GB2523402A

GB2523402A - A sensing device and a monitoring system comprising a plurality of the sensing devices

Info

Publication number: GB2523402A
Application number: GB1403269.2A
Authority: GB
Inventors: Michael Briggs; Shaun Mccafferty; Bryan Miles; Ranjit Bassi; David Butler; Philbert Chan; Stewart Willis; Ian Brixey
Original assignee: Building Research Establishment Ltd; Selex ES Ltd; Skanska UK PLC
Current assignee: Building Research Establishment Ltd; Skanska UK PLC; Leonardo UK Ltd
Priority date: 2014-02-25
Filing date: 2014-02-25
Publication date: 2015-08-26
Anticipated expiration: 2034-02-25
Also published as: GB2523402B; GB201403269D0

Abstract

A sensing device comprises a sensor for monitoring the value of a variable, a data transmission means for transmitting data to a remote sensor data collation device, and a control means for controlling the sensing device, wherein the sensing device is arranged to locally process sensor data to determine whether a predetermined change in the variable has been detected within a predetermined time period. If a change is detected then transmission of data is commenced. The sensing device may also transmit data if additional criteria are met such as the variable being sustained above a predetermined value for a predetermined period. The variable may be water temperature and the sensing device may be part of a monitoring system for water pipes, vessels and tanks to monitor for legionella bacteria.

Description

A sensing device and a monitoring system comprising a plurality of the sensing devices The present disclosure relates to a sensing device and to a monitoring system comprising a plurality of the sensing devices. In particular it relates to a sensing device that is suitable for detecting the flow and measuring the temperature of water or other fluids flowing through pipe work. The sensing device is preferably non-invasive. It may sit external to the pipe work and not require direct contact with the fluid to detect flow condition or temperature.

A significant application for a monitoring system comprising a plurality of the sensing devices would be in the control of legionella or similar bacteria. Legionellosis is the collective name given to the pneumonia-like illness caused by legionella bacteria. This includes the most serious legionnaires' disease. It may be transmitted by inhalation of aerosolized water contaminated with the bacteria. Sources where temperatures allow the bacteria to thrive include hot-water systems, such as those commonly found in buildings, including hotels, hospitals and other commercial and public properties.

Currently, in the UK, duties under the Health and Safety at Work etc Act 1974 (HSWA) extend to risks from legionella bacteria, which may arise from work activities. The Management of Health and Safety at Work Regulations (MHSWR) provide a broad framework for controlling health and safety at work and more specifically the Control of Substances Hazardous to Health Regulations 2002 (COSHH) provide a framework of duties designed to assess, prevent or control the risk from bacteria like legionella and take suitable precautions. Legionnaires' disease: The control of Legionella bacteria in water systems (Health and Safety Executive Approved Code of Practice L8) contains practical guidance on how to manage and control the risks in a system.

Current practices for managing and controlling risks can however be labour intensive and therefore costly, involving manual measurements of water temperatures at each individual water outlet on a regular interval.

Automation of flow detection, temperature measurement and record keeping for each outlet would therefore reduce labour costs and remove human error in measurement recording.

The present invention was realised during extensive work on the development of an improved monitoring system suitable for such purposes. By the provision of real-time flow detection and temperature measurement across a water distribution system, and the provision of auditable records, the management of legionella risk in a building can be made significantly more effective.

According to the present invention in a first aspect, there is provided a sensing device comprising: a sensor for monitoring the value of a variable, a data transmission means for transmitting data to a remote sensor data collation device, and a control means for controlling the sensing device, wherein the sensing device is arranged to locally process sensor data to determine whether a predetermined change in the variable has been detected within a predetermined time period.

The sensing device may be configured to commence transmission of data following the predetermined change being detected in the variable within the predetermined time period.

