GB2545830B - Flow determination - Google Patents

Description

FLOW DETERMINATION

This invention relates to a method and apparatus for flow determination, a fluidconduit provided with such an apparatus, a sensing apparatus and related kit of parts,and a data collection method.

For various reasons, in particular in order to prevent or mitigate against the damagecaused by leaking pipes, it is desirable to be able to determine whether and to whatextent a fluid, and typically water, is flowing through a fluid conduit such as a pipe.Given the extent of extant plumbing networks, it is desirable to provide a solution tothis problem that is non-invasive, simple and easily installed.

We are aware of the PCT application published as WOO 1/25743, which discloses aflow sensor which determines whether there is flow through a pipe if the temperatureof the pipe is different from ambient temperature by more than a predetermined limitfor more than a predetermined period of time. However, this is relatively inflexible inthat it requires the predetermined period of time to have elapsed before adetermination is made, and no measurement of the level of flow is provided.

Aspects and preferred features of the invention are set out in the appended claims.

Disclosed herein is a sensing apparatus, comprising: • a first temperature sensor; • a sensor head housing the first temperature sensor, the sensor head beingarranged so as to hold the first temperature sensor against a fluid conduit, withthe first temperature sensor being arranged so as to produce in use a firsttemperature signal indicative of a first temperature being that of the fluidconduit; • a housing; • a second temperature sensor, arranged to produce in use a second temperaturesignal indicative of a second temperature being the ambient temperature; in which the housing and the sensor head are joined by a flexible cable, the sensingapparatus being arranged to be installable such that, when the sensor head is attachedto the fluid conduit, the housing is suspended from the fluid conduit on the flexiblecable, and such that in use the flexible cable transmits at least one of the first andsecond temperature signals.

As such, this allows more convenient installation on a fluid conduit; only the sensorhead need be attached to the fluid conduit, with a housing suspended on the flexiblecable.

The second temperature sensor may be mounted in the housing. This allows thesecond temperature - the local ambient temperature - to be measured at a positionmore distant from the first temperature, and so less susceptible to interference.Alternatively, the second temperature sensor can be in the sensor head with the firsttemperature sensor, but spaced therefrom. That can avoid any problems where there ismaterial such as processing apparatus, batteries or the like which either create heat orare significant thermal masses, which could affect the second temperature sensor’smeasurement of ambient temperature.

Typically, the flexible cable will be at least 5cm, 7cm or 10cm long, but not more than12cm, 15cm or 20cm long. Typically, the apparatus will also comprise at least one ofa processor, a battery and a transmitter for the first and/or second temperature signalsin the housing. In such a case, and in the preferred embodiment, the apparatus will bearranged such that the flexible cable transmits the first temperature signal.

The sensor head may comprise a clamping mechanism arranged to clamp onto thefluid conduit. The clamping mechanism may comprise at least one jaw arranged toengage the fluid conduit. The clamping mechanism may comprise a biasing memberarranged to bias each jaw into contact with the fluid conduit. Each jaw may comprisea profiled section, which, when biased by the biasing member tends to drive a contactportion of the sensor head into contact with the fluid conduit. Typically, the profiledsection will comprise a surface (typically planar) slanted relative to a biasing directionin which the biasing member applies a biasing force to the jaw, the surface facing thecontact surface. Thus, the profiled section will act to ensure appropriate engagementof the sensor head with the fluid conduit.

Each jaw may further comprise a further profiled section, which is also slantedrelative to the biasing direction, but in an opposing direction, so that application ofthe biasing force tends to drive the contact surface away from the fluid conduit. Thefurther profiled section is typically spaced further from the contact portion than theprofiled section. This arrangement has the effect that, if the sensor head is not pushedonto the fluid conduit sufficiently far to engage, it will be driven off the fluid conduit.This can give an installer confidence that, when the sensor head drives onto the fluid conduit - typically “snaps” on - that the sensor head is properly engaged, as if it werenot properly engaged it would be driven off by the further profiled section.

The contact section may comprise a bridge piece that is wider in a directionperpendicular to the biasing direction than the remainder of the sensor head. This canact to reduce a moment applied to the fluid conduit due to the weight of the housingwhen suspected from the flexible cable.

