Chapter 7 N40475 In some cases it is necessary to have a number of fuel tanks in order to achieve the required operating range. In such cases, where possible, one tank should be regarded as the main tank for each engine and the other tanks should be arranged so that they will drain into the main tank by gravity. If a gravity system is not possible, then the system shown in figure 3 should be used. Figure 3 shows a collector tank (1), fed by all the storage tanks and connected to the engine feed (2) and return systems (3), but with a vent pipe (4) taken to any convenient tank.
There is no doubt however, that a simple fuel system as illustrated in figure 1 should be used wherever possible, as having a completely separate tank and supply to each engine guarantees that if an engine stops, due to running out of fuel or to water or foreign matter in the fuel, the other engine will not be affected simultaneously. This will give some time for appropriate manoeuvring action to be taken. The simple system will also require the minimum number of valves and fittings, which ensures maximum reliability in service. Figure 3 Alarm tank If the engine is equipped with duplex fuel pipes the sensor in the alarm tank detects if there is a leak in the inner fuel pipe.
When there is a leak, the fuel will occupy the cavity between the two fuel pipes and flow down to the alarm tank and activate the sensor alerting the operator. Note: Additional monitoring devices are required that are not incorporated within the ECM. Page 22