Following the determination that the predetermined change in the variable has been detected within the predetermined time period, the sensing device may further be arranged to log and locally process sensor data to determine whether one or more additional criteria have been met. The sensing device may be arranged to commence the transmission of data once the one or more additional criteria have been met, or to transmit event details if the one or more additional criteria have not been met. The additional criteria may comprise the monitored variable being sustained at or above a predetermined value or at or below a predetermined value for a predetermined period.

The sensing device may be arranged to make a data transmission only at a predetermined interval, at predetermined points in time, and/or in response to a remote request made to the sensing device.

The sensing device may be configured to commence transmission of data only when the predetermined change has been detected in the variable within the predetermined time period, or to commence transmission of data only when the one or more additional criteria have been met.

The sensing device may be configured to switch off automatically for a predetermined period of time upon completion of the data transmission and to switch on automatically upon expiry of the predetermined time period.

The sensing device may be configured to commence transmission of data when the predetermined change is detected in the variable within the predetermined time period, or may be configured to commence transmission of data when the one or more additional criteria have been met, and, in either case, to further make a data transmission at a predetermined interval, at a specified time, or in response to a remote request made to the sensing device.

The variable may be temperature and the sensor may include one or more temperature sensors. The sensing device is preferably mountable to the external surface of a pipe, vessel or tank and the sensor is arranged to sense the external surface temperature of the pipe, vessel or tank. The sensing device may be arranged to determine the temperature of a fluid within the pipe, vessel or tank based upon the temperature sensed by the sensor and the thermal characteristics of the pipe, vessel or tank. The thermal characteristics may be stored in a rewritable or read only memory of the sensing device.

There is preferably provided a monitoring system comprising a plurality of sensing devices as defined above, and at least one sensor data collation device located remotely to the sensing devices.

The monitoring system may be arranged such that a detected change in the surface temperature of the pipe or a difference in temperature between two or more points on the pipe is used to determine the start/cessation of fluid flow within the pipe.

Further, preferred, features are detailed in the dependent claims.

According to the present invention in a further aspect, there is provided a method for monitoring a fluid containing system, comprising a plurality of pipes, vessels, tanks and/or outlets, using a monitoring system as detailed above or in any of the dependent claims, wherein one of the sensing devices is provided on each pipe, vessel or tank to be monitored or is provided adjacent to each outlet to be monitored. The fluid containing system may be a water system, wherein the monitoring system is configured to monitor for legionella bacteria.

Non-limiting embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows, schematically, a monitoring system according to the present invention; and Figure 2 shows, schematically, a sensing device for use in the monitoring system of Figure 1.

Figure 1 shows a monitoring system according to a first embodiment for use in the prevention/control of legionnaires' disease. It should be noted that the monitoring system of the present invention need not be limited to such a use, however. As will be readily appreciated by those skilled in the art, the monitoring system may be adapted to various alternative scenarios requiring monitoring, within the scope of the claims. Notably, it may be used to monitor both closed loop and open fluid carrying systems.

The monitoring system comprises, broadly, a network of sensing devices land at least one sensor data collation device 2 located remotely to the sensing devices and preferably also a central control terminal 10 located remotely to the sensing devices. Each of the sensing devices is connected to a respective sensor data collation device through a suitable connection (shown by the connecting lines between the sensing devices and the sensor data collation device). It should be appreciated that whilst five sensing devices are shown, there will generally be a much larger network of sensing devices. The invention is not to be limited to a specific number of sensing devices or to a specific network configuration. The number of sensing devices will be entirely dependent on the plumbing system or network of tanks/pipes/openings at a facility to be monitored with at least one sensing device to be provided at each of the positions where temperature monitoring and flow detection is required. Furthermore, as will also be readily appreciated, there may be multiple sensor data collation devices provided. There may be one or more sub-networks each comprising a plurality of the sensing devices connected to a sensor data collation device. Regardless of the network configuration, each data collation device will preferably connect (through a wired or wireless connection) to a central control terminal for collation, processing and/or storage of data collected by the sensing devices. In arrangements where no central control terminal is provided, such functionality may be implemented by one of the data collation devices. The data collation devices and central control terminal may each comprise a computer of any suitable form. In any configuration, the data collation devices may further communicate with one another. The network may further include wireless repeaters, or similar, between the sensing devices and the data collators. Numerous suitable network arrangements will be readily appreciated by those skilled in the art.

