AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicantss: Liquip International Pty Limited Invention Title: A FLUID STORAGE APPARATUS AND METHOD OF DELIVERING OR COLLECTING FLUID The following statement is a full description of this invention, including the best method for performing it known to me/us: P62891.AU.2 Pa1_Set_Fibng Appication 2009.1-13 doc (S) - 2 FLUID STORAGE APPARATUS AND METHOD OF DELIVERING OR COLLECTING FLUID Technical Field This invention relates to a fluid storage apparatus and 5 to a method of delivering and a method of collecting fluid. Background to the Invention Fluid storage apparatus may be installed at a fixed location, or they may be mobile such as in the case of a road 10 tanker such as a petrochemical tanker or a milk tanker. It is sometimes necessary to collect and store batches of fluid received from several locations. One example of this is in the case of a milk tanker. A milk tanker carries a fluid storage apparatus that usually has one or more large 15 storage chambers. The tanker visits various locations such as milk farms and collects a volume of milk at each location. At each collection, the milk is pumped through a flow meter and into one of the storage chambers. The flow meter measures the volume of milk that is collected by the milk 20 tanker and so the appropriate payment to the operator of each milk farm can be calculated. However, flow meters typically have a number of moving parts and are expensive to purchase. It is necessary to maintain flow meters to ensure accurate measurement and this maintenance is costly. 25 It is known to fit a petrochemical road tanker with a number of small compartments for storing fluid. Each compartment is equipped with a fluid level sensor to gauge the level of fluid in each compartment. The dimensions of each compartment are known and so the volume of fluid in a 30 compartment can be calculated based on the measured liquid level. Each compartment is generally used to store a different type of fluid. This means that the maximum amount -3 of fluid of a particular type that can be collected is limited by the size of each small compartment. Summary of the Invention 5 In a first aspect the present invention provides a fluid storage apparatus including: at least one primary chamber; at least one secondary chamber being substantially smaller than the primary chamber, the secondary chamber is equipped with a fluid volume measuring means to measure the 10 volume of fluid in the secondary chamber; and fluid transfer means for transferring fluid between the primary and secondary chambers. The volume of fluid can be measured in the small compartment and then transferred to be stored in the larger 15 compartment. The volume of fluid is measured without the need for a flow meter. By providing a primary chamber that is substantially larger than the secondary chamber, the volume of liquid that can be stored in the primary chamber is not limited by the volume of the secondary chamber. 20 In an embodiment, the fluid stored apparatus comprises a tank for storing or transporting fluid on an industrial scale. For example, storage or transport of water, petrochemicals, foodstuffs including milk and others. In an embodiment, the fluid storage apparatus is a 25 fluid storage tank arranged to hold large volumes of fluid. For example, the fluid storage tank may be a petrochemical tank arranged to store in excess of 1000 litres of petrochemical fluids. The storage tank may be fitted to a road tanker for transporting the fluids. 30 The secondary chamber may be provided inside the primary chamber. The secondary chamber volume to the primary chamber volume ratio may be between .1% to 20%, but preferably - 4 between .5% to 10%. For example, if the primary tank is arranged to hold 4000 litres, the secondary tank may have a volume of between 200 Litres to 400 Litres. The fluid volume measuring means may include a fluid 5 level sensor. The fluid level sensor may be a radar fluid level sensor. In a second aspect the present invention provides a method of collecting a batch of fluid including the steps of: 10 receiving fluid in a measuring chamber; measuring the volume of fluid in the chamber; and transferring the fluid in the measuring chamber to a storage chamber, the storage chamber being substantially larger than the measuring chamber. In a third aspect the present invention provides a 15 method of delivering a batch of fluid including the steps of: transferring fluid from a storage chamber to a measuring chamber, the storage- chamber being substantially larger than the measuring chamber; measuring the volume of fluid in the measuring chamber; and delivering the fluid from the 20 measuring chamber. In a fourth aspect the present invention provides a method of adapting a fluid storage tank including the steps of: providing a chamber that is substantially smaller than the storage tank and being equipped with a fluid volume 25 measuring means to measure the volume of fluid in the chamber; installing fluid transfer means for transferring fluid between the chamber and the storage tank. In a fifth aspect there is provided a fluid storage apparatus including: a primary chamber; a secondary chamber 30 located within the primary chamber and having a substantially smaller volume than the primary chamber, the secondary chamber including a fluid measuring device for measuring a volume of fluid within the secondary chamber and further - 5 including a valve operable between an open and closed state for allowing fluid to flow between the primary and secondary chamber, such that when the valve is open the first and second chamber assume the same fluid level. 5 In an embodiment the secondary chamber is located substantially at the volumetric centre of the primary chamber. In an embodiment a side wall of the secondary chamber is arranged to be in direct fluid contact with the contents 10 of the primary chamber. In an embodiment the valve is located in the side wall of the secondary chamber. In an embodiment the secondary chamber has a substantially cylindrical outer circumference. 