COOKING OIL/FAT FILTERING APPARATUS

Abstract: A cooking oil/fat filtering apparatus in which contaminated oil/fat is pumped at pressure from a fat fryer (1) through a first filter (5) to remove large food particles therefrom above 80 microns in size. The oil/fat is then pumped at pressure through a second filter (11) containing a removable cartridge (12) preferably made of wood pulp fibres, the clean fat/oil then being pumped under pressure back to the fat fryer (1) or to a separate holding tank. Before the pump is activated, a heater (20) can be activated to melt any coagulated oil/fat residue which may be present in apparatus prior to start up.

Description: COOKING OIL/FAT FILTERING APPARATUS This invention relates to a filtering apparatus for cooking oil or fat. Cooking oil/fat is used in a wide range of cooking methods which fry the food at temperatures of up to 250°C. The food being fried tends to contaminate the oil/fat and this initiates oxidation, hydrolysis and polymerisation which in turn greatly reduces the life and quality of the oil/fat. As a result, the oil/fat needs to be drained from the fryer through a gauze filter to remove the large food particles. This needs to be done on a regular basis, usually daily, which is time consuming and inconvenient particularly as the fat fryer usually needs to be switched off to allow the fat to cool before it can be filtered. It is an object of the present invention therefore to provide a filtering apparatus which can be used to filter fat/oil while it is still at its cooking temperature thereby avoiding any need to interrupt the cooking cycle. According to the invention there is provided a cooking oil/fat filtering apparatus comprising a pump, an inlet for contaminated oil/fat, an outlet for cleaned oil/fat, and first and second filters containing a removable filter element, the arrangement being such that, in use, contaminated oil/fat is pumped at pressure through the first filter where large particles of contaminant are removed and the oil/fat is then pumped through the second filter where smaller particles of contaminant are removed, the clean oil being supplied thereafter to the outle . Preferably, the first and second filters each comprise a housing containing a replaceable filter. Cartridge filters are particularly suitable. The first filter element is preferably operable to remove large food particles above 80 microns in size. The second filter element removes contaminant particles of a lesser size than those removed by the first filter, preferably down to 2 microns in size. Desirably, the second filter element contains a plurality of closely wound fibres which act as the filter medium and wood pulp fibres have been found to be particularly suitable. Preferably the fibres are supported in a roll of material which is received in the filter housing. This has the advantage of providing the maximum possible surface area for filtration. In the preferred embodiment, the pump is a positive displacement pump which operates at a pressure up to a maximum of 120 psi (8 bar) . Preferably the apparatus includes heating means operable to melt any coagulated oil or fat residue which may be in the apparatus prior to start up. The apparatus can be incorporated as an integral part of a fat fryer and can be switched on as required. In this arrangement, the inlet and outlets are connected to the fat fryer and means are provided to activate the pump whereby contaminated oil/fat can be continuously drawn off from the fat fryer, fed through the filter apparatus at pressure and returned clean to the fryer without the need to switch the fryer off. Alternatively, the apparatus can be used as a stand alone piece of equipment, the inlet being connected to a lance or wand which can be inserted into the fat fryer to draw the fat/oil therefrom for filtration in the apparatus. In this arrangement, the outlet is connected to a storage tank associated with the apparatus which includes means such as a wand for returning cleaned fat/oil therefrom to the fat fryer. The advantages of the apparatus of the present invention are that it enables any large food particles to be filtered out by the first filter. As the apparatus can be used to filter the oil/fat at cooking temperatures (up to 250°C) it requires no break in production. Furthermore, the apparatus enables the life of the - 4 - oil/fat in the fat fryer to be extended by up to 5 times and the quality of the oil/fat remains at a higher level for longer and therefore less oil/fat is required to cook the same volume of food. 5 A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing which illustrates an apparatus of the present invention permanently attached to and forming 0 an integral part of a fryer 1 containing cooking oil/fat 2. The bottom of the fryer 1 has an outlet 3 which is connected by conduit 4 to an inlet 4a in the bottom of a first filter 5. The filter 5 comprises a metal cylindrical housing 15 with a removable stainless steel 5 gauze filter cartridge 6 therein and a detachable top 15a sealingly fitted to the top of the filter housing 15. Oil/fat is supplied to the filter 5 through the conduit 4 and passes at pressure upwardly and radially outwardly as indicated by the arrows through the filter element 6 0 which has a mesh size in the range 80-120 microns. Filtered oil then leaves the filter 5 via outlet 4b and it then passes through conduit 8, positive displacement pump 9 and conduit 10 to the second filter 11. 5 The internal parts of the pump 9 are all made of materials which can work at temperatures up to 250°C and the pump operates at pressures from 50 psi up to a maximum of 120psi (8 bar) . The second filter 11 comprises a metal cylindrical housing 16 with a removable lid 16a sealingly attached thereto. The conduit 10 is connected to the bottom of the filter 11 at inlet 10a and cartridge filter 12 is mounted in the filter housing 16. Filtered oil from the pump 9 passes at pressure up a central opening 10b in the filter cartridge 12 and returns downwardly through the filter medium to the outlet 10c. The filter cartridge 12 is preferably made from compact wood pulp fibres which filter contaminant down to 2 microns in size. Other fibre materials can however be used. Preferably the filter cartridge comprises a roll of paper thereby ensuring the maximum surface area for filtration. The second filter 11 is connected by conduit 13 to outlet 14. In the illustrated arrangement, the outlet 14 is formed in the wall of the fat fryer 1. A heater element 20 is provided beneath the conduits 4, 8, 10 and 13 and the first and second filters 5 and 11 for reasons which will be explained shortly. The operation of the illustrated apparatus is as follows. Fat 2 in the fryer 1 is normally at a cooking temperature of up to 250°C. Once the person using the fryer realises that the fat needs to be cleaned usually because it has started to emit a blue smoke haze, a switch (not shown) can be actuated to activate the pump 9 which draws fat/oil from the fryer 1 through the outlet 3 and supplies it at pressure via conduit 4 to the first cartridge filter 5 where large food particles above 80 microns in size are removed by the stainless steel gauze filter 6. The filtered oil leaves the first filter 5 via outlet 4a and is pumped at pressure to the second filter 11 via conduit 10. The removable filter cartridge 12 is made of fibres such as compacted wood pulp fibres and filters smaller particulate contaminant down to 2 microns in size. The clean oil then leaves the second filter 11 and is returned to the fryer 1 via conduit 13 and outlet 14. The oil/fat is preferably pumped at a flow rate of 15 litres per minute by the positive displacement pump 9 which operates at a pressure of up to 120 psi (8 bar) and the oil is circulated and filtered on a continuous basis while the pump 9 is operating. The filter housings 15 and 16 are preferably made of aluminium. The removable lids 15a and 16a allow the cylindrical filter cartridges 6 and 12 to be replaced as required. The lids 15a, 16a are sealingly attached to the filter housings 15 and 16 by known 0 rings (not shown) which form a seal therewith and allow the system to operate at the required pressure of up to 120 psi (8 bar) . It will be appreciated that any residual oil or fat in the apparatus may coagulate and solidify when the apparatus is not in use. It is therefore desirable to provide heater 20 in the apparatus which is operable to melt any coagulated oil or fat residue which may be present prior to starting the apparatus from cold. Instead of incorporating the filter apparatus of the present invention into a fat fryer 1 as an integral part thereof as illustrated, it can be used as a stand-alone mobile unit. In such an assembly, the conduit 4 would have means such as a wand (not shown) attached to its free end which can be inserted into the fat fryer 1 located on site. Outlet 14 would open into a storage tank provided in the stand-alone mobile unit so that oil removed from the fat fryer 1 can be stored in the unit and then returned to the fat fryer once the cleaning process has been completed.

