GB1575548A

GB1575548A - Monitoring of the contents of a container

Info

Publication number: GB1575548A
Application number: GB3708577A
Authority: GB
Original assignee: Scheidt and Bachmann GmbH
Current assignee: Scheidt and Bachmann GmbH
Priority date: 1976-09-18
Filing date: 1977-09-06
Publication date: 1980-09-24
Also published as: NL7707571A; ATA460777A; IT1084197B; DK389377A; DE2642058B1; CH617008A5; AT381389B; DE2642058C2

Abstract

Particularly for underground storage containers (1) for liquid fuels, the contents of which are frequently changed by refilling (2) and removal (3), continuous monitoring of the contents is to be rendered possible by simple means (4, 5). The amounts filled and removed are continuously detected in a summing and subtracting integrated-demand memory (6). The counter reading is automatically recorded when a prescribed liquid level (8) is reached, and compared with the filled amount which corresponds to this state. When the latter is reached, a switch (7) transmits a signal upon the occurrence of which the state of the integrated-demand memory (6) is recorded (10) via a logic circuit (9). <IMAGE>

Description

(54) IMPROVEMENTS IN OR RELATING TO THE MONITORING OF THE CONTENTS OF A CONTAINER (71) We, SCHEIDT & BACHMANN GmbH, a German Body Corporate, of 132 Breite Strasse, 4050 Monchengladbach 2, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to the monitoring of the contents of a container, for example a horizontal underground storage container for liquid fuels.

The monitoring of the contents of a container, for example by means of a float switch or a probe or by electronic, for example capacitive, indicating devices, is only possible in a simple manner when the liquid level which can be ascertained by these monitoring devices can be converted reliably and without difficulties into a statement of amount. This is the case with cubic or cuboid containers and with vertical cylindrical containers in so far as deviations resulting from deformations of the container walls are not taken into account.

A conversion of the ascertained filling height into a statement of amount in the case of horizontal cylindrical containers such as may be used in a petrol filling station is only possible with complicated conversion calculations and is moreover attended by considerable errors through container tilt and changes 'of shape of the container wall.

According to the present invention, there is provided a process for monitoring the amount of liquid stored in a container, wherein the amounts of liquid fed into and discharged from the container are registered continuously in an adding and subtracting counting store, and, each time that a predetermined liquid level is reached, the quantity registered in the counting store is automatically recorded to provide a recorded output indicative of the quantity registered in the store at said predetermined level.

Further according to the present invention, there is provided a system for carrying out the above process comprising means for sensing the amount of liquid fed into the container, means for sensing the amount of liquid with drawn from the container, an adding and subtracting counting store for receiving signals representing the amount of liquid fed into and withdrawn from the container as determined by said sensing means, a liquid level switch arranged in the container, said 'switch being operative, when a predetermined liquid level is reached, to provide a signal, and means operative to provide a recorded output indicative of the net quantity registered in the store when the signal occurs.

Still further according to the invention, there is provided a system for monitoring the contents of a liquid container, comprising a summation device operative to provide an output derived from a measure of the quan tity of liquid fed into the container and the quantity of liquid withdrawn from the con tainer, means operative to produce a signal when the instantaneous liquid level in the container is at a predetermined level corresponding to a known quantity of liquid in the container, and means responsive to the signal to provide a recorded output indicative of the instantaneous output of the summator when the signal is produced.

The invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, the sole figure of which shows schematically a monitoring system in accordance with the present invention.

The drawing shows a horizontal cylindrical container 1, for example an underground storage container for petrol or other liquid fuel, which is provided with an inflow line 2 and a main outflow line 3 from which several outflow lines 3a, 3b and 3c (for example individual petrol pumps) branch off* In the inflow line 2 is arranged a device 4 for registering the amount of liquid fed into the container. In each outflow line 3a, 3b, and 3c there is provided a respective flow meter 5.

The device 4 for registering the amount may Jikewise be a flow meter. On the other hand, it is possible to register, as a whole, the' amount supplied to the container 1 through the inflow line 2 in each case during delivery, fdr example by a tanker vehicle. This may be done for example by transmission of the amount delivered by the tanker vehicle in each case.

Signals representing the amounts of liquid supplied to the container 1 are fed by means of the device 4 to a summation device in the form of a counting store 6 which adds these up continuously. From these values are deducted the amounts withdrawn from the container 1 through the outflow lines 3a, 3b and 3c, which amounts are communicated to the counting store 6 by the flow meters 5. The counting store 6 therefore states the contents of the container 1 for example in litres, when delivered and withdrawn amounts of liquid have teen registered.