15 In an embodiment the secondary chamber has an open upper end. In an embodiment the fluid measuring device is located in the volumetric centre of the secondary chamber. In an embodiment the second chamber includes a second 20 valve operable to allow fluid to flow between the secondary chamber and a fluid source/destination. In an embodiment the fluid source/destination is the primary chamber. In an embodiment the apparatus further comprises a 25 fluid transfer means for transferring fluid between the secondary chamber and fluid source/destination. In accordance with a sixth aspect there is provided a fluid storage apparatus including: a primary chamber; 30 a secondary chamber located within the primary chamber and having a substantially smaller volume than the primary chamber, the secondary chamber including a fluid measuring device for measuring a volume of fluid within the secondary - 6 chamber and further including an opening for allowing fluid to flow between the primary and secondary chamber, such that the first and second chamber assume the same fluid level. 5 Brief Description of the Drawings An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of a prior art road tanker; 10 Figure 2 is a side view of a road tanker according to an embodiment of the present invention; Figure 3 is a side view of a road tanker according to a second embodiment of the invention; and Figure 3A is a partial top view of the road tanker of 15 Figure 3. Figure 4 is a side view of a road tanker according to a further embodiment of the present invention. Detailed Description of the Preferred Embodiment 20 Referring to Figure 1, a prior art road tanker 10 for collecting milk is shown. Road tanker 10 includes two separate storage tanks in the form of compartments 12 and 13. Batches of milk that are collected by tanker 10 are introduced into one of compartments 12, 13 via a flow meter 25 (not shown) which measures the volume of the batches that are collected. The batches of milk that are collected are typically much smaller than the volume of either compartment 12, 13. A liquid level sensor could be provided in either compartment 12 or 13 and this could be used to calculate 30 changes in volume. However, this is not an effective approach because the volumes of the batches collected are typically too small to be accurately measured by level measurement.
-7 Referring to Figure 2, a road tanker 100 is shown, being a modified version of the tanker of Figure 10. Road tanker 100 includes a fluid storage apparatus including primary chamber in this embodiment being in the form of 5 storage compartment 12, and a secondary chamber in this embodiment being in the form of measuring compartment 14. Measuring compartment 14 has substantially right-cylindrical side walls and includes a filling aperture 16 sealable by removable cap 18. Measuring compartment 14 is equipped with 10 a fluid volume measuring means in this embodiment being in the form of radar fluid level sensor 20 provided at the volumetric centre of compartment 14. Fluid transfer means is provided for transferring fluid between the compartments, in this embodiment being in the 15 form of pipe 22 fitted with pump 24 and control valve 26. Operation of road tanker 100 will now be described with reference to collecting milk from various milk farms. Milk Collection: 20 At each milk farm a collection is made by receiving milk in measuring compartment 14. A pump is used to pump milk into compartment 14 through aperture 16. When the full capacity of measuring compartment 14 is almost reached then pumping is stopped and the volume of milk in compartment 14 25 is measured by way of fluid level sensor 20. The measured volume is recorded. The milk in compartment 14 is then transferred to compartment 12 by opening valve 26 and operating pump 24. More milk is then pumped into compartment 14 and the process is repeated. Each time compartment 14 is 30 filled, the volume is recorded and this is added to a running total. The process is repeated until all the milk from that milk farm has been collected. The final volume of milk received in compartment 14 will be a quantity smaller than - 8 the maximum capacity of compartment 14. This volume is recorded and the transfer of the final volume milk from compartment 14 to compartment 12 takes place whilst driving to the next milk farm. The final volume is added to the 5 running total to obtain a figure for the volume of milk collected from that particular milk farm. The same process is repeated at all milk farms and a record of the volume collected at each milk farm is compiled. The milk tanker 100 travels to a location such as a 10 dairy where all of the collected milk is off-loaded for processing. The milk is off-loaded directly from the large compartment 12 and does not pass through compartment 14. An advantage of this embodiment is that expensive to maintain flow meters are not required. Because the measuring 15 compartment is relatively small, and its dimensions are known, level measurement is reliable and volumes of batches can be calculated from the level measurement and from the known dimensions of the measuring compartment. 20 Delivery of Small Batches of Fluid: Road tanker 100 can also be used for delivery of small batches of fluid. The process is essentially a reverse of the collection process. A batch of fluid is transferred from storage compartment 12 to measuring compartment 14. The 25 volume in measuring compartment is measured by way of fluid level sensor 20 and the measured volume is then delivered out of measuring compartment 14 to be received in a storage tank at the delivery location. This process can be repeated at various locations and a record of the volume delivered to 30 each location is compiled.