Claims: CLAIMS 1. Cooking oil/fat filtering apparatus comprising a pump, an inlet for contaminated oil/fat, an outlet for clean oil/fat and first and second filters containing a removable filter element, the arrangement being such that, in use, contaminated oil/fat is pumped at pressure through the first filter where large particles of contaminant are removed and the oil/fat is then pumped at pressure through the second filter where smaller particles of contaminant are removed, the clean oil being supplied thereafter to the outlet. 2. Apparatus as claimed in claim 1 wherein the first and second filters are contained in a filter housing. 3. Apparatus as claimed in claim 2 wherein the removable filter elements are cartridge filters. 4. Apparatus as claimed in claim 3 wherein the second filter cartridge contains a plurality of closely wound fibres. 5. Apparatus as claimed in claim 4 wherein the fibres are wood pulp. 6. Apparatus as claimed in any preceding claim wherein the first filter is operable to remove particles above 80 microns in size. 7. Apparatus as claimed in any of preceding claim wherein the second filter removes particles down to 2 microns in size. 8. Apparatus as claimed in any preceding claim wherein the pump is a positive displacement pump which operates at pressure. 9. Apparatus as claimed in claim 8 wherein the operating pressure of the pump is in the range from 50psi - 120psi (8 bar) . 10. Apparatus as claimed in any preceding claim including heating means to melt any coagulated oil or fat which may be present in the apparatus on start up. 11. Apparatus as claimed in any preceding claim wherein a lance or wand is attached to the inlet for drawing contaminated fat/oil from the fryer. 12. Apparatus as claimed in any preceding claim wherein the outlet is connected to a storage tank including means for returning cleaned fat/oil therefrom to the fat fryer. 13. Apparatus as claimed in any of claims 1-10 wherein the inlet and outlets are connected to the fat fryer and means are provided to activate the pump whereby contaminated oil/fat can be continuously drawn off from the fryer, fed through the filter apparatus and returned clean to the fryer. 14 . Cooking oil/fat filtering apparatus substantially as herein described with reference to the accompanying drawing.

Inventors: GOODHEW BRIAN DAVID, SAYERS JASON CHARLES, GOODHEW, BRIAN, DAVID, SAYERS, JASON, CHARLES
Applicants: GOODHEW BRIAN DAVID, PRO STAT UK LTD, SAYERS JASON CHARLES, GOODHEW, BRIAN, DAVID, PRO-STAT (UK) LIMITED, SAYERS, JASON, CHARLES
Application year: 1996
Main classification: A47J37
IPC codes: A47J37