WO2012052752A2

WO2012052752A2 - Fluid discrimination apparatus and method

Info

Publication number: WO2012052752A2
Application number: PCT/GB2011/052014
Authority: WO
Inventors: Jacque Williams; Keith Anderson
Original assignee: D. Berry & Co. (Pipe Fitting Supplies) Limited
Priority date: 2010-10-18
Filing date: 2011-10-18
Publication date: 2012-04-26
Also published as: GB201202327D0; GB2487311A; GB201220966D0; WO2012052752A3; GB2487311B

Abstract

In an aspect of the invention there is provided fluid discrimination apparatus comprising fluid inspection means, the fluid inspection means comprising a light source (111), a detector (113) and an optical element (121), the inspection means being operable to direct a beam of light from the source (111) through the optical element (121) to an inspection surface (125) of the optical element (121) and to detect by means of the detector (113) light scattered back through the optical element (121), the apparatus being operable to determine whether a fluid (135) in contact with the inspection surface (125) corresponds to a fluid having a prescribed refractive index characteristic responsive to light detected by the detector (113). The apparatus may be useful in applications in which liquid fuels are handled, and may be used for detecting a misfuelling event.

Description

FLUID DISCRIMINATION APPARATUS AND METHOD

FIELD OF THE INVENTION

The present invention relates to fluid inspection or monitoring apparatus and to a method of inspecting a fluid. In particular but not exclusively the invention relates to apparatus and a method for inspecting a fluid being transferred from one storage medium to another.

BACKGROUND

It is known to provide apparatus for delivering fuel to a storage tank. For example, fuel delivery vehicles (known as fuel tankers) having fuel storage tanks may be used to deliver fuel from refineries to refuelling stations for sale to consumers.

Currently there are two primary fuel types used to power vehicles on public roads. They are petroleum spirits (commonly referred to as 'petrol' or 'gasoline') and diesel oil ('diesel'). Vehicles configured to operate using one fuel can experience damage if supplied with the other fuel. Thus it is important to avoid contaminating a petrol storage tank and related equipment with diesel or a diesel storage tank and related equipment with petrol.

It is not uncommon for a driver of a petrol tanker inadvertently to load one type of fuel into a storage tank arranged to store the other type of fuel thereby contaminating the tank. This may be referred to in the industry as a 'misfuelling event', a 'misfuel' or 'cross-contamination'. Cross-contamination can be costly in terms of time and money to rectify due to wastage of fuel and cleaning of the contaminated tank. Furthermore as noted above damage can occur to vehicles and equipment contaminated with the wrong fuel type.

It is an aim of embodiments of the present invention to at least partially mitigate the disadvantages of known refuelling apparatus.

STATEMENT OF THE INVENTION

Embodiments of the invention may be understood by reference to the appended claims.

In one aspect of the invention there is provided fluid discrimination apparatus comprising fluid inspection means comprising a light source, a detector and an optical element, the inspection means being operable to direct a beam of light from the source through the optical element to an inspection surface of the optical element and to detect by means of the detector light scattered back through the optical element, the apparatus being operable to determine whether a fluid in contact with the inspection surface corresponds to a fluid having a prescribed refractive index characteristic responsive to light detected by the detector.

By the term 'scattered' is included 'reflection' of light at or close to the interface.

It is to be understood that by the phrase 'scattered from a fluid' is included scattering from an interface between a fluid and the optical element by refraction, i.e. refraction of light at the interface.

Embodiments of the invention have the advantage that the apparatus may be used to detect when a fluid is present that should not be present in a reliable manner.

It is to be understood that in embodiments of the invention the intensity of light scattered back from the interface is responsive to the refractive index of a fluid, the detector being arranged to detect the intensity of light incident thereon from the interface thereby to distinguish between different respective fluids. It is to be understood that by the term 'discrimination' is meant that the apparatus is operable to distinguish between fluids. In embodiments of the invention the apparatus is operable to determine whether or not the fluid is a fluid having a prescribed refractive index characteristic.

The output of the apparatus is advantageously operable to actuate a fluid control device responsive to a determination whether a fluid has a prescribed refractive index characteristic.

The fluid control device may comprise a fluid control valve.

The apparatus may be operable to actuate the fluid control device thereby to prevent a flow of fluid through the conduit.

Thus the apparatus may be operable to prevent a fluid from flowing through the conduit of the apparatus, for example to a receptor downstream of the conduit. It is to be understood that in some embodiments the fluid control device may be located such that a certain amount of fluid may be able to flow through at least a portion of the conduit before flow of fluid through the conduit ceases due to the state of the fluid control device.

Advantageously the apparatus further comprises means for providing a signal to an operator in dependence on whether a fluid has a prescribed refractive index characteristic.

It is to be understood that in some arrangements the fluid inspection means may be described as (or comprise) an optical refractometry device.

Thus the optical refractometry device provides an output that is responsive to (dependent on) a refractive index characteristic of a fluid.

The apparatus may be operable to divert a flow of fluid such that the fluid enters a first receptor when the fluid inspection means determines that the fluid is a fluid having a prescribed refractive index characteristic and a second receptor when the fluid inspection means determines that the fluid is not a fluid having the prescribed refractive index characteristic.

The refractive index characteristic may for example correspond to a characteristic for which an intensity of light falling on a portion of the detector is within a prescribed range of values.

Advantageously the apparatus may be provided in a fluid receiving portion of a fuel storage facility, the fluid inspection means being arranged to determine whether fluid passing through the conduit to a storage tank of the facility corresponds to a fluid having the prescribed refractive index characteristic.

The fuel storage facility may be a fuel storage facility of a refuelling station such as a fuel service station.

Further advantageously the apparatus may be arranged to prevent flow of fluid not having the prescribed refractive index characteristic into the storage tank.

Alternatively the apparatus may be provided in a fuel receiving portion of one selected from amongst a motor vehicle, an aircraft and a marine vessel.

Advantageously the optical element comprises a substantially cylindrical body.

This feature has the advantage that forming a fluid tight seal between a cylindrical (or otherwise circular or curved) body and a housing may be easier than a body having one or more abrupt corners. Advantageously the optical element comprises a pair of facets inclined with respect to the inspection surface, the device being operable to project a beam of light through a first of the pair of facets towards the inspection surface, the detector being arranged to detect light from the source travelling back from the inspection surface through the second facet.

By facet is meant a face of the optical element not necessarily being a face corresponding to a crystalline plane. That is, the optical element may be formed from a glass or any other suitable crystalline or non-crystalline material.

Optionally light from the source passing through the optical element is arranged to be scattered internally by a surface of the element towards the inspection surface.

This feature has the advantage that if the source is not arranged to directly to project light to the inspection surface at the required angle of incidence the angle of incidence may be set by arranging for light from the source to be internally reflected within the optical element.

Further optionally light from the source passing through the optical element from the inspection surface is arranged to be scattered internally towards the detector.

This feature has the advantage that if the detector is not arranged to detect light scattered at the inspection surface in a direct line of sight to the detector, the light may be redirected towards the detector by internal reflection.

Advantageously the optical element comprises a first portion and a second portion, the second portion comprising a window member bearing the inspection surface.

Further advantageously the apparatus is arranged to direct a beam of light to the interface between a fluid to be inspected and the optical element wherein an angle between the beam of light and the interface is less than 90°.

The detector is advantageously arranged to detect light that is scattered from the interface at substantially the same angle as that with which light is incident upon the interface.

The detector may be operable to provide an output responsive to an intensity of light scattered through a given angle at the interface.

Advantageously the detector comprises a position sensitive detector.

The detector may for example be a linear detector arranged to provide an output responsive to intensity of light incident on the detector as a function of position with respect to a line between first and second locations, the position corresponding to the angle through which light has been scattered. It is to be understood that a divergence of a beam of light from the source incident on the detector may be relatively low (for example in the case a coherent source of illumination is employed, such as a laser) or relatively high (for example in some embodiments in which an incoherent source is employed such as a light emitting diode (LED)). In some embodiments an incoherent source is employed that is relatively highly collimated in order to reduce a divergence angle of the beam generated by the source.

Further advantageously the apparatus is operable to distinguish between fluids having different respective refractive index characteristics by comparing data in respect of an intensity of light detected by the detector with reference data.

Optionally the apparatus is configured to store data in respect of an intensity of light scattered back from the interface through one or more angles or one or more ranges of angles.

Further advantageously the apparatus is operable to acquire reference data in respect of a fluid to which the inspection means is exposed and to store the reference data in a memory thereof. The apparatus may be operable to transmit data in respect of the intensity of light detected by the detector to an external computing device.

The data may be transmitted by means of a wireless connection such as by means of an infrared or short-range radio signal, or via a wired connection.

Thus in some embodiments the apparatus may be arranged to be set to distinguish between one or more fluids to which the apparatus is exposed.

The apparatus may be configured automatically to acquire reference data in order to 'self calibrate' when exposed to a known fluid such as air. This may be useful in accounting for variations in intensity of illumination provided by a source, or the effects of ageing on one or more components such as the detector.

Advantageously the apparatus is operable to receive reference data from an external computing device.

Further advantageously the apparatus comprises a fluid conduit through which a fluid may be passed, the inspection surface of the inspection means being exposed to fluid in the conduit.

Thus in some embodiments the apparatus may be used to detect when a fluid is present in a conduit of the apparatus that should not be present in the conduit.

Optionally the apparatus comprises reference fluid inspection means having an inspection surface in contact with a sample of a fluid, the apparatus being arranged to compare an output of the fluid inspection means with an output of the reference fluid inspection means thereby to determine whether the fluid in contact with the inspection surface of the fluid inspection means corresponds to a fluid having the prescribed refractive index characteristic.

Advantageously the reference fluid inspection means is provided with a sample of fluid having the prescribed refractive index characteristic thereby to provide an output corresponding to that obtained from the fluid inspection means when the fluid inspection means is exposed to fluid having a substantially identical prescribed refractive index characteristic.

The prescribed refractive index characteristic may be one selected from amongst a prescribed value of refractive index and a prescribed range of values of refractive index.

In a further aspect of the invention there is provided a method of inspecting a fluid by means of inspection apparatus comprising the steps of:

directing a beam of light from a source of the apparatus to an inspection surface of an optical element of the apparatus in contact with a fluid to be inspected and detecting by means of a detector of the apparatus light scattered back from an interface between the inspection surface and a fluid in contact therewith; and

determining whether the fluid in contact with the inspection surface corresponds to a fluid having a prescribed refractive index characteristic responsive to the light detected by the detector.

Advantageously the method comprises the step of providing an output responsive to an intensity of light detected by the detector.

Further advantageously the step of determining whether the fluid in contact with the inspection surface corresponds to a fluid having a prescribed refractive index characteristic comprises the step of providing an output responsive to a determination whether the fluid has a refractive index characteristic within a prescribed range of values of refractive index characteristic. The step of actuating a fluid control device responsive to the determination whether the fluid corresponds to a fluid having the prescribed refractive index characteristic. Optionally the step of providing an output comprises the step of actuating a fluid control device responsive to the determination whether the fluid corresponds to a fluid having the prescribed refractive index characteristic.

Advantageously the step of actuating the fluid control device comprises the step of actuating a fluid control valve.

