CA2008495A1 - Incompressible fluid for leaks - Google Patents
Incompressible fluid for leaksInfo
- Publication number
- CA2008495A1 CA2008495A1 CA 2008495 CA2008495A CA2008495A1 CA 2008495 A1 CA2008495 A1 CA 2008495A1 CA 2008495 CA2008495 CA 2008495 CA 2008495 A CA2008495 A CA 2008495A CA 2008495 A1 CA2008495 A1 CA 2008495A1
- Authority
- CA
- Canada
- Prior art keywords
- conduit system
- volume
- fluid
- main valve
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B7/00—Water main or service pipe systems
- E03B7/003—Arrangement for testing of watertightness of water supply conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D5/00—Protection or supervision of installations
- F17D5/02—Preventing, monitoring, or locating loss
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Public Health (AREA)
- Water Supply & Treatment (AREA)
- Examining Or Testing Airtightness (AREA)
Abstract
A B S T R A C T
Disclosure is made of a method and apparatus for monitoring a conduit system for an incompressible fluid for leaks, wherein a testing fluid is introduced into the conduit system during a testing period when no fluid is being withdrawn from the conduit system and the conduit system is closed on the supply side by a main valve. Now, without increasing the pressure in the conduit system, a check is to be made whether fluid is escaping from the conduit system despite the closed withdrawal valve. For this purpose, without the entry of testing fluid from the supply side of the main valve (1), a predetermined test volume of the testing fluid is introduced into the conduit system (8) under a pressure of the same order as the fluid pressure on the supply side of the main valve (1) and the time required by the test volume to flow into the conduit system is measured. A suitable apparatus for this comprises a chamber (12) for introducing the test fluid into the conduit system, the chamber communicating only with the conduit system (8) and having a volume which can be changed between a predetermined first larger value and a predetermined second smaller value.
Further, time measuring means (16) are provided for measuring the time during which the chamber changes from the first volume to the second volume.
Single figure.
Disclosure is made of a method and apparatus for monitoring a conduit system for an incompressible fluid for leaks, wherein a testing fluid is introduced into the conduit system during a testing period when no fluid is being withdrawn from the conduit system and the conduit system is closed on the supply side by a main valve. Now, without increasing the pressure in the conduit system, a check is to be made whether fluid is escaping from the conduit system despite the closed withdrawal valve. For this purpose, without the entry of testing fluid from the supply side of the main valve (1), a predetermined test volume of the testing fluid is introduced into the conduit system (8) under a pressure of the same order as the fluid pressure on the supply side of the main valve (1) and the time required by the test volume to flow into the conduit system is measured. A suitable apparatus for this comprises a chamber (12) for introducing the test fluid into the conduit system, the chamber communicating only with the conduit system (8) and having a volume which can be changed between a predetermined first larger value and a predetermined second smaller value.
Further, time measuring means (16) are provided for measuring the time during which the chamber changes from the first volume to the second volume.
Single figure.
Description
2~ 95 , ;
D A N F O S S A t S , D K -6 34 O N O R D B O R G
Method and apparatus for monitoring a conduit system ror an incompressible fluid for leaks The inventlon relates to a method of monitoring a conduit system for an incompressible fluid for leaks, wherein a testing fluid is lntroduced into the conduit system during a testing period when no fluid is being withdrawn from the condult system and the conduit sy~tem is closed on the supply side by a maln valve. The lnventlon also relates to an apparatus for monitorlng a condult system for an lncompressible fluid, comprisine a maln valve on the supply side of the conduit system and control apparatus for controlling actuatlon Or the main valve.
Fluid condult systems have to be monltored for untlght ~oints and leaks. This applies fundamentally to all conduit systems, regardless Or whether they are employed to convey mains water into a house, heating liquids in heating and remote heating systems or ga3es or fuels in distribution clrcuits.
The monltorlng Or mains water ln bulldlngs has particularly lncreased in lmportance in recent years. The problem will be explalned by uslng the example Or a malns water installation in a residentlal bullding. Normally, the consumption Or water through withdrawal by a consumer rrom a water tap amounts to between about 50 and 1,500 l/h. In extreme cases, for . -2~
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example toiletcisterns or washing machines, the consumption could be between 30 and 2,500 l/h. Leakages accounted for by a pipe fracture or by bursting of a supply hose for a washing machine or dishwasher (large leak) are typically in the range of 500 to 2,500 l/h, sometimes higher, and can therefore not be distinguished from normal consumption. For this reason, wlth such large volumes above a predetermined value the 3upply ~-of water ls interrupted after a predetermined withdrawal perlod regardles3 of whether a consumer is using the water or there is a large leak.
In contrast, there are faults hereinafter referred to as a "small leak". In this case, the 1099 of water i~3 in the range Or about 1 to 25 l/h and could be caused by dripping water taps and overflowing toilet clsterns on the one hand and untlght pipe connections, commencement of fatigue failure in pipes occasioned by corroslon, halrllne fractures ln pipes and vessels or slmllar damage ln the condult system on the other hand. Whereas the flrst set of examples may not be dangerous but only lncrease the costs of fresh water and dralnage and place a demand on drinklng water sources and thus on the ;; environment, ~mall leaks of the second kind could cause con-siderable damage. More particularly, the outflowing quantity ,. ~
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: : , : ' : .: ' ' , ' : ' ' ' . ' ' ' ' ' . . ' , ' ' of 1 to 25 l/h may appear very small but, over a prolonged period, walls or other parts of the building can become ir-repairable as a result Or being saturated with moisture. The resulting damage is often noticed too late because the dampness starts inside a wall and does not become visible until the whole wall is saturated. If one were to discover such a small leak at an early stage, it could be repaired in time.
To check a central heating system for leakages, W0 ~7/04520 discloses an arrangement consisting of two flow meters Or the vane-wheel type in the supply and return conduits Or the system. Both vane-wheels determine the total volume flowing through the heating system. If there ls no leak, the two volumes must be the same. If there is a difference between the two volumes, a leak is suspected and the circuit is shut down by way Or a motorised valve. However, since the volumet-ric flow meters are provided for the main flow, that i9 to say ror large volumes, they are unable to detect small leakages below, say, 25 l/h with the required degree Or accuracy.
W0 86/06457 disclo~es equipment for monitoring pressure con-duits for leakage polnts, thls equipment measuring the pressure 263C8495:
in the condult system downstream of the main valve and shutting the main valve down either when a large amount Or fluid rlows through the main valve for a prolonged perlod or, if the main valve is closed, the period required by the pressure to drop from a first pressure to a second pressure is shorter than a permitted time interval. However, since the pressure on the supply side Or the main valve varies considerably, for example pressure rluctuations at the waterworks that might be in the order Or 1.2 bar or as a result Or sudden consumption in an ad~oining conduit system where the pressure could drop by about 0.6 bar and, on termination Or this consumption, rise about 0.4 bar above the normal waterworks pressure and because Or the pressure drop across the main valve as a result Or the consumption in the conduit system being monitored, only unsat-isfactory results can be achieved with the pressure measurement disclased in WO 86/06457.
