TECHNICAL FIELD

[0001] This invention relates to a waste oil recovery unit.

BACKGROUND ART

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

[0003] Oils are used for a wide variety of purposes, for example in mechanical lubrication or in a cooking process. As oils are used, they degrade with solids formation and discolouration being typical features of degradation. Used oils need also to be replaced by fresh oil with the used oil being disposed of or, sometimes, recycled.

[0004] Collection of oils is not necessarily a straightforward process. A degraded or used oil may have high solids content and a thick viscous consistency. The solid particles may be charred or partly charred and may have a wide particle size distribution. Such an oil is typically difficult to pump and solids may be difficult to remove or may be difficult to dispose of. To add to these difficulties, the degraded oil may contain potentially toxic chemical degradation products. For example, it is known that acrolein - a carcinogen - may form in cooking oils when they burn. Hot oils also present a safety hazard with burns being a common injury.

[0005] Waste oil recovery units are known which recover a degraded oil to a vessel including a pump to collect oil from an oil source and a strainer to remove solids. In particular, such waste oil recovery units may seek to address pumping difficulties by replacing a pressure pump with a vacuum pump arrangement which keeps the solids away from the pump avoiding blockages.

[0006] Such waste oil recovery units also often include a base with rollers or castors so that they may more easily be moved from place to place. One such waste oil recovery unit includes a pump located at the base, potentially in a ground engaging position. The Applicant has found that such a location for a pump, while allowing some increase in vessel volume, renders it prone to damage as the waste oil recovery unit is moved, for example impacting with kerbs or other obstacles. The base location for a pump also makes it more difficult to access for service and maintenance with additional risks from spillage of hot oil. In the case of commercial waste cooking oil applications (e.g. restaurants), it is convenient and common for waste oil recovery units to be housed within the kitchen areas of those premises. During regular clearing of these premises, the motors (with associated electrical connections) at the base of such tanks are particularly susceptible to being exposed to water, detergent and debris emanating during the cleaning process.

[0007] The Applicant has proposed a waste oil recovery unit as described in co-pending International Patent Publication No. WO 2022082270, the contents of which are hereby incorporated herein for all purposes. The proposed waste oil recovery tank addresses the pump damage issue by locating the vacuum pump in an upper portion of the vessel below the top surface of the unit. The proposed waste oil recovery unit has further advantages, amongst others, in terms of the vacuum pump cooling arrangement and separation of solids outside the vessel. However, particularly for applications where there is limited space for storing the waste oil recovery unit, it would be desirable to find ways of increasing effective capacity and improving separation of oil droplets upstream of the vacuum pump.

[0008] It is against this background that the present invention has been developed.

SUMMARY OF INVENTION

[0009] In one aspect, the present invention provides a waste oil recovery unit comprising:

(a) a housing;

(b) a vessel within said housing for collecting waste oil, said vessel having a base and a top portion;

(c) an oil transfer line for connecting the vessel to a source of oil external to the housing; and (d) a vacuum pump connected by a vacuum duct to the vessel, said vacuum duct being separate from the oil transfer line and said vacuum pump causing suction of air from the vessel and waste oil from the oil source through the oil transfer line and into the vessel; wherein said vacuum pump is located above the vessel. This location for the vacuum pump avoids need for an associated pump compartment to take up space within the vessel and increases the effective volumetric capacity of the waste oil recovery unit without taking up any more floor area than the waste oil recovery tank described in International Patent Publication No. WO 2022082270.

[0010] The vacuum pump is conveniently mounted to the top portion of the unit. While the vacuum pump could be mounted anywhere along the length of the top portion, an end location is most preferred particularly where the top portion forms a lid. In that case, the lid is conveniently connected to the remainder of the housing by a hinge. Location of the vacuum pump at the end of the waste oil recovery unit closest the hinge would have an advantage in terms of minimising weight to be lifted by an operator, whether manually or automatically, when opening the lid.