Advantageously the method comprises the step of actuating the fluid control device in dependence on whether the fluid passing through the conduit has a refractive index characteristic within the prescribed range of values thereby to prevent a fluid not having a refractive index characteristic within the prescribed range from flowing into a receptor.

Further advantageously the step of providing an output comprises the step of providing a signal to an operator in dependence on whether the fluid corresponds to a fluid having the prescribed refractive index characteristic.

The method may comprise the step of storing data in respect of a fluid inspected by the apparatus when it is determined that the fluid has a refractive index characteristic that is not within a prescribed range of values of refractive index characteristic.

Advantageously the method further comprises the step of transmitting the stored data in respect of fluid inspected by the apparatus to an external computing device.

Further advantageously the step of determining whether the fluid in contact with the inspection surface corresponds to a fluid having a prescribed refractive index characteristic comprises the step of comparing an intensity of light detected by the detector with reference data in respect of a reference intensity.

The method may comprise the step of obtaining new reference data by measuring an intensity of light detected by the detector and storing the data in a memory of the apparatus.

Alternatively of in addition the method may comprise the step of obtaining new reference data by transmitting reference data to the apparatus from an external computing device.

Thus in some methods of operation the apparatus may receive new calibration data from an external computing device being a device the presence of which is not required during normal operation of the apparatus.

Advantageously the method comprises uploading data in respect of light intensity detected by the apparatus to an external computing device.

Thus in some arrangements the method may involve obtaining calibration data for use by one or more other similar apparatus. Alternatively the data uploaded may be for a monitoring purpose or forensic investigation purposes, for example to determine an identity of a fluid that has been inspected by the apparatus. Other uses of the uploaded data are also useful.

Advantageously the step of detecting light by means of a detector comprises the step of detecting an intensity of light scattered through a plurality of different respective angles from the interface between the optical element and the fluid.

Optionally the method comprises the step of controlling a flow of fluid such that the fluid enters a first receptor when it is determined that the fluid has the prescribed refractive index characteristic and the fluid enters a second receptor when it is determined that the fluid does not have the prescribed refractive index characteristic.

The second receptor may be a receptor storing liquids that are not to be stored in the first receptor, thereby to prevent introduction of foreign liquid into the first receptor. For example in the case the first receptor is for petroleum spirits, in the event an attempt is made to deliver diesel oil into the first receptor the method involves the step of diverting the flow of diesel oil into the second receptor. In some embodiments the first receptor may be for diesel oil and the second receptor arranged to receive foreign fluids such as petroleum spirits.

Advantageously the method comprises the step of logging in a memory of the apparatus the occurrence of an event in which a fluid is detected not having a refractive index characteristic within a prescribed range of values of refractive index characteristic.

The method may comprise the step of not logging the detection of air in the event air is detected.

Advantageously the step of inspecting a fluid comprises inspecting a fluid passing through a fuel delivery conduit of a fuel receiving portion of a fuel storage plant.

Optionally the method comprises the step of inspecting a fluid comprises inspecting a fluid passing through a fuel delivery conduit of a fuel receiving portion of one selected from amongst a motor vehicle, an aircraft and a marine vessel.

The step of inspecting a fluid may comprise the step of inspecting a beverage.

Alternatively the step of inspecting a fluid comprises the step of inspecting a foodstuff.

In one aspect of the invention there is provided apparatus comprising:

fluid inspection means operable to provide an output responsive to at least one optical characteristic of a fluid,

wherein the inspection means is operable to direct a beam of light to a fluid and to detect light scattered back to the inspection means responsive to the presence of a fluid, the device being operable to distinguish between fluids having different respective refractive indices responsive to light detected by the inspection means.

In an aspect of the invention there is provided apparatus comprising: fluid inspection means operable to provide an output responsive to at least one optical characteristic of a fluid, wherein the inspection means comprises a light source and a detector, the inspection means being operable to direct a beam of light from the source to a fluid and to detect by means of the detector light scattered back responsive to the presence of a fluid, the device being operable to distinguish between fluids having different respective refractive index characteristics responsive to light detected by the inspection means.

In one aspect of the invention there is provided apparatus comprising: a fluid conduit through which a fluid may be passed; and fluid identification means for determining whether fluid passing through the conduit corresponds to a fluid having a prescribed property, wherein the apparatus is configured to provide an output responsive to the determination whether the fluid has the prescribed property.

The apparatus may be configured to actuate a fluid control device in dependence on whether the fluid has the prescribed property.

The fluid control device may comprises a fluid control valve.

Advantageously the apparatus is operable to actuate the fluid control device thereby to prevent a flow of fluid into a receptor downstream of the conduit. The apparatus may further comprise means for providing a signal to an operator in dependence on whether the fluid has the prescribed property.

The fluid identification means may comprise an optical refractometry device arranged to provide an output responsive to a refractive index of the fluid.

Advantageously the fluid is arranged to flow in contact with the refractometry device.

The refractometry device may comprise a prismatic element, the device being arranged to project a beam of light through the prismatic element and to detect by means of a detector light scattered back through the prismatic element.

For example, the prismatic element may be a prism or similar optical element.

However it is to be understood that in some embodiments the prismatic element need not be in the shape of a geometric prism as such, but be any solid element allowing light of a prescribed frequency or range of frequencies (such as those corresponding to visible light) to pass therethrough and to be internally reflected or refracted at a surface thereof.

The prismatic element may comprise a first portion in juxtaposition with a second portion, optionally in abutment with the second portion. The second portion may be a window portion exposed to fluid in the conduit. Light from the source may be arranged to pass from the first portion to the second portion and to be scattered at an interface between the second portion and fluid in the conduit back through the first portion to the detector.

In some arrangements the refractometry device may comprise a substantially transparent optical element, the device being arranged to project a beam of light from the source through the optical element and to detect by means of a detector light scattered back through the optical element from an interface between the optical element and fluid in the fluid conduit.

It is to be understood that the transparent optical element may be arranged to be transparent to light of the wavelength or range of wavelengths of interest. The range of wavelengths may correspond to that of visible light.

The transparent optical element may have one or more substantially flat surfaces through which a beam of light from the source enters the element and through which light scattered from the interface between the element and fluid in the conduit exits the element.

The optical element may comprise a first portion in juxtaposition with a second portion, optionally in abutment with the second portion. The second portion may be a window portion exposed to fluid in the conduit. Light from the source may be arranged to pass from the first portion to the second portion and to be scattered at an interface between the second portion and fluid in the conduit back through the first portion to the detector.

It is to be understood that the scattered light may be considered to be reflected light, for example where the light is scattered back through the prismatic element or other transparent optical element.

Advantageously the intensity of light scattered back through the element is responsive to the refractive index of the fluid, the detector being arranged to detect the intensity of light incident thereon.

Alternatively or in addition the angle through which the light is scattered back through the element may be responsive to the refractive index of the fluid, the detector being responsive to the angle through which the light is scattered. The element may comprise a block of a transparent medium.

Advantageously the block has a substantially cylindrical portion having a cylinder axis and a pair of inclined facet portions at a first end of the block, the light source being arranged to project a beam of light through a first of the pair of facet portions, the detector being arranged to detect light scattered out from the block through the second facet portion.

The feature of the cylindrical portion allows a seal to be formed more conveniently between the block and a holder in which the block may be supported. For example an Ό'-ring type seal may be conveniently employed, or other circular seal although other types of seal are also useful.

Advantageously light from the source that is internally reflected from an end face of the block at a second end of the block opposite the first end is arranged to be detected by the detector. Optionally the end face of the block at the second end of the block is oriented substantially normal to the cylinder axis.

Alternatively the end face may be inclined with respect to a plane normal to the cylinder axis. The detector may comprise a position sensitive detector.

The refractometry device may be arranged to project the beam of light to an interface between the device and the liquid thereby to cause scattering of the light.

The apparatus may be operable to divert a flow of fluid such that the fluid enters a first receptor when the fluid identification means determines that the fluid is a fluid having the prescribed property and a second receptor when the fluid identification means determines that the fluid is not a fluid having the prescribed property.

The apparatus may be provided in a fluid receiving portion of a refuelling station, the fluid identification device being arranged to determine whether fluid passing through the conduit to a storage tank of the refuelling station corresponds to a fluid having the prescribed property.

The apparatus may be provided in a fuel receiving portion of one selected from amongst a motor vehicle, an aircraft and a marine vessel.

The apparatus may further comprise reference fluid identification means, the apparatus being arranged to compare an output of the fluid identification means with the reference fluid identification means thereby to determine whether the fluid passing through the conduit corresponds to a fluid having the prescribed property.

The reference fluid identification means may be provided with a sample of fluid having the prescribed property thereby to provide an output corresponding to that obtained from the fluid identification means when the fluid identification means is exposed to fluid having the prescribed property.

Preferably the prescribed property is a prescribed value of a refractive index of the fluid.

In a further aspect of the invention there is provided a method of detecting a misfuelling event comprising: passing a fluid through a conduit; determining by means of fluid identification means whether the fluid passing through the conduit corresponds to a fluid having a prescribed property; and providing an output in dependence on whether the fluid has the prescribed property.

Advantageously the step of providing an output comprises the step of actuating a fluid control device responsive to the determination whether the fluid has the prescribed property. Further advantageously the step of actuating the fluid control device comprises the step of actuating a fluid control valve.

The method may comprise the step of actuating the fluid control device in dependence on whether the fluid passing through the conduit has the prescribed property thereby to prevent a flow of fluid into a receptor downstream of the conduit.

The step of providing an output may comprise the step of providing a signal to an operator in dependence on whether the fluid has the prescribed property.

The method may comprise the step of projecting a beam of light through a prismatic element to the fluid and detecting by means of a detector light scattered back through the prismatic element following exposure of the fluid identification means to the fluid.

Thus the light (and the fluid identification means) is exposed to the fluid in the sense that an interaction takes place between the light and the fluid resulting in scattering of the light at an interface between the apparatus and the fluid.

The intensity of light scattered back through the element may be responsive to the refractive index of the fluid, the method comprising measuring an intensity of light scattered back through the element by means of a detector.

Alternatively or in addition the angle through which the light is scattered back through the element may be responsive to the refractive index of the fluid, the method comprising detecting a position of the scattered light with respect to the element upon detection of the light, said position being responsive to the angle through which the light is scattered back.

The detector may comprise a position sensitive detector.

The method may comprise the step of diverting a flow of fluid such that the fluid enters a first receptor when the fluid identification means determines that the fluid is a fluid having the prescribed property and a second receptor when the fluid identification means determines that the fluid is not a fluid having the prescribed property.

The method may comprise the step of determining by means of the fluid identification means whether fluid passing through a conduit of a refuelling station to a storage tank thereof corresponds to a fluid having the prescribed property.

Alternatively the conduit may be the conduit of a fuel receiving portion of one selected from amongst a motor vehicle, an aircraft and a marine vessel.

The apparatus may further comprising reference fluid identification means, the method comprising compare an output of the fluid identification means with that of the reference fluid identification means thereby to determine whether the fluid passing through the conduit corresponds to a fluid having the prescribed property.

The method may comprise the step of providing the reference fluid identification means with a sample of fluid having the prescribed property thereby to provide an output corresponding to that obtained from the fluid identification means when the fluid identification means is provided with the fluid having the prescribed property.

