A Hydraulic System of Petrol Storage.
Page 14
Page 15
If you've noticed an error in this article please click here to report it so we can fix it.
Few fluids are so difficult to handle by use of pumps -as are the lighter grades of petroleum. Petrol or any paraffin has an irritating way of oozing through joints and glands which would form effective barriers against the passage of practically any other fluid, even if such fluids be under considerable pressure. For that reason alone, the use of welded or jointless tanks is highly desirable. The Steel Barrel Co., Ltd., of Uxbridge, and T. Toward and Co., Ltd., of Ouseburn, Newcastle-on-Tyne, are two of the most-prominent manufacturers who have produced really-satisfactory storage vessels, and, so far as that portion of a fuelstorage installation is concerned, the products of these wo companies leave nothing to be desired. Bulk storage tanks are usually placed in vaults, and, there fore, the liquid fuel must ba pumped up or otherwise raised from the tanks to measuring vessels before its transference to the tanks of motor vehicles. If pumps are employed, there will be an appreciable leakage past the working parts, and, further, as the suction pipe for the pump must of necessity be led down to within an inch or two of the bottom of each storage tank, a n y water and dirt which may have settled to the bottom is sucked up and discharged from the pump deliver.. nozzle into the vessel which is being filled. Then again, as fuel is drawn off from the 'storage tanks, the .space occasioned by the removal .of the liquid becomes occupied by petrol vapour and air, which mixture, apart from its being a source of danger; represents a considerable amount of wasted fuel A system of storage in which, it is claimed, these objections have been entirely removed has been installed, and is giving mostsatisfactory results, in the garage of the New York Taxicab Co. The system to -which we refer is that of tie Hydraulic Oil Storage Co., built under the S n ell patents. Messrs. E. A. Cadwell and Co., of 40, Broad Street House, E.C., who represent the Hydraulic St age Co. Co. in this country, are at present putting down a large storage plant for the British Motor Cab Co., Ltd. The system, as may be 'imaged from the accompanying illustrations and derription, is remarkable for its simplicity. A referencs to the diagram on the foll ing page will show that the storage tank is at all times quite full of petrol, water,
or petrol and water, so that there is never any space left within the containing vessels for the accumulation of explosive gases. Water is admitted into the storage tank at the bottom from a constant-level cistern through a water inlet valve, the cistern itself being in direct communication with the town's watersupply service or any other convenient source. The system depends upon the well-known difference in the specific gravities of petrol and water, and upon the fact that these two fluids are not miscible. Anyone who cares to demonstrate these facts may easily do so with a glass U tube ; not only will it be found impossible permanently to mix the two fluids, but, with such a tube, it may easily be demonstrated that a column of water 12 in. high will balance a column of petrol about 17 in. high, the height of the petrol column varying slightly with its specific gravity.
The pressure due to the head of water between the storage tank and the cistern is used to force from the storage tank any petrol which may be stored within it, and to deliver that petrol, through a draw-off nozzle, at a point well above the water level in the cistern. Assuming that the storage tank is quite full of water, and it is desired to replace it with petrol, the first operation consists of raising the lever of the water-inlet valve, whic h action first of all shuts off the supply of water from the cistern and opens a passage from the storage tank to a convenient sewer. Petrol is then poured in through a bucket-shaped filter, and it passes through a non-return valve into the main storage tank, displacing an equal volume of water, which water escapes to the drain. Any water or dirt which may be present in the petrol settles to the bottom of the tank, and by no chance can it pass to the draw-off nozzle ; a perfectly-clean supply of petrol, therefore, is insured at all times. In a large installation there would, of course, be two or more sets of these tanks, and, before petrol w a s drawn off from any one tank, it could be given at least a few hours "rest," so as to enable all solid matter and water to separate and to settle to the bottom of the tank. Suitable gauges are, of course, provided, so that the store-keeper may readily check the amount of petrol which is being fed into the reservoir. It is claimed that the tanks cannot be over filiod, and this, of course, is very important, otherwise some petrol might escape from the storage tanks by way of the pipe which leads to the drains.
In order to draw off any quantity of petrol, the measuring vessel may be hung upon a hook provided at the draw-off nozzle, and the water-inlet valve should then be manipulated so as to shut off all exit to the drain and to admit water from the cistern into the main storage tank. The entering water, which has a greater effective constant head or pressure, due to the action of the float valve in the cistern, will drive out petrol so tong as the water valve remains open. Owing to the fact that the draw-off nozzle is some inches higher than the level of the water in the cistern, the discharge of petrol will cease as soon as the storage vessel becomes entirely fell of water, and water rises in the stand pipe to the same height as that in the cistern, unless, of course, the water valve has been closed earlier. A gauge glass is fitted in the stand pipe, so that the operator may receive due warning of the approaching exhaustion of the petrol supply in the cistern. Messrs. Cadwell and Co., at their offices in Broad Street House, have a beautifully-made model for demonstration purposes, a photograph of which we illustrate herewith. From that view' the sharp line of demarcation between petrol and water may clearly be seen. In that model, it should be noted, the top tank, which is marked "Water supply," would not, of course, be necessary were the cistern connected to the town mains, but, for the sake of convenience, such a. tank is fitted to the model. The exact arrangement of piping and the disposition of the tanks may, of course, be varied indefinitely to suit the existing conditions of any garage in which the. system may be installed.
We look forward to the time when we may examine the large installation which is now being put down at the British Motor Cab Co.s depot. Meanwhile, as the invention is of considerable merit, we would recommend operating engineers and depSt superintendents to get into touch with Messrs. Cadwell and Co., and there, at first hand, to observe the working ef this ingenious yet simple system.