includes a controller 210 coupled to the sensor electrode 205 by an operative connection 215 such as, but not limited to, a wire. As such, the controller 210 receives a signal generated by the sensor electrode 205 for processing, as will be described below. The controller 210 can include: a processing unit 220, for example, a micro-controller such as an Arduino controller, memory 225, an I/O device 230, analog circuitry 235 including miscellaneous electrical components such as resistors, capacitors and the like to interface the sensor electrode 205 to the processing unit 220, a power source 240, e.g., a battery, or power connector to receive external power, all connected to one another by a bus 245 and all mounted on a printed circuit board (PCB), not shown. The controller 210 is configured to store, process and output data indicative of whether or not fluid is detected in the discharge pipe 125. An Arduino controller is an open-source hardware and software project and user community that designs and manufactures single-board microcontrollers and microcontroller kits for building digital and interactive devices that can sense and control objects in the analog and digital domains.

(22) Referring to FIG. 3, in one non-limiting example, the sensor electrode 205 is positioned around the discharge pipe 125 but is not within the discharge pipe 125 and, therefore, is never in contact with any fluid that might be within. Accordingly, the sensor electrode 205 can be encapsulated or insulated by a wall portion 305 of the discharge pipe 125, i.e., placed within the material of the discharge pipe 125. The sensor electrode 205 can be a circular ring, or portion of a ring, that surrounds the discharge pipe 125. The sensor electrode 205 may be made from copper or any suitable metal or material.

(23) The sensor electrode 205 can comprise any conductive material wrapped around the discharge pipe 125 that is made of a material with a low dielectric constant. The materials are selected to create as large as a difference between the dielectric constant of the sensor electrode 205 and the discharge pipe 125. Air has a dielectric constant, for most purposes, of one, whereas water is closer to 80, while most plastics are generally no higher than five.

(24) Capacitive sensing technology is known and applied in many common applications, e.g., smartphone touch screens, proximity detection devices and keyboards. Capacitive sensors utilize Gauss' law for electricity:

(25) $\oint \stackrel{\_}{E}.Math.d\stackrel{\_}{A}=\frac{q}{{\mathrm{.Math.}}_0}$

(26) For two parallel plates, this simplifies down to:
C=(k*ε.sub.0*A)/d

(27) where: C=capacitance (farads) k=relative permittivity of material between two plates (unitless) ε.sub.0=permittivity of space (8.854*10.sup.−12 F/m) d=separation between two parallel plates (m)

(28) Accordingly, with a fixed sensor area, the following parameters will affect the RC time constant producing a reading: a distance between the sensor and the target object/ground electrode; a dielectric constant of the target object; and an area of the target object.

(29) In operation, as discussed below, the fluid detection assembly 130 continuously, i.e., periodically, measures a capacitance value of the discharge pipe 125 with the sensor 205. A change in the measured capacitance value, e.g., greater than a predetermined threshold value or outside a predetermined range of values, may be indicative of fluid in the discharge pipe 125 as the measured capacitance is a function of an amount of fluid within the discharge pipe 125.

(30) Referring to FIG. 4, the time constant in the sensor/discharge pipe combination 205/115 in accordance with an aspect of the present disclosure, is analogous to that in an RC circuit, and will be the resistance of the line multiplied by the combined capacitance. The sensor electrode 205 forms a capacitance with the surrounding ground and its size and shape will affect the flux field orientation, and the sensing distance. The surrounding ground could be a ground plate, the surrounding structure/plumbing or a target object. It should be noted that in most residential water supply systems, the piping through which the water flows is coupled to ground and, therefore, the water is also coupled to ground. In operation, the capacitor is cyclically charged and the discharge time is constantly recorded or stored, i.e., how long the capacitor takes to discharge, which is representative of the capacitance. As the measured capacitance for a “dry” discharge pipe 125 will be different from a “wet” discharge pipe 125, the presence of fluid, specifically, water, can be detected.

(31) The circuit consists of a capacitor and a resistor connected in parallel, both going to ground. The processing unit 220 cyclically switches between send and receive states, while measuring the time it takes for discharge. The sensitivity can be adjusted as necessary by altering the resistance, changing the discharge time for a given capacitance and altering what the clock can and cannot pickup. The maximum distance sensed and the amounts of discharge cycles that occur per unit time are inversely proportional.

(32) FIG. 5 is a graph of the capacitance reading of the sensor electrode 205 through five cycles where a T&P valve releases fluid into the discharge pipe 125 to relieve an over-pressure condition. FIG. 6 is a graph of the capacitance measured by the sensor electrode 205 in which a ramp response 605 from a flow increase due, in this example, to an over-temperature condition, can be seen. Once full flow 610 occurs, the capacitance value is essentially constant. As the flow returns to no flow 615, i.e., the T&P valve closes, the capacitance returns to the lower no flow reading 615.