One or more of the sensing devices 1, and preferably every one of the sensing devices 1, comprises, broadly, a sensor 3, a means to transmit data 4, and a control means for controlling the sensing device 5. The sensor is arranged to measure the value of a variable and the term sensor as used herein is used to define any device that is capable of converting variations in a physical quantity into an electrical signal, or any device which is capable of detecting or measuring a physical property. In the present embodiment, the variable is temperature and the temperature sensor is a thermistor. Additional sensors may be included for the measurement of further variables. The data transmission means 4 is arranged to transmit data from the sensor to the sensor data collation device that is associated with the respective sensing device. The data transmission means may comprise any suitable wired, optical or wireless communication interface. A wireless communication interface is preferable and suitable wireless communication interfaces include, but are not limited to, Wi-Fi, Bluetooth and ZigBee. The control means 5 controls the sensing device, wherein the sensing device may be configured such that sensor data is logged locally (at the sensing device) and transmitted to the sensor data collation device under the control of the control means, or alternatively wherein data is transmitted to the sensor data collation device without being logged locally and is then logged at the sensor data collation device.

Further details of the processing and logging of data are provided below. The control means may, for example, comprise a processor of any suitable architecture, as will be readily appreciated by those skilled in the art. Preferably, a rewritable memory, a read only memory and a clock are further provided. Any locally logged data may be stored in the rewritable memory. Control and configuration data may be stored in the read only memory and/or in the rewritable memory. The sensing devices may be constructed from commercially available components.

Each of the sensing devices will further comprise a power source. The power source used for each sensing device is driven by the operational environment and also by any financial constraints. The power source may comprise mains power or an energy storage medium, which may be re-chargeable or not. A non-rechargeable battery may be used ora rechargeable battery and/or capacitor may be used. It is most preferable that a rechargeable storage medium is used. When a rechargeable storage medium is used it is preferable that an energy harvesting device is provided for recharging the storage medium, of type dependent on the environment and ambient energy sources. For example, a re-chargeable battery and a photovoltaic cell may be provided, wherein the photovoltaic cell is used to recharge the battery. The sensing devices are arranged to have a very low power draw to maximize the lifetime of the system should a finite energy reserve be utilized.

The sensing devices are preferably entirely self-contained units. The sensors of the sensing devices are arranged such that they can be attached to the surface of a water pipe at any point across the system, including the surface of a water pipe near a respective measurement point (tap, shower, mixing valve, etc), or attached to any other element in the system such as the external surface of a water tank. The sensing devices may be configured in any manner such that they can be attached to an external surface tightly and securely to obtain a suitable thermal contact and prevent unintended dislodgement. The temperature sensor, which may, for example, comprise a thermistor, is positioned such that it is in thermal contact with the outer surface of the pipe to be monitored. It is preferable that the sensing devices are not insulated from the ambient environment so that changes in the surface temperature of the water pipes, or other elements, are more rapidly sensed. The sensing devices are arranged such that they may be retrofitted by attachment to the external surface of existing pipes or elements.

The principle behind the present embodiment is that the temperature on the surface of pipes provides a highly accurate indication of the actual fluid temperature inside the pipe if account is taken and compensation made for the thermal properties of the pipe. The same principles apply to other elements in a system, such as tanks. By the use of the sensing devices, the fluid temperature can be measured automatically and continuously.

The measured data is preferably locally logged at the sensing device on a continuous basis.

The sensing devices uniquely determine that there is a flow of fluid by detecting a predetermined increase/decrease in fluid temperature within a predetermined time period.

