GB1575401A

GB1575401A - Oil detector

Info

Publication number: GB1575401A
Application number: GB3988575A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-02-28
Filing date: 1977-02-28
Publication date: 1980-09-24

Description

(54) OIL DETECTOR (71) I, DAVID MORREN BARTLETT BROWN, a British subject, of 1 Milton Park, Coylton, Ayr, Ayrshire, Scotland, do .hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be per formed,.to be particularly described in and by the following statement: - This invention relates to an oil detector.

In situations where large quantities of oil are being handled near water .(for ex ample, at tanker terminals), it is important that any oil leaks or spillage are detected as quickly as possible in order that they may be dealt .with before they can cause serious environmental damage. In daylight, any oil or water is easily detected visually .but tanker terminals normally operate throughout the day and night and the detection of leaks or spillages during dark ness presents considerable problems. In deed, there have been incidents in which large quantities of oil have escaped during darkness without being detected.

The present invention provides a detector which can indicate the presence of oil-on water.

Accordingly, the invention provides an oil detector for use in detecting the presence of oil floating on water,.the oil detector comprising a pair of electrical contact means as defined hereinafter, a capillary channel extending between said contact means and having its open side in substantially direct communication with the exterior of the detector, a bore inter secting said capillary channel and having an opening arranged so that, when the oil detector is immersed in water, water can enter the channel through said bore, and means for electrically connecting the con tact means, in use of the detector, to a measuring circuit, the -capillary channel being of- such a. size that, when the oil detector is immersed in water substantially ree'f--oW- wrffwilf' bnter the channel, but if thereafter oil floats on the surface of the water and relative movement takes place between the water surface and the oil detector with the detector passing through the oil layer, oil will replace the water in the channel, thereby increasing the resistance between the contact means.

The expression "contact means" - is used herein to indicate means for providing an electrical connection in contact with the interior of the channel, at least in use of the detector. The contact means may be metal electrodes or may be either a mass of porous material (which may be a non conductor, such as blotting paper which in use can be impregnated with an electro lyte to provide the necessary conductivity) or chambers, which can be filled with an electrolyte, so that the electrolyte is in contact with the channel interior.

In use, the detector of the invention is connected to a measuring circuit capable of responding to changes in the electrical resistance between the contact means.

When the detector is then placed, immersed in but adjacent the surface of, water free from oil, the channel becomes filled with 'water and current can flow between the contact means. If, however, there is oil floating on the water, it is oil which enters the channel, thereby greatly raising the elec trical resistance between the contact means.

The change in the resistance between the contact means is detected by a measuring circuit and used to activate a warning system. It has been found that appropriate selection of the size of the capillary channel will enable the detector to signal the presence of small quantities of oil but not -be affected by the surface film which is almost always present near to moored -ships or in harbours.

The bore intersecting the channel facilitates the entry of viscous oil into the capillary channel.

Preferred embodiments of the invention will now be described, though by way of illustration only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a first oil detector of the invention; Figure 2 is an enlarged side elevation, partly in section, of the oil detector shown in Figure 1; Figure 3 is a plan view of a second oil detector of the invention; Figure 4 is an enlarged section along the line IV-IV in Figure 3; The oil detector shown in Figures 1 and 2 comprises a synthetic resin body 1 having two separate chambers within, in each of which is housed a contact means 3 in the form of a pad of compressed blotting paper.

A capillary channel 5 is formed in the synthetic resin body 1 of the detector and runs alongside the contact means 3, com municating there with via two capillary bores 9 and 10. Between the bores 9 and 10 is located a bore 20 intersecting the channel 5 which extends through the body 1 and through which water can enter the channel 5.In order to avoid the problems associated with connecting wires directly to the contact means (due to the constant movement of the detector caused by wave action, the wires tend to suffer metal fatigue and may eventually break), electrical con nections to the contact means 3 are estab lished by means of columns of electrolyte 11 confined within bores in the body 1 and within heavy-walled synthetic rubber tubes 8 which extend to the outer end of hollow tubes 12 of insulating material fixed in one wall 13 of the buoy to which the detector is attached (see Figure 2). At the opposed ends of the tubes 12, further short lengths 14 of the same heavy-walled rubber tubing connect the tubes 12 to tubular metal connectors 15, to which are attached wires 16 leading to a resistance measuring cir cuit.Electrolyte is fed to the connectors 15 via rubber tubes 17 either by gravity or under pressure so that there is a slow flow of electrolyte through the contact means 3.

