GB2291710A

GB2291710A - Liquid level monitoring apparatus

Info

Publication number: GB2291710A
Application number: GB9514941A
Authority: GB
Inventors: David Francis Bullock; Stephen Ernest David Bullock
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-07-23
Filing date: 1995-07-20
Publication date: 1996-01-31
Also published as: GB9414874D0; GB9514941D0; IE950554A1

Abstract

An apparatus 2 for monitoring the level of liquid in a container comprises a liquid level monitoring assembly 4 adapted in use to receive liquid from the container, and a float-operated air-vent valve means 6 thereabove. The liquid level monitoring assembly may comprise a monitoring device such as a float-operated switch 16 or an optical sensor (Figs 2b and 4) in a liquid housing. The apparatus may be located independently of the container, and be connected to an alarm. The same float may operate a switch and the air-vent valve (Fig 3). <IMAGE>

Description

LIOUID LEVEL MONITORING APPARA?ZTS This invention relates to liquid level monitoring apparatus.

Many apparatus for monitoring the level of a liquid in a container, such as an oil tank, are known. One purpose of such apparatus is as warning devices to warn when the level of oil falls below a predetermined minimum. It is important not to allow such tanks to empty as air then enters the pumping system requiring subsequent 'bleeding' of the system. One apparatus is shown in GB 2230 144A. It comprises a float in a housing connected to the oil tank. At a predetermined level of oil in the tank, and thus correspondingly in the housing, the float pivots between a first and second position thereby operating a switch connected to an indicating light.

Such an apparatus may be separate from the tank. However, it is necessary for the apparatus to be vented to allow for the changing level of oil in the housing, just as the oil tank itself must be vented. Presently, the venting of the housing is a simple external breather pipe. However, the breather pipe has to extend beyond the top of the oil tank to avoid spillage of oil from the warning apparatus housing when the oil tank is full. This limits the possible positioning and compactness of the apparatus.

Therefore, according to one aspect of the present invention, there is provided an apparatus for monitoring the level of liquid in a container comprising a liquid level monitoring assembly adapted in use to receive liquid from the container, and a float operated air-vent valve means thereabove.

The air-vent valve means preferably comprises a valve housing and float means therein designed to reversibly seal an air vent. Liquid from the container which rises above the monitoring assembly determines the level of the float. At the maximum height of the float in the valve housing, the float causes sealing of the vent and prevents any liquid escaping through the vent. A lowering of the liquid level in the valve housing lowers the float, which causes the vent to open allowing the passage of air therethrough.

Thus the apparatus of the present invention may be positioned anywhere relative to the container. The valve means need not be above the level ofthe top ofthe container as no liquid can escape therefrom. The positioning ofthe apparatus is therefore independent of the positioning of the container. Furthermore, the monitoring assembly and valve means may be in close juxtaposition. This may provide a compact 'unit', which may be placed in any convenient location, e.g. a control room or in the home.

The float of the air-vent valve means may be connected to a hinged arm, the movement of which seals and unseals the air vent. The level of the float determines the position of the arm, and thus the degree to which the air vent is open.

The air vent preferably has a dust cap thereon. There may also be a filter means between the monitoring assembly and valve means. The filter inhibits debris in the liquid entering the valve means and thereby possibly blocking the air vent.

The liquid level monitoring assembly preferably comprises a liquid level monitoring means and a liquid housing. The liquid housing receives the liquid from the container. The monitoring means may be in direct or indirect contact with the liquid in the liquid housing. The monitoring means may be partly or completely within the liquid housing, and can be any suitable means designed to detect the presence or absence of liquid, or a level of liquid, in the liquid housing.

According to one embodiment of the present invention, the liquid level monitoring means is an optical sensor, e.g. a photoelectric sensor, which can determine whether the liquid is above or below a predetermined level in the liquid housing.

According to one alternative embodiment of the present invention, the monitoring means comprises a float moveable between a first and second position, the movement of which is determined by the level of liquid in the liquid housing. Above or below a predetermined level, the movement of the float activates a switch or signal, etc.

According to a second alternative embodiment of the present invention, the monitoring means comprises a float and attached magnet. The level of the float is determined by the level of liquid in the liquid housing, and the fall of liquid to or below a pre-determined level causes the magnet to come close to a magnetically operated switch, which could be outside the housing of the float. The switch is operated by the close proximity of the magnet.