For hot water there will be an increase and for cold water there will generally be a decrease (there may be an increase in temperature when the ambient temperature is lower than the fluid temperature). The predetermined values will be dependent upon the ambient temperature, the thickness of the pipe wall, the diameter of the pipe and the pipe material, and can be set accordingly. In order to obtain reliable readings from surface mounted sensors on different pipes, there may be provided a laboratory determined calibration which can be applied to the individual sensing devices, dependent upon the characteristics of the pipe they are to be connected to, to enable accurate measurement of the temperature of a fluid within the pipe. The calibration data may, for example, be programmed in the read only memory of the sensors when they are manufactured or into the rewritable memory during installation by an engineer by connection to a computer or otherwise. The pipe characteristics have been determined for a range of variables and can be established for other variables to calibrate the processing according to requirements, as will be readily appreciated by those skilled in the art.

A key problem with prior art monitoring systems that feature wireless links between sensing devices and control units/computers/data loggers has been power consumption.

Whilst sensors such as thermistors have a very low power draw, even when continuously monitoring a variable (as is preferable in the present embodiment, wherein the thermistors of the sensing devices will continually monitortemperature unless the sensing devices are switched off), there is a significant power drain by the wireless radio (Wi-Fi or similar) during data transmission. Unless a very short battery life is acceptable, prior art sensing units have been provided with a wired connection and/or mains power, which significantly reduces flexibility and makes them unsuitable for long term monitoring.

The sensing devices in accordance with the present invention are intelligent devices that are preferably configured to transmit sensor data to their associated sensor data collation device on an ad-hoc basis, at a regular pre-determined interval, at pre-determined points in time and/or in response to a remote request (which may be received from the associated data collation device, central control terminal or otherwise).

Any of the sensing devices may periodically send data regarding the sensor irrespective of any flow of fluid being detected.

The sensing devices may be arranged to only transmit data following a predetermined temperature change being detected within a predetermined time change, i.e. only following detection of a rate of change of temperature (indicating a flow of fluid).

Alternatively, the sensing devices may be arranged to only transmit data when, following the predetermined temperature change, it is further determined that an additional criteria is met, such as that the sensed temperature is sustained at or above a predetermined temperature or at or below a predetermined temperature for a predetermined period of time.

The sensing devices may transmit data periodically and additionally when a flow of fluid is detected and/or when the additional criteria are determined to be met.

Data sent periodically, which may be sent at a regular pre-determined interval or at pre-determined points in time, may comprise a signal indicating the temperature measured within a pre-defined interval. Such data may comprise a statistical representation of the measured data over the period, or a parcel of individual data points. The benefit of periodically sending a signal irrespective of fluid flow being detected is that it may be confirmed at the sensor data collation device that the sensing devices are working correctly.

The sensing devices may be configured to switch off for a predetermined period of time upon completion of a data transmission indicating that the further criteria have been met and to switch on automatically upon the expiry of a predetermined period of time. The switching on may occur under the control of the clock. It is further preferable that there are no means available for manually switching on the sensing devices, such that they have substantially zero power draw when switched off.

It will be clear to those skilled in the art that by virtue of the intelligence of the sensing devices of the present invention, the conditions under which data is transmitted from sensors and the form of the data transmitted may be configured to suit the use/design of the system and to maximise the battery life of the sensing devices.

By only sending temperature data infrequently, energy use is minimised.

Furthermore, the risk of a data transmission or processing bottleneck in buildings with a very large sensor network is minimised.

For each instance of a sensing device having transmitted data, the central control terminal may determine whether pre-determined criteria have been met. In the present embodiment, as indicated above, this may be whether a pre-determined fluid temperature has been reached within a pre-determined time from detection of flow and maintained for a predetermined period of time.

As discussed, the data collected by the sensing devices is transmitted to the sensor data collation device, which, as discussed, may also act as the central control terminal.

Local processing at the sensing device may comprise averaging the sensor data, determining the minimum and maximum sensed temperature, confirming that the predetermined criteria have been met, etc. In its simplest form the local processing will be the determination of the predetermined temperature change within a predetermined time, wherein this will trigger the transmission of data from the sensing device that will be collated and processed by an associated data collation device.

