A METHOD FOR MONITORING A FLOW CONDITION, A LEAK INDICATOR AND A LOW HEAT EXCHANGE INDICATOR, BOTH TO BE USED BY THE METHOD

Abstract: The invention relates to a method of automatic monitoring a flow condition and to indicators to be used by the method. A method is intended for indicating a possible leak in a cold water supply pipe and a method is intended for indicating a possible low heat exchange in a domestic heat exchanger. The methods use measurements of temperatures on the surface of a pipe and measurements of temperatures of the surroundings or of another pipe. The leak indicator monitors a temperature difference between the surface of the cold water supply pipe and the temperature of the surroundings, and the low heat exchange indicator monitors a temperature difference between the surface of an inlet pipe and the surface of an outlet pipe of the heat exchanger.

Description: A METHOD FOR MONITORING A FLOW CONDITION, A LEAK INDICATOR AND A LOW HEAT EXCHANGE INDICATOR, BOTH TO BE USED BY THE METHOD An automatic method for monitoring a flow condition in a number of pipes in a water system and indicating when the flow condition over a period of time has predetermined characteristics defining a minute flow or a minimum heat exchange in the water system, and a leak indicator or a heat exchange indicator for indicating a possible leak or a possible low heat exchanger in the water system. BACKGROUND OF THE INVENTION It is known to have a water measurement device such as normal domestic water meters that are placed in the water system with the water flowing through them. These water meters are normally provided with a meter on which the consumption of water is indicated as a number related to the amount of water that has been flowing through the water meter since it was installed. It is also known to have a water meter that has a digital display to indicate the use of water and it is known that some of these digital displays are able to be reset, in all cases the water meter is placed as a part of the pipe system and is thus very difficult to remove or move as the system has to be drained and the meter removed with hand tools. Furthermore, it is known to have to have a water measurement device in a domestic central heating system receiving heat through a heat exchanger form a district heating system through an inlet and outlet. The water measurement device of such a heating system may comprise, apart from a water meter, a temperature measurement device for measuring the difference in temperature between the inlet and the outlet. However the measurement takes place by means of measurement devices providede within the pipes constituting the inlet and the outlet. US 4,336,708 relates to a leak locator for pipelines which locator includes an electronic circuit having temperature sensors attachable to the pipeline and a time and temperature monitor. The system utilises time and temperature differences to determine the direction and along with the known volume loss can determine the distance of a pipeline leak relative to the locator. The pipeline leak locator further includes a cooling coil for reducing the pipe wall temperature to a predetermined value in the area of the sensors. US 5,287,884 relates to a water flow monitoring system using a microphone for determining the presence of leaks in plumbing pipes having water flowing through the pipes under high pressure. The system includes a flow monitor which is mounted to the pipe for sensing the flow of water through the pipe. FR 2 763 665 relates to a device for detecting a leak in a supply pipe for a fluid such as water. The invention relates to a device using a sequential method, one sequence measuring the surrounding sound or temperature, this defining the state [0] that relates to a non-flow situation, and another sequence measuring the sound or temperature by a small flow defining the state [1], the state [1] defining a leak. It is an object of the present invention to provide a method for automatic monitoring of a flow condition in a pipe and indicating when the flow over a period of time has a predetermined character It is also an object of the present invention to provide a method for automatic monitoring of a flow condition in a number of pipes and indicating when a heat exchange between the number of pipes over a period of time has a pretermined character. DESCRIPTION OF THE INVENTION The objects of the invention is obtained by method comprising the steps of determining a possible difference between a lower temperature and a higher temperature, starting a measurement of a time if the possible difference between said lower and higher temperatures is within a predetermined temperature interval, starting at a first temperature and ending at a second temperature, said measurement of the time span being maintained for as long as the temperature difference is within the predetermined temperature interval and for as long as the actual time span does not exceed a predetermined maximum time span, and indicating the presence of a non-desired flow condition according to the predetermined character of flow condition in the number of pipes when the time span measured exceeds the predetermined time span and when the difference between said lower temperature and said higher temperature exceeds the