In a known apparatus ror monitoring installatlons ror tightness (DE-OS 21 58 901), when no fluid is being wlthdrawn, a leak is detected by withdrawing compressible fluid from the source, for example the supply mains, upstream Or the main valve, compressing lt wlth a compressor, and feedlng lt lnto the conduit system downstream of the main valve. Arter reaching 2~G~ 95 a test pressure, the compressor is shut Orr. One now contols whether the pressure loss does not exceed a predetermined value within a predetermined time. In a difrerent embodiment, one checks whether the compressor can build up the required testing pressure during a predetermined runnlng time. Since the volume conveyed by the compressor alway~ depends on the pressure difference between the inlet and outlet Or the com-pre3sor, it is practically impossible to come to any conclusion about the conveyed quantity if both of the pressures are not also monitored. The known equipment is therefore only suit-able ror determining whether there is a leak. One cannot say how large this leak might be. In addition, a separate drive i8 required for the compressor and this might lead to undesir-able noise. After detecting a leak, the main valve is locked in the closed position but fluid can neverthele!ss penetrate into the conduit system by way Or the compressor and continue to escape through the leak.
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; It ls the problem Or the lnvention to provide a method and apparatu~ wlth whlch even small leaks can be reliably detected.
; This problem is solved in a method Or the aforementioned kind ln that, without the entry Or testlng fluld from the supply slde Or the maln valve, a predetermlned test volume Or the testing fluid is introduced into the conduit system under 2~1G8~95 pressure and the time required by the test volume to flow into the conduit system is measured.
During testing, exactly the same amount of fluid leaves through the leakage point as during normal operation. Since this escaping amount Or fluid is immediately replenished, the volume Or leakage flow can be measured exactly lf one assumes that it does not fluctuate appreciably over a period of tlme.
It is simply detected by dividing the known test volume, i.e.
the replenished quantity, by the measured time. In addition, a constant pressure is maintained through replenishment Or the testing fluid in the conduit system to be monitored, whereby a sufricient amount of fluid is immediately available upon commencement of consumption.
In one embodiment of the method, the pressure with which the test fluid is introduced into the conduit system i9 Or the same order as the fluld pressure on the supply slde Or the main valve. In a known apparatus, an increase in pressure is required which might increase the leak caused by a weakness in the material. To detect a leak, no excess pressure i9 there-fore applied but testing rluid is introduced into the conduit system under normal pressure. Since the normal pressure, ;~ . . ~ . ~. I . . . . . . . ... ..
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2~3~8~95 i.e. the supply pressure Or the mains, for example the water mains of a clty, i9 applied to the leakage points when the main valve is open, replenishment of the testing volume under the same pressure can practically reproduce the escape of leakage fluid under normal conditions. Since excessive pressure is avoided, the conduit system to be monitored is not stressed any more intensively than during normal opera-tion.
Preferably, the testing fluid is withdrawn from the conduit system berore the testing period. For testing purposes, therefore, exactly the same fluid is employed as that which is normally distributed by the conduit system to be monitored.
No special testing fluid has to be provided and this makes the method considerably cheaper. Accordingly, all of the testing fluid that is employed has also already passed through the main valve and any upstream metering clock- 90 that no difficultles are encountered for example when accounting for the mains water consumptlon to the waterworks. Also, no additional rilters or llke equipment have to be provided for the testlng fluid. Since the withdrawal of the testing fluid takes place immediately prior to the testing period, it is also practically impossible ror any error to occur because Or the time difference between withdrawal of the testing 2~R~9s , :
rluid and the testlng period.
Advantageously, the test volume is less than 0.5 1. Even the largest test volume of 500 ccm is still relatlvely small;
it only fills a cylinder of about 8 cm diameter and 10 cm high. This reduces the construction costs and very conslder-ably reduces the space taken up by the testing apparatus.
The smaller the test volume, the higher wlll be the time resolution.
Prererably, arter the complete introduction of the testing fluid, further testing fluid with the test volume is withdrawn rorm the conduit syste~ and held ready for renewed Lntroduc-tion into the conduit system. This makes continuous measure-ment Or the leakage volume possible. The time taken ror the leakage flow can thus be more efriciently monitored.
Preferably, the entire volume Or the lntroduced testine rluid is determined by adding the lndivldual volumes that were introduced. Thls not only gives an indication Or the indl-vidual volume Or leakage rlOw but also determines the quantity the total discharged fluld as an additlonal criterlon for consideratlon.
It ls also advantageous ror the leakage flow to be determined ., .. -.-, . . -.: ; - , X~8~95 continuously. This enables rapid recognitlon Or a change in the leakage behaviour of the conduit system being monitored and hence suitable protective or countermeasures can be taken in good time.
Preferably, an alarm signal is produced when the entire volume exceeds a predetermined fir3t value and/or when the flow of leakage volume lies between a rirst and a second value.
The alarm may be an optical or acoustic signal. To release the alarm, two criterla are therefore available, namely the entire volume that has escaped at the leakage point on the one hand and the actual leakage flow on the other hancl. Ir the actual leakage flow lies below a certain limlt, for example 1 l/h, the system is declared to be leakproof. With a flow Or leakage volume between, for example, 1 l/h and 3 l/h, a small leak i9 assumed whlch, although lt has to be monltored, will not cause much damage. With a flow Or leakage volume between for example 3 l/h and 20 l/h, one assumes a large small leak which could glve rise to serlous dama~e. A small small leak can, for example, be indicated immediately. However, lt could al90 be indicated only when the amount discharged through the small leak has exceeded a .. . . . ~
;~ 495 predetermined first value.
Preferably, the supply of fluid to the conduit system i9 completely interrupted when the total volume exceeds a prede-termined second value. Irrespective Or the size Or the leak, an escaped amount Or water can present a grave danger to the bullding and therefore lt ls better to close the maln valve completely in order to avoid further damage. Natur-ally, shuttlng down can also be made dependent on the actual flow Or leakage volume.
In a preferred embodiment, the total volume is returned to zero when the flow of leakage volume has been reduced by a predetermined extent. For example, it can happen that the leak is caused by a dripping water tap which the user failed to close completely. When the user notices his mistake and closes the water tap, the leak will also disappear. In this case, lt is senslble to correct the total volume that was assumed to escape lnto the wall from a faulty polnt in the condult system. Thls wlll then enable one to work wlth realistlc parameters during the next testlng period.
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In an apparatus Or the aforementioned kind, the problem is solved ln that the conduit system communicates with a chamber : .. ~ . . - ,.
~........ ' .-- , , .: . :
-, ~ ,: :
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X~(~89~95 for introducing a testlng fluid with a predetermined test volume, the volume of the chamber being variable between a predetermined first larger value and a predetermined second smaller value. The chamber communicates only with the conduit system and time measuring means are provided for measuring the time during which the chamber reduces in volume from the first value to the second value.
Thus, the chamber serves as a store for testing fluid with-drawn from the conduit system. Since the chamber can a3sume two termlnal conditions, namely one with a larger volume and one with a smaller volume, during the time between these two conditlons it must be the exact dlrference ln volume that has flowed out of the chamber lnto the conduit system or out of the condult system lnto the chamber. Slnce the chamber communicates only wlth the conduit system and not wlth the supply side of the main valve, everything flowlng out of or into the chamber must also flow through the conduit system.