The first temperature sensor may be provided with a sensor biasing member, whichtends to bias the first temperature sensor into contact with the fluid conduit in use.The first temperature sensor may be mounted in the sensor head using a couplingwhich can be repeatedly released and engaged. This allows for a single firsttemperature sensor (a relatively high cost component) to be used with multipledifferent sensor heads (typically a lower cost component).

Also disclosed herein is a kit of parts, comprising: • a first temperature sensor; • a plurality of sensor heads arranged to house the first temperature sensor, eachsensor head being arranged so as to hold the first temperature sensor against afluid conduit, with the first temperature sensor being arranged so as to producein use a first temperature signal indicative of a first temperature being that ofthe fluid conduit; • a housing; • a second temperature sensor in the housing, arranged to produce in use asecond temperature signal indicative of a second temperature being theambient temperature around the housing; in which the housing and the first temperature sensor are joined by a flexible cable,the kit of parts being arranged to be installable such that: the sensor heads caninterchangeably engage the first temperature sensor; when a selected one of the sensorheads is attached to the fluid conduit with the first temperature sensor engaged, thehousing is suspended from the fluid conduit on the flexible cable; and in use, theflexible cable transmits at least one of the first and second temperature signals.

Thus, this allows an installer to pick from several sensor heads relating to differentpipes, using the same first temperature sensor.

The kit of parts may have any of the optional features of the sensing apparatusdescribed above.

There now follows, by way of example only, description of an embodiment of theinvention, described with reference to the accompanying drawings in which:

Figure 1 shows a schematic view of a plumbing network having a flowdetermination apparatus;

Figure 2 shows a perspective view of the housing of the flow determinationapparatus of Figure 1;

Figure 3 shows an exploded perspective view of the housing of Figure 2;

Figure 4 shows a block diagram of the flow determination apparatus ofFigure 1;

Figures 5 and 6 show graphs of data collected by the sensors of the flowdetermination apparatus of Figure 1;

Figure 7 shows another graph of data collected by the sensors of the flowdetermination apparatus of Figure 1;

Figure 8 shows further data collected by the sensors of the flow determinationapparatus of Figure 1;

Figure 9 shows a plan view of a sensing apparatus in accordance with anembodiment of the invention;

Figures 10 to 12 show front, side and perspective views respectively of asensor head of the sensing apparatus of Figure 9;

Figures 13 to 15 show front, side and perspective views respectively of analternative sensor head of the sensing apparatus of Figure 9;

Figures 16 and 17 show further data collected by the sensors of the flowdetermination apparatus of Figure 1; and

Figure 18 shows an embodiment of a data collection system in accordancewith the present invention.

In the following description, embodiments of the disclosed sensing apparatus that donot fall within the scope of the appended claims, including in particular those depictedin Figures 1-4, are to be considered merely as examples useful for understanding theinvention. A fresh water plumbing network for a domestic dwelling is shown schematically inFigure 1 of the accompanying drawings. In this embodiment, a single supply pipe 14enters the dwelling and branches into multiple branches 15, 16. Herein, we refergenerically to the pipe 14, 15, 16 as 4, the pipe being a form of fluid conduit carryingclean water 5, a fluid.

In order to make a flow determination - typically to determine whether there is a leakfrom the plumbing network - a flow determination apparatus is used. This comprisesmultiple housings 1, 2 at different locations on the plumbing network, and a remoteprocessor 21 (Figure 4 of the accompanying drawings).

The housings 1, 2 are identical. A main housing 1 is provided on the main supplypipe 14, whereas an auxiliary housing 2 can be provided on each branch 15, 16. Thehousings 1, 2 are described in more detail using the example of the main housing 1with reference to Figures 3 and 4.

In these Figures, it can be seen that the housing is provided as a body 1 whichsupports a first temperature sensor 10 against the pipe 4. It is held against the pipe 4by means of a V-shaped aluminium block 17. The housing 1 is provided withthermally insulating foam 18 which separates a second temperature sensor 11 from theblock. An optional third temperature sensor 20 can be provided between theinsulating foam 18 and the block 17. A perforated lid 19 caps the housing 1 in orderto allow ambient air to flow over the second temperature sensor 11.

The auxiliary housing is identical, but is provided with first 12, second 13 andoptionally third (not shown) auxiliary temperature sensors respectively.