The prescribed property is preferably a prescribed value of a refractive index.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to the accompanying figures in which: FIGURE 1 is a schematic illustration of (a) apparatus according to one embodiment of the invention and (b) apparatus according to a further embodiment of the invention;

FIGURE 2 shows (a) a schematic illustration of a fluid identification device according to an embodiment of the invention suitable for use in the apparatus of FIG. 1 showing a path of beams of light through the device when a liquid is in contact with a window of the device; (b) the device of (a) showing a path of beams of light in the absence of liquid in contact with the window of the device; (c) a simulation using ray tracing software of a path of beams of light through the device with a liquid of refractive index 1 .47 in contact with the window of the device, the device having a position sensitive detector for detecting scattered light; (d) a simulated intensity map of a distribution of light over the position sensitive detector shown in (c); (e) a plot of light intensity I as a function of distance x from an end of the detector for air (trace A), petrol (trace P) and diesel (trace D); (f) a plan view of a linear position sensitive detector having a linear array of light detectors; and (g) a plot of light intensity as a function of pixel number for the linear detector shown in (f);

FIGURE 3 is a schematic illustration of apparatus having the fluid identification device of FIG. 2; FIGURE 4 is a schematic illustration of apparatus according to an embodiment of the invention having the fluid identification device of FIG. 2(a) and a reference fluid identification device similar to that of FIG. 2(a) in fluid communication with a reference fluid chamber;

FIGURE 5 is a schematic illustration of a refuelling station having apparatus according to an embodiment of the present invention;

FIGURE 6 is a schematic illustration of a lever control device according to an embodiment of the invention;

FIGURE 7 is a schematic illustration of a prism element according to an embodiment of the invention;

FIGURE 8 is a schematic illustration of a prism element in combination with a light source and a detector;

FIGURE 9 shows ray trace simulations of light travelling through the prismatic element shown in FIG. 8 with an inspection surface in contact with (a) petrol and (b) air;

FIGURE 10 is a perspective view of apparatus according to an embodiment of the present invention with a cover removed showing a fluid inspection device of the apparatus in the form of a refractometer;

FIGURE 1 1 is a perspective view of the apparatus from an opposite side with a further cover removed;

FIGURE 12 is a cut-away view of the apparatus in the orientation shown in FIGURE 10;

FIGURE 13 is a perspective view of the fluid inspection device; and

FIGURE 14 is a cut-away view of the fluid inspection device of FIGURE 13.

DETAILED DESCRIPTION

In one embodiment of the invention apparatus 100 is provided as shown schematically in FIG. 1. The apparatus 100 has a fluid identification device 101 in the form of a refractometer is provided in fluid communication with fluid flowing through a conduit 180. A valve 190 is provided in the conduit 180 downstream of the device 101 , the valve 190 being operable by means of a control signal from the device 101 to assume an open or closed condition. Thus the valve 190 is operable to allow or to prevent a flow of fluid through the conduit 180 from a first portion 181 of the conduit upstream of the valve 190 to a second portion 182 of the conduit 180 downstream of the valve 190.

FIG. 1 (b) shows apparatus 200 in which a similar fluid identification device 101 installed in a conduit 280 in a similar manner to the arrangement of FIG. 1 . However in the case of the embodiment of FIG. 1 (b) the fluid identification device 101 is arranged to control a valve 290 that is operable to control a flow of fluid through the apparatus 200 from a first portion 281 of the conduit 280 along either a second portion 282 or a third portion 283 in dependence on a control signal from the fluid identification device 101 .

The fluid identification device 101 is shown in further detail in FIG. 2. The device 101 has a light source 1 1 1 arranged to project a beam of light through a first optical component 121 in the form of a block of light transmitting material. In the present embodiment the material is a glass material although other materials such as plastics materials are also useful. Component 121 will be referred to as a prismatic element 121 since it is a substantially transparent optical element having substantially flat, optionally polished, surfaces that may refract light. It is to be understood that the component 121 may be formed to have one of a wide range of shapes and need not be in the shape of a traditional triangular prism.

The prismatic element 121 has a pair of opposed parallel faces 123, 125 which will be referred to respectively as an entrance face 123 and a window face 125. The window face 125 is provided in abutment with one side of a window 131 being a plate of light transmitting material provided between the element 121 and fluid to be inspected. The element 121 and window 131 are typically formed from materials of similar refractive index. An opposite side of the window 131 is exposed to fluid flowing through the conduit 180. It is to be understood that in some embodiments the window 131 is omitted from the apparatus 100. In such embodiments the liquid to be inspected (in the conduit 180) may flow in direct contact with the prismatic element 121 .

The prismatic element 121 is further provided with first and second reflector faces 127, 129 provided between the entrance face 123 and window face 125.

The first reflector face 127 is arranged to direct light incident thereon from the source 1 1 1 that is following path P1 of FIG. 2(a) towards the window face 125 of the prismatic element 121 . The light passes from the prismatic element 121 through the window face 125 and the window 131 to an interface between the window 131 and fluid 185 that is within the conduit 180. The device 101 is arranged such that a proportion of the light that passes from the window 131 into the conduit 180 along path P1 is dependent upon a difference in refractive index between the window 131 and the fluid 185.

If a refractive index of the fluid 185 is similar to that of the window 131 then a substantial proportion of the light passing from the prismatic element 121 through the window 131 may pass through the interface between the window 131 and fluid 185 and into the fluid 185, as shown in FIG. 2(a). Light not passing out from the window 131 into the fluid 185 may be scattered vack through the element 121 .

In contrast, if the refractive index of the fluid 185 is not similar to that of the window 131 , for example if the fluid is air, a substantial proportion of the light passing from the prismatic element 121 through the window 131 will be scattered (or reflected) at the interface between the window 131 and air in the conduit 180 back through the element 121 . Such a situation is shown in FIG. 2(b) where light from the light source passing along path P2 is reflected by the first reflector face 127 through the window 131 . The light is subsequently scattered (or reflected) towards the second reflector face 129, from which it is reflected towards active sensor 1 13. A reference sensor 1 15 is also provided in order to allow correction of the signal detected by the active sensor 1 13 for variations in light intensity that are not due to variations in refractive index between the window 131 and fluid 185. Such variations may occur for example due to temperature of the device 101 , age, power supply voltage and failure of the source 1 1 1 .

In order to allow such correction, the device 1 01 is arranged to provide an optical signal from the light source 1 1 1 to the reference sensor 1 1 5 that is independent of the type of fluid 185 in the fluid conduit 180.

In the embodiment of FIG. 2 this is achieved by providing a window 131 having a thinned portion 1 33. The thinned portion 133 has a thickness that is less than that of the remainder of the window 131 such that a gap 135 is provided between the thinned portion 1 33 and the window 131 . In the embodiment shown the gap 135 is arranged to be filled with air regardless of the type of fluid 185 in the conduit 1 80.

Light from the light source 1 1 1 falling on the window face 125 of the prismatic element 121 over a region of the window face 125 exposed to air in the gap 1 35 (path RP1 ) is reflected at the interface towards the second reflector face 129 of the prismatic element 121 and thereby to the reference sensor 1 15. It is to be understood that the amount of light reflected at the interface will depend on a difference in refractive index between the prismatic element 121 and air in the gap 135. Thus it is to be understood that the amount of light reflected will be substantially independent of the type of fluid 185 in the conduit 180, since the refractive index of air in gap 135 will remain substantially constant (the refractive index of air is approximately unity). Thus the path followed by light incident on this region of the window face 125 is substantially the same in FIG. 2(a) and (b), i.e. whether or not a fluid 185 in the conduit 1 80 and in contact with the window 131 has a similar refractive index to that of the window 131 .

It is to be understood that in some alternative embodiments the window face 125 of the prismatic element 121 may have a thinned (or recessed) portion instead of or in addition to the window 131 having a thinned (or recessed portion).

In some embodiments no gap 135 is provided between the window face 1 25 of the prismatic element 121 and the window 131 .

It is to be understood that the signal generated by the active sensor 1 1 3 (being a signal dependent on the amount of light falling on the sensor 1 13) will be responsive to a difference in refractive index between the fluid 185 and window 131 . This signal is provided to a processor module 103 (FIG. 3) arranged to determine whether the refractive index difference is within an allowed range. If the difference is within the allowed range the processor module 103 is arranged to provide a control signal to a controller module 1 05 to maintain the valve 190 in the open condition. If the difference falls outside the allowed range the processor module 103 is arranged to provide a control signal to the controller module 105 to close the valve 190. It is to be understood that the processor module 1 03 may be arranged to determine whether the refractive index is outside the allowed range due to the absence of any liquid in the conduit (i.e. because the conduit is empty) or due to the presence of an incorrect liquid in the conduit.

The device 101 is configured such that relatively small changes in refractive index difference may be detected. Thus, in some embodiments the device 101 is operable to open or maintain the valve 190 in an open condition when petrol (having a refractive index of 1 .420 at 20 °C) is in contact with the window 131 but to close the valve 1 90 when diesel (having a refractive index of 1 .460 at 20 ^<€) is in contact with the window 131 .

In some alternative embodiments the device 101 is operable to close the valve 190 when petrol is in contact with the window 131 and to open the valve when diesel is in contact with the window 131 . It is to be understood that the refractive index of a given fluid is typically a function of density of the fluid which is in turn a function of temperature. Thus in some embodiments the device 101 is provided with a temperature sensor. The sensor may be arranged to sense a temperature of the liquid flowing through the conduit and to use different values of allowed range of refractive index difference for different ranges of temperature.

In order to determine whether the refractive index difference as determined by the device 101 is within an allowed range the controller 103 may be arranged to access a look-up table.

For example, the look-up table may be provided with one or more datasets having values of refractive index difference between the fluid of interest (e.g. petrol or diesel) and the window 131 (or element 121 in the case where no window 131 is employed) as a function of temperature, the controller 103 being arranged to access the look-up table to determine whether the refractive index difference currently being measured falls within the required range. Alternatively or in addition the look-up table may be provided with acceptable values or ranges of values of an output signal from the active sensor 1 13, the output signal having been subject to correction by reference to an output of the reference sensor 1 15 or a signal detected by a corresponding portion of a position sensitive detector 1 17 where appropriate.

In one embodiment of the invention the sensors 1 13, 1 15 are replaced by a single position sensitive detector (PSD) 1 17 as shown in FIG. 2(c). The PSD 1 17 is operable to provide an output indicative of an intensity of light incident thereon as a function of position of the illumination on the PSD 1 17. FIG. 2(c) shows the path RP of rays of illumination from the light source 1 1 1 through the prismatic element 121 and window 131 with a fluid in contact with the window 131 . FIG. 2(c) was generated using a ray trace package, assuming a fluid having a refractive index of 1.47.

The package was used subsequently to generate corresponding data for a fluid with a refractive index of 1 .46 and a fluid with a refractive index of 1.43. The position of the region of greatest illumination intensity on the PSD 1 17 was found to shift relative to that for a fluid of refractive index 1.47. The region shifted along a length of the PSD 1 17 in a direction towards a second end 1 17B of the PSD 1 17 and away from a first end 1 17A. The position shifted by a readily detectable amount, allowing the apparatus to discriminate between the two liquids.

FIG. 2(d) shows a map M of detected optical intensity as a function of position over the PSD 1 17 for the arrangement of FIG. 2(c). Darker regions of the map M indicate regions of increased light intensity. A position of maximum intensity of optical illumination incident on the PSD 1 17 is marked IM in FIG. 2(d).