Since flowing out of the chamber for testing purposes only takes place with the main valve closed and without any pres3-ure increase in the conduit system, the chamber introduces exactly aq much fluid into the conduit system as escapes from the conduit system through a leakage polnt. The tlme measur-ing means measure the time required by the testlng fluld to 2~ 95 rlow into the condult system. In other words, they measure the time required by a certain volume to flow out Or the conduit system through the leakage point. This enables one to obtain an indication about the actual rlow Or leakage volume ir one assumes that this rlOw i9 not sub~ected to marked varlations in time.
Preferably, the chamber is closed on one side by a movable wall. The chamber is sealed at all sides with the exception Or the aperture to the conduit system, the volume being changeable by the wall. The volume therefore changes linear-ly with the displacement Or the wall which makes the evalua-tion simple.
Preferably, the wall i9 movable towards the smaller value Or volume against the rorce Or a spring. If the same pressures obtain on both sides Or the wall, the sprlng wlll move the wall so that the chamber wlll assume lts largest volume.
The sprlng thererore asslsts resetting.
Prererably, on the slde remote rrom the chamber, the movable wall is subJected to a force which ls constant throughout the path Or movement. Regardless Or the dlsplaced dlstance, thererore, always the qame pressure will act on the wall and thus on the chamber ir one disregards the counter-force Or the spring which becomes more intensively compressed as the ~ :
: :
2~3~8'~95 -di3placement increases. However, since the spring is rela-tively weak ln relatlon to the force actlng on the slde of the wall remote from the chamber, the change ln the counter-force Or the sprlng may be disregarded.
With particular advantage, the side Or the wall remote from the chamber communicates with the supply side Or the maln valve. Thus, the supply pressure Or the source, for example Or the mains water from the waterworks, acts on the chamber wlthout establlshing communlcation between the source and the conduit system that ls belng monitored, l.e. wlthout enabling fluid to enter the conduit system by bypassing the main valve. In addltion, no auxiliary energy is required.
Instead, an available pressure 1~ utilised. The pres~ure in the conduit system being monitored can become no higher than the supply pressure from the source and this avoids excessive stressing Or the monitored conduit system during monitoring.
In a prererred embodiment, a sensor ls provlded which trans-mits a slgnai to the control apparatus when the volume Or the ; chamber has reached the smaller value. Thls termlnal po31-tion ls, for example, requlred for the tlme measurement.
It is also preferred that the control apparatus will open the main valve in respon~e to this signal. When the chamber 2 ~ ~ 8 ~ 9 5 volume has reached its smaller value, a pressure drop mu~t have occured ln the conduit sy3tem. This pressure drop may be caused by consumption or by a leak. For consumption, the maln valve must open so that the user can withdraw fluid rrom the conduit system. In the case of a leak, monitoring has to occur.
~or monitoring a large leak, the time element preferably produces a command to close the main valve a predetermined time after the main valve was opened. Since the leakage monitoring system is unable to differentiate between consump-tion and a large leak, this measure ensures that only a maximum amount of fluid can leave the conduit system. A
consumer who wlshes to withdraw more fluid can glve prlor lndlcation of this to the control apparatu~ or he wlll inter-rupt the consumption momentarily to make it known to the control apparatus that there is no large leak.
In a further preferred embodiment, the control apparatus compriseq an lntegrator whlch lntegrates the volumes Or fluld red into the conduit system from the chamber. Thls enables a value to be avallable at all tlmes that indlcates the amount Or leakage flow that has escaped up to that time.
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. . - ~ , 8~95 It is also advantageous if the control apparatu~ locks the main valve in the closed position when the integrator has determined a total volume which lies above a predetermined value and/or the rlow of volume exceeds a predetermined value. When the flow volume exceeds a predetermined value there will, as prevlously explained, be no fear Or extensive damage even ln the case Or a small leak. Another criterion, which could also be combined with the fir3t criterion, i3 the fact that a certain amount Or leakage fluid has escaped altogether. This amount can be adapted to sult the condi-tions. Upon exceeding thi3 predetermined leakage rlOw~
however, the main valve should be closed to avold extensive damage.
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An example Or the invention will now be described in conJunc-tion with the drawing which is a diagram~atic representation Or an apparatus ror monitoring a conduit system ror an incom-pressible fluid ror leaks.
A conduit system 8, ror example for mains water in a residen-tial building, i9 red by way Or a main valve 1 from a source 7, for example the mains water from a waterwork3. The main valve 1 18 remote controlled by an actuating apparatus 5 whlch is operated by a control apparatus 6. When the main ~ ~.
.. ' . ~ ' . ' .. . . . . .
~8~95 .
valve l i9 closed, no water can reach the conduit sy3tem 8 from the source 7. Parallel to the maln valve 1 there is the actual leakage monitoring equipment. This consists Or a cylinder 2 which ls divided by a movable wall 4 lnto a pre3s-ure chamber 11 and a chamber 12. The pressure chamber 11 communicates with the 3upply side of the main valve l. The chamber 12 communicates with the discharge side Or the main valve 1, l.e. with the conduit system 8. The wall 4 seals the chamber 12 from the pressure chamber 11.
The wall 4 is movable in the cylinder 2 90 that the volume Or : ;
the chamber l2 is variable between a larger value at which the wall 4 abuts the left-hand end of the cylinder Z and a smaller value at whlch the wall 4 abuts the right-hand end of the cylinder 2. The wall 4 is pressed towards the left-hand end of the cylinder 2 by the force Or a spring 10.
It will now be assumed that the main valve 1 13 open wlthout water being wlthdrawn from the condult system through a tap9.
No water therefore flows through the maln valve 1 and there wlll be no pressure drop. The pres~e Pl on the supply side of the maln valve and equal to the pressure of the source 7 ls therefore equal to the pressure P2 on the discharge side of the main valve, i.e. equal to the pressure in the conduit ~, .
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system 8. The pressure P1 also obtains ln the pressurechamber 11 whilst the pressure P2 obtains in the chamber 12.
Accordingly, the same pressures act on both sides of the wall 4. However, since the wall 4 is additionally Rub~ected to the force of the spring 10 on the side facing the chamber 12, the wall 4 will be displaced towards the left-hand end Or the cylinder 2. At the rlght-hand end of the cylinder 2, there ls a sensor 14 whlch i9 actlvated by a generator 13 ln the wall 4 when the wall 4 is at its right-hand terminal position, l.e. when the chamber 12 has assumed its smallest volume.
When the wall 4 ls pushed towards the left under the force Or the sprlng 10, thls 19 detected by the sensor and notlfied to the control apparatus 6. A time element now runctlons in ths control apparatus 6 and, after a predetermined time, signals the valve actuator 5 to close the valve. If no fluld 19 being withdrawn from the conduit system 8, the pressure will remaln constant there, i.e. the wall 4 remalns in lts left-hand termlnal posltlon.
.. ..
However, lr a small leak occurs, rluid wlll trickle rrom the condult system 8 to the exterior thereby gradually reducing the pressure P2 in the conduit system. Slnce the wall 4 i9 subJected to the pressure P1 of the source obtaining in the 2~8'~9~
pressure chamber 11, lt will wander to the right, whereby the test volume Or fluid located in the chamber 12 i8 replenlshed to the condult system. After a certain tlme, which is measured by the time element 16, the wall 4 will reach its right-hand terminal position, which is detected by the sensor 14 which may be in the form of a reed relay. Since the test volume is known, the test volume and the time required by the test volume to rlOw into the condult system 8 will enable one to calculate the flow of volume, i.e. the volume per unit time, that has escaped the conduit system ô through the leakage point. Since the te3t volume enters the conduit system 8 without elevated pressure, no higher pressure loads will occur ln the condult system 8 than lf the maln valve 1 were to open and allow the pressure from the source 7 to pass dlrectly into the conduit system 8.