In use, the detector shown in the figures is mounted channel end downwards, on a small float so that it lies adjacent the water surface, the small float being attached by means of a flexible connector to a conven tional buoy. As the float moves vertically with passing waves (a very small wave height will suffice), the detector is moved in and out of the water and comes into contact with any oil which lies on the surface thereof. It has been found- that under these conditions, if even a small amount of oil is present on the surface, the oil will quickly replace the water in the channel, thereby greatly increasing the electrical resistance between the contact means and causing the measuring circuit to giye a warning signal, which may be in any convenient form such as a bell, a buzzer or a lamp.

The second oil detector of the invention shown in Figures 3 and 4 has contact means in the form of chambers 3 which communicate via capillary bores 9 and 10 with a capillary channel 5 formed in the syn thetic resin body 1 of the detector. Before the detector is immersed in water, the chambers 3 are filled with water through the bores 9 and 10. An aperture 20 is again provided between the bores 9 and 10 to assist the entry of water into the channel 5.

To enable the contact means to be connected to a measuring circuit insulated wires 6 pass through the body 1 of the detector and terminate in metal electrodes 18 within the chambers 3.

It will be appreciated that, when this detector is used in salt water, an alternating voltage must be applied- to the electrodes 18 to prevent the generation of chlorine gas.

It may be convenient to mount a number of oil detectors of the invention upon a series of floats which are connected together by wires, ropes or the like and placed around an area where oil leaks or spills are likely to occur. Alternatively, the detectors may be mounted upon buoys or other floating structures in areas where such leaks or spills may be expected, or on small floats flexibly attached to such buoys or structures.

WHAT I CLAIM IS: - 1. An oil detector for use in detecting the presence of oil floating in water, the oil detector comprising a pair of electrical contact means as defined hereinbefore, a capillary channel extending between said contact means and having its open side in substantially direct communication with the exterior of the detector, a bore intersecting the said capillary channel and having an opening arranged so that, when the oil detector is immersed in water, water can enter the channel through said bore, and means for electrically connecting the contact means, in use of the detector, to a measuring circuit, the capillary channel being of such a size that, when the oil detector is immersedin water substantially free of oil, water will enter the channel, but if thereafter oil floats on the surface of the water and relative movement takes place between the water surface and the oil detector with the oil detector passing through the oil layer, oil will replace the water in the channel, thereby increasing the resistance between the contact means.

2. An oil detector as claimed in Claim 1, in which the contact means comprises

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Claims

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capillary channel.

Preferred embodiments of the invention will now be described, though by way of illustration only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a first oil detector of the invention; Figure 2 is an enlarged side elevation, partly in section, of the oil detector shown in Figure 1; Figure 3 is a plan view of a second oil detector of the invention; Figure 4 is an enlarged section along the line IV-IV in Figure 3; The oil detector shown in Figures 1 and

2 comprises a synthetic resin body 1 having two separate chambers within, in each of which is housed a contact means 3 in the form of a pad of compressed blotting paper.