(33) Referring to the graphs in FIGS. 5 and 6, it is clear that the sensor assembly of the present disclosure can detect an initial leak event that is occurring. It has been observed that, during this initial time, the relief valve produces a stream of fluid that engulfs under a quarter of the inner surface area of the discharge tube 125. As the release event continues, however, the flow increases and fluctuates until it develops into a full flow covering most of the inner surface are of the discharge tube 125. Advantageously, the fluid detection assembly generates three readings: no flow, some flow, i.e., the first continuous stream, and full flow, i.e., a full discharge state.

(34) It should be noted that the release event presented in FIG. 6 is an over-temperature event, which is believed to present the changing capacitance as a ramp input onto the sensor electrode 205. In contrast, the over-pressure event shown in FIG. 5 presents like a step input. The rise time during a pressure relief event is minimal as the seat of the T&P valve would reach its full open position very quickly. Even with a relatively fast closure of the relief valve, there is a drip region as the water leaves the valve. This difference can be utilized in a feedback mechanism to control either the pressure or the temperature response.

(35) Furthermore, this difference in the rate of change allows for aspects of the present disclosure to be used to diagnose other parts of the water system, for example, the thermal expansion tank. Accordingly, for example, if a thermal expansion tank has a ruptured bladder that causes the T&P valve to open under pressure, and this is occurring cyclically, that could be indicative of an expansion tank problem.

(36) Referring now to FIGS. 7A-7C, a fluid discharge event detection apparatus 700 in accordance with an aspect of the present disclosure comprises a housing 702, a first conduit 705, a second, sensing conduit 710 and a control valve 715, coupled between the first conduit 705 and the sensing conduit 710. The control valve 715 is configured to activate and fluidly couple the first conduit 705 and the sensing conduit 710 to one another when the control valve 715 detects at least one predetermined condition of a fluid within the first conduit 705. The valve 715 can be, for example, a T&P valve 120 and can include a thermal actuator 716 similar to the thermal actuator 164 as described above. A sensor electrode 720 is disposed about the sensing conduit 710 and a controller 725 is coupled to the sensor electrode 720.

(37) As set forth above, the controller 725 is configured to: measure a capacitance value of the sensing conduit 710; detect a change in the sensing conduit capacitance value; and assert an alarm condition upon detection of the change in the sensing conduit capacitance value.

(38) The sensing conduit 710 can be coupled to an extension pipe and the first conduit 705 can be coupled to, for example, a hot water heater tank; a boiler; a backflow relief valve; a fire sprinkler apparatus or the like.

(39) Referring now to FIGS. 8A-8D, an exemplary embodiment of an apparatus 800 for detecting a fluid discharge event in accordance with an aspect of the present disclosure is presented. The apparatus 800 is configured for attachment to either a T&P relief valve or its discharge pipe via a conduit 810. This embodiment includes a sensor electrode 820 integrated into a housing 825 that also encloses a controller 830 as set forth above.

(40) Another fluid discharge event detector 900 is shown in FIGS. 9A-9D in accordance with an aspect of the present disclosure for attachment to either a T&P relief valve or its discharge pipe. Similar to the detector 800 shown in FIGS. 8A-8D, this embodiment includes a housing 905 with a sensor electrode 920, and a controller 930 as set forth above. As can be seen, the housing 905 includes a threaded nipple 935 for coupling into a fluid system. The housing 905, of course, may include any desired coupling as may be needed for a particular application.

(41) For all of the sensor electrodes discussed herein, a larger sensor will allow for a higher resolution. The device can only pick up the capacitance via the time delay, and the added capacitance of the water will create a comparable time delay regardless of the capacitance of the sensor. That being said, the device only needs to be designed so that the SNR is adequate for the desired application; i.e., a 1 inch length of metal for the T&P valve is more than sufficient, and likewise can be said for the 2 inch application.

(42) In one aspect of the disclosure, sensor assemblies in accordance with the subject technology can be powered by a battery and/or have the option to be wired to a power source.

(43) The fluid detection assembly may include wired and/or wireless communications to notify of leaks and full discharge.

(44) It will be appreciated by those of ordinary skill in the pertinent art that the functions of several elements may, in alternative embodiments, be carried out by fewer elements, or a single element. Similarly, in some embodiments, any functional element may perform fewer, or different, operations than those described with respect to the illustrated embodiment. Also, functional elements (e.g., modules, databases, interfaces, computers, servers and the like) shown as distinct for purposes of illustration may be incorporated within other functional elements in a particular implementation.

(45) While the subject technology has been described with respect to various embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the subject technology without departing from the spirit or scope of the invention as defined by the claims as set forth herein.