When the sensor 14 has recorded the ract that the wall 4 ls in lts rlght-hand terminal position, the control apparatus 6 will give a signal to the valve actuator 5 ror the main valve 1 to open agaln. The wall 4 will now be displaced to lts left-hand terminal position agaln ln the manner described above and the testlng cycle wlll start afresh.
The control apparatus 6 comprlses an lntegrator 15 whlch summates the number Or cycles Or the wall 4 and, since the ' ' . ' ~
B~95 test volume is known, thereby enables an indlcation to be obtained about how much rluid has escaped through the leak altogether.
Slnce the test volume is always again introduced into the conduit system it is possible to obtain a continuous indica-tion about the actual flow of leakage volume. In addition, there i8 an indication of the leakage flow that has already escaped so that, with the aid Or these two leakage loss criteria, an indicator can be reliably actuated and/or the main valve 1 can be closed. For example, an indicator is actuated when the leakage volume exceeds a first predetermined value, e.g. 1 l/h. When the leakage volume exceeds the predetermined first value, e.g. 60 1, and the escaped leakage volume exceeds a predetermined first value, an indication can likewise be given and the integrator 15 is returned to zero again. Naturally, the number of times for which-the integra-tor is reset to zero can be llmlted so as to prevent an excessively large amount Or leakage fluld to escape through the leak. For example, one can ensure that on the third occa~ion the integrator 15 is not reset to zero but the main valve 1 19 locked in the closed condition.
If the leakage volume is larger than a predetermined second .. , value, e.g. 3 l/h, the integrator is not reset to zero when reachlng the predetermined first leakage value but only an indicator i9 actuated. Integration, i.e. summation of the lndividual test volumes, is continued. If the lntegrator 5 finds that an amount of leakage fluid has escaped that is larger than a predetermined second test volume, e.g. 180 1, the control apparatus 6 likewise locks the main valve l in the closed position. In addition, the main valve can like-wise be locked in the closed position when the leakage volume exceeds a predetermined second value. Preferably, however, the closing crlterion will also be made dependent on the previously escaped leakage volume, i.e. the amount of leakage rluid that has escaped.
The individual values for the flows of leakage volume can, as mentioned, for example be 1 l/h for the first value and 3 l/h for the second value. Below a value Or l l/h; the conduit system is oonsldered to be leakproor. Above 3 l/h, one derines a large small leak with which only a certaln amount Or fluid can pass berore the main valve l is closed.
If a consumer wishes to withdraw water at the point 9 he may, for example, turn a water tap 9, whereby the pressure P2 will suddenly drop in the conduit system. The wall 4 is ~ery ~'~ '', ~ - ' .
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X~38~5 rapidly pushed to the right-hand terminal wall Or the cylinder 1 under the pressure P1, whereupon the main valve 1 opens.
The water can now flow into the conduit system 8 from the source 7. The same will take place if there is a large leak, for example if a pipe breaks or there i9 a burst in the supply hose for a washing machine or dishwasher. To prevent too much water from escaping in ~uch a case, the time element 16 will close the main valve 1 agaln a predetermined time after the pressure drop. This time is, for example, suffi-cient for filllng a bath or having a generous shower, e.g. 15 minutes. or course there are also cases in which the consu-mer will want to withdraw water throughout a longer period, e.g. to wash his car or water the garden. In this case, he can signal this to the control apparatus 6, for example by actuating a switch whereby the apparatus will fix the maximum withdrawal time ror the next consumption to, say, two hours.
For all subsequent consumer activities, however, the original time Or, say, l5 minute~ will apply. Another posslbillty 19 ror the tlme element 16 to transmit an acoustical optical slgnal Just berore expiry Or the predetermined period, where-upon the consumer can close the tapping point 9 momentarily.
The pressure P2 will thereupon rise to move the wall 4 to the lert again. At the instant when the control apparatus 6 detects that the wall has left its rlght-hand terminal posl-: . ~. . : : ' ~ . : .
263~8~95 ~ . .
tion, i.e. the volume Or the chamber 12 has increased again, the maximum tapping time can start afresh. Such a pressure ri~e would be most unlikely in the case Or a large leak.
One therefore ensures that damage caused by a large leak will likewise be reliably kept relatively small.
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D A N F O S S A t S , D K -6 34 O N O R D B O R G
Method and apparatus for monitoring a conduit system ror an incompressible fluid for leaks The inventlon relates to a method of monitoring a conduit system for an incompressible fluid for leaks, wherein a testing fluid is lntroduced into the conduit system during a testing period when no fluid is being withdrawn from the condult system and the conduit sy~tem is closed on the supply side by a maln valve. The lnventlon also relates to an apparatus for monitorlng a condult system for an lncompressible fluid, comprisine a maln valve on the supply side of the conduit system and control apparatus for controlling actuatlon Or the main valve.
Fluid condult systems have to be monltored for untlght ~oints and leaks. This applies fundamentally to all conduit systems, regardless Or whether they are employed to convey mains water into a house, heating liquids in heating and remote heating systems or ga3es or fuels in distribution clrcuits.
The monltorlng Or mains water ln bulldlngs has particularly lncreased in lmportance in recent years. The problem will be explalned by uslng the example Or a malns water installation in a residentlal bullding. Normally, the consumption Or water through withdrawal by a consumer rrom a water tap amounts to between about 50 and 1,500 l/h. In extreme cases, for . -2~
: ` :
:~' ~ ':
example toiletcisterns or washing machines, the consumption could be between 30 and 2,500 l/h. Leakages accounted for by a pipe fracture or by bursting of a supply hose for a washing machine or dishwasher (large leak) are typically in the range of 500 to 2,500 l/h, sometimes higher, and can therefore not be distinguished from normal consumption. For this reason, wlth such large volumes above a predetermined value the 3upply ~-of water ls interrupted after a predetermined withdrawal perlod regardles3 of whether a consumer is using the water or there is a large leak.
In contrast, there are faults hereinafter referred to as a "small leak". In this case, the 1099 of water i~3 in the range Or about 1 to 25 l/h and could be caused by dripping water taps and overflowing toilet clsterns on the one hand and untlght pipe connections, commencement of fatigue failure in pipes occasioned by corroslon, halrllne fractures ln pipes and vessels or slmllar damage ln the condult system on the other hand. Whereas the flrst set of examples may not be dangerous but only lncrease the costs of fresh water and dralnage and place a demand on drinklng water sources and thus on the ;; environment, ~mall leaks of the second kind could cause con-siderable damage. More particularly, the outflowing quantity ,. ~
- . . . ~ , , , ' , . :, .
: : , : ' : .: ' ' , ' : ' ' ' . ' ' ' ' ' . . ' , ' ' of 1 to 25 l/h may appear very small but, over a prolonged period, walls or other parts of the building can become ir-repairable as a result Or being saturated with moisture. The resulting damage is often noticed too late because the dampness starts inside a wall and does not become visible until the whole wall is saturated. If one were to discover such a small leak at an early stage, it could be repaired in time.