predetermined temperature interval. The higher temperature is the temperature of the media surrounding the pipe, or is a surface temperature of the inlet, and where the higher temperature is exchanging energy with the water inlet pipe or the outlet pipe of a heat exchanger. When there is no flow of cold water in the pipe or there is no heat exchange, this exchange of energy will result in an equalisation of the temperature of the cold water pipe and the surrounding media or of the temperature in the inlet pipe and the outlet pipe, eventually leading to substantially no temperature difference. The temperature difference is calculated so that it has a positive sign when the cold water pipe temperature has a lower value than the surrounding temperature or the outlet pipe temperature has a lower value than the inlet pipe temperature. The character of the flow condition may be of any magnitude but in a preferred method it is a minute flow or a minimum heat exchange. The minute flow is a flow that compared with the normal flow of the pipe is a minute such as 1 % of the normal flow, preferably 0,1% of the normal flow. The minimum heat exchange is a heat exchange that compared to the temperatures of the inlet pipe and the outlet pipe is a minimum difference between the temperatures of the pipes. The normal flow is an individual value depending on the specific use of the pipe and the normal heat exchanger is an individual value depending on the season and on the temperatures of the inlet pipe and the outlet pipe, respectively.. It is a further object of the invention to provide a method in which the second temperature has a high value, e.g. over 100°C, or a not defined value coursing the predetermined temperature interval to be a open interval over the first temperature, which will make the method indicate any flow over a given magnitude. The two methods may also be used simultaneously so that both a minute flow occurring for a relative short time and a flow over a given magnitude for a relatively long time will be indicated. Additionally, the method of indicating the minimum heat exchange may be performed simultaneously with the indicating of a minute flow. In a first preferred embodiment of the invention the temperature interval and the time period are defined by an external source such as an operator or a central computer. The temperature interval for indicating a leak is an open interval above the first temperature and the first temperature is within the range of 0 - 5°C, preferred within the range of 0,1 - 4°C, more preferred within the range of 0,3 - 2°C, most preferred 0,4°C, is in this embodiment the predetermined time between 12 and 36 hours preferably 24 hours. The temperature interval for indicating a low heat exchange is closed interval above the first temperature and the temperature interval is within the range of 10°C-80°C, more preferred within the range of 20°C-60°C, most preferred within a range of 20°C-40°C. In an other preferred embodiment of the invention, the temperature interval and the time period are defined by an external source such as a operator or a central computer. The temperature interval is an interval between the first temperature and the second temperature, the second temperature being a higher temperature than the first temperature. In this embodiment the first temperature is within the range of 0 - 5°C, preferred within the range of 0,01 - 4°C, more preferred within the range of 0,1 - 2°C, most preferred within the range of 0,15 - 0,3°C. The second temperature is within a range of 0,2 - 20°C, preferred within the range of 0,3 - 10°C, more preferred within the range of 0,4 - 5°C most preferred within the range of 3-4°C. In this embodiment the predetermined time value is between 0.5 and 24 hours, preferred between 1 and 10 hours more preferred between 1.5 and 3 hours most preferred 2.5 hours. In a preferred embodiment of the invention, these methods are used in a domestic water system, such as a private house or a private apartment. Alternatively these methods are used in an industrial water system such as an office building or a factory. The measurements are either carried out on the surface of cold water inlet pipe and on the surroundings around the inlet pipe, e.g. the room in which the pipe enters the house or apartment or are carried out on the surface of outlet pipe of the heat exchanger and on the inlet pipe of the heat exchanger. The water system in such a house, apartment, office buliding or factory contains piping, water heaters, valves, taps etc. In an even further preferred embodiment, the method indicates the possible non-desired flow condition by an audio indication such as a buzzer or a visual indication such as a flashing light. In a possible embodiment, a signal is communicated to a central logical unit. It is also an object of the present invention to provide a leak indicator or a low heat exchange indicator for use by the methods described above. The indicator has a time measurement device, a signalling device, a first temperature measurement device for measuring a pipe temperature, and a second temperature measurement device for measuring a surrounding temperature or the inlet pipe temperature. In this way the leak indicator or the heat exchange indicator is able to determine the temperature difference