In "order to monitor periodically the contents of the container which are recorded by the counting store 6, there is arranged in the con'trainer 1 a liquid level switch 7 which is assigned to a predetermined liquid level 8.

This 'assignment is effected for example during the first filling of the container 1 in that the liquid level switch 7, after the con tainer.l has been filled with a known amount of liquid, is adjusted to the liquid level resulting hereby. In the case of a total capacity of the container 1 of, for example, 25000 litres, the liquid level switch 7 would be adjusted to a liquid level corresponding to a stored volume of 20000 litres. This liquid level 8 is shown by a sdlid line in the drawing. The broken line indicates the maximum filling level.

With a completely filled container 1, the reading of the counter of the counting store 6 would in the above-mentioned example be 25000 litres From this value are deducted the amounts of liquid which are removed from the container 1 by the outflow lines 3a, 3b and 3c.

As soon as the predetermined liquid level 8 is reached, the hquid level switch 7 gives a signal to a logic device 9 which, in turn, scans the reading of the counting store 6 and prints out this reading on a printer 10. The printedoust result should, within a predetermined error, lie at 20000 litres in the case of the above example. If, for example, it deviates more than 50 litres from this value, the logic device 9 causes an error signal to be given.

Since the predetermined liquid level 8 will usually be passed both during the filling of liquid into, and the removal of liquid from, the container 1, there results, during each filling of the container 1 and during the sub setldent removal, a comparison of the actual value with the'' theoretical value recorded in the counting store 6 so that inadmissible deviations can be determined during the delivery or removal process. In this way, erroneous measuring systems and manipulations during delivery or during withdrawal of liquid can be reliably detected.

Thus, with the system particularly described, by using a known (and usually present on a storage container) flow meter, and counting store, there is effected, through the use of a known device for registering a' certain liquid - level, a periodic monitoring of the container contents by the adding and subtracting counting store, since, each time the level of liquid in the container passes through the predetermined liquid level an investiga- tion of the counter's reading takes place.

Since the filling amount corresponding to the predetermined liquid level can be ascertained exactly during the first filling of the container, the deviations occurring during the periodic monitoring can give precise information about the causes of the deviation, for example through defective measuring systems during filling or removal, or through leakages. In this manner, malfunctions or malpractices during the delivery or during the sale of the container's contents can be detected. The frequency of the monitoring increases automatically with the turnover, since, in the case of a frequent refilling of the container, the predetermined liquid level is always passed both during refilling and during the subsequent removal.

The system is, in part, composed of components already present on storage containers and of other commerically available components which can be incorporated in a simple manner. The liquid level switch can be, for example, a float switch or an element for monitoring the level by capacitive means.

With the system described it is possible to monitor, from a remote position, the contents of a container which could not be deduced directly from the liquid level without the use of a computer operating according to a relatively complex program. Deviations occurring within a certain tolerance range are suppressed, whereas deviations exceeding the tolerance range lead to a warning signal. The reaching of the predetermined liquid level causes automatically a recording of the instantaneous reading of the counting store, so that through a comparison of successive values an indicator of the nature and cause of the deviations is possible.

WHAT WE CLAIM IS 1. A process for monitoring the amount of liquid stored in a container, wherein the amounts of liquid fed into and discharged from the container are registered continuously in an adding and subtracting store, and, each time that a predetermined liquid level is reached, the quantity registered in the counting store is automatically recorded to provide a recorded output indicative of the quantity registered in the store at said predetermined level.

2. A process according to claim 1, further comprising the steps of automatically comparing the quantity registered in the store at