[0011] The source of oil typically contains solids whether from cooking or another oil consuming process. Solids removal or filtration is desirably achieved by a solids separator located within the vessel and downstream of an oil discharge port where the oil transfer line communicates with the vessel. The solids separator may take a number of forms and may be selected from the group consisting of a strainer, basket or mesh with openings narrow enough to capture a major proportion of solids but without substantially affecting pressure drop and rate of collection of oil through the oil transfer line whilst the vacuum pump is operating. The solids separator may have a box like shape, for example in the form of a square or rectangular cube and walls the box may include a filter, for example being perforated - including in the form of a mesh - to capture solids and allow oil to flow through the perforations at a speed which minimises splashing back up through the top when the lid is open. The solids separator may include a splash guard at the top, the splash guard also being perforated if desired. A space may be left between the splash guard and walls of the solids separator to allow oil flow into the solids separator. The solids separator is conveniently metallic, allowing for efficient handling of hot oil. [0012] The vacuum pump is connected to the vessel through a vacuum duct. The vacuum duct opens to the vessel at a vacuum port, conveniently located in a wall portion of the top portion of the housing. The vacuum duct and vacuum port are conveniently circular in cross section with the vacuum duct desirably having lesser diameter than the vacuum port to increase the vacuum effect.

[0013] Air drawn by suction into the vacuum port would typically contain oil droplets and vapour which could damage the vacuum pump, for example by impeding operation of its impeller. Build-up of oil could also, over time, present a fire hazard. An oil separator is therefore desirably included at or proximate the opening of the vacuum duct into the vessel, or vacuum port, to separate oil droplets and/or vapour. The oil separator may comprise one or a plurality of filter elements, whether of metallic or textile material. The oil separator may be in the form of a stack filter comprising a stack of filter elements or a folded filter material providing a plurality of filter layers. The oil separator may include a holder or retainer for the filter element(s). The holder may be fixed to the wall of the top portion of the housing below the vacuum port. The holder may be integrated with a lid of the unit. Conveniently, filter element(s) are replaceable and may be slid into or out of the holder as required.

[0014] As described above, the oil transfer line connects the vessel to a source of oil external to the housing. The oil transfer line conveniently includes a plurality of portions: a hose or hose portion (conveniently flexible) located externally of the vessel, and an oil inlet line portion connected to the hose portion. The oil inlet line portion feeds an oil delivery pipe portion which delivers oil into the vessel. The hose portion is conveniently mounted to the housing. The oil transfer line also includes a transfer portion which communicates with the source of waste oil, if desired through an oil flow control valve. The transfer portion may comprise a lance for connection to the source of oil.

[0015] In an embodiment, the oil discharge port of the oil delivery pipe portion is located within the housing upstream of, conveniently above, the solids separator and conveniently opens above or into the solids separator. Opening into the solids separator may eliminate escape of solid containing oil into the vessel without filtration. In any event, the oil discharge port is located sufficiently spatially distant from the vacuum port to reduce oil carryover into the vacuum port. The oil delivery pipe portion conveniently has a terminal portion which conveniently includes the oil discharge port opening toward the solids separator. The terminal portion may be inclined or radiused downward toward the solids separator and may terminate within the solids separator. The oil delivery pipe portion may have increasing internal flow diameter along its path from the intake or feed port on an external surface of the housing to the oil discharge port.

[0016] Preferably, the oil transfer line includes a temperature sensor to measure temperature of oil entering the waste oil recovery unit. The temperature sensor may form part of a control system which shuts off, for example, through closing a solenoid valve or switching the vacuum pump off, oil delivery to the vessel if temperature exceeds a predetermined value. It will be appreciated that pumping of hot oil is a safety hazard and transfer to the waste oil recovery unit of excessively hot oil, at a temperature which could burn an operator, is to be avoided. Further, pumping of excessively hot oil may introduce significant vapour into the vessel which could carry over into the vacuum pump, more quickly causing a maintenance issue or requiring a more complex and/or expensive filter element for oil separation at or proximate the vacuum port.