Each housing is also provided with a transmitter 22, 22a (Figure 4) - such as aBluetooth (RTM) Low Energy transmitter - which can carry out some processing andtransmits data to the remote processor 21. Each housing is also provided with a powersource (not shown), such as a battery, to power the transmitter 22, 22a and thetemperature sensors.

The data collected by the sensors shown in Figures 5 and 6 of the accompanyingdrawings can be used to demonstrate how a flow determination can be made with thisapparatus.

The apparatus relies on the fact that, if there is no flow in the pipe 4, then thetemperature of the pipe - sensed by the first temperature sensor 10 will converge withthe ambient temperature - sensed by the second temperature sensor 11 following apredictable curve.

When there is a substantial flow, the temperature of the pipe 4 will typically divergesubstantially from the ambient temperature. This is most notable in domesticplumbing networks the closer to the point of entry of the supply pipe 14 into thepremises. This is because the temperature of the fluid flowing through the pipe 4 -here, water - is likely to be different to the ambient temperature. In the domesticplumbing context, this is because pipes external to the dwelling are buried in theground. In temperate climates such as the United Kingdom, it is likely that the waterflowing into a dwelling will be significantly lower than ambient temperature and thisexplanation will be based on that assumption, although this embodiment will functionwell also with water significantly above ambient (for example, in an air-conditionedhome in a hot climate).

This means that, in the example of a temperate climate, a substantial flow will lead toa sudden drop in temperature of the fluid flowing through the pipe 4 and so a drop inthe temperature of the pipe 4 itself.

Where there is a low flow, the temperature of the fluid in the pipe 4 and so the pipe 4itself will still move towards ambient temperature. We have appreciated that thecurve with which the temperature moves towards the ambient temperature with time isdifferent from that when there is no flow, and that this can be used to determinewhether there is any flow and to estimate the level of that flow.

This can be demonstrated by considering Figure 5 of the accompanying drawings.This shows measured data from a domestic dwelling, from the main housing 1. Trace30 shows the ambient temperature as measured by the second temperature sensor 11and trace 31 shows the pipe temperature as measured by the first temperaturesensor 10, both plotted against time (shown in 24 hour clock).

In this example, at time ti, the water through the dwelling was switched off; thus itwas known that there was no flow. It can be seen that the trace 31 followed aparticular curve between times ti and a later time t2. This can be used to generate anexpected convergence curve (or one can be calculated depending on the size andmaterial of the pipe using standard fluid thermodynamic techniques). At time t3 thewater supply was restored to the dwelling and a small amount of divergence is seen asthere is some flow to repressurise the plumbing system.

Subsequent to time t3, it can be seen that there is some convergence with the ambienttemperature 30. However, at time t4, a toilet which had previously been disabled wasreconnected, which had a leaking cistern. This had a leak of approximately 0.06ml/second. This caused a substantial divergence from the ambient temperature untiltime t5 when a tap was used, causing a substantial flow and a sudden divergence fromthe ambient temperature until time t6.

At this point, the pipe temperature 31 begins to converge once more with the ambienttemperature 30, but it can be seen that the convergence is slower than the curvebetween times ti and t2. This is indicative of a small flow. In this example, the flowturned out to be another toilet that had a then undiagnosed leak.

As such, it can be seen that a binary determination of whether there is flow can bemade based upon a determination of whether there is convergence at the expectedconvergence curve. An indication of the level of flow can be made by determining the difference between the actual and expected convergence; the larger the difference, thehigher the flow.

In one particular embodiment, the rate of change of temperature of the pipe 4 ismodelled. In this model, the change of temperature in one time interval - the timeover which the algorithm is used - is given by:

where Tambient is the ambient temperature measured by the second temperaturesensor 2, Tpipe is the temperature of the pipe wall as measured by the first temperaturesensor, Tsuppiy is the temperature of the water in the pipe at the supply (which can bedetermined as the lowest pipe wall temperature reached, as that is the temperature thatthe pipe wall will reach after sustained flow).

The values HeatGain and Flow Gain are two proportionality constants; HeatGain willdepend on the particular installation of the flow determination apparatus and so isunlikely to vary significantly over the timescales over which the measurements aretaken. FlowGain, however, will depend on the level of flow through the pipe 4.However, an estimate of the level of the flow can be taken by modelling HeatGain andFlowGain as constant over a short period, and then attempting to fit the measured pipewall temperature to the model given above by solving for HeatGain and FlowGain.

