3.The screw 4 moves the valve 6 up or down. The liquid flows out from the side hole of the upper valve body 5 through the lower valve body 7. If an emergency occurs during the oil discharge process, such as a fire, and it is too late or impossible to climb to the top of the tank to close the bottom valve, the emergency valve operating handle can be pulled to quickly cover the oil outlet of the lower valve body with the emergency valve 8, so that the vehicle can leave the scene quickly.
The operating position of the emergency valve is generally set at the rear or side of the car to ensure that people can easily operate it on the ground.
Emergency valve: Some tank trucks are equipped with an emergency valve separately. This valve is in the open position (the dotted position of the handle 5 and valve 10) during normal use. When the bottom valve leaks or an emergency occurs during the oil discharge process, the handle 5 can be pushed up, and the valve 10 closes the oil outlet under the action of the spring 9 and the liquid to stop the oil discharge. In addition, when the tank truck is transported over long distances, the emergency valve should also be closed to prevent the bottom valve from loosening due to the bumps and vibrations of the vehicle, causing a large amount of oil leakage and causing accidents.
The maintenance of valves is the key to ensuring the safe production of tank trucks. Mainly check whether the valve rotation or opening and closing is flexible and reliable, and whether there is any leakage. If leakage occurs, it can generally be repaired by grinding the valve, replacing the sealing ring, adjusting the sealing gap (preload), replacing the spring, etc.
4.Static elimination device
In order to eliminate the static electricity generated by the tank truck during refueling, draining and transportation, prevent static electricity from causing fires, and ensure safe production, the tank truck is equipped with a variety of static elimination devices.
(1) Mopping tape or chain: The mopping tape or chain is installed at the rear of the tank truck and is a necessary device for the vehicle, often called a grounding chain. One end is connected to the tank body and the other end is used to mop the ground. During use, the mopping tape or chain is absolutely not allowed to leave the ground to eliminate the static electricity generated by the tank truck during driving. When the mopping tape or chain is worn out after a period of use, the fixing bolts at the rear section of the frame can be loosened to pull out a section of the mopping tape or release a few sections of the mopping chain. If the mopping tape or chain cannot be extended any further, it should be replaced or connected with a few more chains.
(2) Winch-type grounding device: This grounding device is a commonly used static elimination device for tank trucks, as shown in Figure 7-17. During the entire process of refueling or draining the tank truck, the plug 5 must be inserted into the socket at the oil pipeline of the tank truck, and then the grounding rod 1 must be inserted into the ground or connected to the ground wire of the oil depot (or gas station) to form an equal potential between the tank body and the oil pipeline and the earth, thereby achieving the purpose of eliminating static electricity. Wires 2 and 4 are respectively wound and unwound with a hand-cranked reel to adjust the length of the wire.
In order to reduce the curb weight of the tank truck, some tank trucks are now only equipped with a static conductive connection plate. When in use, pull out the ground wire of the oil depot or gas station and clamp it on the static conductive connection plate on the tank truck with its clamp.
Similarly, a grounding wire must be installed at the end of the drain hose.
(3) Electrostatic neutralization device: The working principle of the electrostatic neutralization device is to neutralize static electricity by ionizing the surrounding medium and generating ions with opposite polarity.
Commonly used electrostatic neutralization devices include induction neutralizers (or anti-static tubes) and radioactive neutralizers. Electrostatic neutralization devices are generally installed on the oil outlet pipeline of the filter to eliminate more static electricity accumulated due to the increase in the mutual friction area between the oil and the filter element.
5.Oil pump
The oil pump used in the refueling truck generally adopts a self-priming vortex pump with low pressure and large flow. In recent years, not only lubricating oil refueling trucks have adopted circular arc gear pumps, but also fuel refueling trucks have adopted circular arc gear pumps as the power element of the refueling truck, as shown in Figure 7-19. This pump has a small size, is easy to install on the car, and has the advantages of small pulse, smooth operation, high efficiency, low noise, and long life. The power of the oil pump generally comes from the car engine, and the gear pump is driven to rotate through the power output device and the drive shaft to suck the oil into or discharge the device.