-9 Alternative Configurations: Referring to Figures 3 and 3A, a road tanker 200 is shown. This tanker employs two measuring compartments 214 & 215 which are of the same construction as measuring 5 compartment 14 described above. This allows for faster operation as one measuring compartment can be filling whilst the other is emptying. In other embodiments, more than two measuring compartments may be provided. Two secondary chambers in the form of measuring 10 compartments 214 & 215 are provided inside storage compartment 212. In this embodiment, an air pocket 216 is provided around chambers 214, 215. Similarly, the outside walls of chambers 214, 215 could be in direct contact with the fluid in compartment 212. 15 Referring to Figure 4, a road tanker 400 according to an alternative embodiment is shown. According to this embodiment, a plurality of secondary chambers 414 are provided; each secondary chamber 414 being located substantially in the volumetric centre of a corresponding 20 primary chamber 412 (for simplicity, operation of only one compartment will be described hereafter in detail). The secondary chamber 414 is in the form of a measuring compartment 414 having a substantially smaller volume than the primary chamber 412 (hereafter "storage compartment") 25 In this example, the storage compartment 412 has a volume of 4000 litres and the measuring compartment 414 has a volume of 300 litres. The measuring compartment 414 comprises substantially right-cylindrical side walls which are in direct fluid contact with the contents of the storage 30 compartment 412. A fluid volume measuring means, such as a radar liquid level sensor, is located at the volumetric centre of the measuring compartment 414.
- 10 An opening is provided at a lower extremity of the measuring compartment's side wall. The opening can be closed off by way of a controllable valve 427 situated within the opening. When open, the valve 427 allows fluid to flow 5 between the measuring and storage compartments, thereby allowing the internal volume of the measuring compartment 414 to effectively form part of the storage compartment's 412 total volume. When valve 427 is closed, the measuring compartment 414 is isolated from the storage compartment 412 10 and becomes an accurate measuring chamber for measuring small fluid volumes. Fluid can be pumped into or out of the measuring compartment 414, via a second opening and valve configuration 426. A similar fluid transfer means to that described with reference to Figure 2 may be utilised to 15 effect such a transfer. When a small volume of fluid is required to be delivered/stored by the road tanker 400, the valve 427 can be closed and the fluid pumped into the now isolated measuring compartment 414 for accurately measuring the fluid volume. 20 Once a measurement has been taken, the fluid can subsequently be pumped to the desired location (e.g. to an external storage tank or to one of the tank's storage compartments 412), via the valve 426. Conversely, when a large fluid volume pickup/delivery is required (e.g. where the volume of 25 fluid to be measured greatly exceeds the total volume of the measuring compartment), the valve 427 can be opened to thereby allow the fluid measuring means to take a measurement of the total fluid volume collectively held by the measuring and storage compartments 412, 414. Opening the valve 427 for 30 large fluid volume deliveries/pickups provides that a sufficiently accurate measurement will still be obtained while minimising the time taken to complete the fluid - 11 transfer (i.e. there is no need to carry out multiple batch readings as would be the case if the valve 427 were closed). The above embodiment involved a fluid storage apparatus that was fitted to a road tanker. Similarly, the apparatus 5 could be fitted to a trailer, B-double, a dog trailer, semi rigid trailer or rigid trailer, or the like. The above described embodiment involved a fluid storage apparatus that was mobile by way of being mounted to a road vehicle. In an alternative embodiment, the fluid storage 10 apparatus is installed at a fixed location and can be used to receive or dispense batches of fluid. The above described embodiment concerned handling of milk but it will be understood by persons skilled in the art that the apparatus is suitable for handling any fluid whose 15 volume can be measured in measuring compartment 14 and stored in storage compartment 12. In the above described embodiment the volume of fluid in measuring compartment 14 was determined by use of a radar fluid level sensor. Similarly, other volume measuring 20 sensors could be used such as a float system or measurement by ultrasound. Although the secondary chamber described in the preceding paragraphs was in the form of a compartment having substantially right-cylindrical side walls it will be 25 understood by persons skilled in the art that any relatively slender/elongate shape would be suitable. Furthermore, it will be understood that the secondary chamber need not be constant cross-section so long as the chamber is suitably calibrated. 30 Embodiments of the present invention are suitable for use in measuring any liquid transfer which requires batching of relatively small (with respect to the total tank volume) fluid volumes. For example embodiments may be utilised for - 12 filling drums from large storage tanks (e.g. oils, paints, etc.); blending of fluid products according to a specific ratio (e.g. blending ethanol into petrol to produce/manufacture "E10" fuels), etc. 5 Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated. Finally, it is to be appreciated that various alterations or additions may be made to the parts previously 10 described without departing from the spirit or ambit of the present invention.