By then comparing the relative values of HeatGain and FlowGain, a measurement ofthe level of flow can be determined. If HeatGain is significantly larger thanFlowGain (for example, if HeatGain is more than 50 times larger than FlowGain),then it is likely that there is no flow. If HeatGain is around 20 times larger thanFlowGain, then convergence between the pipe and ambient temperatures can beexpected to within 0.5 degrees. However, where this method is particularly useful iswhere a low level of flow is found; if HeatGain and FlowGain are roughly equal, thenthe pipe temperature will converge on a temperature which may be intermediate to theambient and supply temperatures, which can indicate a small flow potentiallyindicative of a leak; we have found that this method can quickly determine such leaks.

As such, we can use a hierarchy of determinations:

• Actual convergence of the pipe and ambient temperatures: no flow, no leak • Stable non-convergence of pipe and ambient temperatures (that is, convergenceof the pipe temperature to a level intermediate to the supply and ambienttemperatures): small flow indicative of a leak; • Convergence fits to curve: use model to see whether pipe and ambienttemperatures will converge and determine flow status in accordance with thatdetermination.

The confidence with which the convergence fits to a curve, or to which theHeatGain/FlowGain model fits the measured data, can be used as a confidence in thedetermination made.

Data processed with this method can be seen in Figure 7 of the accompanyingdrawings. In this figure, the ambient temperature is shown on trace 50, and the pipetemperature on trace 51. The data was collected in a domestic dwelling. We canconsider each of the time periods on the graph in turn: • Period 52: The water in the dwelling is turned off. No flow, and the twotemperatures converge to within 0.5 degrees. • Period 53: The water in the dwelling is turned back on. Some flow occurs asthe water system pressurises. However, the temperatures then converge. • Period 54: A tap is caused to start dripping. Whilst there is no convergence,the temperature difference becomes stable, and so the HeatGain methoddescribed above will function well. • Period 55: A large flow due to a toilet flushing. • Period 56: The dripping tap is still dripping, so after the toilet flush, thetemperatures do not converge, but remain in the relationship they were inPeriod 54. As such, the HeatGain method will function well. • Period 57: The dripping tap is turned off; convergence occurs which impliesno flow. • Period 58: Toilet is flushed twice to demonstrate major flow. • Period 59: A tap is turned back on again, and the temperatures stabilisewithout convergence, thus making the HeatGain method useful.

Data collected with the optional third temperature can be seen in Figure 6 of theaccompanying drawings. In this example, trace 32 shows the ambient temperaturefrom the second temperature sensor 11, trace 33 shows the measurements made by thethird temperature sensor 20 and trace 34 shows the measurements made by the firsttemperature sensor 10. Time is again measured using the 24 hour clock.

It can be seen that the effect of mounting the third temperature sensor above thealuminium block 17 is to smooth the measurement of the pipe temperature. Thus, itcan be seen that between 04:30 and 05:45 the trace 34 is noisier than the trace 33.This noise can be used to indicate the presence of a small flow, without having to takesufficient measurements to measure the convergence. Thus, by comparing the firstand third temperature measurements, and in particular the relative noisiness of thethird temperature measurement, a further flow determination can be made. It may bepossible to make such a flow determination quicker than waiting for convergence,although the accuracy and precision of such a measurement are likely to be less thanthe convergence technique.

In one embodiment, the standard deviation of the difference in temperature is takenover a period of time. If this exceeds a first limit - indicating that the data is noisy -then it is likely that a low level flow is occurring. If this exceeds a higher limit, thenit is likely that there is a high flow indicative of usage.

Returning now to Figure 1 of the accompanying drawings, it can be seen that anauxiliary housing 2 is provided in branch 16 with its own auxiliary temperaturesensors 12, 13. In the same manner as above, these can be used to determine whetherthere is any flow (and the level of the flow) in the branch 16. Thus, if it is thoughtthat there is a leak in the plumbing network, the auxiliary housings 2 (of which therecould be many, one for each branch) can be used to determine which branch the leakis in.