To check a central heating system for leakages, W0 ~7/04520 discloses an arrangement consisting of two flow meters Or the vane-wheel type in the supply and return conduits Or the system. Both vane-wheels determine the total volume flowing through the heating system. If there ls no leak, the two volumes must be the same. If there is a difference between the two volumes, a leak is suspected and the circuit is shut down by way Or a motorised valve. However, since the volumet-ric flow meters are provided for the main flow, that i9 to say ror large volumes, they are unable to detect small leakages below, say, 25 l/h with the required degree Or accuracy.
W0 86/06457 disclo~es equipment for monitoring pressure con-duits for leakage polnts, thls equipment measuring the pressure 263C8495:
in the condult system downstream of the main valve and shutting the main valve down either when a large amount Or fluid rlows through the main valve for a prolonged perlod or, if the main valve is closed, the period required by the pressure to drop from a first pressure to a second pressure is shorter than a permitted time interval. However, since the pressure on the supply side Or the main valve varies considerably, for example pressure rluctuations at the waterworks that might be in the order Or 1.2 bar or as a result Or sudden consumption in an ad~oining conduit system where the pressure could drop by about 0.6 bar and, on termination Or this consumption, rise about 0.4 bar above the normal waterworks pressure and because Or the pressure drop across the main valve as a result Or the consumption in the conduit system being monitored, only unsat-isfactory results can be achieved with the pressure measurement disclased in WO 86/06457.
In a known apparatus ror monitoring installatlons ror tightness (DE-OS 21 58 901), when no fluid is being wlthdrawn, a leak is detected by withdrawing compressible fluid from the source, for example the supply mains, upstream Or the main valve, compressing lt wlth a compressor, and feedlng lt lnto the conduit system downstream of the main valve. Arter reaching 2~G~ 95 a test pressure, the compressor is shut Orr. One now contols whether the pressure loss does not exceed a predetermined value within a predetermined time. In a difrerent embodiment, one checks whether the compressor can build up the required testing pressure during a predetermined runnlng time. Since the volume conveyed by the compressor alway~ depends on the pressure difference between the inlet and outlet Or the com-pre3sor, it is practically impossible to come to any conclusion about the conveyed quantity if both of the pressures are not also monitored. The known equipment is therefore only suit-able ror determining whether there is a leak. One cannot say how large this leak might be. In addition, a separate drive i8 required for the compressor and this might lead to undesir-able noise. After detecting a leak, the main valve is locked in the closed position but fluid can neverthele!ss penetrate into the conduit system by way Or the compressor and continue to escape through the leak.
.
; It ls the problem Or the lnvention to provide a method and apparatu~ wlth whlch even small leaks can be reliably detected.
; This problem is solved in a method Or the aforementioned kind ln that, without the entry Or testlng fluld from the supply slde Or the maln valve, a predetermlned test volume Or the testing fluid is introduced into the conduit system under 2~1G8~95 pressure and the time required by the test volume to flow into the conduit system is measured.
During testing, exactly the same amount of fluid leaves through the leakage point as during normal operation. Since this escaping amount Or fluid is immediately replenished, the volume Or leakage flow can be measured exactly lf one assumes that it does not fluctuate appreciably over a period of tlme.
It is simply detected by dividing the known test volume, i.e.
the replenished quantity, by the measured time. In addition, a constant pressure is maintained through replenishment Or the testing fluid in the conduit system to be monitored, whereby a sufricient amount of fluid is immediately available upon commencement of consumption.
In one embodiment of the method, the pressure with which the test fluid is introduced into the conduit system i9 Or the same order as the fluld pressure on the supply slde Or the main valve. In a known apparatus, an increase in pressure is required which might increase the leak caused by a weakness in the material. To detect a leak, no excess pressure i9 there-fore applied but testing rluid is introduced into the conduit system under normal pressure. Since the normal pressure, ;~ . . ~ . ~. I . . . . . . . ... ..
.~. .,, - - ~ ~, . . - . :. .
~ ! . , . . . . . . ..
~' ' ' ' . . " ' , ' ~ ' , ' ', ' ~, . ', ' ': .
2~3~8~95 i.e. the supply pressure Or the mains, for example the water mains of a clty, i9 applied to the leakage points when the main valve is open, replenishment of the testing volume under the same pressure can practically reproduce the escape of leakage fluid under normal conditions. Since excessive pressure is avoided, the conduit system to be monitored is not stressed any more intensively than during normal opera-tion.
Preferably, the testing fluid is withdrawn from the conduit system berore the testing period. For testing purposes, therefore, exactly the same fluid is employed as that which is normally distributed by the conduit system to be monitored.
No special testing fluid has to be provided and this makes the method considerably cheaper. Accordingly, all of the testing fluid that is employed has also already passed through the main valve and any upstream metering clock- 90 that no difficultles are encountered for example when accounting for the mains water consumptlon to the waterworks. Also, no additional rilters or llke equipment have to be provided for the testlng fluid. Since the withdrawal of the testing fluid takes place immediately prior to the testing period, it is also practically impossible ror any error to occur because Or the time difference between withdrawal of the testing 2~R~9s , :
rluid and the testlng period.
Advantageously, the test volume is less than 0.5 1. Even the largest test volume of 500 ccm is still relatlvely small;
it only fills a cylinder of about 8 cm diameter and 10 cm high. This reduces the construction costs and very conslder-ably reduces the space taken up by the testing apparatus.
The smaller the test volume, the higher wlll be the time resolution.
Prererably, arter the complete introduction of the testing fluid, further testing fluid with the test volume is withdrawn rorm the conduit syste~ and held ready for renewed Lntroduc-tion into the conduit system. This makes continuous measure-ment Or the leakage volume possible. The time taken ror the leakage flow can thus be more efriciently monitored.
Preferably, the entire volume Or the lntroduced testine rluid is determined by adding the lndivldual volumes that were introduced. Thls not only gives an indication Or the indl-vidual volume Or leakage rlOw but also determines the quantity the total discharged fluld as an additlonal criterlon for consideratlon.
It ls also advantageous ror the leakage flow to be determined ., .. -.-, . . -.: ; - , X~8~95 continuously. This enables rapid recognitlon Or a change in the leakage behaviour of the conduit system being monitored and hence suitable protective or countermeasures can be taken in good time.
Preferably, an alarm signal is produced when the entire volume exceeds a predetermined fir3t value and/or when the flow of leakage volume lies between a rirst and a second value.
The alarm may be an optical or acoustic signal. To release the alarm, two criterla are therefore available, namely the entire volume that has escaped at the leakage point on the one hand and the actual leakage flow on the other hancl. Ir the actual leakage flow lies below a certain limlt, for example 1 l/h, the system is declared to be leakproof. With a flow Or leakage volume between, for example, 1 l/h and 3 l/h, a small leak i9 assumed whlch, although lt has to be monltored, will not cause much damage. With a flow Or leakage volume between for example 3 l/h and 20 l/h, one assumes a large small leak which could glve rise to serlous dama~e. A small small leak can, for example, be indicated immediately. However, lt could al90 be indicated only when the amount discharged through the small leak has exceeded a .. . . . ~
;~ 495 predetermined first value.
Preferably, the supply of fluid to the conduit system i9 completely interrupted when the total volume exceeds a prede-termined second value. Irrespective Or the size Or the leak, an escaped amount Or water can present a grave danger to the bullding and therefore lt ls better to close the maln valve completely in order to avoid further damage. Natur-ally, shuttlng down can also be made dependent on the actual flow Or leakage volume.
