The vacuum suction truck uses a vacuum pump to evacuate the tank and then uses atmospheric pressure to press sewage into the tank. Normally the vacuum suction truck will be equipped with an anti-overflow valve. The anti-overflow valve can prevent the tank from being pumped to a certain extent. But because the principle of the anti-overflow valve is to connect the air inside and outside the tank after being floated by the sewage, so that the air pressure can be balanced, and the vacuum environment can be destroyed to prevent the full suction effect. There is no sound in actual use. If you do other things and don’t pay attention when suctioning sewage, it will lead to flooding. Because after the anti-overflow valve of the sewage suction truck is opened, it will take time for the air pressure inside and outside the tank to balance, about a few seconds. It may have filled the tank in a few seconds. And if it is working at high power, the air flowing into the tank from the anti-overflow valve cannot make up for the suction of the vacuum pump, resulting in continuous suction into the tank, and the sewage will enter the circulation to reach the water vapor separator, oil and gas separator and vacuum pump. Especially there are many impurities in the sewage. After entering the vacuum pump, the vacuum pump is still rotating at a high speed at this time, and the impurities will rub against the scraper of the vacuum pump and the inner wall of the pump, which will cause the scraper and inner wall of the vacuum pump to wear, and cannot form an efficient seal. The suction effect is reduced, or even can not be pumped.


When the tank overflows, the power take-off should be closed first, and then the sewage in the tank should be discharged. Then clean the entire loop. Including the water vapor separator, oil and gas separator, there is a drain valve below, open it to discharge the sewage, then clean it with clean water, then drain it and clean it with engine oil.


The cleaning of the vacuum pump is troublesome. If the impurity does not enter the pump body, you can open the drain screw under the pump body, add oil into the oil barrel, and turn the vacuum pump by hand to make the oil clean the impurities in the pump and flow out from the drain screw. If impurities have entered, it is necessary to disassemble the vacuum pump and clean it with water and oil. After cleaning, you should check whether there are scratches on the scraper and the inner wall of the pump, and whether there is any gap after the scraper is installed. If it is indicated that the scraper and the pump body have been worn out and are not suitable for continued use, the scraper or vacuum pump must be replaced as needed.


At present, the new sewage suction trucks of CLVEHICLES manufacturers have been equipped with double insurance of anti-overflow valve and buzzer alarm according to user requirements. When the liquid level reaches a certain height, the buzzer alarm starts to howl. At this time, the vacuum pump can be turned off, which greatly reduces the possibility of filling the tank.