between the pipe temperature and the surrounding temperature or between the outlet pipe temperature and the inlet pipe temperature. The time measurement device is measuring the time during which the temperature difference is within the predetermined temperature interval. It is also an object of the invention to provide a leak indicator for using both the first and the second method, having two separate time and temperature intervals that determines if there is a leak in the system. Also a leak indicator having more than two time and corresponding temperature intervals is an embodiment of this invention. To indicate that a leak has occurred, the indicator has a signalling device such as an audio alarm such as a buzzer and/or a visual alarm such as a flashing light. In a preferred embodiment the housing of the indicator is the main frame part on to which preferably all parts are secured, so that every part is placed on or in the housing. The housing has fastening means such as a magnet or elongated flexible means such as plastic strips for wrapping around a rod or pipe to secure the indicator in a predetermined place e.g. on the pipe. The housing also has a first holder for the first temperature measurement device. The holder ensures that the first temperature measurement device has sufficient thermal contact to the pipe and a second holder for the second temperature measurement device ensures that the second temperature measurement device has sufficient thermal contact to the surrounding air or to the inlet pipe so that the two temperature measurement devices measure the temperature without interference. The preferred embodiment further has a holder for the signalling device that is placed in such a way that it is free to signal to a person or to a main computer the appearance of a flow or minute flow. In a further preferred embodiment of the housing he housing is made from a plastic such as ABS, Acetal, Acrylic, ASA, Cellulose Butyrate, ETFE (Tefzel), EVA Ethylene, Vinyl Acetate, LCP, Nylon, Polyallomer, Polyamide, Polycarbonate, PBT Polyester, Polyethene, PEEK Polyetheretherkeytone, PEI Polyetherimid (Ultem), Polyethersulfone, Polyethylene, Polyimide Thermoplastic (Aurum), Polypropylene, PPA Polyphthalamide (Amodel), PPO Modified Polyphenylene Oxide (Noryl), PPS Polyphenylene Sulfide, Polypropylene, Polystyrene Crystal, Polystyrene, Polysulfone, Polytetrafluoroethylene, Polyurethane, PVC Polyvinyl Chloride, PVDF Polyvinylidene Fluoride (Kynar), SAN Styrene Acrylonitrile, or TPE Thermoplastic Elastomers. The housing may also be made from a metal or metal alloy or any other kind of material. In a further possible embodiment, one of or both the temperature measurement device(s) is/are placed away from the indicator and the indicator is placed away from the pipe such as on a nearby wall or in a central unit that may comprise means for indicating a flow or a minute flow in several pipes. Alternatively to measuring a difference in temperatures between a temperature of a pipe and a temperature of the surroundings, in a second application it will be possible to measure a difference in temperatures between a temperature of a first pipe of a water system and a temperature of a second pipe of the water system. The first pipe will be an outlet of water from a a central heating system to a district heating system, and the second pipe will be an inlet of hot water from the district heating system to the central heating system. The second pipe will be the pipe with a flow of water having a higher temperature, and the first pipe will be the pipe with a flow of water having a lower temperature because the water will have passed from the second pipe through a heat exchanger to the first pipe. Thus, contrary to the first application of the indicator where the temperature difference is between a pipe and the surroundings, then the second application of the indicator involves a temperature difference between a first pipe and a second pipe. The indicator may be provided with a remote temperature measurement device so that the indicator itself comprises a first temperature measurement device and is mounted to the second outlet pipe with water having a lower temperature and the remote temperature measurement device is mounted to the first inlet pipe with water having a higher temperature. By measuring the difference in temperatures between an inlet and an outlet by means of an indicator according to the invention, then it will be possible to verify or to check the efficiency of the heat exchanger. If the difference in temperatures is to small compared to a predetermined value, then it is a sign of the heat exchanger not functioning efficiently enough, because not enough heat is exchanged form the water in the district heating system to the water in the central heating system. The difference in temperature defining the predetermined difference may vary depending on different regional temperatures of the district heating system and different regulations concerning the demands form official authorities to a certain efficiency of the heat exchanger of the central heating systems. Thus, a certain difference in temperatures must be accomplished in order to comply with the demands of the official authorities. However, the temperature of the inlet and the temperature of the