[0017] Preferably, the vessel comprises a level sensor to sense oil level in the vessel. The level sensor may form part of a control system which, like the temperature control system above, shuts off oil delivery to the vessel if oil level exceeds a predetermined level in the vessel. Oil delivery is conveniently shut off by stopping, or cutting off, operation of the vacuum pump. The predetermined level may be a function of oil temperature.

[0018] Operation of the vacuum pump and oil delivery may be controlled dependent on at least one of sensed oil temperature in the oil transfer line and sensed oil level in the vessel.

[0019] Typically, the waste oil recovery unit has a lid. The vacuum pump and oil delivery may be shut off if the lid is imperfectly closed as conveniently determined by a suitable sensor.

[0020] The waste oil recovery unit as above described allows a higher oil capacity for a given space requirement and allows solids separation within the vessel. This allows blockages caused by solids separation within the oil transfer line to be avoided. The upper location of the vacuum pump above and outside the vessel also makes pump motor cooling arrangements less complex as conventional cooling arrangements can be used without complicating fabrication of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Further features of the waste oil recovery unit of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:

[0022] Figure 1 is a schematic side sectional view of a waste oil recovery unit of the prior art.

[0023] Figure 2 is a schematic front view of the waste oil recovery unit of Figure 1 .

[0024] Figure 3 is a schematic perspective view of a waste oil recovery unit according to one embodiment of the present invention.

[0025] Figure 4 is a photograph of a top portion of the waste oil recovery unit schematically arranged as shown in Figure 3.

[0026] Figure 5 is a photograph of a rear end wall of a waste oil recovery unit of Figure 4.

[0027] Figure 6 is a photograph from above the waste oil recovery unit of Figures 4 and 5 and showing the interior of the vessel of the waste oil recovery unit.

[0028] Figure 7 is a photograph from above the waste oil recovery unit of Figures 4 to 6 also showing the interior of the vessel of the waste oil recovery unit and the solids separator.

[0029] Figure 8 is a photograph showing a detail external view of the pump compartment for the waste oil recovery unit of Figures 4 to 7.

[0030] Figure 9 is a photograph of the front end of the waste oil recovery unit of Figures 4 to 8. [0031] Figure 10 is a photograph showing part of one embodiment of a mechanical float switch system for use in level control in the waste oil recovery unit of Figures 4 to 9.

[0032] Figure 11 is a photograph showing another part of the mechanical float switch system shown in Figure 10.

[0033] Figure 12 is a photograph of an alternative rear end wall arrangement to that shown in Figure 5.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] Referring to Figures 1 and 2, waste oil recovery unit 10 comprises a housing 11 ; and a vessel 18 within the housing 11 for collecting waste cooking oil from a restaurant using cooking oil for frying. However, other sources of waste oil - whether from cooking or otherwise - are common and may be used in other embodiments. The vessel 18 has a base 15 and an upper portion 19, the base being provided with four rollers in the form of castors 90 to allow the waste oil recovery unit 10 to be moved through the restaurant as required. Housing 11 is also provided with a handle 92 to make moving the waste oil recovery unit 10 easier.

[0035] The waste oil recovery unit 10 further includes an oil transfer line 30, 39, 40, 45, 75 for connecting the vessel 18 to a source of oil (not shown); and a vacuum pump 20 connected to the vessel 18, separately from the oil transfer line, for causing suction of waste oil from the oil source external to the waste oil recovery unit 10 through the oil transfer line 30, 39, 40, 45, 75 and into the vessel 18. Vacuum pump 20 is located in a pump compartment 12 having a removable cover 60. As shown in Figure 2, the removable cover 60 includes an electric socket 50 for connection to a power supply external to the housing 11 and a power switch 44 for the waste oil recovery unit 10.

[0036] The vacuum pump 20 is located in the upper portion of the vessel 18. In this location, the vacuum pump 20 is within the envelope of the housing 11 of the waste oil recovery unit 10, away from a ground engaging location. The risk of damage of a vacuum pump located below the base 15 and location outside the envelope of the housing 11 , for example by collision with kerbs or other ground located objects, is therefore avoided. Exposure to water and detergents, and debris, during kitchen floor cleaning routines is also avoided.