After the processing and analysis of the data by the respective sensing device and/or data collation device, the data can be logged within the central control terminal, off loaded to secure storage media or other systems or fed into an existing water management software system.

Each of the sensing devices will have a unique ID which can be correlated to an asset numbering system for the building or facility in which the system is deployed. Accordingly, there can be no risk of a water outlet or fluid sensing point being missed or forgotten during testing, as may occur in a manual system.

This concept is not limited to the measurement of water pipe surface temperature, and for example can be extended to temperature monitoring in fridges for food, vaccines, or any other situations where temperature monitoring and control is critical. It may further be extended to situations that require the monitoring of additional/alternative variables by the introduction of one or more additional sensors or the replacement of the temperature sensor with one or more alternative sensors.

The above described embodiment can provide significant savings in the amount of labour cost by not requiring manual measurements at regular intervals. It will provide the benefit that a continuous log of data will be available for audit trial instead of one-off measurement which will provide a high degree of risk management to reduce the potential for adverse conditions occurring between manual or other checks. The possibility of human error will also be significantly reduced.

Numerous alternatives and modifications within the scope of the appended claims are possible, as will be readily appreciated by those skilled in the art.

Claims

Claims 1. A sensing device comprising: a sensor for monitoring the value of a variable, a data transmission means for transmitting data to a remote sensor data collation device, and a control means for controlling the sensing device, wherein the sensing device is arranged to locally process sensor data to determine whether a predetermined change in the variable has been detected within a predetermined time period.
2. A sensing device as claimed in Claim 1, which is configured to commence transmission of data following the predetermined change being detected in the variable within the predetermined time period.
3. A sensing device as claimed in Claim 1 or 2, wherein, following the determination that the predetermined change in the variable has been detected within the predetermined time period, the sensing device is further arranged to log and locally process sensor data to determine whether one or more additional criteria have been met.
4. A sensing device as claimed in Claim 3, which is arranged to commence the transmission of data once the one or more additional criteria have been met, orto transmit event details if the one or more additional criteria have not been met.
5. A sensing device as claimed in Claim 4, wherein the additional criteria comprises the monitored variable being sustained at or above a predetermined value or at or below a predetermined value for a predetermined period.
6. A sensing device as claimed in any preceding claim, which is arranged to make a data transmission only at a predetermined interval, at predetermined points in time, and/or in response to a remote request made to the sensing device.
7. A sensing device as claimed in Claim ito 3, which is configured to commence transmission of data only when the predetermined change has been detected in the variable within the predetermined time period, or as claimed in Claim 4 or 5, which is configured to commence transmission of data only when the one or more additional criteria have been met.
8. A sensing device as claimed in Claim 7, which is configured to switch off automatically for a predetermined period of time upon completion of the data transmission and to switch on automatically upon expiry of the predetermined time period. :10
9. A sensing device as claimed in Claim ito 3, which is configured to commence transmission of data when the predetermined change is detected in the variable within the predetermined time period, or as claimed in Claim 4 or 5, which is configured to commence transmission of data when the one or more additional criteria have been met, and, in either case, to further make a data transmission at a predetermined interval, at a specified time, or in response to a remote request made to the sensing device.
10. A sensing device as claimed in any preceding claim, wherein the control means comprises a processor and the sensing device further comprises a re-writable memory for storing data from the sensor.
11. A sensing device as claimed in Claim iO, which further comprises a read only memory and a clock.
12. A sensing device as claimed in any preceding claim, which is configured so that the sensor continually monitors the value of the variable when the sensing device is switched on.
13. A sensing device as claimed in any preceding claim, wherein the variable is temperature and the sensor includes one or more temperature sensors.
14. A sensing device as claimed in Claim 13, which is arranged to be mountable to the external surface of a pipe, vessel or tank and the sensor is arranged to sense the external surface temperature of the pipe, vessel or tank.