In a preferred embodiment, the total volume is returned to zero when the flow of leakage volume has been reduced by a predetermined extent. For example, it can happen that the leak is caused by a dripping water tap which the user failed to close completely. When the user notices his mistake and closes the water tap, the leak will also disappear. In this case, lt is senslble to correct the total volume that was assumed to escape lnto the wall from a faulty polnt in the condult system. Thls wlll then enable one to work wlth realistlc parameters during the next testlng period.
.
In an apparatus Or the aforementioned kind, the problem is solved ln that the conduit system communicates with a chamber : .. ~ . . - ,.
~........ ' .-- , , .: . :
-, ~ ,: :
,, . :
X~(~89~95 for introducing a testlng fluid with a predetermined test volume, the volume of the chamber being variable between a predetermined first larger value and a predetermined second smaller value. The chamber communicates only with the conduit system and time measuring means are provided for measuring the time during which the chamber reduces in volume from the first value to the second value.
Thus, the chamber serves as a store for testing fluid with-drawn from the conduit system. Since the chamber can a3sume two termlnal conditions, namely one with a larger volume and one with a smaller volume, during the time between these two conditlons it must be the exact dlrference ln volume that has flowed out of the chamber lnto the conduit system or out of the condult system lnto the chamber. Slnce the chamber communicates only wlth the conduit system and not wlth the supply side of the main valve, everything flowlng out of or into the chamber must also flow through the conduit system.
Since flowing out of the chamber for testing purposes only takes place with the main valve closed and without any pres3-ure increase in the conduit system, the chamber introduces exactly aq much fluid into the conduit system as escapes from the conduit system through a leakage polnt. The tlme measur-ing means measure the time required by the testlng fluld to 2~ 95 rlow into the condult system. In other words, they measure the time required by a certain volume to flow out Or the conduit system through the leakage point. This enables one to obtain an indication about the actual rlow Or leakage volume ir one assumes that this rlOw i9 not sub~ected to marked varlations in time.
Preferably, the chamber is closed on one side by a movable wall. The chamber is sealed at all sides with the exception Or the aperture to the conduit system, the volume being changeable by the wall. The volume therefore changes linear-ly with the displacement Or the wall which makes the evalua-tion simple.
Preferably, the wall i9 movable towards the smaller value Or volume against the rorce Or a spring. If the same pressures obtain on both sides Or the wall, the sprlng wlll move the wall so that the chamber wlll assume lts largest volume.
The sprlng thererore asslsts resetting.
Prererably, on the slde remote rrom the chamber, the movable wall is subJected to a force which ls constant throughout the path Or movement. Regardless Or the dlsplaced dlstance, thererore, always the qame pressure will act on the wall and thus on the chamber ir one disregards the counter-force Or the spring which becomes more intensively compressed as the ~ :
: :
2~3~8'~95 -di3placement increases. However, since the spring is rela-tively weak ln relatlon to the force actlng on the slde of the wall remote from the chamber, the change ln the counter-force Or the sprlng may be disregarded.
With particular advantage, the side Or the wall remote from the chamber communicates with the supply side Or the maln valve. Thus, the supply pressure Or the source, for example Or the mains water from the waterworks, acts on the chamber wlthout establlshing communlcation between the source and the conduit system that ls belng monitored, l.e. wlthout enabling fluid to enter the conduit system by bypassing the main valve. In addltion, no auxiliary energy is required.
Instead, an available pressure 1~ utilised. The pres~ure in the conduit system being monitored can become no higher than the supply pressure from the source and this avoids excessive stressing Or the monitored conduit system during monitoring.
In a prererred embodiment, a sensor ls provlded which trans-mits a slgnai to the control apparatus when the volume Or the ; chamber has reached the smaller value. Thls termlnal po31-tion ls, for example, requlred for the tlme measurement.
It is also preferred that the control apparatus will open the main valve in respon~e to this signal. When the chamber 2 ~ ~ 8 ~ 9 5 volume has reached its smaller value, a pressure drop mu~t have occured ln the conduit sy3tem. This pressure drop may be caused by consumption or by a leak. For consumption, the maln valve must open so that the user can withdraw fluid rrom the conduit system. In the case of a leak, monitoring has to occur.
~or monitoring a large leak, the time element preferably produces a command to close the main valve a predetermined time after the main valve was opened. Since the leakage monitoring system is unable to differentiate between consump-tion and a large leak, this measure ensures that only a maximum amount of fluid can leave the conduit system. A
consumer who wlshes to withdraw more fluid can glve prlor lndlcation of this to the control apparatu~ or he wlll inter-rupt the consumption momentarily to make it known to the control apparatus that there is no large leak.
In a further preferred embodiment, the control apparatus compriseq an lntegrator whlch lntegrates the volumes Or fluld red into the conduit system from the chamber. Thls enables a value to be avallable at all tlmes that indlcates the amount Or leakage flow that has escaped up to that time.
. ' . ~ ':
. . - ~ , 8~95 It is also advantageous if the control apparatu~ locks the main valve in the closed position when the integrator has determined a total volume which lies above a predetermined value and/or the rlow of volume exceeds a predetermined value. When the flow volume exceeds a predetermined value there will, as prevlously explained, be no fear Or extensive damage even ln the case Or a small leak. Another criterion, which could also be combined with the fir3t criterion, i3 the fact that a certain amount Or leakage fluid has escaped altogether. This amount can be adapted to sult the condi-tions. Upon exceeding thi3 predetermined leakage rlOw~
however, the main valve should be closed to avold extensive damage.
.
An example Or the invention will now be described in conJunc-tion with the drawing which is a diagram~atic representation Or an apparatus ror monitoring a conduit system ror an incom-pressible fluid ror leaks.
A conduit system 8, ror example for mains water in a residen-tial building, i9 red by way Or a main valve 1 from a source 7, for example the mains water from a waterwork3. The main valve 1 18 remote controlled by an actuating apparatus 5 whlch is operated by a control apparatus 6. When the main ~ ~.
.. ' . ~ ' . ' .. . . . . .
~8~95 .
valve l i9 closed, no water can reach the conduit sy3tem 8 from the source 7. Parallel to the maln valve 1 there is the actual leakage monitoring equipment. This consists Or a cylinder 2 which ls divided by a movable wall 4 lnto a pre3s-ure chamber 11 and a chamber 12. The pressure chamber 11 communicates with the 3upply side of the main valve l. The chamber 12 communicates with the discharge side Or the main valve 1, l.e. with the conduit system 8. The wall 4 seals the chamber 12 from the pressure chamber 11.
The wall 4 is movable in the cylinder 2 90 that the volume Or : ;
the chamber l2 is variable between a larger value at which the wall 4 abuts the left-hand end of the cylinder Z and a smaller value at whlch the wall 4 abuts the right-hand end of the cylinder 2. The wall 4 is pressed towards the left-hand end of the cylinder 2 by the force Or a spring 10.
It will now be assumed that the main valve 1 13 open wlthout water being wlthdrawn from the condult system through a tap9.
No water therefore flows through the maln valve 1 and there wlll be no pressure drop. The pres~e Pl on the supply side of the maln valve and equal to the pressure of the source 7 ls therefore equal to the pressure P2 on the discharge side of the main valve, i.e. equal to the pressure in the conduit ~, .