outlet may also vary depending on the season, thus the temperature of the inlet being higher during winter than during summer seasons. During summer seasons the temperature in the second pipe, the inlet pipe from the district heating system to the heat exchanger of the central heating system, may have a temperature of between 20°C and 50°C, preferably between 30°C and 50°C, more preferred between 40°C and 50°C. The tempretaure in the first pipe, the outlet pipe from the heat exchanger of the central heating system to the district heating system, may have a temperature of between 20°C and 50°C, preferably between 20°C and 40°C, more preferred between 20°C and 30°C During winter seasons the temperature in the second pipe may have a temperature between 50°C and 100°C, preferably between 50°C and 90°C, more preferred between 70°C and 90°C. The temperature in the first pipe may have a temperature between 40°C and 70°C, preferably between 40°C and 60°C, more preferred between 40°C and 60°C. In an embodiment the indicator has a logical control unit e.g. a computer which at least temporally can be connected to a central logical unit. The logical unit may be connected to the two temperature measurement devices, e.g. thermistors, through an interface securing the communication between the computer and the two temperature measurement devices. In another embodiment the indicator is made as an analogue electronically device. DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of an indicator placed in a system. Fig.2 is a table of measurements over a period of time. Fig.3 is a table of measurements over a period of time. Fig. 1 the figure shows a schematic example of a placement of the indicator. The water runs into the system at 3, runs through the water meter 1 past the indicator 2 and on to the system at the point 4. The indicator has a time measurement device and has a first temperature measurement device and a second measurement device. The first temperature measurement device is for measuring the temperature of the surface of the cold water inlet pipe from a public or private water supply system or for measuring the surface temperature of an outlet pipe from a heat exchanger to a district heating system. The second temperature measurement device for measuring the temperature of the surroundings of the cold water inlet pipe or for measuring the surface temperature of an inlet pipe from the district heating system to the heat exchanger. Fig. 2 relates to an example of the first method applied in a leak indicator with a low temperature difference level at 0,3°C and no upper temperature difference level. This will course the time span measurement device to run as long as the temperature difference is over 0,3°C and the alarm will start when the time span exceeds 24 hours. The letters in the table are short for: t The actual time, T p Pipe temperature in degree centigrade, T s Surrounding temperature in degree centigrade, F 0 Flow in the system in litres per hour, The time span measured by the time measurement device in real time, k Measurement code. 1. There is a normal flow and the measurement of the time span is set to run. 2. There is no flow and the measurement of the time span is stopped and reset. 3. A minute flow is present from this time and on. The time span measurement start as the temperature drops in the pipe. 4. The minute flow results in a little temperature difference and the time measurement of the time span is running. 5. A normal flow and the measurement of the time span is still running. 6. Only the minute flow is present and the measurement of the time span is running. 7. A normal flow and the measurement of the time span is still running. 8. Only the minute flow is present and the measurement of the time span is running. 9. Only the minute flow is present and the measurement of the time span is running and exceeds the predetermined time limit of 24 hours which sets the alarm to start. Fig. 3 relates to an example of the second method applied in a leak indicator with a low temperature difference level at 0,2°C and a upper temperature difference level at 5°C. This will course the time span measurement device to run as long as the temperature difference is between 0,2°C and 5°C and the alarm will start when the time span exceeds 3 hours. The letters in the table are short for: t The actual time. T p Pipe temperature in degree centigrade. T s Surrounding temperature in degree centigrade. F 0 Flow in the system in litres per hour. t. The time span measured by the indicator in real time. 1. There is a normal flow and the measurement of the time span is stopped and reset. 2. A minute flow is present from this time and on. The time measurement starts as the temperature drops in the pipe and the temperature difference is within the temperature interval. 3. The minute flow results in a minor temperature difference and the time measurement of the time span is running. 4. A normal flow and the measurement of the time span is stopped and reset. 5. A minute flow is present from this time, the time measurement starts as the temperature difference is within the temperature interval. 6. Only the minute flow is present and the measurement of the time span is running and exceeds the predetermined time limit on 3 hours which sets the alarm to start.