15. A sensing device as claimed in Claim 14, which is arranged to determine the temperature of a fluid within the pipe, vessel or tank based upon the temperature sensed by the sensor and the thermal characteristics of the pipe, vessel or tank.
16. A sensing device as claimed in Claim 15 when dependent on any of Claims 10 to 12, wherein the thermal characteristics are stored in the rewritable or read only memory of the sensing device.
17. A sensing device as claimed in any of Claims 14 to 16, which is arranged such that a detected change in the surface temperature of the pipe or a difference in temperature between two or more points on the pipe is used to determine the start/cessation of fluid flow within the pipe.
18. A sensing device as claimed in any preceding claim, which is connected to the sensor data collator using optical, wired or wireless communication means.
19. A sensing device as claimed in any preceding claim, which is mains powered or is powered by a battery or by a rechargeable energy storage medium.
20. A sensing device as claimed in Claim 19, wherein the rechargeable energy storage medium comprises one or more batteries and/or one or more capacitors.
21. A sensing device as claimed in Claim 20, which further comprises an energy harvesting device that is operatively connected to the rechargeable energy storage medium.
22. A sensing device as claimed in any preceding claim which comprises one or more further sensors for monitoring one or more further variables.
23. A monitoring system comprising a plurality of sensing devices as claimed in any preceding claim, and at least one sensor data collation device located remotely to the sensing devices.
24. A monitoring system as claimed in Claim 23, wherein the sensor data collation device is arranged to analyse and store sensor data received from the sensing device that is connected thereto.
25. A monitoring system as claimed in Claim 23 or 24, wherein the sensor data collation device is arranged to pass data received from the sensing device to another system or device for storage, reporting and/or analysis.
26. A monitoring system as claimed in any of Claims 23 to 25 further comprising a central control terminal, wherein the or each sensor data collation device is connected to the central control terminal and the system is arranged such that data received by each sensor data collation device is forwarded to the central control terminal.
27. A monitoring system as claimed in Claim 26, wherein the sensor data collation device is arranged to analyse and/or store sensor data received from the sensing device that is connected thereto.
28. A monitoring system as claimed in Claim 26 or 27, wherein the sensor data collation device is arranged to pass data received from the sensing device to another system or device for storage, reporting and/or analysis.
29. A method for monitoring a fluid containing system, comprising a plurality of pipes, vessels, tanks and/or outlets, using a monitoring system as claimed in any preceding claim, wherein one of the sensing devices is provided on each pipe, vessel or tank to be monitored or is provided at or adjacent to each outlet to be monitored.
30. A method as claimed in Claim 29, wherein the fluid containing system is a water system and the monitoring system is configured to monitor for legionella bacteria.
31. A sensing device as hereinbefore described with reference to the accompanying drawings.
32. A monitoring system as hereinbefore described with reference to the accompanying drawings.
33. A method for monitoring a fluid containing system as hereinbefore described with reference to the accompanying drawings.Amendments to the Claims have been filed as follows:-Claims 1. A sensing device comprising: a sensor for monitoring the value of a variable, a data transmission means for transmitting data to a remote sensor data collation device, and a control means for controlling the sensing device, wherein the sensing device is arranged to locally process sensor data to determine whether a predetermined change in the variable has been detected within a predetermined time period, wherein, following the determination that the predetermined change in the variable has been detected within the predetermined time period, the sensing device is further arranged to log and locally process sensor data to determine whether one or more additional criteria have been met, wherein the additional criteria comprises the monitored variable being sustained at or above a predetermined value or at or below a predetermined value for a predetermined 0) o period, and c wherein the sensing device is arranged to commence the transmission of data, in C) dependence on the determination that the predetermined change in the variable has been detected within the predetermined time period, only once the one or more additional criteria have been met, or to transmit event details, in dependence on the determination that the predetermined change in the variable has been detected within the predetermined time period, only following determination that the one or more additional criteria