.
::
-.
8~L95 :~
system 8. The pressure P1 also obtains ln the pressurechamber 11 whilst the pressure P2 obtains in the chamber 12.
Accordingly, the same pressures act on both sides of the wall 4. However, since the wall 4 is additionally Rub~ected to the force of the spring 10 on the side facing the chamber 12, the wall 4 will be displaced towards the left-hand end Or the cylinder 2. At the rlght-hand end of the cylinder 2, there ls a sensor 14 whlch i9 actlvated by a generator 13 ln the wall 4 when the wall 4 is at its right-hand terminal position, l.e. when the chamber 12 has assumed its smallest volume.
When the wall 4 ls pushed towards the left under the force Or the sprlng 10, thls 19 detected by the sensor and notlfied to the control apparatus 6. A time element now runctlons in ths control apparatus 6 and, after a predetermined time, signals the valve actuator 5 to close the valve. If no fluld 19 being withdrawn from the conduit system 8, the pressure will remaln constant there, i.e. the wall 4 remalns in lts left-hand termlnal posltlon.
.. ..
However, lr a small leak occurs, rluid wlll trickle rrom the condult system 8 to the exterior thereby gradually reducing the pressure P2 in the conduit system. Slnce the wall 4 i9 subJected to the pressure P1 of the source obtaining in the 2~8'~9~
pressure chamber 11, lt will wander to the right, whereby the test volume Or fluid located in the chamber 12 i8 replenlshed to the condult system. After a certain tlme, which is measured by the time element 16, the wall 4 will reach its right-hand terminal position, which is detected by the sensor 14 which may be in the form of a reed relay. Since the test volume is known, the test volume and the time required by the test volume to rlOw into the condult system 8 will enable one to calculate the flow of volume, i.e. the volume per unit time, that has escaped the conduit system ô through the leakage point. Since the te3t volume enters the conduit system 8 without elevated pressure, no higher pressure loads will occur ln the condult system 8 than lf the maln valve 1 were to open and allow the pressure from the source 7 to pass dlrectly into the conduit system 8.
When the sensor 14 has recorded the ract that the wall 4 ls in lts rlght-hand terminal position, the control apparatus 6 will give a signal to the valve actuator 5 ror the main valve 1 to open agaln. The wall 4 will now be displaced to lts left-hand terminal position agaln ln the manner described above and the testlng cycle wlll start afresh.
The control apparatus 6 comprlses an lntegrator 15 whlch summates the number Or cycles Or the wall 4 and, since the ' ' . ' ~
B~95 test volume is known, thereby enables an indlcation to be obtained about how much rluid has escaped through the leak altogether.
Slnce the test volume is always again introduced into the conduit system it is possible to obtain a continuous indica-tion about the actual flow of leakage volume. In addition, there i8 an indication of the leakage flow that has already escaped so that, with the aid Or these two leakage loss criteria, an indicator can be reliably actuated and/or the main valve 1 can be closed. For example, an indicator is actuated when the leakage volume exceeds a first predetermined value, e.g. 1 l/h. When the leakage volume exceeds the predetermined first value, e.g. 60 1, and the escaped leakage volume exceeds a predetermined first value, an indication can likewise be given and the integrator 15 is returned to zero again. Naturally, the number of times for which-the integra-tor is reset to zero can be llmlted so as to prevent an excessively large amount Or leakage fluld to escape through the leak. For example, one can ensure that on the third occa~ion the integrator 15 is not reset to zero but the main valve 1 19 locked in the closed condition.
If the leakage volume is larger than a predetermined second .. , value, e.g. 3 l/h, the integrator is not reset to zero when reachlng the predetermined first leakage value but only an indicator i9 actuated. Integration, i.e. summation of the lndividual test volumes, is continued. If the lntegrator 5 finds that an amount of leakage fluid has escaped that is larger than a predetermined second test volume, e.g. 180 1, the control apparatus 6 likewise locks the main valve l in the closed position. In addition, the main valve can like-wise be locked in the closed position when the leakage volume exceeds a predetermined second value. Preferably, however, the closing crlterion will also be made dependent on the previously escaped leakage volume, i.e. the amount of leakage rluid that has escaped.
The individual values for the flows of leakage volume can, as mentioned, for example be 1 l/h for the first value and 3 l/h for the second value. Below a value Or l l/h; the conduit system is oonsldered to be leakproor. Above 3 l/h, one derines a large small leak with which only a certaln amount Or fluid can pass berore the main valve l is closed.
If a consumer wishes to withdraw water at the point 9 he may, for example, turn a water tap 9, whereby the pressure P2 will suddenly drop in the conduit system. The wall 4 is ~ery ~'~ '', ~ - ' .
.
, ::
X~38~5 rapidly pushed to the right-hand terminal wall Or the cylinder 1 under the pressure P1, whereupon the main valve 1 opens.
The water can now flow into the conduit system 8 from the source 7. The same will take place if there is a large leak, for example if a pipe breaks or there i9 a burst in the supply hose for a washing machine or dishwasher. To prevent too much water from escaping in ~uch a case, the time element 16 will close the main valve 1 agaln a predetermined time after the pressure drop. This time is, for example, suffi-cient for filllng a bath or having a generous shower, e.g. 15 minutes. or course there are also cases in which the consu-mer will want to withdraw water throughout a longer period, e.g. to wash his car or water the garden. In this case, he can signal this to the control apparatus 6, for example by actuating a switch whereby the apparatus will fix the maximum withdrawal time ror the next consumption to, say, two hours.
For all subsequent consumer activities, however, the original time Or, say, l5 minute~ will apply. Another posslbillty 19 ror the tlme element 16 to transmit an acoustical optical slgnal Just berore expiry Or the predetermined period, where-upon the consumer can close the tapping point 9 momentarily.
The pressure P2 will thereupon rise to move the wall 4 to the lert again. At the instant when the control apparatus 6 detects that the wall has left its rlght-hand terminal posl-: . ~. . : : ' ~ . : .
263~8~95 ~ . .
tion, i.e. the volume Or the chamber 12 has increased again, the maximum tapping time can start afresh. Such a pressure ri~e would be most unlikely in the case Or a large leak.
One therefore ensures that damage caused by a large leak will likewise be reliably kept relatively small.
~. ~. ~ ' '.',. '' :
.. . .: . , : ,, . .~ .: ,.
:: :,
Claims (20)
1. A method of monitoring a conduit system for an incom-pressible fluid for leaks, wherein a testing fluid is intro-duced into the conduit system during a testing period when no fluid is being withdrawn from the conduit system and the conduit system is closed on the supply side by a main valve, characterized in that, without the entry of testing fluid from the supply side of the main valve, a predetermined test volume of the testing fluid is introduced into the conduit system under pressure and the time required by the test volume to flow into the conduit system is measured.
2. A method according to claim 1, characterized in that the pressure at which the testing fluid is introduced in the conduit system is in the same order as the fluid pressure on the supply side of the main valve.
3. A method according to claim 1 or claim 2, characterized in that the testing fluid is withdrawn from the conduit system before the testing period.
4. A method according to one of claims 1 to 3, character-ized in that the test volume is less than 0.5 1.
5. A method according to one of claims 1 to 4, character-ized in that, after complete introduction of the testing fluid, further testing fluid with the test volume is again withdrawn from the conduit system and held available for introduction into the conduit system for monitoring purposes.