It is to be understood that in some embodiments the active sensor 1 13 may be a position sensitive detector and a separate reference sensor 1 15 may be provided.

FIG. 2(e) shows a plot of light intensity I incident on the PSD 1 17L shown in FIG. 2(f) installed in a fluid inspection apparatus similar to that of FIG. 1 (a). Operation of apparatus having such a PSD 1 17L will be described with reference to the features of the embodiment of FIG. 1 (a) although it is to be understood that the PSD 1 17L may be used in many different embodiments of the present invention.

The PSD 1 17L is in the form of a linear array of light detectors (pixels) 1 17LP. The plot of FIG. 2(f) shows light intensity as a function of position x of a pixel 1 17LP along the PSD 1 17L from a first end 1 17LF thereof. It is to be understood that the pixel position x corresponds to a distance of the pixel 1 17LP from the first end 1 17LF since in the embodiment described the pixels are equally spaced and of identical size although other arrangements are also useful. Trace A corresponds to the variation in intensity I as a function of x when the conduit 180 is empty of liquid and air is in contact with the window 131 . Trace P shows the variation in I as function of x when the conduit 180 is full of unleaded petrol and trace D corresponds to the variation in I when the conduit 180 is full of diesel. It can be seen that the values of I measured for air, petrol and diesel at a given value of x are sufficiently different to allow the apparatus readily to distinguish between them. It can be seen that in this particular arrangement the differences between the values of I at certain values of x are larger than at others. In some embodiments these positions may be particularly useful in enabling the apparatus to reliably distinguish between fluids present in the conduit 180.

In some embodiments the apparatus may be arranged to measure a value of I at a single pixel or a group of pixels at a position that is displaced by a prescribed amount from a peak in intensity of a plot of I as a function of x for a given liquid. In some embodiments this may correspond to a region of a plot of I as a function of x that allows the apparatus more reliably to distinguish between fluids.

In one embodiment the pixels of a linear detector 1 17L are each assigned to one of five groups G1 to G5 according to position. In the case of a detector having 256 pixels, the first 51 pixels (pixels 1 to 51 ) may be placed in a group G1 , pixels 52 to 102 may be placed in a group G2, pixels 103 to 153 in a Group G3 and so forth. Other arrangements in which a different number of groups are employed are also useful. Other arrangements are also useful, for example in the event that one or more pixels at one or more ends of the detector are not used.

The apparatus is arranged to measure an intensity of light incident on a particular group of pixels and to determine a value corresponding to a sum of the values of intensity of light incident on each of the pixels of the group. The value so determined may be compared with a stored reference value responsive to which the apparatus may distinguish between fluids. Thus, the apparatus may be arranged to distinguish petrol and non-petrol (e.g. air or diesel) by determining whether the sum of values corresponds to the stored reference value. In some embodiments the apparatus may determine whether the sum is within a prescribed range of stored values in order to distinguish between petrol and non-petrol. Embodiments of the invention may be arranged to distinguish a single fluid from fluids that do not have an optical refractive index characteristic corresponding to the single fluid, or to distinguish two or more fluids from fluids not having an optical refractive index characteristic corresponding to the two or more fluids.

The apparatus may be configured wherein the reference value corresponds to a value obtained for a particular group of pixels when an allowed fluid is in contact with the inspection means such as window 131 in the embodiment of FIG. 2(a). In some embodiments the apparatus may be arranged to determine in which group of pixels a peak in intensity of illumination of the detector 1 17L is found and to determine the value corresponding to the sum of values of intensity of light incident on each pixel of that group. In some embodiments the apparatus is configured to determine this sum for a prescribed group only and not for any other group. Thus the apparatus may be arranged to determine this sum for the prescribed group without determining a position of a peak in intensity of illumination of the detector 1 17L.

FIG. 2(g) shows a plot of light intensity incident on a linear detector such as detector 1 17L as observed with air in contact with the window 131 of the inspection means (trace A), petroleum spirits in contact with the window 131 (trace P) and diesel oil in contact with the window 131 . For the avoidance of doubt, as stated elsewhere herein, in some embodiments a window 131 is not employed and fluid to be inspected is provided in direct contact with the optical element (such as prism 121 ).

The particular blend of petroleum spirits and diesel oil employed to obtain the plot of FIG. 2(g) were selected from those sold in the United Kingdom at the time the measurements were made as motor vehicle fuels at fuel filling stations. It is to be understood that the apparatus disclosed herein may be used with a wide range of fuel types and fuel blends and is capable of distinguishing between blends of a given type of fuel such as between blends of petroleum spirits, diesel oil and so forth. Embodiments of the invention are useful with other fuels, and with non-fuel liquids such as foodstuffs, beverages and the like. Other liquids may also be distinguished between in some embodiments.

It can be seen from FIG. 2(g) that apparatus arranged to sum the values of intensity of light incident on the pixels of group G4 will be able readily to determine whether the inspection means is exposed to air, petrol or diesel responsive to the value of the sum. In particular, in some embodiments the apparatus may be arranged to determine whether the value of the sum is within a prescribed range of values thereby to distinguish between fluids.

It is to be understood that in some embodiments, a single detector may be provided that is arranged to detect an amount of light falling thereon in order to allow the apparatus to distinguish between fluids, for example as described above with respect to the embodiment of FIG. 2(a) where a single active sensor 1 13 is shown. It is to be understood that in some embodiments a single detector (which may be an active detector or a passive detector) may be arranged to detect an amount of light falling over an area corresponding to that of a given group of pixels such as group G4 of the embodiment of which FIG. 2(g) shows data obtained therefrom. Thus in some embodiments a cost and/or a complexity of the apparatus may be reduced by using a single detector rather than an array of detectors.

Embodiments such as those having position sensitive detectors (whether 1 D linear detectors such as that of FIG. 2(f) or area detectors in the form of a 2D array) may advantageously allow reconfiguration of the apparatus to distinguish between fluids other than those for which a given group of pixels (such as group G4 of the detector of FIG. 2(f)) allows a reliable distinction to be made therebetween.

In one embodiment of the invention the apparatus 100, 200 is provided with a reference sample or reference samples of a fluid, for example a sample or samples of a fluid that it is intended the apparatus to allow to pass through the conduit 180, 280. This is in order to allow comparison of refractive index of the reference sample(s) with a fluid in the conduit 180, 280 and in contact with the window 131 , 231 of the apparatus 100, 200.

In some embodiments the apparatus 100, 200 may be arranged to allow substantially real time comparison of refractive index of the reference sample(s) and fluid in the conduit 180, 280. For example, the reference fluid may be provided in optical communication with the fluid identification device 101 , 201 , for example in a region between the window 131 , 231 and the prismatic element 121 , 221 or at any other suitable location. In some embodiments the gap 135, 235 is arranged to contain the reference sample instead of air or other gas. In some alternate embodiments separate gap regions may be provided for air (or other gas or liquid) for calibrating light intensity and a reference liquid. Other arrangements are also useful.

The device 101 , 201 may be arranged such that the reference fluid is maintained at a temperature substantially the same as that of fluid in the conduit 180, 280. Thus, the thinned portion 133 of the window 131 may be arranged to be sufficiently thin to allow the reference fluid to assume the same temperature as fluid in the conduit 180, 280 relatively quickly once fluid begins to flow in the conduit 180, 280. The thinned portion 133 may be sufficiently thin to allow the determination to be made before actuating the valve 190, 290 such that if the wrong fluid is present the amount of contamination of a storage tank downstream of the valve 190, 290 is sufficiently low to be acceptable.

It is to be understood that in some embodiments arranged to inspect liquids, the valve 190, 290 is arranged to be closed when the first portion of the conduit 181 , 281 is full of air or other gas. The valve 190, 290 remains closed until the first portion 181 , 281 is filled with liquid and the apparatus 100, 200 has determined that the liquid corresponds to a correct (allowable) liquid. In some embodiments the apparatus 100, 200 may be arranged to wait until the reference fluid (or liquid) and the liquid in the first portion of the conduit 180, 280 are at substantially the same temperature before making the determination. Other arrangements are also useful. For example, the apparatus may be arranged to allow calibration of the apparatus by exposure of the device 101 , 201 to a sample of a particular fluid during a calibration procedure, for example a sample of a fluid that is to be permitted to pass along the conduit 180, 280. In one application the sample may be a sample of diesel fuel in the case of apparatus 100, 200 installed in a conduit 180, 280 through which diesel is supplied to a diesel storage tank of a filling station. A sample of petrol may alternatively be provided in the case that the conduit 180, 280 is intended for the supply of petrol.

Alternatively the sample may be a sample of fluid that is not to be permitted to pass along the conduit 180, 280 but for which the risk exists that an attempt may be made to pass such a fluid along the conduit 180, 280. For example, the fluid may be petroleum spirits in the example above where the conduit 180, 280 is a conduit through which diesel is to be supplied to a diesel storage tank of a filling station.

Embodiments of the invention allowing recalibration with a reference fluid or the storage of a reference sample have the advantage that variations in composition of a given type of fluid (such as diesel or petroleum spirits) may be accommodated readily, improving a reliability of the apparatus 100, 200. Such a variation may occur for example due to seasonal variations in composition deliberately applied by manufacturers, where additives to improve low temperature operation may be added to a fuel during winter months.

In some embodiments, apparatus 300 is provided having a reference fluid identification device that is permanently provided with a sample of reference fluid in addition to the fluid identification device 101 , 201 described above. FIG. 4 is a schematic illustration of such apparatus 300.

The apparatus 300 has a fluid identification device 101 arranged in fluid communication with a conduit 380 as described above. In addition, the apparatus 300 has a reference fluid identification device 301 provided in fluid isolation from the conduit 380. Like features of the reference device 301 to the device 101 are shown with like reference signs prefixed numeral 3 instead of numeral 1 .

Thus the reference device 301 has a window 331 arranged in fluid communication with a reference fluid chamber 387 arranged to contain a sample of fluid that is to be permitted to pass through the conduit 380. The apparatus 300 is arranged to compare output signals from the fluid identification device 101 and the reference device 301 . It is to be understood that the respective output signals correspond to the differences in refractive indices between window 131 and fluid in the conduit 380 (device 101 ) and window 331 and fluid in the reference chamber 387 (device 301 ). The apparatus 300 is configured to determine that an incorrect fluid is present in the conduit 380 if the difference or 'delta' between the respective refractive index differences exceeds an allowable value.

In the embodiment 300 shown the reference fluid in the reference chamber 387 may be readily changed. In some embodiments this has the advantage that the type of allowed (or 'required') fluid may be changed without a requirement to reprogram the processor module 303 of the apparatus 300. Thus in some embodiments the operator may be required to provide a sample of the allowable fluid to the reference device 301 rather than (or in addition to) reprogramming the processor module 303. Such an action may be performed manually or automatically by the apparatus.

FIG. 5 shows a refuelling station 1 employing apparatus 200 according to the embodiment of FIG. 1 (b).