Claims: CLAIMS 1. A method for automatic monitoring a flow condition in a number of pipes and indicating when the flow condition in the number of pipes, over a period of time, has a predetermined character, comprising the steps of determining a possible difference between a lower temperature and a higher temperature, starting a measurement of a time span if the possible difference between said lower and higher temperatures is within a predetermined temperature interval, said interval starting at a first temperature and ending at a second temperature, said measurement of the time span being maintained for as long as the temperature difference is within the predetermined temperature interval and for as long as the actual time span does not exceed a predetermined maximum time span, and indicating the presence of a non-desired flow condition according to the predetermined character of flow condition in the number of pipes when the time span measured exceeds the predetermined time span and when the difference between said lower temperature and said higher temperature exceeds the predetermined temperature interval. 2. A method according to claim 1 for automatic monitoring a flow condition in a pipe and indicating when a flow in the pipe, over a period of time, has a predetermined character defined as the presence of a flow, comprising the steps of determining a possible difference between a lower pipe temperature and a higher surrounding temperature, starting a measurement of a time span if the possible difference between said lower temperature and said higher temperature is within a predetermined temperature interval, said interval starting at a first temperature and ending at a second temperature, said measurement of the time span being maintained for as long as the temperature difference is within the predetermined temperature interval and for as long as the time span does not exceed a predetermined maximum time span, and indicating the presence of the flow according to the predetermined character of flow in the pipe when the time span measured exceeds the predetermined time span. 3. A method according to claim 2, wherein the second temperature has a higher value e.g. over 100°C or a not defined value causing the predetermined temperature interval to be an open interval over the first temperature, this will make the method indicate any flow over a given magnitude. 4. A method according to claim 2 or claim 3, wherein the first temperature has a value being within the range of 0 - 5°C, preferred within the range of 0,1 - 4°C, more preferred within the range of 0,3 - 2°C, and most preferred 0,4°C. 5. A method according to claim 2 or claim 3, wherein the first temperature has a value within the range of 0 - 5°C, preferred within the range of 0,01 - 4°C, more preferred within the range of 0,1 - 2°C, most preferred within the range of 0,15 - 0,3°C. 6. A method according to any of claims 2-5, wherein the second temperature has a higher value within the range of 0,2 - 20°C, preferred within the range of 0,3 - 10°C, more preferred within the range of 0,4 - 5°C most preferred within the range of 3-4°C. 7. A method according to any of claims 2-6, wherein the predetermined time span is between 3 and 72 hours, preferably between 12 and 48 hours, more preferably between 12 and 36 hours, most preferably is 24 hours. 8. A method according to any of claims 2-7, wherein the time span measured is between 0,5 and 24 hours, preferably between 1 and 10 hours, more preferably between 1 ,5 and 3 hours, most preferably 2,5 hours. 9. A method according to any of claims 1-8, wherein indicating the possible flow comprises an audible indication. 10. A method according to any of claims 1-9, wherein indicating the possible flow comprises a visual indication. 11. A method according to any ' of claims 1-10, where the pipe temperature is measured on a cold water supply pipe from a public fresh water system to a domestic water system. 12. A method according to any of claims 1-10, where the pipe temperature is measured on a cold water supply pipe from a private fresh water system to a domestic water system. 13. A method according to any of claims 1-12, where the pipe temperature is measured on a cold water supply pipe to a public fresh water system. 14. A method according to any of claims 1-13, where the method is used for indicating a possible leak in a domestic water system e.g. a private house hold water system. 15. A method according to claim 1 for automatic monitoring a flow condition in a heat exchanger and indicating when the heat exchange in the heat exchanger, over a period of time, has a predetermined character defined as a certain low heat exchange, comprising the steps of determining a possible difference between a lower pipe temperature and a higher pipe temperature, starting a measurement of a time span if the possible difference between said lower temperature and said higher temperature is within a predetermined temperature interval, starting at a first temperature and ending at a second temperature, said measurement of the time span being maintained for as long as the temperature difference is within a predetermined temperature interval and for as long as the time span does not exceed a predetermined maximum time span, and indicating the presence of a low heat exchange according to the predetermined character of heat exchange in the heat exchanger when the time span measured exceeds the predetermined maximum time span. 16. A method according to claim 15, wherein the second temperature has a lower value within the range of 20-100°C, preferred within the range of 20-60°C, more preferred within the range of 20-50°C most preferred within the range of 20-40°C. 17. A method according to claim 15 or claim 16, wherein the first temperature has a higher value within the range of 20 - 100°C, preferred within the range of 30 - 90°C, more preferred within the range of 40 - 80°C, most preferred is within the range of 30-80°C. 18. . A method according to any of claims 2-6, wherein the predetermined time span is between 3 and 72 hours, preferably between 12 and 48 hours, more preferably between 12 and 36 hours, most preferably is 24 hours. 