have not been met.2. A sensing device as claimed in any preceding claim, which is arranged to make a further data transmission, independently of the determination that the predetermined change in the variable has been detected, at a predetermined interval, at predetermined points in time, and/or in response to a remote request made to the sensing device.3. A sensing device as claimed in Claim 1 or 2, which is configured to switch off automatically for a predetermined period of time upon completion of the data transmission, following the determination that the predetermined change in the variable has been detected within the predetermined time period, and to switch on automatically upon expiry of the predetermined time period.4. A sensing device as claimed in any preceding claim, wherein the control means comprises a processor and the sensing device further comprises a re-writable memory for storing data from the sensor.5. A sensing device as claimed in Claim 4, which further comprises a read only memory and a clock.6. A sensing device as claimed in any preceding claim, which is configured so that the sensor continually monitors the value of the variable when the sensing device is switched on.7. A sensing device as claimed in any preceding claim, wherein the variable is o temperature and the sensor includes one or more temperature sensors.CC) 8. A sensing device as claimed in Claim 7, which is arranged to be mountable to the external surface of a pipe, vessel or tank and the sensor is arranged to sense the external surface temperature of the pipe, vessel or tank.9. A sensing device as claimed in Claim 8, which is arranged to determine the temperature of a fluid within the pipe, vessel or tank based upon the temperature sensed by the sensor and the thermal characteristics of the pipe, vessel or tank.10. A sensing device as claimed in Claim 9 when dependent on Claim 4 or 5, wherein the thermal characteristics are stored in the rewritable or read only memory of the sensing device.11. A sensing device as claimed in any of Claims 8 to 10, which is arranged such that a detected change in the surface temperature of the pipe ora difference in temperature between two or more points on the pipe is used to determine the start/cessation of fluid flow within the pipe.12. A sensing device as claimed in any preceding claim, which is connected to the sensor data collator using optical, wired or wireless communication means.13. A sensing device as claimed in any preceding claim, which is mains powered or is powered by a battery or by a rechargeable energy storage medium.14. A sensing device as claimed in Claim 13, wherein the rechargeable energy storage medium comprises one or more batteries and/or one or more capacitors.15. A sensing device as claimed in Claim 14, which further comprises an energy harvesting device that is operatively connected to the rechargeable energy storage medium.16. A sensing device as claimed in any preceding claim which comprises one or more o further sensors for monitoring one or more further variables.CC) 17. A monitoring system comprising a plurality of sensing devices as claimed in any preceding claim, and at least one sensor data collation device located remotely to the sensing devices.18. A monitoring system as claimed in Claim 17, wherein the sensor data collation device is arranged to analyse and store sensor data received from the sensing device that is connected thereto.19. A monitoring system as claimed in Claim 17 or 18, wherein the sensor data collation device is arranged to pass data received from the sensing device to another system or device for storage, reporting and/or analysis.20. A monitoring system as claimed in any of Claims 17 to 19 further comprising a central control terminal, wherein the or each sensor data collation device is connected to the central control terminal and the system is arranged such that data received by each sensor data collation device is forwarded to the central control terminal.21. A monitoring system as claimed in Claim 20, wherein the sensor data collation device is arranged to analyse and/or store sensor data received from the sensing device that is connected thereto.22. A monitoring system as claimed in Claim 20 or 21, wherein the sensor data collation device is arranged to pass data received from the sensing device to another system or device for storage, reporting and/or analysis.23. A method for monitoring a fluid containing system, comprising a plurality of pipes, r"lS vessels, tanks and/or outlets, using a monitoring system as claimed in any preceding claim, 0') wherein one of the sensing devices is provided on each pipe, vessel or tank to be monitored or is provided at or adjacent to each outlet to be monitored. 24. A method as claimed in Claim 23, wherein the fluid containing system is a water system and the monitoring system is configured to monitor for legionella bacteria.25. A sensing device as hereinbefore described with reference to the accompanying drawings.26. A monitoring system as hereinbefore described with reference to the accompanying drawings.27. A method for monitoring a fluid containing system as hereinbefore described with reference to the accompanying drawings.