In all the above, the pre-determined level of liquid in the monitoring assembly corresponds to a pre-determined level of liquid in the container. The monitoring assembly may be connected to an indicating means, visual, audible etc, e.g. in the home, to provide warning of the level of the liquid in the container. The monitoring assembly may be deactivated manually, or by raising the level of liquid above the pre-determined level in the apparatus. The monitoring assembly could also activate a means to send a signal automatically to a remote indicator.

The monitoring assembly and valve means may be integral, or may be separately formed before being brought together. The two parts could be brought together directly, or may fit together with a connecting means, e.g. a Junction. Breakdown of either part may therefore require only the fixing or replacement of that part. Furthermore, any specific design requiring an unusual or irregular location or inter-relationship of the whole apparatus or of the two parts can be more easily accommodated.

Alternatively, there is oniy one float in the apparatus, designed to act both as the float part of a float-operated monitoring assembly and as the float in the air-vent valve means. In this embodiment, the float is designed to act in the same manner as described above for the apparatus comprising two floats. Thus, at the maximum height of the liquid and therefore float in the apparatus, the float seals the air vent and prevents any liquid escaping through the vent. As the liquid level falls, the float falls also. Once the level of the float reaches or passes through a certain pre-determined point, the movement of the float causes operation of the monitoring assembly, thus activating an indicating means. The apparatus of this embodiment is simplified both mechanically and economically by having fewer parts. The apparatus may also be more compact than that as described above.

The apparatus of the present invention may be used to monitor the level of any suitable liquid in any container. One preferred application is the monitoring of oil levels in industrial and domestic oil storage tanks.

Embodiments of the present invention will now be described by way of example only and with reference to the accompanying diagrammatic drawings, in which: Figs. 1 and 4 show schematic views of apparatus according to different embodiments of the present invention; Figs. 2a and 2b show alternative monitoring assemblies for use in the present invention; and Fig. 3 shows a combined monitoring assembly and air vent valve apparatus according to a further embodiment of the present invention; Referring to the drawings, Fig. 1 shows an apparatus 2 for monitoring the level of a liquid in a container (not shown) comprising a float-operated monitoring assembly 4 and valve means 6. The monitoring assembly 4 is adapted to receive liquid from the container (whose liquid level is being monitored) via pipe 8. The monitoring assembly 4 comprises a liquid housing 10 and a liquid level monitoring device of a float 12, abutment 14 and switch 16. The float 12 is connected to a pivot 20. When the level of liquid in the housing 10 is above a pre-determined level, the float 12 is separate from the abutment 14. When the liquid falls below the pre-determined level, the float 12 falls with the liquid until it is in contact with the abutment 14. Either by the contact thereby created or by a new contact formed in the pivot housing caused by the change of angle of the float 12 extending therefrom, the switch 16 is activated. The switch 16 is connected to an indicating means (not shown) via an electrical connection 18.

The valve means comprises a valve housing 22 enclosing a float 24, connected to an arm 26 hinged at one end 28. In the top ofthe housing 22 is an air vent 30 housing a dust cap 32 thereon. The level of the float 24 is determined by the level of liquid in the housing 22. Raising of the float 24 causes rotation of the arm 26 about its hinged end 28.

When the float 24 is sufficiently raised, the arm 26 becomes flush with the lower end of the air vent 30 thus sealing it, and preventing escape of liquid should it rise to the top of the housing 22.

Over rotation of the arm 26 is prevented by stop 32. Lowering of the liquid level in the housing 22 rotates arm 26 breaking its seal with the lower end of the air vent 30.

Air may now flow into the housing 22. The float 24 should not be allowed to rest on the bottom of the housing 22 and hence possibly block the connection 34 with the monitoring assembly housing 10.

In the connection 34, a filter 36 inhibits debris in the liquid entering the valve means housing 22. The connection 34 may either be an integral connection, or separable, e.g. by screw thread.

Figs. 2a and 2b show alternative monitoring assemblies comprising monitoring means and liquid housings. In Fig. 2a, the monitoring mean comprises a float 40 including a magnet 42, in a liquid housing 38. The float 40 floats freely with the level of liquid 43 in the housing 38. Next to the housing 38 is an electrical magnetically operated switch 44 at a pre-determined level, also a part of the monitoring means. When the liquid 43 and hence float 40 reach the same pre-determined level in the housing 38, the close proximity of the magnet 42 activates the switch 44. This activation is passed to an indicating unit (not shown) via electrical connection 46. Fig. 2b shows the same liquid housing 38 incorporating a photoelectric sensor 47 as the monitoring device.The sensor 47 activates an indicating means (not shown) when the level of the liquid in the housing 38 is below the level ofthe sensor 47.

