1. Tank top, breather, oil injection port
The top structure of the fuel tank depends on the components installed on it. When the pump set is installed on the top of the box, the thickness of the top plate is four times that of the side plate to avoid vibration.
Ventilators and oil injection ports are generally provided on the top of the box, and the air vents are often structured with oil injection ports. Remove the breather cap to fill it with oil, and put it back into the breather cap to complete the breather filter. The mesh of the ventilation filter should be less than 250, the flow rate should be greater than 20L/min, the filtration accuracy should not be less than 40, and its capacity should be twice the capacity of the hydraulic pump.
The threaded holes on the top of the fuel tank should be blind holes (non-through holes) to prevent pollutants from falling into the fuel tank.
The connection details of the tank top and the tank wall are shown in Reference [6], Figure 7-67.
2. Box wall, cleaning hole, lifting lug (ring), level gauge
When the box top and the box wall are not detachably connected, at least one cleaning hole should be provided on the box wall. The number and location of the cleaning holes should be convenient for cleaning all inner surfaces of the fuel tank by hand. The cleaning port cover should be removable by one person. The cleaning hole cover plate should be equipped with a reusable elastic sealing ring.
For details of cleaning hole cover and flange cover, please refer to reference [6], as shown in Figure 7-66.
For details of cleaning hole size, flange cover and seals, please refer to Reference [6], Figure 7-66, Table 7-20.
In order to facilitate the transportation of the fuel tank, lifting lugs should be welded on the four corners of the fuel tank, and lifting holes should be provided for the fuel tank without feet. The level gauge is generally installed on the outer wall of the oil tank and close to the oil filling port to facilitate the observation of the liquid level during oil filling. The lower engraved line of the level gauge is at least 75mm higher than the upper edge of the suction filter or the suction pipe to prevent air suction.
3. The bottom of the box, the drain plug, and the feet
An oil drain plug (≥M18×1.5) should be installed at the bottom of the tank to facilitate cleaning of the tank and oil replacement. For this reason, the bottom of the tank should be inclined toward the cleaning hole and the drain plug. The slope is usually 1/25～1/20, so that the sediment (sludge and water) can be collected to the lowest point in the tank.
In order to facilitate oil discharge and transportation, the oil tank should be erected, and the oil tank should be at least 150mm above the ground. However, the fuel tank without feet is used in this design, so feet are not provided.
4. Diaphragm and degassing net
In the fuel tank, especially in the fuel tank with an oil capacity of more than 100L, a partition should be provided. The baffle should separate the oil suction area and the oil return area of the system, and make the oil circulate along the wall of the oil tank as much as possible. There should be a large enough flow area at the gap of the partition so that the circulation velocity is 0.3 ~ 0.6m/s. See reference [6], Figure 7-70 for the partition structure. The height of the overflow baffle should not be lower than 2/3 of the liquid level; there should be a gap under the baffle so that the sediment on the oil suction side passes through the gap and the oil return side, and is discharged through the oil discharge port. For the structure of the fuel tank, refer to Reference [5], Table 8-33 Rectangular fuel tank without feet.
In order to help the bubbles in the oil to surface, a degassing net can be installed in the oil tank. The degassing net is made of a metal net with a mesh diameter of 0.5mm, and is arranged obliquely. If the baffle plate and the inner surface of the fuel tank are connected by welding, the weld should be fully welded.
5. Pipeline configuration
1) Oil suction pipe and oil return pipe The oil suction pipe and oil return pipe of the hydraulic pump should enter the oil suction area and the oil return area separated by the baffle respectively, and the pipe ends should be processed into oblique openings facing the tank wall. The upper edge of the nozzle should be at least 75mm lower than the lowest liquid level, and the lower edge of the nozzle should be at least 50mm from the highest point of the bottom of the tank.
2) Sealing of perforations Oil pipes often pass through the top or wall of the tank and enter the fuel tank. The perforations must be properly sealed. It is best to weld a boss 20mm higher than the top of the tank at the interface to prevent dirt from falling into the tank during maintenance.
