If the fuel tank is placed higher than the engine feed pump, a shut-off cock should be installed in the fuel line to the feed pump. During downtime, this cock should be closed. Maximum permitted fuel level in the fuel tank is 3.5 m in relation to the feed pump.
The fuel tank must not be positioned so low that the vacuum in feed pump suction pipe is greater than 0.3 bar. The risk of air leaks in the suction pipe increases with increased vacuum. See also the section Flow and pressure.
If the fuel tank is mounted so low that the maximum permissible vacuum is exceeded, or if a large fuel tank is required which cannot be mounted close to the engine, a buffer tank must be installed at a suitable distance and height. A feed pump must be fitted directly downstream of the tank. The flow for the auxiliary feed pump must be minimum 15% higher than the flows specified in the Feed pump flow rates section, scania trucks,trucks scania,scania trucking,scania cars,scania car,scania truck usa.
If a reliable and quick starting response is required, the buffer tank should be positioned adjacent to the engine with the lowest fuel level at the same level as the feed pump. If the fuel tank(s) are built in, the space should be well ventilated. The fuel tank should normally be drained once a year, but this may vary depending on the quality of the fuel.