[0037] However, the vessel 18 includes a tank 18a extending from the base to the upper portion 19 for storing waste oil. The pump compartment 12 located in the upper portion 19 for accommodating the vacuum pump 20 takes up space in the vessel 18 which reduces the effective volumetric capacity of tank 18a. This is problematic when a trade off has to be made between the volume of the waste oil recovery unit 10, the space available for accommodating the waste oil recovery unit 10, practical handling of the waste oil recovery unit 10 and the volume of oil to be removed into the vessel 18 of the waste oil recovery unit 10.

[0038] Further, the vacuum pump 20 is connected through a vacuum intake duct 24 extending to a vacuum port 22. Intake duct 24 is protected by a shroud 23 with asymmetric box-like design, as described in International Patent Publication No. WO 2022082270, adapted for deflecting oil droplets downward and away from the vacuum port 20 so minimising the suction of waste oil into the vacuum pump 20 since this will damage the pump. Possible challenges from this arrangement arise from somewhat complicated manufacture of the shroud 23 and also from an incomplete removal of oil vapour travelling through vacuum intake duct 24 to vacuum pump 20.

[0039] Further, the restaurant waste oil recovered by tank 10 contains solids - some carbonised - which also require disposal by the restaurant operator. The solids separator 48 is therefore provided external to housing 11 of waste oil recovery unit 10. The hose 40 is provided with a suction nozzle 45 for connection to the waste oil source. A strainer, in the form of mesh 48, is located at the suction nozzle opening 46 to prevent substantially any solids reaching the oil tank 18a. This arrangement is effective but unsuitable for applications where it would be desirable to recover solids into waste oil recovery unit 10. Blockage at the mesh 48 during pumping of waste oil is also an issue.

[0040] Referring now to Figures 3 to 9, there is shown a waste oil recovery unit 110 of preferred embodiments of the invention. The waste oil recovery unit 110 has a housing 111 and a vessel 118a within the housing 111 for collecting waste oil. The housing 111 is conveniently of a metallic material, such as Grade 304 stainless steel, which resists vacuum without buckling which can be an issue with a moulded polymeric material as was preferred for the waste oil recovery unit 10 as shown in Figures 1 and 2 though the Applicant has contemplated using bracing of the housing 10 to address the buckling issue.

[0041] The vessel 118a, which could also be described as a tank, has a base 115 and a top portion 110a. The top portion 110a has a wall or lid 115a which may be lifted by hinge(s) (not shown) located at end 115b of wall 115a. Thus, the vessel 118a can be accessed for maintenance and cleaning. When the top portion 110a is closed, vessel 118a is sealed minimising escape of oil vapour. The upper surface of wall 115a also provides a convenient working surface for the restaurant compensating for space constraints.

[0042] A pump housing or compartment 112 is also located proximate end 115b of wall or lid 115a. The pump housing 112 accommodates vacuum pump 120 and is located above wall portion 112a of wall 115a and mounted to it. In this embodiment, the vacuum pump 120 is mounted on a short side of the waste oil recovery unit 110 closest to the hinge(s). This minimises the weight that needs to be lifted to lifted by an operator (or motor) when opening the lid 115a and allows a simpler design than would be required with a dedicated lid for the pump compartment 112. In other embodiments, vacuum pump 120 could potentially located at any convenient location on the wall 115a. However, a central location of vacuum pump 120, for example mid-way along the length of the waste oil recovery unit 110, would likely be disadvantageous, through possible bowing of the wall 115a (dependent on its thickness and weight) when vacuum is applied. If such bowing were to occur, at least the vacuum port 124a would be away from the highest oil level in vessel 118a avoiding risk of flooding the vacuum system with oil.

[0043] As shown in Figure 9, pump compartment 112 includes a vent 112a comprising a plurality of slots which is straightforward to fabricate and which allows air circulation around the motor of the vacuum pump 120 for cooling purposes.