Fig. 3 shows a combined monitoring assembly and air vent valve apparatus 48.

In housing 50, there is a float 52, arm 54, vent 56 and stop 60 similar to the float 24, arm 26, vent 30 and stop 34 in Fig. 1. On the housing is a dust cap 58. The monitoring device comprises the same float 52 connected to a switch 61 by hinged arm 62 about pivots 63 and 64. When the float 52 is raised to its maximum height, the arm 54 seals vent 56. When the level of liquid in the housing 50 falls to a pre-determined level, the float 52, falling therewith, activates the switch 61, e.g. by the change of angle of pivot 63 in its housing. The switch 61 is connected to an indicating means (not shown) via the electrical connection 65.

It would also be possible to arrange the apparatus shown in Fig. 2a to operate in a similar manner. That is, the float 42 could, when raised to its maximum height in the housing 38 because of liquid therein, seal the connection 45. As the liquid level falls, the float 42 operates as described above.

Fig. 4 shows another arrangement of monitoring assembly 66 and air vent valve means 68 according to the present invention. The monitoring device of the monitoring assembly 66 is a photoelectric sensor comprising an optical sensor head mounted in a suitable housing. The valve means 68 is similar to the valve means 6 shown in Fig. 1.

The monitoring assembly 66 and valve means 68 are fitted together with a T-junction connecting means 70, both by screw thread to allow for easy assembly and disassembly for maintenance and repair/replacement. The lower end of the connecting means 70 is connected to an outflow pipe of the container whose liquid level is being monitored.

Variations and modifications can be made without departing from the scope of the invention described above.

Claims

1. Apparatus for monitoring the level of liquid in a container comprising a liquid level monitoring assembly adapted in use to receive liquid from the container, and a float-operated air-vent valve means thereabove.

2. Apparatus as claimed in Claim 1 wherein liquid from the container operates the air-vent valve means.

3. Apparatus as claimed in Claim 1 or Claim 2 wherein the float of the air-vent valve means is connected to a hinged arm, the movement of which seals and unseals the air vent.

4. Apparatus as claimed in any one of Claims 1, 2 or 3 wherein a filter means is located between the liquid level monitoring assembly and the air-vent valve means.

5. Apparatus as claimed in any one of the preceding Claims wherein the liquid level monitoring assembly comprises a liquid level monitoring means and a liquid housing adapted to receive the liquid from the container.

6. Apparatus as claimed in Claim 5 wherein the liquid level monitoring means is an optical sensor.

7. Apparatus as claimed in Claim 5 wherein the liquid level monitoring means is a float moveable between a first and second position, the movement of which is determined by the level of the liquid in the liquid housing.

8. Apparatus as claimed in Claim 5 wherein the liquid level monitoring means is a float and attached magnet, the level of which is determined by the level of liquid in the liquid housing, and a magnetically operated switch.

9. Apparatus as claimed in Claim 7 or Claim 8 wherein the apparatus has only one float designed to act both as the float part of a float-operated monitoring assembly and as the float in the air-vent valve means.

10 Apparatus as claimed in any one of Claims 1 to 8 wherein the liquid level monitoring assembly and air-vent valve means are separable.

11. Apparatus as claimed in any one of Claims 1 to 8 and 10 wherein the liquid level monitoring assembly and air-vent valve means fit together with a connecting means.

12. Apparatus as claimed in Claim 11 wherein the connecting means is a Junction.

13. Apparatus as claimed in any one ofthe preceding Claims wherein the liquid level monitoring assembly activates in use an indicating means when the level of liquid in the assembly reaches or falls below a predetermined level.

14 Apparatus as claimed in Claim 13 wherein the predetermined level in the monitoring assembly corresponds to a predetermined level of liquid in the container.

15. Apparatus as claimed in any one of the preceding Claims wherein the container is a domestic or industrial oil storage tank.

16. Apparatus as claimed in any one ofthe preceding Claims wherein the apparatus is located independently of the location of the container.

17. Apparatus for monitoring the level of liquid in a container as substantially herein described with reference to Fig. 1.

18. Apparatus for monitoring the level of liquid in a container as substantially herein described with reference to either Fig. 2a or Fig. 2b.

19. Apparatus for monitoring the level of liquid in a container as substantially herein described with reference to Fig. 3.

20. Apparatus for monitoring the level of liquid in a container as substantially herein described with reference to Fig. 4.