In FIG. 5 it can be seen that a fuel tanker 5 is in the process of transferring a charge of fuel from the tanker 5 into an underground fuel storage tank 30. The fuel flows from the tanker 5 via a hose 7 to conduit 280 installed in a section of a pipe running from ground level to the level of the storage tank 30. A fluid identification device 101 according to the embodiment of FIG. 1 (b) is provided in the conduit 280 upstream of valve 290, the device being substantially identical to the device 101 of FIG. 2(a). As noted above, the valve 290 is operable to allow fluid flowing down conduit 280 to flow either into the fuel storage tank 30 or into an auxiliary storage tank 35. In the present embodiment the valve 290 is further operable to prevent flow of fluid past the valve 290, for example when an initial amount of liquid is discharged from the tanker 5.

The device 101 is arranged to control the valve 290 to divert a flow of fuel into the auxiliary storage tank 35 when the refractive index difference between the window 131 and fuel in contact with the window 131 as measured by the device 101 falls outside an allowed range.

Thus, in the case that the refuelling station 1 is configured to store diesel in the storage tank 30 the valve 290 is arranged to allow a flow of fluid into the tank 30 provided the refractive index difference (corrected for temperature if required) between the fluid and window 131 is within an allowed range. If the difference falls outside of the allowed range the apparatus 200 is arranged to close the valve 290 to prevent flow of fluid through the conduit 280. An operative may then stop further supply of fuel from the tanker 5 and control the valve 200 to divert fluid that is already in the hose 7 and conduit 180 into the auxiliary storage tank 35 rather than storage tank 35. The apparatus 200 is also arranged to provide an audible alert to an operator of the station 1 in a control room 1 1 by means of an alarm sounder 15. The apparatus 200 may alternatively or in addition be arranged to provide an alert to an operator of the tanker 5.

As shown in FIG. 5 a pump 21 is provided in fluid communication with the tank 30 to pump fuel from the tank 30 into a fuel storage tank of a vehicle 25.

It is to be understood that embodiments of the invention are also useful in other applications. For example, apparatus 100 similar to that of FIG. 1 (a) may be employed in a vehicle where the conduit 180 is a conduit from a fuel inlet of the vehicle to a fuel storage tank of the vehicle. The apparatus 100 may be arranged to close the valve 190 when it is determined that a misfuelling event is in progress.

It is to be understood that if a driver is refuelling the vehicle with fuel from a pump 21 and closure of the valve 190 occurs it will have the effect of causing the first portion of the conduit 181 to fill with fuel. If the pump 21 has a conventional automatic flow termination device, filling of the conduit 181 with fuel will have the effect of causing the pump 21 automatically to terminate supply of fuel to the vehicle 25. For example, some automatic flow termination devices are arranged to detect an increase in a backpressure of fluid in the first portion of the conduit 181 , for example at the location of a nozzle through which the pump 21 dispenses fuel to the vehicle 25 and to terminate the flow of fuel.

The apparatus 100 may be arranged to trigger an alert to the vehicle driver that a misfuelling event is in progress, causing the driver to cease the attempt to refuel the vehicle 25 with the wrong fuel.

In some embodiments the apparatus 100 may be operable to open the valve 190 even when it is determined that an incorrect fluid is present in the conduit 180. For example, when the driver ceases refuelling following the provision of the alert. This is to allow the incorrect fluid to drain from the conduit 180 into the tank once a misfuelling event has been detected. It is to be understood that such an arrangement may be acceptable in applications where the quantity of incorrect fuel in the conduit 180 resulting from a misfuelling event may be diluted to an acceptable level by (say) filling the tank with correct fuel once the incorrect fuel has been allowed to drain into the tank.

Thus in the case of a misfuelling event in respect of a vehicle 25, once misfuelling has been stopped the driver might allow the content of the conduit 180 (containing incorrect fuel) to drain into the fuel tank. The quantity of incorrect fuel so drained would become diluted by correct fuel with which the operator would subsequently fill the tank.

Similarly, in the case of a misfuelling event in respect of the underground fuel storage tank 30 of the refuelling station 1 , once a misfuelling event has been detected and flow of fuel into the conduit 280 has been terminated, the apparatus 200 may be arranged to allow the dispensed fuel to drain into the storage tank 30 provided dilution of the fuel to an acceptable level in the tank 30 can be expected. Thus apparatus such as that of FIG. 1 (a) not having an auxiliary storage tank and diverter valve maybe employed, reducing overall system cost.

It is to be understood that other arrangements are also useful.

Embodiments of the invention have the advantage that misfuelling events can be identified substantially immediately they occur, allowing termination of the misfuelling event before contamination or damage is caused to a fuel storage facility or vehicle.

It is to be understood that embodiments of the present invention are useful in handling fluids other than liquid fuels. For example embodiments of the invention are useful in applications involving beverages such as alcoholic beverages, non-alcoholic beverages and any other liquids or gases that may be distinguished based on one or more optical properties. Other arrangements are also useful.

In some embodiments the apparatus may have a fluid discrimination (or inspection) device arranged to pass a beam of light through a fluid that is to be identified and to detect light that has passed through the fluid rather than detecting light that has passed through a solid medium and been reflected at an interface between the solid medium and the fluid without passing directly through the fluid.

In some embodiments apparatus is provided having a plurality of conduits coupled thereto upstream of the window, the apparatus being operable to provide an alert and/or control a fluid control device according to the type of liquid that is passed through the apparatus from one or more of the plurality of conduits at a given moment in time. For example, the apparatus may be configured to allow a first type of liquid therethrough from a conduit upstream of the apparatus at one moment in time and then at another moment in time be configured only to allow liquid of a second type different from the first type therethrough. Thus, in the event it is required to pass liquids such as beverages of different respective types through the apparatus at different times, for example in a beverage bottling plant, the apparatus may be controlled to allow only beverage of a first type therethrough when beverage of the first type is being bottled and only beverage of a second type therethrough when beverage of the second type is being bottled.

Other arrangements are also useful.

In one embodiment of the invention, instead of the apparatus being arranged automatically to open or close a valve or the like, the apparatus is configured to allow an operator of the apparatus manually to open a valve when it is determined that it is permitted to do so. Thus for example when the apparatus determines that an allowable fluid is present the apparatus may be operable to allow an operator to open a valve to allow the fluid to flow through the apparatus to a required location. In the event a non-allowable fluid is present the apparatus may be operable not to allow the operator to open the valve. In some embodiments, when the valve is open and the apparatus determines that the valve should be closed, the apparatus may be configured automatically to close the valve.

FIG. 6 shows a lever control device 360 suitable for use in embodiments of the invention and allowing manual operation of a valve such as valve 290 of the arrangement of FIG. 5. The device 360 has a lever 361 operable between a first position labelled A and a second position labelled B.

The device 360 has a biasing element 365 coupled to the lever 361 and arranged to bias the lever 361 to position A. Thus if the lever 361 is displaced away from position A towards position B the biasing element 365 urges the lever 361 back towards position A.

The biasing element may be a coil spring, a leaf spring, an elastomeric material or any other suitable biasing element 365.

The device 360 has first and second solenoid elements 363, 364 each operable between first and second conditions corresponding to first and second axial positions. In the first condition the respective solenoid elements 363, 364 prevent swing of the lever 361 therepast whilst in the second condition the respective solenoid elements 363, 364 allow swing of the lever 361 therepast.

The first solenoid element 363 is arranged such that when the lever 361 is in position A and the element 363 is in the first condition it does not permit the lever 361 to be swung past the element 363 towards position B. Only when the element 363 is in the second condition can the lever be swung towards position B.

It is to be understood that in some embodiments position A may be referred to as a closed position of the lever 361 since it will typically correspond to a closed condition of the inlet valve to a fuels (or other liquid) storage tank.

The second solenoid element 364 is arranged such that when the lever 361 is in position B and the element 364 is in the first condition the element 364 does not allow the lever 361 to swing past the element 364 towards position A. Only when the second solenoid element 364 is in the second condition can the lever 361 so move.

It is to be understood that in some embodiments position B may be referred to as an open position of the lever 361 since it will typically correspond to an open condition of the inlet valve to the storage tank.

In use, the lever control device 360 may be installed in a refuelling station 1 such as that shown in FIG. 5. In the case of the station 1 of FIG. 5 the device 360 may be installed so as to control operation of valve 290.

Prior to a refuelling operation taking place the lever 361 is provided in the closed position (position A of FIG. 6) and the first solenoid element is provided in the first condition such that the lever cannot be moved to the open position (position B).

If the fluid identification device 201 determines that a permitted fuel is present in the conduit 280 the device 201 is configured to control the first and second solenoid elements 363, 364 to assume the second condition, allowing the lever 361 to be moved to the open position. The second solenoid element 364 then assumes the first condition, maintaining the lever 361 in the open position.

Once the refuelling operation has been completed and fuel is no longer present in the conduit 280, the second solenoid element 364 is controlled to assume the second condition. The lever 361 then returns automatically to the closed position under the influence of the biasing element 365 and the first solenoid element 363 is controlled to assume the first condition, preventing the lever 361 from being moved to the open condition unless a permitted fuel is present in the conduit 280 as discussed above.

Embodiments of the invention have the advantage that an amount of power required to operate the apparatus 200 may be reduced. This is because the apparatus 200 is not required to supply power to actuate the valve 290. Rather the apparatus 200 is required only to supply power to actuate the first and second solenoid elements 363, 364, power to actuate the valve 290 being provided by the person operating the lever 361 .

In some embodiments of the invention a lever control device is provided in which a single solenoid element is employed to control permitted movement of the lever 361 rather than two or more solenoid elements.

For example, in some embodiments the solenoid may be operable to be actuated to allow movement of the level 361 from position A to position B and subsequently to be actuated to allow the lever to be moved automatically from position B back to position A by means of the biasing element 365.

In some embodiments a cam action may be employed in order to achieve this aim. For example the solenoid element 363 may be arranged to move to one condition (such as the first or second condition) to allow movement of the lever 361 from the closed position to the open position, the lever 361 becoming latched in the open condition by a ratchet or like mechanism. The solenoid element may then be further operable to release the lever 361 from the open position and to allow it to move back to the closed position under the influence of the biasing element 365, for example if a misfuel event is detected.

Other arrangements are also useful.

In some embodiments the apparatus is provided with detecting means for detecting that an operator wishes to deliver liquid into a liquid storage tank. The apparatus may also be provided with means for providing power to one or more portions of the apparatus responsive to the detecting means.

In some embodiments, the apparatus may be arranged to be 'powered down' and placed in a standby (low power consumption) condition or a 'power off condition when an operator does not wish to deliver liquid into the liquid storage tank. However, once the detecting means determines that an operator does wish to deliver liquid to the storage tank the apparatus may be arranged to resume an active (non-standby) condition and/or have power to the apparatus fully restored.

This has the advantage that an amount of power consumed by the apparatus when not in use may be reduced. This can be particularly important in applications where the apparatus is powered at least in part by batteries. The use of batteries as a power source may be particularly important in applications where the apparatus is installed in an environment where the provision of external power is difficult or impossible.

Such applications may include applications in remote locations or in hazardous areas where the provision of external power is expensive or requires special measures. For example refuelling stations are typically considered to be hazardous areas, the provision of electrical power to such areas being subject to strict regulations.

The detecting means may be a mechanical means such as a float valve arrangement in which the presence of liquid causes displacement of a buoyant member and actuation of a power switch. Alternatively or in addition the detecting means may include a motion sensor or a switch such as a proximity switch actuated by opening an inlet cover of the apparatus. Other arrangements are also useful.