[0044] In its location above wall portion 112a and vessel 118a, the pump compartment 112 takes up no volume within the vessel 118a in contrast to pump compartment 9 of the waste oil recovery unit 10 as shown in Figure 1. Thus, vessel 118a has a higher volumetric capacity for given width dimensions of the waste oil recovery unit 110 and this allows a better trade off between the several factors of the volume of the waste oil recovery unit 10, the space available for accommodating the waste oil recovery unit 10, practical handling of the waste oil recovery unit 10 and the volume of oil to be removed into the vessel 18 of the waste oil recovery unit 10 as mentioned above. Figure 3 is schematic and it will be understood that the width dimensions are likewise schematic and, as supplied, waste oil recovery unit 110 may have the same cross sectional area as the waste oil recovery unit 10. A further advantage of the upper location of the pump compartment 112 is that, unlike the waste oil recovery unit 10 shown in Figures 1 and 2, the housing 111 does not require fabrication to accommodate a particular type of cooling duct arrangement.

[0045] The pump housing 112 may be removed to enable access to the vacuum pump 120 forming, with vacuum duct 124 and vacuum port 124a, the vacuum system of wastre oil recovery unit 110. As shown in Figure 8, pump compartment 112 includes an electric socket 170 for connection to a power supply external to the housing 111 , an on switch 172 and an off switch 174 for the waste oil recovery unit 110.

[0046] Vacuum pump 120, in this embodiment, is fixed to the wall portion 112 through a suitable mounting that minimises pump vibration and associated noise. In this embodiment, the vacuum pump 120 is arranged directly above a vacuum port 124a located in wall portion 112a. The vacuum port 124a is of circular shape. Vacuum port 124a communicates with the vacuum pump 120 through vacuum duct 124 which has lesser diameter than the vacuum port 124a enhancing flow rate through the vacuum duct 124. Vacuum suction is low profile with preferred vacuum in this embodiment having a minimum 123mm Hg and a maximum or sealed vacuum of 175mm Hg.

[0047] Air drawn toward the vacuum port 124a by suction of vacuum pump 120 is expected to contain oil droplets and vapour which could damage the vacuum pump 120, for example by impeding operation of its impeller (not shown). Build up of oil in the vacuum duct 124 and vacuum pump could also, over time, present a fire hazard as well as lowering the efficiency of the vacuum system.

[0048] An oil separator 123 is therefore located below vacuum port 124a, to separate oil droplets and/or vapour before these can enter the vacuum system comprising vacuum port 124a, the vacuum duct 124 and the vacuum pump 120. The oil separator 140, in this embodiment, includes a suitable filter material 142 for removal of oil droplets as known in the art of oil separation by filtration. As shown in Figure 4, the oil separator 123 may include a holder 144 for the replaceable filter element which here comprises filter material 142 (e.g. Scotch Brite type) folded to provide a plurality of filter layers or pads and acting as a stack filter. The holder 144 is fixed to the wall portion 112a of the housing 111 below the vacuum port 124a. Conveniently, the filter material 142 may be slid into and out of position within the holder 144. The oil separator 123 is easily accessible by opening of hinged lid 115a and no additional hinging or vacuum seals are required though, in other embodiments, such features could be included if desired.

[0049] The vacuum pump 120 is of a conventional design having a snail shell casing providing a snail shell shaped volute which assists in reducing escape, from the waste oil recovery unit 110, of any oil vapour remaining downstream of the oil separator 140.

[0050] The waste oil recovery unit 110 further includes an oil transfer line which is not shown in Figure 3 but would enter the vessel 118a as indicated by arrow A in Figure 3 and the components of which are described with reference to Figure 5. As evident from Figure 3, the oil transfer line is separate from the vacuum pump 120 and it is vacuum drawn by vacuum pump 120 through vacuum duct 124 that, through vacuum effect, causes oil to flow through the oil transfer line and into the vessel 118a. That is vacuum pump 20 does not, and is not intended to, pump oil directly through it.

[0051] In addition, to reduce quantity of oil droplets and possibly vapour impacting the oil separator 140 and the vacuum duct 124, the oil delivery line, and more particularly oil delivery pipe portion 132, enters the waste oil recovery unit 110 at the opposite end of the vessel 118a to the location of the oil separator 140 and vacuum port 124a proximate end 115b of wall portion 115a.