The size of the divergence of the temperature of the water (and hence the pipe) on theone hand and the ambient temperature may be less when far into the plumbingnetwork. As such, for the branches 16 deeper into the network, a heating/coolingapparatus 7 can be provided which selectively provides heating 9 or cooling 8 to thepipe 16 and hence the fluid, so as to increase the divergence in temperature when water flows. Typically, the heater 9 would be provided to heat the fluid, with smallercoolers 8 to cool preferentially the pipe 16 so that heat from the heater 9 does notpropagate down the pipe rather than through the water.

The data collected may also be used to determine whether there is flow - typically aleak - upstream of the first temperature sensor 12, as is illustrated in Figure 8 of theaccompanying drawings. This graph shows the data collected by a first temperaturesensor 12 at trace 60 and a second temperature sensor 13 at trace 61 for a particularinstallation over a five day period.

It can be seen that there is an upper limit on the first temperature 60 - that is thetemperature of the pipe. We have appreciated that an upstream leak causes adownstream temperature plume in the liquid such that the pipe temperature will not goabove a certain point (assuming that the supply temperature is lower than ambient; ifthe opposite was true, than the limit would be a floor rather than a ceiling). This effectcreates a plateau in periods of no downstream flow with an upstream leak. This canbe seen at times 60a, where it can be seen that the first temperature 60 will notincrease above an absolute (that is, not relative) limit regardless of what the ambienttemperature 61 is doing.

Thus, by analysing the first temperature to determine the presence of a limit - forexample, by looking for long periods of time (e.g. greater than an hour) where the firsttemperature is constant as the ambient temperature changes - the presence of anupstream flow can be determined.

An embodiment of the sensing apparatus in accordance with the invention can be seenin Figures 9 to 15 of the accompanying drawings. Integers corresponding to those ofthe example of Figure 1 have been given corresponding reference numerals, raised by100.

In this embodiment, a housing 101 is provided, but which, out of the temperaturesensors, only houses second temperature sensor 120, which therefore senses theambient temperature local to the housing 101. The housing 101 is coupled via aflexible cable 130 to the first temperature sensor 110, which is therefore distant fromthe second temperature sensor. A sensor head 140 is also provided, shown in Figures 10 to 12 of the accompanyingdrawings. This has a through bore 151 into which the first temperature sensor 110 canbe inserted, and a bayonet coupling 147 which can be engaged by a correspondinglocking collar 148 of the first temperature sensor, so as to lock the first temperaturesensor 110 into the sensor head 140.

The sensor head also comprises a pair of jaws 141, 142, comprising fixed jaw 140 andpivoting jaw 142. Pivoting jaw 142 is mounted on the sensor head 140 through apivoting joint 143, so that the pivoting jaw can open and close relative to the fixedjaw 141. A pair of tension springs 144 are each mounted between mounting points145 on the jaws 141, 142 to bias the jaws together.

The first temperature sensor 110, when installed in the sensor head 140 will protrudeslightly from bore 151 so as to define a contact face 139 for the sensor head. Whilstthe jaws extend generally away from the contact face 139, each jaw 141, 142 has afirst surface 138 which slopes inwards towards the other jaw moving away from thecontact face, and a second surface 137, which slopes away from the other jaw movingaway from the contact face 139. The two surfaces 137, 138 on each jaw meet at apinch point 136.

Thus, if the jaws are pressed over a pipe so that the widest part of the pipe passes thepinch points 136, then the springs 144 will act to squeeze the jaws 141, 142 together,and so the first surfaces will force the pipe into contact with the contact face. If thepipe is not pushed in sufficiently far so that the widest part does not pass the pinchpoints 136, then the biasing of the jaws 141, 142 by the springs 144 will cause thesecond surfaces to push the pipe away relative to the sensor head 140. Thus, aninstaller can be confident that the sensor head has been correctly pushed onto the pipe.The jaws are also shaped to have minimal thermal contact with the pipe. The sensorhead 140 will also fall off the pipe at a lower force than is required to removestandard pipe clips, so that the sensor head is pulled off before the pipe is pulled offthe wall or other surface on which it is mounted.

The first temperature sensor 110 is provided with a biasing spring 149, which biases itout of the bore 147, into contact with a pipe between the jaws 141, 142.