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the inflow line 2 in each case during delivery, fdr example by a tanker vehicle. This may be done for example by transmission of the amount delivered by the tanker vehicle in each case. Signals representing the amounts of liquid supplied to the container 1 are fed by means of the device 4 to a summation device in the form of a counting store 6 which adds these up continuously. From these values are deducted the amounts withdrawn from the container 1 through the outflow lines 3a, 3b and 3c, which amounts are communicated to the counting store 6 by the flow meters 5. The counting store 6 therefore states the contents of the container 1 for example in litres, when delivered and withdrawn amounts of liquid have teen registered. In "order to monitor periodically the contents of the container which are recorded by the counting store 6, there is arranged in the con'trainer 1 a liquid level switch 7 which is assigned to a predetermined liquid level 8. This 'assignment is effected for example during the first filling of the container 1 in that the liquid level switch 7, after the con tainer.l has been filled with a known amount of liquid, is adjusted to the liquid level resulting hereby. In the case of a total capacity of the container 1 of, for example, 25000 litres, the liquid level switch 7 would be adjusted to a liquid level corresponding to a stored volume of 20000 litres. This liquid level 8 is shown by a sdlid line in the drawing. The broken line indicates the maximum filling level. With a completely filled container 1, the reading of the counter of the counting store 6 would in the above-mentioned example be 25000 litres From this value are deducted the amounts of liquid which are removed from the container 1 by the outflow lines 3a, 3b and 3c. As soon as the predetermined liquid level 8 is reached, the hquid level switch 7 gives a signal to a logic device 9 which, in turn, scans the reading of the counting store 6 and prints out this reading on a printer 10. The printedoust result should, within a predetermined error, lie at 20000 litres in the case of the above example. If, for example, it deviates more than 50 litres from this value, the logic device 9 causes an error signal to be given. Since the predetermined liquid level 8 will usually be passed both during the filling of liquid into, and the removal of liquid from, the container 1, there results, during each filling of the container 1 and during the sub setldent removal, a comparison of the actual value with the'' theoretical value recorded in the counting store 6 so that inadmissible deviations can be determined during the delivery or removal process. In this way, erroneous measuring systems and manipulations during delivery or during withdrawal of liquid can be reliably detected. Thus, with the system particularly described, by using a known (and usually present on a storage container) flow meter, and counting store, there is effected, through the use of a known device for registering a' certain liquid - level, a periodic monitoring of the container contents by the adding and subtracting counting store, since, each time the level of liquid in the container passes through the predetermined liquid level an investiga- tion of the counter's reading takes place. Since the filling amount corresponding to the predetermined liquid level can be ascertained exactly during the first filling of the container, the deviations occurring during the periodic monitoring can give precise information about the causes of the deviation, for example through defective measuring systems during filling or removal, or through leakages. In this manner, malfunctions or malpractices during the delivery or during the sale of the container's contents can be detected. The frequency of the monitoring increases automatically with the turnover, since, in the case of a frequent refilling of the container, the predetermined liquid level is always passed both during refilling and during the subsequent removal. The system is, in part, composed of components already present on storage containers and of other commerically available components which can be incorporated in a simple manner. The liquid level switch can be, for example, a float switch or an element for monitoring the level by capacitive means. With the system described it is possible to monitor, from a remote position, the contents of a container which could not be deduced directly from the liquid level without the use of a computer operating according to a relatively complex program. Deviations occurring within a certain tolerance range are suppressed, whereas deviations exceeding the tolerance range lead to a warning signal. The reaching of the predetermined liquid level causes automatically a recording of the instantaneous reading of the counting store, so that through a comparison of successive values an indicator of the nature and cause of the deviations is possible. WHAT WE CLAIM IS

1. A process for monitoring the amount of liquid stored in a container, wherein the amounts of liquid fed into and discharged from the container are registered continuously in an adding and subtracting store, and, each time that a predetermined liquid level is reached, the quantity registered in the counting store is automatically recorded to provide a recorded output indicative of the quantity registered in the store at said predetermined level.

the predetermined level with the actual quantity which corresponds to said level, and providing automatically an error signal if the two quantities differ by more than a predetermined value.

3. A system for carrying out the process according to claim 1 comprising means for sensing the amount of liquid fed into the container, means for sensing the amount of liquid withdrawn from the container, an adding and subtracting counting store for receiving signals representing the amount of liquid fed into and withdrawn from the container as determined by said sensing means, a liquid level switch arranged in the container, said switch being operative, when a predetermined liquid level is reached, to provide a signal, and means operative to provide a recorded output indicative of the net quantity registered in the store when the signal occurs.

4. A system for monitoring the contents of a liquid container, comprising a summation device operative to provide an output derived from a measure of the quantity of liquid fed into the container and the quantity of liquid withdrawn from the container, means operative to produce a signal when the instantaneous liquid level in the container is at a predetermined level corresponding to a known quantity of liquid in the container, and means responsive to the signal to provide a recorded output indicative of the instantaneous output of the summator when the signal is produced.

5. A system according to claim 4, comprising means for producing an error signal if the quantity of liquid as recorded at the output of the summation device differs from said known quantity by more than a predetermined value.

6. A process substantially as hereinbefore described with reference to the accompanying drawing.

7. A system substantially as hereinbefore described with reference to the accompanying drawing.