FIG. 7(a) is a perspective view of a prismatic element 421 of a fluid identification device 401 according to a further embodiment of the invention. The prismatic element 421 is in the form of a solid cylindrical body 421 B formed from a transparent glass. A pair of chamfered portions are formed at one end of the cylindrical body 421 B at radially opposite locations. The portions present substantially flat, polished entrance and exit surfaces 423A, 423B respectively. The entrance and exit surfaces 423A, 423B each have a surface normal N_A, N_B respectively lying at an angle Θ of around 70° to a cylinder axis A of the body 421 B.

A polished cylindrical exposure surface 425 at an end of the body 421 B opposite the end at which the chamfered portions are provided is arranged to be exposed to fluid flowing in a conduit in which the device 401 is installed. At an opposite end of the body 421 B a rear surface 423C parallel to the exposure surface 425 of the body 421 B is provided between the entrance and exit surfaces 423A, 423B.

FIG. 7(b) shows the element 421 as viewed along the direction of arrow A1 of (a). FIG. 7(c) shows the element 421 from below (i.e. when looking directly at exposure surface 425). FIG. 7(d) shows the element 421 as viewed along the direction of arrow A2 of (a) and FIG. 7(e) shows the element 421 in plan view.

As shown in FIG. 8 the device 401 has a light source 41 1 arranged to direct a beam of light through the entrance surface 423A towards the exposure surface 425. An active sensor 413 is arranged to receive light from the source 41 1 that is reflected from the exposure surface 425 through the exit surface 423B.

In the embodiment shown the light source 41 1 and active sensor 413 are each mounted to a cap member 421 C having a shape corresponding to that of the body 421 B. The cap member 421 C is designed to ease assembly of the device 401 by supporting the light source 41 1 and active sensor 413 in a fixed relationship with respect to one another, enabling the light source 41 1 and sensor 413 to be coupled to the body 421 B at locations of the entrance and exit surfaces 423A, 423B that are in alignment with one another by presenting the cap member 421 C to the body 421 B. In some embodiments the cap member 421 C is arranged to be coupled to the body 421 B.

In the embodiment of FIG. 7 and FIG. 8 the body 421 B has a groove 421 G formed in the rear surface 423C across a diameter thereof. In the embodiment shown the groove 421 G is formed parallel to edges 423AE, 423BE of the entrance and exit surface 423A, 423B respectively although other orientations of the groove 421 G are also useful. The cap member 421 C has a corresponding ridge element 421 R integrally moulded therewith having a shape corresponding to that of the groove 421 G.

It is to be understood that the cap member 421 C is arranged to be placed over the cylindrical body 421 B of the prismatic element 421 and to be slid along the side 421 S of the prismatic element 421 thereby to locate the ridge element 421 R within the groove 421 G. With the ridge element 421 R so located the light source 41 1 and active sensor 413 are provided in alignment with one another and in abutment with the entrance and exit surfaces 423A, 423B of the cylindrical body 421 B respectively.

In the embodiment of FIG. 8 the light source 41 1 and active sensor 413 are glued to the body 421 B by means of an adhesive although in some arrangements an adhesive is not employed.

As shown in FIG. 8 the prismatic element 421 is arranged to be inserted into a cylindrical recess 402R formed in a housing 402 of the fluid identification device 401 . The housing 402 is arranged to house the prismatic element 421 , light source 41 1 , sensor 413 and associated control electronics.

A fluid tight seal is formed between the body 421 B and housing 402 by means of an 'O'-ring seal element 425S provided within the recess 402R between the exposure surface 425 of the body 421 B and the housing 402.

In some alternative embodiments the groove 421 G is formed in the cap member 421 C and the ridge element is provided by the prismatic element 421 . The cap member 421 C is arranged such that if a slight rotational misalignment exists between the ridge element 421 R and groove 421 G as they are slid towards one another, when they contact one another the cap member 421 C may be forced to rotate about the cylinder axis A thereof thereby bringing the ridge element 421 R and groove 421 G into correct rotational alignment with one another. It is to be understood that this 'self-aligning' feature has the advantage that the light source 41 1 and active sensor 413 may be aligned correctly with the prismatic element 421 in a convenient one-step assembly operation.

In some alternative embodiments other means for alignment of the cap member 421 C with the body 421 B of the prismatic element 421 may be provided, such as a plug and socket arrangement, a flat formed at a circumferential edge of the rear surface 423C or any other suitable means.

FIG. 9 shows ray trace simulations of light from the source 41 1 travelling through the prismatic element 421 with the inspection surface 425 in contact with (a) petrol and (b) air. It can be seen that a pattern of illumination of the exit surface 423B is different in each case. As discussed above, the pattern of illumination is also different in the case that diesel oil or other fluid having a different refractive index from petrol is in contact with the inspection surface 425. In other words, an intensity distribution over the exit surface 423B of light from the source 41 1 is different in each case.

In some arrangements, the apparatus is operable to calibrate an intensity of the light source 41 1 by detecting light incident on the detector 413 in the absence of liquid in contact with the exposure surface 425 (or window in the case the device has a window). It is to be understood that calibration of the intensity of the light source 41 1 is useful in that it permits the device to compensate for any decrease in intensity of light generated by the source 41 1 due for example to ageing of the source 41 1 or fluctuations in temperature.

In some embodiments the device is arranged to determine that no liquid is in contact with the exposure surface 425 by comparing a pattern of illumination of the detector 413 by the source 41 1 with a pattern corresponding to a stored pattern determined for air or other gas that may be found in contact with the exposure surface 425.

In some embodiments a separate signal is provided to the device indicating that delivery of liquid has ceased.

When it is determined that delivery of liquid has ceased and that liquid is no longer in contact with the exposure surface the device may be arranged to perform a calibration operation in which a controller of the device stores data in a memory thereof corresponding to an intensity of light incident on the detector, thereby allowing recalibration of the device in respect of intensity of the source 41 1 .

Embodiments of the invention have the advantage that a risk of cross-contamination of liquid storage tanks may be reduced. The liquid storage tanks may be for storing liquid fuel, liquid foodstuffs, other liquids such as beverages, pharmaceutical drugs, or any other suitable liquids.

In some embodiments the apparatus is arranged to store data in respect of measurements made by the apparatus of the amount of light incident on the detector. In some embodiments data is stored each time a liquid is detected that does not correspond to a liquid that is permitted to pass through the apparatus into a liquid storage tank.

For example, in some embodiments a tally is kept of the number of attempted misfuelling operations performed. In some embodiments only data in respect of a prescribed number of the most recent misfuelling operations are stored. In some embodiments a date, time and identity of an operator performing the misfuelling operation is stored in a memory of the apparatus. In some embodiments the apparatus is configured to require an authorised key to be presented to the apparatus before the apparatus may be used. The key may be in the form of a physical key that must be used to open a lock or turn a key switch, an RFID tag, a wireless signal generator such as an infra-red of radio fob or any other suitable device. Once an authorised key is presented the apparatus may be arranged to allow a fuelling operation to take place.

The key may be encoded with data corresponding to the identity of a person carrying the key. The apparatus may be operable to be over-ridden responsive to an input from an authorised key. Thus in the event of a misfuelling operation in which an incorrect fuel has been detected and delivery of the fuel to a fuel storage tank prevented, the apparatus may be operable to open a valve such as valve 190 of the embodiment of FIG. 1 to allow fuel that has already been introduced into the apparatus to flow into the storage tank even though it is not the correct fuel, in the presence of the authorised key.

The apparatus may be arranged to log an identity of the key in the event an over-ride operation takes place. Thus if an operative forces incorrect fuel to be delivered an identity of the operative may be determined.

In some embodiments the apparatus is not configured to open and close a valve in order to prevent a misfuelling operation. Rather, the apparatus detects when liquid is being passed through the fluid conduit of the apparatus and acquires data in respect of the refractive index of the liquid. If the apparatus determines that the liquid corresponds to an allowed liquid the apparatus may be configured to store data indicating a delivery of approved liquid or to store no data at all (for example so as to avoid wastage of memory capacity).

However in the event that a liquid is detected that does not correspond to allowed liquid the apparatus may be arranged to take action responsive to this determination. In some embodiments the action may be or include the step of storing data indicating that such a delivery has taken place. In the case of apparatus having a position sensitive detector the apparatus may be arranged to store data corresponding to light intensity as a function of angle through which the light has been scattered. A person reviewing this data following the event may be able to determine from the data the nature of the liquid that was delivered. This may be achieved for example by comparing this data with data in respect of one or more other liquids.

In addition or instead the apparatus may be configured to trigger transmission of an alert to an owner or operator of the refuelling facility, or other agency.

Thus in the case of an operator who requires only a certain fuel to be delivered to the refuelling station, such as fuel from a certain source, the operator may be able to detect when fuel from an alternative source (such as fuel from an unauthorised supplier) has been introduced into a storage tank and take appropriate action.

In some embodiments the apparatus is operable to allow calibration data to be updated in a memory thereof. The calibration data may correspond to an identity of liquid that is permitted to be delivered through the apparatus and/or an identity of liquid that is not permitted to be delivered through the apparatus.

Thus the apparatus may be operable to receive new calibration data by a wired or wireless interface such as a short range radio interface such as Bluetooth (RTM) or like interface.

It is to be understood that if a facility operator wishes to change the type of liquid dispensed, for example changing from diesel to petrol or petrol to diesel, or the blend of a given fuel such as from one seasonal blend to another or one octane rating to another, the operator may store new calibration data in the apparatus. This is so that the apparatus can determine whether or not a fuel being delivered corresponds to an allowable fuel. In some embodiments, the apparatus is operable to download new calibration data via the interface (such as a wireless interface) and to store the data in a memory of the apparatus. In some embodiments a maintenance operative may be provided with a portable device for transmitting the calibration data to the apparatus. Thus in the event that it is required to recalibrate apparatus installed at multiple locations with data in respect of a new seasonal blend, the maintenance operative may visit the locations and download the required data. The operative may also change one or more parameter settings of the apparatus using the portable device.

In some embodiments the apparatus may be operable to receive calibration data by a fixed communications network such as a wi-fi network, bluetooth network or the like.

The apparatus may be operable to log data in respect of usage of the apparatus. In some embodiments the apparatus may be arranged to log data in respect of an identity of an operative operating the apparatus, for example whenever fuel is delivered through the apparatus. For example, the apparatus may obtain data as to the identity of the operative by means of a key of the operative as discussed above, such as an RFID key. The apparatus may in addition or instead be operable to log data in respect of one or more characteristics of the fuel delivered. In some embodiments the apparatus may store data in respect of a light intensity detected by a detector of the apparatus at a given position. The apparatus may employ a position sensitive detector and store data corresponding to an intensity of light falling on the detector over a given region of the position sensitive detector.

It is to be understood that light intensity at a given position or light distribution at a plurality of positions of a detector is typically characteristic of one or more optical properties of a liquid being inspected by the apparatus, i.e. it may provide a 'fingerprint' in respect of the liquid allowing later identification of a liquid that has been inspected by the apparatus.

In some embodiments the apparatus is arranged to store data in respect of one or more characteristics of the fuel delivered for a prescribed number of preceding deliveries. In some arrangements the apparatus stores the data only when it is determined that the fuel does not correspond to an approved fuel. Thus later interrogation of the apparatus may allow an operator to identify a type of fuel delivered to a facility.