The contact face 139 is provided with a wider portion 160, which acts to distribute theforces caused by the housing 101 dangling from the sensor head 140 by means of theflexible cable 130 along the pipe. This means that, for vertical pipes, there is lessmoment exerted on the pipe.

Each jaw 141, 142 is provided with a groove 136, into which a tool can be inserted toforce the jaws 141, 142 apart to allow for uninstallation of the sensor head 140.

An alternative sensor head 161 is shown in Figures 13 to 15 of the accompanyingdrawings. This again has a through bore 164 for the first temperature sensor 110,provided with the same bayonet coupling 162 as for the sensor head 140 of Figures 10to 12. However, rather than having jaws, it has a simple arcuate surface 163. This isuseful for pipes that are larger than the jaws can fit, or which are irregularly shaped orotherwise inconvenient. The sensor head can then be attached to the pipe by means ofadhesive tape, or by using tie wraps.

It can be seen that the installer of the sensor head can be provided with multipledifferent sensor heads, such as different sized versions of the sensor head 140 shownin Figures 10 to 12 as well as that of Figures 13 to 15. They can then choose which ismost appropriate to the installation at hand, couple that to the first temperature sensor110 and attach it to a pipe or other fluid conduit.

Other than as described above, this embodiment functions largely as that of Figure 1.The flexible cable transmits, typically, the output of the first temperature sensor 110 —a signal indicative of temperature - to the housing 101, which will house thetransmitter 22 and possibly also a processor. By housing the second temperaturesensor 120 distant from the pipe - allowing it to dangle from the pipe - temperaturechanges in the pipe will have less effect than if the housing were directly mounted onthe pipe as in the embodiment of Figure 1. Furthermore, there the sensor heads 140,161 are smaller than the housings 1, 2 of the embodiment of Figure 1 and are moreconvenient to install, with the bulky parts of the housing 101 being spaced from thepotentially congested pipe area by the flexible cable 130.

Whilst in this embodiment the second temperature sensor 120 is shown in the housing101, it could also be in the sensor head 140, 161; that would be closer to the firsttemperature sensor 110, but would mean that the thermal mass and the potentialheating effects of the housing 101 containing the processor etc would have less effecton the measured second temperature (that is, ambient temperature).

Using multiple auxiliary temperature sensors 12, 13 as shown in Figure 1 in a singlebuilding allows the formulation of a situational profile of water movement through thebuilding. Measurements can be taken from feed pipes to header tanks, exit pipes fromheader tanks, in building pipework locations (branch points) through to end pointusages e.g. toilet cistern or a tap. The collation of the data allows: 1. A thermal profile of how water travels through the building showingpoints of thermal loss to the liquid as well as thermal gain to the liquid. 2. What water flows through which tanks and when - a hydraulic profileas shown in Figure 16 of the accompanying drawings. In this figure,traces of the pipe temperature leading from three different tanks isshown over a time period of four days; the top trace is only usedroughly a third of the way through the trace (where there is a suddendrop in temperature), whereas for the other two tanks, significant dropsand so flows occur roughly halfway and two thirds of the way throughthe traces; 3. What water flows through which branches and when - hydraulic profile 4. Identification of dead ends or low usage points 5. Uegionella risk points due to no flow or thermal variances 6. Areas of leakage - specific network branches 7. Identification of user patterns - e.g. which toilets get used most oftenand therefore need more maintenance and or cleaning - as shown inFigure 17 of the accompany drawings, in which the usage for each ofthe locations listed on the right hand side of the graph are shown in thatorder for each day (DHW being domestic hot water).

The remote processor 21 may be that of a mobile telephone, such as an iPhone (RTM)sold by Apple Inc, or a dedicated device such as a hub receiving signals from severalhousings. The processing of the temperature signals to produce a flow determination can be carried out in a processor in the housing - typically that of the transmitter 22,22a - so that the transmitter transmits only the flow indication (typically as eventssuch as differing levels of flow). Alternatively, the transmitter 22, 22a can transmitthe temperature signals to the remote processor 21 which can then make the flowdetermination.

The functions described above can be implemented in an application (an “app”),communicating with any number of housings 1, 2, typically in one plumbing network.Alerts can be configured to notify a user should there be a flow above a threshold fora given period (indicative of a small persistent leak) or if there is significant flow atan unexpected time (for example, a substantial flow in the middle of the night or whenthe occupants are on holiday).