A capillary channel 5 is formed in the synthetic resin body 1 of the detector and runs alongside the contact means 3, com municating there with via two capillary bores 9 and 10. Between the bores 9 and

10 is located a bore 20 intersecting the channel 5 which extends through the body

1 and through which water can enter the channel 5.In order to avoid the problems associated with connecting wires directly to the contact means (due to the constant movement of the detector caused by wave action, the wires tend to suffer metal fatigue and may eventually break), electrical con nections to the contact means 3 are estab lished by means of columns of electrolyte

11 confined within bores in the body 1 and within heavy-walled synthetic rubber tubes

8 which extend to the outer end of hollow tubes 12 of insulating material fixed in one wall 13 of the buoy to which the detector is attached (see Figure 2). At the opposed ends of the tubes 12, further short lengths

14 of the same heavy-walled rubber tubing connect the tubes 12 to tubular metal connectors 15, to which are attached wires

16 leading to a resistance measuring cir cuit.Electrolyte is fed to the connectors

15 via rubber tubes 17 either by gravity or under pressure so that there is a slow flow of electrolyte through the contact means 3.

In use, the detector shown in the figures is mounted channel end downwards, on a small float so that it lies adjacent the water surface, the small float being attached by means of a flexible connector to a conven tional buoy. As the float moves vertically with passing waves (a very small wave height will suffice), the detector is moved in and out of the water and comes into contact with any oil which lies on the surface thereof. It has been found- that under these conditions, if even a small amount of oil is present on the surface, the oil will quickly replace the water in the channel, thereby greatly increasing the electrical resistance between the contact means and causing the measuring circuit to giye a warning signal, which may be in any convenient form such as a bell, a buzzer or a lamp.

The second oil detector of the invention shown in Figures 3 and 4 has contact means in the form of chambers 3 which communicate via capillary bores 9 and 10 with a capillary channel 5 formed in the syn thetic resin body 1 of the detector. Before the detector is immersed in water, the chambers 3 are filled with water through the bores 9 and 10. An aperture 20 is again provided between the bores 9 and 10 to assist the entry of water into the channel 5.

To enable the contact means to be connected to a measuring circuit insulated wires 6 pass through the body 1 of the detector and terminate in metal electrodes 18 within the chambers 3.

It will be appreciated that, when this detector is used in salt water, an alternating voltage must be applied- to the electrodes 18 to prevent the generation of chlorine gas.

It may be convenient to mount a number of oil detectors of the invention upon a series of floats which are connected together by wires, ropes or the like and placed around an area where oil leaks or spills are likely to occur. Alternatively, the detectors may be mounted upon buoys or other floating structures in areas where such leaks or spills may be expected, or on small floats flexibly attached to such buoys or structures.

WHAT I CLAIM IS: - 1. An oil detector for use in detecting the presence of oil floating in water, the oil detector comprising a pair of electrical contact means as defined hereinbefore, a capillary channel extending between said contact means and having its open side in substantially direct communication with the exterior of the detector, a bore intersecting the said capillary channel and having an opening arranged so that, when the oil detector is immersed in water, water can enter the channel through said bore, and means for electrically connecting the contact means, in use of the detector, to a measuring circuit, the capillary channel being of such a size that, when the oil detector is immersedin water substantially free of oil, water will enter the channel, but if thereafter oil floats on the surface of the water and relative movement takes place between the water surface and the oil detector with the oil detector passing through the oil layer, oil will replace the water in the channel, thereby increasing the resistance between the contact means.

2. An oil detector as claimed in Claim 1, in which the contact means comprises

either a mass of porous material capable of being impregnated with an electrolyte or chambers which can be filled with electrolyte, so that said electrolyte is in contact with the channel interior.

3. An oil detector as claimed in Claim 2, in which the porous material is blotting paper.

4. An oil detector as claimed in Claim 2, in which the chambers have metal electrodes fixed therein.

5. An oil detector as claimed in Claim 2 or 3, where includes means for supplying electrolyte to the porous material.

6. An oil detector as claimed in Claim 5, in which the means for supplying electrolyte to the porous material comprises columns of electrolyte confined within flexible tubes, said columns of electrolyte also serving as the means for electrically connecting the contact means to a measuring circuit.

7. An oil detector as claimed in any of the preceding claims, which includes a measuring circuit for measuring the resistance between the contact means and a signalling device capable of emitting a signal when the resistance exceeds a predetermined value.

8. An oil detector substantially as herein described with reference to and as illustrated in Figures 1 and 2 or Figures 3 and 4 of the accompanying drawings.