Thus in the case that the device stores characteristic data in respect of the fuel, the operator may be able to determine an identity and/or origin of the fuel based on the characteristic data.

The apparatus may be arranged to log data in respect of events in which an operative over- rides a function of the apparatus, for example an event in which the operative forces the apparatus to allow a certain type of fuel to be delivered when the apparatus has determined that the particular type of fuel should not be delivered. This feature may allow the operator to determine the identity of the operative that forced the fuel to be delivered.

Similarly, in some embodiments the apparatus is arranged to store data in respect of a malfunction of the apparatus such as a mechanical and/or electrical fault.

In addition or instead apparatus may be provided that is arranged to store data in respect of a calibration event when such an event takes place, even if only to register the fact that a calibration event has taken place. This feature may allow an operator or maintenance technician to determine whether a third party has recalibrated the apparatus, for example in order to cause the apparatus to allow a different (possibly unauthorised) fuel to be delivered.

In some arrangements, if the apparatus determines that the fuel to be delivered has an optical characteristic within an allowed tolerance but which differs from a reference characteristic by more than a prescribed amount the apparatus may be arranged to store data in respect of the event. Such an event may be referred to as an Off spec' or 'borderline' fuelling event. As noted above, it may become necessary to re-calibrate the apparatus due for example to a change in a type of fuel that is allowed to be delivered through a given apparatus.

In one arrangement, the apparatus may be re-calibrated by selecting (or 'unlocking') a parameter over-ride mode of the apparatus. The apparatus may then be operable to be recalibrated. For example, in some embodiments the apparatus may be re-calibrated by passing fuel into or through the apparatus and selecting an 'over-ride' feature. The apparatus may then be arranged to perform a prescribed number of measurements of an optical characteristic of the apparatus and to store data in respect of the measurements in a memory thereof. Alternatively or in addition the apparatus may transmit the data to an external device such as a portable computing device carried by a maintenance operative. In some arrangements the apparatus may not be able to store sufficient data in a memory thereof to allow the apparatus to set calibration data therein.

Thus the apparatus may be configured to transmit the data to the external computing device. In some arrangements the external computing device is arranged to determine one or more calibration parameters by reference to the data from the apparatus and to transmit the one or more calibration parameters to the apparatus for storage therein.

The external device may be arranged to transmit the data to a server, where the data may be stored. In some embodiments the apparatus is arranged to receive calibration data from an external server. Thus the server may be arranged to transmit calibration data obtained using one apparatus to one or more further apparatus in order to allow the further apparatus to be recalibrated using the same data.

In some embodiments this feature allows multiple apparatuses to be recalibrated after performing only a single calibration data acquisition operation using one apparatus.

As discussed above, apparatus according to embodiments of the invention such as the apparatus 100 of FIG. 1 may be provided with a valve such as valve 190 as shown in FIG. 1 (a). The valve may be arranged to be a substantially airtight valve. Thus in the case that the apparatus 101 is connected to an underground storage tank such as tank 30 (FIG. 5) and the tank 30 is a pressurised tank, the valve 190 prevents pressurised gases in the tank 30 from leaking to atmosphere through the apparatus 101.

This feature is particularly advantageous in filling stations provided with gas suction delivery nozzles arranged to capture volatile gases evolved due to evaporation of fuel during filling of a motor vehicle with fuel. The problem exists that because the tank 30 becomes pressurised when captured gases are pumped into the tank, the gases can escape when a refuelling hose 7 from a tanker 5 is connected to the tank 30 to re-fill the tank 30.

Embodiments of the present invention have the advantage that because the apparatus 100 is provided between the tank 30 and hose 7 and may be provided with a valve for preventing misfuelling, leakage of gases from the tank 30 when the hose 7 is connected to the apparatus 100 may be prevented or at least substantially reduced in the presence of the valve 190.

It is to be understood that a number of different operational methodologies may be employed for refuelling a fuel storage tank 30 using embodiments of the present invention.

In one arrangement the apparatus is arranged to receive an input signal from a fuel level sensor provided in the tank 30 indicating the level of the fuel in the tank 30. When the level of fuel in the tank 30 reaches a first prescribed fill level (for example a level corresponding to 95% of a maximum fill level) the apparatus may be configured to provide an alert to a tanker operative. The alert thus informs the operative that the level of fuel in the tank has reached the first fill level. At this time the driver may prepare to close a valve at the tanker to prevent further fuel from being delivered to the tank. When the level of fuel in the tank 30 subsequently reaches a second prescribed fill level (for example corresponding to 97% of the maximum fill level) the driver may close the valve at the tanker 5. At this time the flow of fuel into the tank 30 through the apparatus begins to slow and the apparatus will eventually detect that air is present in the conduit of the apparatus, as the conduit empties. The apparatus is arranged to keep the valve 190 in an open condition for a first prescribed period following detection of air by the fluid identification device (such as device 101 of FIG. 1 ). In one embodiment this first prescribed period is a period of around 45s. Thus, if liquid is detected by the device within 45s of the detection of air, the valve 190 remains open. This is so as to allow sufficient time for an operative to empty a hose 7 of liquid before disconnecting the hose.

In some arrangements, if further liquid is subsequently detected by the fluid identification device within a second prescribed period of closure of the valve 190 (following detection of air for more than the first prescribed period), the apparatus is arranged to re-open the valve 190 to allow draining of the further liquid from the apparatus. In some embodiments the second prescribed period corresponds to a period of two minutes. Other periods are also useful.

In some embodiments if the apparatus 101 detects air for longer than a prescribed period such as a period of 30 minutes, the apparatus 101 is configured to assume a standby or low power consumption mode. The apparatus 101 may be operable to exit the standby or low power mode when activated by a signal from an operative's key.

In some embodiments a bleed hole is provided to allow fuel that remains in the conduit 180 of the apparatus to drain into the tank 30 even if the valve 190 is closed. This feature has the advantage that if a misfuelling event occurs, fuel in the conduit 180 that cannot pass into the tank 30 (because the valve 190 is closed) can drain slowly into the tank 30 thereby clearing the apparatus 101 (and the hose 7) of fuel, without requiring the valve 190 to be re-opened. The feature of a drain hole may reduce a risk of abuse of the apparatus. That is, if an operative or other person can readily over-ride the apparatus and cause the valve 190 to open even when incorrect fuel is present, delivery of substantial quantities of unauthorised fuel may occur.

FIG. 10 shows apparatus 500 according to a further embodiment of the invention. Like features of the apparatus 500 of FIG. 10 to that of FIG. 1 are shown with like reference signs prefixed numeral 5 instead of numeral 1 .

The apparatus 500 has a body 500B formed from a cast metallic material although other materials and methods of fabrication are also useful. The apparatus 500 has a fluid inspection device 501 in the form of a refractometer provided in fluid communication with fluid that may be passed through a fluid conduit 580 of the apparatus.

The body 500B is provided with flanged upper and lower surfaces 500F1 , 500F2 respectively, allowing the apparatus to be installed in a fuel input conduit of a refuelling facility whereby the conduit 580 of the apparatus 500 forms part of a flowpath for fuel from a fuel tanker inlet of the facility to a corresponding fuel storage tank of the facility.

The fluid inspection device 501 is connected to a computing device 503 (FIG. 1 1 ) that controls the device 501 .

A butterfly valve 590 is provided in the conduit 580 downstream of the fluid inspection device 501 . The valve 590 may be actuated by an electric motor 595 and is operated by means of a control signal from a controller 505 that is in turn controlled by the computing device 503. The computing device 503 and controller 505 are co-located on a common circuit board in the embodiment shown.

The controller 505 is operable to control the valve 590 to assume an open or closed condition. In the configuration shown in FIG. 12 the valve 590 is in the open condition. Thus the valve 590 is operable to allow or to prevent a flow of fluid through the conduit 580 from a first portion 581 of the conduit upstream of the valve 590 to a second portion 582 of the conduit 580 downstream of the valve 590.

The computing device 503 is operable to control an alarm module 509 to emit an audible signal in the event that fluid is detected in the conduit 580 having a refractive index characteristic that does not correspond to that stored in a memory thereof in respect of an authorised fluid.

The apparatus 500 is also arranged to control the valve 590 to assume the closed condition in the event that such a fluid is identified in the conduit 580.

The apparatus 500 has a display panel 502 having a pair of light emitting diodes. The panel 502 is arranged to indicate when a system fault has occurred and maintenance is required (steady red light only). The panel is also arranged to indicate when the system is switched on and fully operational (steady green light only). In the event a misfuelling event is detected the red and green lights are arranged to flash together. It is to be understood that other visual indications and combinations of visual indications are also useful.

FIG. 13 is a perspective view of the fluid inspection device 501. The device 501 has a number of features in common with that of the embodiment shown in FIG 8.

The device 501 has a prismatic element 521 in the form of a solid cylindrical body 521 B formed from a transparent glass. A pair of chamfered portions 523A, 523B are formed at one end of the cylindrical body 521 B at radially opposite locations. The portions 523A, 523B present substantially flat, polished entrance and exit surfaces 523A, 523B respectively. The entrance and exit surfaces 523A, 523B each have a surface normal N_A, N_B respectively lying at an angle Θ of around 70° to a cylinder axis A of the body 521 B as illustrated in FIG. 14.

A polished cylindrical exposure surface 525 at an end of the body 521 B opposite the end at which the chamfered portions are provided is arranged to be exposed to fluid flowing in the conduit 580. At an opposite end of the body 521 B a rear surface 523C parallel to the exposure surface 525 of the body 521 B is provided between the entrance and exit surfaces 523A, 523B. A light source 51 1 is arranged to direct a beam of light through the entrance surface 523A towards the exposure surface 525. An active sensor 517 is arranged to detect light from the source 51 1 that is reflected from the exposure surface 525 through the exit surface 523B.

In the embodiment shown the light source 51 1 and active sensor 517 are each coupled to a substantially circular frame 501 F that is attached to the body 521 B although in some embodiments the source 51 1 and sensor 517 may be coupled to a cap member having a shape corresponding to that of the body 521 B in a similar manner to the embodiment of FIG. 8.

The active sensor 517 is a position sensitive detector in the form of a linear detector. A longitudinal axis of the linear detector is oriented such that the detector 517 is able to detect an intensity of light falling on the detector 517 as a function of an angle through which the light has been scattered at the exposure surface 525. It is to be understood that the light source 51 1 may be arranged to direct light to be incident on the exposure surface 525 over a non-zero range of angles such that light is scattered at the surface 525 through a corresponding range of angles (where an angle of incidence Q_lN of a given ray of light is equal to the angle of reflection 9REFL of that ray).

The prismatic element 521 has a pair of parallel sides 521 D along a portion of a length of the element 521 that run between the entrance and exit surfaces 523A, 523B. The frame 501 F has an internal shape corresponding to an external shape of the prismatic element 521 including the parallel sides 521 D allowing the frame 501 F to be attached to the prismatic element 521 in a manner such that the element 521 cannot rotate with respect to the frame 501 F. In the embodiment shown the frame 501 F is bonded to the prismatic element 521 although other methods of attachment are also useful.

The source 51 1 and detector 517 are attached to the frame 501 F by means of screw fixings although again other arrangements are also useful.