An alternative embodiment of a data collection system is shown in Figure 18 of theaccompanying drawings. In this system, there are a plurality of locations 200 such asindividual houses. Each location has one or more data capture devices 201, whichwould typically be the housings 1, 2 discussed above. Each of these data capturedevices will capture data (here, either temperatures or flow determinations) and storethe data until it can be transmitted on as discussed below. Each data capture device201 will comprise a transmitter, which will use a relatively short range transmissionprotocol such as Bluetooth (RTM), Wi-Fi (RTM) or Zigbee (RTM), which can bereceived in a reception area 202 for each data capture device.

The system will comprise a plurality of mobile telecommunications devices 203, suchas mobile telephones running a suitable application stored in a memory and run on aprocessor. Each mobile telecommunications device will have a receiver for therelatively short range transmission protocol, and a transceiver for a mobiletelecommunications network (such as GPRS (RTM) or 3GPP (RTM)). When eachmobile telecommunications device 203 passes into a reception area 202, it will receivethe data that has been captured by the relevant data capture devices 201. It will thenpass that data over the mobile telecommunications network to a central server 204.

Typically, each of the mobile telecommunications devices 203 will be associated withat least one data capture device 201, and typically all of the data capture devices at agiven location 200 (say, the user’s home). The mobile telecommunications devices 203 will receive data and transmit it to the central server 204 regardless of whether itis associated with the relevant data capture devices. However, each mobiletelecommunications device 203 will only allow the user access to data from datacapture devices 201 with which it is associated.

The central server 204 will then typically transmit the data from each data capturedevice 201 back to the mobile telecommunications device 203 with which the datacapture device 201 is associated. This may not be necessary if the central server 204received the data from the mobile telecommunications device 203 with which the datacapture device 201 was associated; indeed, in such a case the mobiletelecommunications does not necessarily need to transmit that data to the centralserver 204.

Accordingly, any mobile telecommunications device 204 passing the locations 200through the reception areas 202 can cause the data to be uploaded to the central server,so that a user can then access it. This is helpful where the data is the temperature orflow data discussed above, as that means that a user may be able to receiveinformation about flows in the pipework of their house when they are absent, if a thirdparty running the application on their mobile telecommunications device hashappened, serendipitously or otherwise, to pass through the reception area 202. Ineffect, the data collection has been crowd sourced.

As such, we have found the apparatus discussed above with respect to the variousembodiments can provide an indication that there is a flow down to 0.2 litres per hour(0.06 ml/second). It is not invasive, in that no penetration of the pipe or measurementequipment inside the pipe is required. It requires only very simple components - thetemperature sensors can be thermistors, for example. Overall, it provides a cheap andflexible way to make a flow determination.

The data generated by this embodiment can be used in multiple situations. Examplesinclude leak detection, the monitoring of particularly domestic water usage patterns oreven ensuring temperature and flow rates are sufficient to avoid legionellaproliferation.

Claims (24)

1. A sensing apparatus, comprising: • a first temperature sensor; • a sensor head for housing the first temperature sensor, the sensor head beingarranged so as to hold the first temperature sensor against a fluid conduit, withthe first temperature sensor being arranged so as to produce in use a firsttemperature signal indicative of a first temperature being that of the fluidconduit; • a housing; • a second temperature sensor arranged in the housing or at the sensor head,arranged to produce in use a second temperature signal indicative of a secondtemperature being the ambient temperature; in which the housing and the sensor head are joined by a flexible cable, the sensingapparatus being arranged to be installable such that, when the sensor head is attachedto the fluid conduit, the housing is suspended from the fluid conduit on the flexiblecable, and such that in use the flexible cable transmits at least one of the first andsecond temperature signals.

2. The sensing apparatus of claim 1, in which the second temperature sensor is inthe sensor head with the first temperature sensor, but spaced therefrom.

3. The sensing apparatus of any of the preceding claims, in which the flexiblecable is at least 5cm, 7cm or 10cm long.

4. The sensing apparatus of any of the preceding claims, in which the sensor headcomprises a clamping mechanism arranged to clamp onto the fluid conduit.