6. A method according to claim 5, characterized in that the total volume of testing fluid introduced is determined by adding the individually introduced volumes.
7. A method according to claim 5 or claim 6, characterized in that the flow of leakage volume is determined continuously.
8. A method according to claim 6 or claim 7, characterized in that an alarm signal is produced when the total volume exceeds a predetermined first value and/or the flow of leakage volume is between a predetermined first and a predetermined second value.
9. A method according to one of claims 6 to 8, character-ized in that the supply of fluid to the conduit system is completely interrupted when the total volume exceeds a pre-determined second value.
10. A method according to one of claims 7 to 9, character-ized in that the total volume is reset to zero when the flow of leakage volume is reduced by a predetermined amount.
11. Apparatus for monitoring a conduit system for an incom-pressible fluid for leaks, particularly for performing the method of any one of claims 1 to 10, comprising a main valve on the supply side of the conduit system and a control appa-ratus for controlling the actuation of the main valve, char-acterized in that for introducing a testing fluid of a pre-determined test volume, the conduit system (8) communicates with a chamber (12) of which the volume is variable between a predetermined first larger value and a predetermined second smaller value, the chamber communicating only with the conduit system (8), and that time measuring means (16) are provided for measuring the time during which the chamber is reduced from the first volume to the second volume.
12. Apparatus according to claim 11, characterized in that the chamber (12) is closed by a movable wall (4) at one side.
13. Apparatus according to claim 12, characterized in that the wall (4) is movable towards the smaller value of volume against the force of a spring (10).
14. Apparatus according to claim 12 or claim 13, character-ized in that the movable wall (4) is subjected on the side remote from the chamber (12) to a force which is constant throughout the path of movement of the wall (4).
15. Apparatus according to claim 14, characterized in that the side of the wall (4) remote from the chamber (12) communi-cates with the pressure on the supply side of the main valve (1).
16. Apparatus according to one of claims 11 to 15, charac-terized in that a sensor (13, 14) is provided which transmits a signal to the control apparatus (6) when the volume of the chamber (4) has reached the second smaller value.
17. Apparatus according to claim 16, characterized in that the control apparatus (6) opens the main valve (1) in response to this signal.
18. Apparatus according to one of claims 11 to 17, charac-terized in that the time element (16) sends a command for closing the main valve (1) a predetermined time after opening of the main valve (1).
19. Apparatus according to one of claims 11 to 18, charac-terized in that the control apparatus (6) comprises an inte-grator (15) which integrates the fluid test volumes fed into the conduit system (8) from the chamber (12).
20. Apparatus according to claim 19, characterized in that the control apparatus (6) locks the main valve (1) in the closed position when the integrator (15) has detected a total volume which 19 above a predetermined value and/or when the flow of volume exceeds a predetermined value.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19893904487 DE3904487C1 (en) | 1989-02-15 | 1989-02-15 | |
| DEP3904487.4 | 1989-02-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2008495A1 true CA2008495A1 (en) | 1990-08-15 |
Family
ID=6374103
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2008495 Abandoned CA2008495A1 (en) | 1989-02-15 | 1990-01-24 | Incompressible fluid for leaks |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPH02247534A (en) |
| CA (1) | CA2008495A1 (en) |
| DE (1) | DE3904487C1 (en) |
| DK (1) | DK25690A (en) |
| GB (1) | GB2228336A (en) |
| SE (1) | SE9000251L (en) |
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|---|---|---|---|---|
| DE4127104A1 (en) * | 1991-08-16 | 1993-02-18 | Kraewer Hans Peter | DEVICE FOR TESTING THE TIGHTNESS OF GAS PIPES |
| DE4128750C2 (en) * | 1991-08-29 | 1995-03-16 | Psi Ges Fuer Prozessteuerungs | Method for locating a leak in a fluid pipeline network |
| DE4131573C1 (en) * | 1991-09-23 | 1993-01-21 | Bernhard 4830 Guetersloh De Esders | Automatic watertightness testing appts. for section of mains drainage - monitors test pressure and controls supply of water through pumps and valves within defined pressure tolerance band |
| DE19959115C1 (en) * | 1999-12-08 | 2001-05-10 | Innovatherm Prof Dr Leisenberg Gmbh & Co Kg | Determining pressure losses in pressure line comprises adding adjustable amount of stopped medium to pressure line which is connected to pressure control device in specified time interval |
| DE102004016378A1 (en) * | 2004-04-02 | 2005-11-03 | Stefan Windisch | Method and arrangement for active monitoring of pipelines |
| DE102011075168B4 (en) * | 2011-05-03 | 2022-02-17 | Zf Friedrichshafen Ag | Method for detecting and taking into account a leak in the actuating device of a fluid-operated clutch |
| WO2015139760A1 (en) * | 2014-03-20 | 2015-09-24 | Husqvarna Ab | Dripping alert function |
| GB2553833B (en) * | 2016-09-16 | 2019-10-23 | Univ Cape Town | Pipe condition assessment device and system |
| US10838434B2 (en) | 2016-11-22 | 2020-11-17 | Wint Wi Ltd | Differentiating between multiple overlapping water events |
| CN108385776A (en) * | 2018-01-31 | 2018-08-10 | 翟文杰 | A kind of tap water water leakage monitoring device Internet-based |
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| CN111609324B (en) * | 2020-05-29 | 2021-02-19 | 北京化工大学 | Pipeline leakage detection method and device |
| CN113702077B (en) * | 2021-08-05 | 2022-04-26 | 北京科技大学 | Metal mineral paste filling complex pipe network pipe plugging and leakage monitoring simulation experiment system |
| CN113882472B (en) * | 2021-10-27 | 2023-03-07 | 何丽萍 | Static energy non-negative pressure secondary water supply equipment |
| CN115790988B (en) * | 2023-02-10 | 2023-05-19 | 青岛宾川智能科技有限公司 | Waterproof testing device for instrument and meter |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT356010B (en) * | 1977-09-09 | 1980-04-10 | Seba Mess Ortungstech | METHOD FOR DETERMINING LEAKS IN GROUND WATER PIPES |
| JPS58179331A (en) * | 1982-04-14 | 1983-10-20 | Toyoda Gosei Co Ltd | Leak detecting device of brake hose |
-
1989
- 1989-02-15 DE DE19893904487 patent/DE3904487C1/de not_active Expired - Lifetime
-
1990
- 1990-01-24 CA CA 2008495 patent/CA2008495A1/en not_active Abandoned
- 1990-01-24 SE SE9000251A patent/SE9000251L/en not_active Application Discontinuation
- 1990-01-31 DK DK25690A patent/DK25690A/en not_active Application Discontinuation
- 1990-02-07 GB GB9002723A patent/GB2228336A/en not_active Withdrawn
- 1990-02-14 JP JP3357990A patent/JPH02247534A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE3904487C1 (en) | 1990-07-05 |
| JPH02247534A (en) | 1990-10-03 |
| SE9000251L (en) | 1990-08-16 |
| DK25690D0 (en) | 1990-01-31 |
| DK25690A (en) | 1990-08-16 |
| GB9002723D0 (en) | 1990-04-04 |
| GB2228336A (en) | 1990-08-22 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| FZDE | Dead |