Book - School of Science and Technology

Liquid fuel 305VentDip pipeFill pipeBurner return(if required)Suctionto plantNon returnvalveStop valveDrain cockOil proof renderingFigure 11.3 Oil tank and connections, below groundTank fittingsStorage tanks must be provided with a variety of fittings, some as part of the tankand others related to filling. The following is a brief summary of the principalitems:Manhole. Except in the case of small domestic tanks, a manhole with an air-tight coverjoint must be fitted. Internal and external ladders should be fitted.Vent pipe. A vent from each tank, preferably of the same size as the fill pipe, is required. Itshould be carried up to some point where any fumes will not be troublesome, perhapsto the roof of an adjacent building. A bird guard should be fitted at the terminal. Oilmay rise in the vent pipe when a tank is over-filled and thus impose an excessivepressure on the shell. An alarm device of some sort is desirable to give warning of thiscondition and an oil-seal trap or one of the proprietary unloading devices should befitted.Sludge valve. Water, being denser than oil, collects at the bottom of a tank together withsludge and other solid matter. This accumulation must be removed at intervals througha sludge valve which should be easily accessible. In the case of buried or undergroundtanks, this can be a messy business.Level indicator. Gauge glass indicators, although positive, are not very durable; dip-sticksare inconvenient; direct mounted dial gauges are subject to damage and what areknown as `cat and mouse' float levels are thought by some to be fallible. There is avariety of hydrostatic remote reading gauges available, as Figure 11.4, and electricallyor (better) pneumatically operated versions may be obtained.