In use, the apparatus 500 is activated from a standby mode when it receives a signal from a radiofrequency (RF) remote control device 500R (FIG. 10). The device 500R may for example be carried by an operative The remote control device 500R is arranged to transmit data in respect of an identity of a person using the device 500R. The apparatus 500 then assumes an operations mode in which the valve 590 remains closed until the apparatus determines (by means of the inspection device 501 ) that a correct fuel is present in the conduit 580. The valve 590 is then opened automatically by the apparatus 500.

If the apparatus 500 determines that a fluid is in the conduit 580 (other than air) that does not meet one or more prescribed criteria in respect of an intensity of light scattered through a prescribed angle the computing device 103 determines that the liquid does not correspond to an approved liquid. The apparatus 500 controls the valve 590 to remain in (or to assume if it is not already in) the closed condition.

The apparatus is arranged to compare data in respect of an intensity of light detected by the detector 517 with reference data stored in a memory of the computing device 503. In some embodiments the device 503 obtains data from the detector 517 corresponding to a prescribed angle through which detected light has been scattered. The angle may be the angle through which a maximum amount of light has been scattered (i.e. an angle at which a peak in scattered light intensity as a function of angle is observed) or an angle that is offset from the angle of peak intensity by a prescribed amount. If the measured data corresponds to the reference data the computing device 503 may determine that the liquid is a liquid that is permitted to flow through the conduit 580 and therefore open the valve 590.

If the measured data does not correspond to the reference data the computing device 503 may determine that the liquid is not a liquid that is permitted to flow through the conduit 580 and therefore maintain the valve 590 in a closed condition.

In some alternative embodiments the apparatus 500 is configured to close the valve 590 or maintain the valve 590 in the closed condition only if liquid is detected that is not permitted to flow through the conduit 580.

Embodiments of the invention are useful in applications in which liquid fuels are handled. In some embodiments the apparatus is used in processing of beverages such as wines, spirits and/or beers. Embodiments of the invention are also useful in the processing of other liquids such as foodstuffs, solvents such as thinners and paints and other liquids.

Some embodiments of the invention may be useful in distinguishing between gaseous fluids.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

CLAIMS:

1. Fluid discrimination apparatus comprising fluid inspection means, the fluid inspection means comprising a light source, a detector and an optical element, the inspection means being operable to direct a beam of light from the source through the optical element to an inspection surface of the optical element and to detect by means of the detector light scattered back through the optical element, the apparatus being operable to determine whether a fluid in contact with the inspection surface corresponds to a fluid having a prescribed refractive index characteristic responsive to light detected by the detector.

2. Apparatus as claimed in claim 1 wherein the apparatus is operable to actuate a fluid control device responsive to a determination whether a fluid has a prescribed refractive index characteristic.

3. Apparatus as claimed in claim 2 wherein the fluid control device comprises a fluid control valve.

4. Apparatus as claimed in claim 2 or 3 as depending through claim 16 operable to actuate the fluid control device thereby to prevent a flow of fluid through the apparatus.

5. Apparatus as claimed in any preceding claim further comprising means for providing a signal to an operator in dependence on whether a fluid has a prescribed refractive index characteristic.

6. Apparatus as claimed in any preceding claim operable to divert a flow of fluid such that the fluid enters a first receptor when the fluid inspection means determines that the fluid is a fluid having a prescribed refractive index characteristic and a second receptor when the fluid inspection means determines that the fluid is not a fluid having the prescribed refractive index characteristic.

7. Apparatus as claimed in any preceding claim provided in a fluid receiving portion of a fuel storage facility, the fluid inspection means being arranged to determine whether fluid passing through the conduit to a storage tank of the facility corresponds to a fluid having the prescribed refractive index characteristic.

8. Apparatus as claimed in claim 7 arranged to prevent flow of fluid not having the prescribed refractive index characteristic into a storage tank.

9. Apparatus as claimed in any one of claims 1 to 6 provided in a fuel receiving portion of one selected from amongst a motor vehicle, an aircraft and a marine vessel.

10. Apparatus as claimed in any preceding claim further comprising a fluid conduit through which a fluid may be passed, the inspection surface of the inspection means being arranged to be exposed to fluid in the conduit.

1 1 . Apparatus as claimed in any preceding claim wherein the optical element comprises a substantially cylindrical body.

12. Apparatus as claimed in any preceding claim wherein the optical element comprises a pair of facets inclined with respect to the inspection surface, the device being operable to project a beam of light through a first of the pair of facets towards the inspection surface, the detector being arranged to detect light from the source travelling back from the inspection surface through the second facet.

13. Apparatus as claimed in any preceding claim wherein light from the source passing through the optical element is arranged to be scattered internally by a surface of the element towards the inspection surface.

14. Apparatus as claimed in any preceding claim wherein light from the source passing through the optical element from the inspection surface is arranged to be scattered internally by a surface of the element towards the detector.

15. Apparatus as claimed in any preceding claim wherein the optical element comprises a first portion and a second portion, the second portion comprising a window member bearing the inspection surface.

16. Apparatus as claimed in any preceding claim arranged to direct a beam of light through the optical element to the inspection surface wherein an angle between the beam of light and the inspection surface is less than 90°.

17. Apparatus as claimed in any preceding claim wherein the detector is arranged to detect light that is scattered from the inspection surface at substantially the same angle as that with which light is incident upon the inspection surface.

18. Apparatus as claimed in any preceding claim wherein the detector is operable to provide an output responsive to an intensity of light scattered through a given angle at the inspection surface.

19. Apparatus as claimed in any preceding claim wherein the detector comprises a position sensitive detector.

20. Apparatus as claimed in any preceding claim operable to distinguish between fluids having different respective refractive index characteristics by comparing data in respect of an intensity of light detected by the detector with reference data.

21. Apparatus as claimed in claim 20 configured to store data in respect of an intensity of light scattered back from the inspection surface through one or more angles or one or more ranges of angles.

22. Apparatus as claimed in claim 20 or claim 21 operable to acquire reference data in respect of a fluid to which the inspection surface is exposed and to store the reference data in a memory thereof.

23. Apparatus as claimed in any one of claims 20 to 22 operable to transmit data in respect of the intensity of light detected by the detector to an external computing device.

24. Apparatus as claimed in any one of claims 20 to 23 operable to receive reference data from an external computing device.

25. Apparatus as claimed in any preceding claim further comprising reference fluid inspection means having an inspection surface in contact with a sample of a fluid, the apparatus being arranged to compare an output of the fluid inspection means with an output of the reference fluid inspection means thereby to determine whether the fluid in contact with the inspection surface of the fluid inspection means corresponds to a fluid having the prescribed refractive index characteristic.

26. Apparatus as claimed in claim 25 wherein the reference fluid inspection means is provided with a sample of fluid having the prescribed refractive index characteristic thereby to provide an output corresponding to that obtained from the fluid inspection means when the fluid inspection means is exposed to fluid having a substantially identical prescribed refractive index characteristic.

27. Apparatus as claimed in any preceding claim wherein the prescribed refractive index characteristic is one selected from amongst a prescribed value of refractive index and a prescribed range of values of refractive index.

28. A method of inspecting a fluid by means of inspection apparatus comprising the steps of: directing a beam of light from a source of the apparatus to an inspection surface of an optical element of the apparatus in contact with a fluid to be inspected and detecting by means of a detector of the apparatus light scattered back from an interface between the inspection surface and a fluid in contact therewith; and

29. A method as claimed in claim 28 comprising the step of providing an output responsive to an intensity of light detected by the detector.

30. A method as claimed in claim 28 or 29 wherein the step of determining whether the fluid in contact with the inspection surface corresponds to a fluid having a prescribed refractive index characteristic comprises the step of providing an output responsive to a determination whether the fluid has a refractive index characteristic within a prescribed range of values of refractive index characteristic.

31 . A method as claimed in any one of claims 28 to 30 comprising the step of actuating a fluid control device responsive to the determination whether the fluid corresponds to a fluid having the prescribed refractive index characteristic.

32. A method as claimed in claim 31 wherein the step of actuating the fluid control device comprises the step of actuating a fluid control valve.

33. A method as claimed in any one of claims 31 or 32 comprising the step of actuating the fluid control device in dependence on whether the fluid passing through the conduit has a refractive index characteristic within the prescribed range of values thereby to prevent a fluid not having a refractive index characteristic within the prescribed range from flowing into a receptor.

34. A method as claimed in any one of claims 28 to 33 comprising the step of providing a signal to an operator in dependence on whether the fluid corresponds to a fluid having the prescribed refractive index characteristic.

35. A method as claimed in any one of claims 28 to 34 comprising the step of storing data in respect of a fluid inspected by the apparatus when it is determined that the fluid has a refractive index characteristic that is not within a prescribed range of values of refractive index characteristic.

36. A method as claimed in claim 35 further comprising the step of transmitting the stored data in respect of fluid inspected by the apparatus to an external computing device.

37. A method as claimed in any one of claims 28 to 36 wherein the step of determining whether the fluid in contact with the inspection surface corresponds to a fluid having a prescribed refractive index characteristic comprises the step of comparing an intensity of light detected by the detector with reference data in respect of a reference light intensity.

38. A method as claimed in claim 37 comprising obtaining new reference data by measuring an intensity of light detected by the detector and storing the data in a memory of the apparatus.

39. A method as claimed in claim 37 or 38 comprising obtaining new reference data by transmitting reference data to the apparatus from an external computing device.

40. A method as claimed in any one of claims 37 to 39 comprising uploading data in respect of light intensity detected by the apparatus to an external computing device.

41. A method as claimed in any one of claims 28 to 40 whereby the step of detecting light by means of a detector comprises the step of detecting an intensity of light scattered through a plurality of different respective angles from the interface between the optical element and the fluid.

42. A method as claimed in any one of claims 28 to 41 comprising the step of controlling a flow of fluid such that the fluid enters a first receptor when it is determined that the fluid has the prescribed refractive index characteristic and the fluid enters a second receptor when it is determined that the fluid does not have the prescribed refractive index characteristic.

43. A method as claimed in any one of claims 28 to 42 comprising the step of logging in a memory of the apparatus the occurrence of an event in which a fluid is detected not having a refractive index characteristic within a prescribed range of values of refractive index

characteristic.

44. A method as claimed in claim 43 comprising the step of not logging the detection of air in the event air is detected.

45. A method as claimed in any one of claims 28 to 44 comprising the step of logging in a memory of the apparatus the occurrence of an event in which a fluid is detected having a refractive index characteristic within a prescribed range of values of refractive index

characteristic.

46. A method as claimed in any one of claims 28 to 45 wherein the step of inspecting a fluid comprises inspecting a fluid passing through a fuel delivery conduit of a fuel receiving portion of a fuel storage plant.

47. A method as claimed in any one of claims 28 to 45 wherein the step of inspecting a fluid comprises inspecting a fluid passing through a fuel delivery conduit of a fuel receiving portion of one selected from amongst a motor vehicle, an aircraft and a marine vessel.

48. A method as claimed in any one of claims 28 to 45 wherein the step of inspecting a fluid comprises the step of inspecting a beverage.

49. A method as claimed in any one of claims 28 to 45 wherein the step of inspecting a fluid comprises the step of inspecting a foodstuff.

50. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.

51 . A method substantially as hereinbefore described with reference to the accompanying drawings.