19. A method according to any of claims 15-18, wherein the time span measured is between 0.5 and 24 hours, preferred between 1 and 10 hours, more preferred between 1.5 and 3 hours, most preferred 2.5 hours. 5 20. A method according to any of claims 15-19, wherein indicating the possible flow comprises an audible indication. 21. A method according to any of claims 15-20, wherein indicating the possible flow comprises a visual indication. 10 22. A method according to any of claims 15-21 , where the higher pipe temperature is measured on a surface of an inlet pipe of water from a district heating system to a central heating system. 15 23. A method according to any of claims 15-22, where the lower pipe temperature is measured on the surface of an outlet pipe of water from a central heating system to a district heating system. 24. A method according to any of claims 15-23, where the method is used for indicating a 0 possible low heat exchange in a domestic heating system e.g. a private house hold heating system. 25. An indicator for indicating a possible fault in a water system, wherein the indicator comprises a time measurement device, a signalling device, a first temperature 5 measurement device for measuring a lower temperature, and a second temperature measurement device for measuring a higher temperature, said first and second temperature measurement devices being intended for determining a possible temperature difference between the lower temperature and the higher temperature, 0 the time measurement device being intended for measuring a time span during which the temperature difference is within a predetermined temperature interval, and the signalling device being intended for signalling when said time span has a predetermined value, and the signalling device thereby indicating the presence of a fault in the water system. 5 26. An indicator according to claim 25, wherein the predetermined temperature interval is provided to the indicator by an external source. 27. A leak indicator according to claim 25, that is capable to perform the method 5 according to any of the claims 1-14. 28. A leak indicator according to claim 25, that is capable to perform the method according to any of the claims 15-24. 10 29. A leak indicator according to claim 27, wherein the indicator has a housing part comprising fastening means, a first holder for the first temperature measurement device, a second holder for the second temperature measurement device, and a holder for the signalling device, the fastening means for securing the housing in its operational place e.g. on the pipe, in a way that allows 15 the first temperature measurement device to measure the pipe temperature with substantially no influence from the surrounding temperature, and the second temperature measurement device being allowed to measure the surrounding temperature with substantially no influence from the pipe temperature. 20 30. A leak indicator according to claim 29, wherein the fastening means fastens the indicator at an operational place away from the pipe e.g. on a wall and fastens the first temperature measurement device on the pipe. 31. A low heat exchange indicator according to claim 28, wherein the indicator has a 25 housing part comprising fastening means, a first holder for the first temperature measurement device, a second holder for the second temperature measurement device, and a holder for the signalling device, the fastening means for securing the housing in its operational place e.g. on the pipe, in a way that allows the first temperature measurement device to measure the outlet pipe temperature with 30 substantially no influence from the surrounding temperature and form the inlet pipe temperature, and the second temperature measurement device being allowed to measure the inlet pipe temperature with substantially no influence from the surrounding temperature and form the outlet pipe temperature. 35 32. A leak indicator according to claim 31 , wherein the fastening means fastens the indicator at an operational place away from the pipe e.g. on a wall and fastens the first temperature measurement device on the surface of the outlet pipe and fastens the second temperature measurement device on the surface of the inlet pipe. 5 33. An indicator according to any of claims 25-32, wherein the fastening means comprises a magnet. 34. An indicator according to any of claims 25-32, wherein the fastening means is an 10 elongated flexible means, e.g. a plastic strip for wrapping around the housing and a rod or pipe. 35. An indicator according to any of claims 25-34, wherein the indicator comprises a logical control unit for controlling the functions of the indicator. 15 36. An indicator according to claim 35, wherein the logical unit is at least temporally connected to a central logical unit for transmitting and receiving signals from and to the central computer. 20 37. An indicator according to any of claims 25-36, further comprising an interface determined to provide communication between the first and the second temperature measurement devices e.g. thermistors and the logical unit.

Inventors: ESPENSEN FRANK NELSON, ESPENSEN, FRANK, NELSON
Applicants: ESPENSEN FRANK NELSON, ESPENSEN, FRANK, NELSON
Application year: 2000
Main classification: G01M3
IPC codes: G01M3