[0052] The oil transfer line comprises a plurality of portions additional to oil delivery pipe portion 132 including, as shown in Figure 5, a transfer portion 128 which connects to the oil source (not shown). The transfer portion 128 further includes a flexible hose portion 135, located externally of the vessel 118a and which is conveniently mounted to housing 111. Flexible hose portion 135 has length selected for convenient mounting to housing 111 while allowing flexibility and ease of connection when connecting oil source to waste oil recovery unit 110. The oil source is connected to flexible hose portion 135 via lance 129. The transfer portion 128 may include an oil flow control valve.

[0053] At its other end, flexible hose portion 135 is connected to oil inlet line portion 131 which feeds oil delivery pipe 132. Oil inlet line portion 131 is connected to oil delivery pipe portion 132. Both oil inlet portion 131 and oil delivery pipe portion 132 are both of stainless steel. In an alternative embodiment, as shown in Figure 12, oil delivery line 131 is replaced by a shorter spigot 137 which connects with the flexible hose portion 135 for feeding oil delivery pipe portion 132. Spigot 137 and oil inlet line portion 131 are of stainless steel which is both corrosion and temperature resistant. Spigot 137 is arranged at an angle which, together with shorter length than oil inlet line portion 131 , allows better suction than for the arrangement shown in Figure 5. In the embodiment of Figure 12, lance 129 is located on the left-hand side of waste oil recovery unit 110.

[0054] Insulation of oil transfer line portions is not necessary in embodiments where waste oil is being recovered other than as a safety feature.

[0055] Oil delivery pipe portion 132 discharges into the vessel 118a through oil discharge port 134 located above the solids separator 148. Oil delivery pipe portion 132 has a downwardly inclined or radiused terminal portion 132a which terminates in the oil discharge port 134 to deliver oil to the solids separator 148. In embodiments, the oil delivery pipe portion 132 may have increasing internal flow diameter along its path from the intake or feed port on the external surface of housing 111 to the oil discharge port 134.

[0056] Solids separator 148 is located within the vessel and below the oil discharge port 134. The solids separator 148 may take a number of forms and may be selected from the group consisting of a strainer, basket or mesh with openings narrow enough to capture a major proportion of solids but without substantially affecting pressure drop and rate of collection of oil through the oil transfer line whilst the vacuum pump is operating. The solids separator 148 is conveniently replaceable.

[0057] More particularly, in this embodiment, the solids separator 148 is in the form of a square cube comprising perforated side walls 148c, base wall and perforated splash guard 148a with a plurality of perforations 148b distributed across each of their respective surfaces as shown in Figures 5 to 7. The side walls 148c and splash guard 148a are conveniently metallic, here Grade 304 stainless steel, suitable for handling of hot oil. In other preferred embodiments, splash guard 148a and its perforations 148b may be omitted. [0058] A rectangular space 148d is left between the splash guard 148a and three of the side walls 148c in embodiments where splash guard 148a is included. Oil discharging from oil discharge port 134 flows through the space 148d and into the solids separator 148 and flows predominantly through the perforated base. The perforated wall and base arrangement tends to slow the velocity of the oil flowing from the oil discharge port 134 and reduces splashing. Splash guard 148a is located in position to capture splashing in the direction of the vacuum port 124a. However, it will be appreciated that the solid separator 148 itself functions as a splash guard allowing the flow rate of oil into the vessel 118a to be optimised (i.e to speed discharge of oil from the oil source) while minimising the load of oil droplets and vapour impacting the vacuum port 124a, vacuum duct 124 and vacuum pump 120. It will also be appreciated that, in other embodiments, the oil separator 148 may have different construction and geometry.