5. The sensing apparatus of claim 4, in which the clamping mechanism comprisesat least one jaw arranged to engage the fluid conduit and a biasing member arranged tobias each jaw into contact with the fluid conduit.

6. The sensing apparatus of claim 5, comprising a pair of jaws, in which thebiasing member comprises a pair of tension springs each mounted between mountingpoints on respective jaws to bias the jaws together.

7. A sensing apparatus according to claim 5 or 6, wherein each jaw comprises agroove into which a tool can be inserted to force the jaws apart.

8. The sensing apparatus of any of claims 5 to 7, in which each jaw comprises aprofiled section, which, when biased by the biasing member tends to drive a contactportion of the sensor head into contact with the fluid conduit.

9. The sensing apparatus of claim 8, in which the profiled section comprises asurface slanted relative to a biasing direction in which the biasing member applies abiasing force to the jaw, the surface facing the contact portion.

10. The sensing apparatus of claim 9, in which each jaw comprises a furtherprofiled section, which is also slanted relative to the biasing direction, but in anopposing direction, so that application of the biasing force tends to drive the contactportion away from the fluid conduit, the further profiled section being spaced furtherfrom the contact portion than the profiled section.

11. The sensing apparatus of claim 9 or 10, in which the contact portion comprisesa bridge piece that is wider in a direction perpendicular to the biasing direction thanthe remainder of the sensor head.

12. The sensing apparatus of any of claims 1 to 4, wherein the sensor headcomprises an arcuate surface for attaching the sensor head to the pipe.

13. The sensing apparatus of any of the preceding claims, in which the firsttemperature sensor is provided with a sensor biasing member, which tends to bias thefirst temperature sensor into contact with the fluid conduit in use.

14. The sensing apparatus of any of the preceding claims, in which the firsttemperature sensor is mountable in the sensor head using a coupling which can berepeatedly released and engaged.

15. The sensing apparatus of any preceding claim, further comprising at least oneof: a processor, housed within the housing, a battery, housed within the housing, and a transmitter in the housing for the first and/or second temperature signals.

16. The sensing apparatus of claim 15, wherein, in use, the flexible cable transmitsthe first temperature signal to the processor in the housing.

17. The sensing apparatus of any preceding claim, wherein the sensor headcomprises a through bore into which the first temperature sensor can be inserted.

18. The sensing apparatus of claim 17, wherein the first temperature sensor isarranged, when installed, to protrude from the bore so as to define a contact face forthe sensor head.

19. The sensing apparatus of claim 18, wherein the first temperature sensor isprovided with a biasing member for biasing the first temperature sensor out of thebore.

20. The sensing apparatus of any preceding claim, wherein the first temperaturesensor is arranged to be locked into the sensor head.

21. A kit of parts, comprising: • a first temperature sensor; • a plurality of sensor heads arranged to house the first temperature sensor, eachsensor head being arranged so as to hold the first temperature sensor against afluid conduit, with the first temperature sensor being arranged so as to producein use a first temperature signal indicative of a first temperature being that ofthe fluid conduit; • a housing; • a second temperature sensor, arranged to produce in use a second temperaturesignal indicative of a second temperature being the ambient temperature; in which the housing and the first temperature sensor are joined by a flexible cable,the kit of parts being arranged to be installable such that: the sensor heads can interchangeably engage the first temperature sensor; when a selected one of the sensor heads is attached to the fluid conduit withthe first temperature sensor engaged, the housing is suspended from the fluid conduiton the flexible cable; and in use, the flexible cable transmits at least one of the first and secondtemperature signals.

22. A kit of parts as set out in claim 21, wherein the plurality of sensor heads arearranged for use with different pipes and/or have different sizes.

23. A temperature sensing arrangement comprising: a fluid conduit; and a sensing apparatus as set out in any of claims 1 to 20; wherein the sensor head of the sensing apparatus is attached to the fluidconduit such that the first temperature sensor is held against the fluid conduit, withthe housing suspended from the fluid conduit on the flexible cable.

24. A method of installing a sensing apparatus as defined in any of claims 1 to 20,comprising: attaching the sensor head of the sensing apparatus to a fluid conduit such thatthe first temperature sensor is held against the fluid conduit; and suspending the housing from the fluid conduit on the flexible cable.