[0059] Waste oil recovery unit 110 has a volume capacity which is higher than that for waste oil recovery unit 10 which takes up the same amount of space in the restaurant kitchen. However, there is an upper limit to the acceptable oil level within the vessel 118a and oil level within vessel 118a is therefore sensed by level sensor system, one embodiment of which may be a float valve system 160 for which a range of configurations are available. The float valve system of Figure 6 is a difference fluid level measuring system, for example that float valve available from Atelec Australia, 9006 Series as described at www ,mateteoaustraha, the contents of which are hereby incorporated herein by reference. The cable of the float valve system 160 (which is rated up to 60°C) is secured to achieve the selected upper limit oil level for vessel 118a.

[0060] The float valve system 160 may be connected to a controller for waste oil recovery unit 110 or to a cut off switch for vacuum pump 120. Level control may be of ON/OFF type using the float valve system 160 with 1 ) an “on” state in which oil is supplied to vessel 118a where available and oil level is below the upper oil level limit and vacuum pump 120 turned off; or 2) an “off” state where an oil flow control valve is closed when the oil level reaches the upper oil level limit of travel of the float valve (larger blue item) of the float valve system 160.

[0061] Referring to Figures 10 and 11 , another embodiment of float valve system 160 comprises a float valve 162, a cut rod 164 and electrical cut off contactor 168. Float valve 162 is heat resistant being made, in this embodiment, of stainless steel. Cut rod 164 is connected to pivot about a swing hinge 170 and has a riser portion 167 which connects with the electrical cut off contactor 168. Cut rod 164 is also connected to float valve 162.

[0062] As to operation of float valve system 160, float valve 162 rises as the oil level in the vessel 118a reaches it. This places upward pressure on cut rod 164 which pivots upwardly due to its ability to rotate relative to swing hinge 170. When the upper level limit of float valve 162 travel is reached, the riser portion 167 of cut rod 164 actuates the electrical cut off contactor 168 to ‘off’ position which shuts off operation of vacuum pump 120. Consequently, delivery of oil to vessel 118a is also shut off without operation of vacuum pump 120.

[0063] The oil level sensor or float valve system 160 is selected so as not to obstruct other components of waste oil recovery unit 110 such as the solids separator 148. Other float valves, switches or other level control systems may be employed.

[0064] The oil transfer line 128, 132, 135 may include a temperature sensor (not shown) to measure oil temperature. The temperature sensor is connected to the controller for waste oil recovery unit 110. The controller shuts off, for example through switching vacuum pump 120 off, oil delivery to the vessel 118a if oil temperature exceeds a relatively low predetermined value, for example 50°C. It will be appreciated that pumping of hot oil is a safety hazard, with burn injuries common and potentially serious, and transfer to the waste oil recovery unit 110 of excessively hot oil is to be avoided irrespective of economic considerations which encourage this. A lower temperature oil also indicates less oil vapour within vessel 118a that could be carried through to vacuum pump 20 and this assists maintenance as well.

[0065] Vacuum pump 120 may also be shut off and incapable of drawing oil into the vessel 118a if the lid 115a is open or imperfectly closed, as detected for example by a suitable sensor.

[0066] As shown in Figure 9, waste oil recovery unit 110 is also provided with four rollers in the form of castors 90 to allow the waste oil recovery unit 110 to be moved through a restaurant kitchen or other premises as required. As shown in Figures 3, 6 and 7, the housing 111 is also provided with a handle 92 to make moving the waste oil recovery unit 110 easier. However, the castors 90 are, in this embodiment, of greater dimension than for waste oil recovery unit 10. This allows a higher ground clearance to be achieved to clear kerbs and other features of a ground surface, the castor dimension being a function of the ground clearance required for a particular premises.

[0067] With further reference to handle 92, this is at the opposite end of the waste oil recovery unit 110 to the end 115b and vacuum pump 120. Having the handle 92 at the opening end of lid 115a may help an operator hold the waste oil recovery unit 110 steady whilst the lid 115a is being opened. In other embodiments, the waste oil recovery unit 110 would not need to be moved manually but could be provided with a motor and controller that allows autonomous or semi-autonomous operation.

[0068] Modifications and variations to the waste oil recovery unit described in this specification may be apparent to skilled readers of this disclosure. Such modifications and variations are within the scope of the present disclosure.

[0069] Throughout this specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers