The anti blocking design of the impeller of the self-priming sewage pump ensures high efficiency and no blocking. Excellent hydraulic model is adopted, and the efficiency is 3~5% higher than that of general self-priming sewage pump. The self-priming height is 1m higher than the general self-priming sewage pump, and the self-priming time is shorter. The self-priming sewage pump adopts the pump body structure of axial liquid return. The self-priming sewage pump body is composed of a suction chamber, a liquid storage chamber, a scroll chamber, a liquid return hole, a gas-liquid separation chamber, etc. after the self-priming sewage pump is normally started, the impeller sucks in the liquid stored in the suction chamber and the air in the suction pipe together, and is fully mixed in the impeller. Under the action of centrifugal force, the liquid entrains the gas to flow to the outer edge of the scroll chamber, forming a white foam belt with a certain thickness and a high-speed rotating liquid ring on the outer edge of the impeller. The gas-liquid mixture enters the gas separation chamber through the diffusion tube. At this time, due to the sudden decrease of the flow rate, the lighter gas is separated from the mixed liquid, and the gas continues to rise and discharge through the pump body outlet. The degassed liquid returns to the liquid storage chamber, enters the impeller again through the return hole, mixes with the gas inhaled from the suction pipe inside the impeller, and flows to the outer edge of the impeller under the action of the high-speed rotating impeller. As this process goes on repeatedly, the air in the suction pipe decreases continuously until the air is exhausted, and the self-priming sewage pump completes the self-priming process, and the self-priming sewage pump is put into normal operation. The self-priming sewage pump is a sewage pump with a certain self-priming capacity, and its self-priming height is also limited. How to improve its self-priming height in product technology and how to improve its self-priming capacity during installation and use are the focus of our research and analysis. The self-priming sewage pump is known as a vacuum pump product that can pump water. It combines the structural characteristics of the water ring vacuum pump and the self-priming sewage pump, which can quickly generate high negative pressure and transport high proportion of chemical media. It uses the impeller, pump body and cover plate to form a multi-channel sealing chamber for rapid exhaust. It takes only 2 seconds to fill water at a height of 3 meters, and 8 seconds to fill water at a height of 5 meters. Compared with ordinary self-priming sewage pumps, it greatly improves the efficiency and replaces traditional self-priming sewage pumps in many fields. The self-priming sewage pump produced by our company has a high suction lift, which is also known as the high suction lift self-priming sewage pump. The pump shaft and motor shaft are integrated, and have better stability. It is easier to use than the oil barrel pump in barrel loading and transportation. It can not only completely transport the media at the bottom of the barrel, but also directly switch between two barrels in one second. It can work continuously by making a multi way connector at the import. The actual use cost is lower than that of the oil barrel pump. Multiphase mixed conveying technology is a practical product in the field of conveying chemical media with high viscosity and high proportion, as well as in the food and beverage industry. The general self-priming sewage pump does not need to install the bottom valve when the suction head is about 5 meters. If it is more than 5m, the suction head can be improved by adding a bottom valve at the end of the inlet, generally about 1m. The horizontal distance at the entrance and the number of elbows, especially the 90 degree angle and continuous turns, shall be minimized. Like centrifugation, irrigation and diversion can effectively shorten the self-priming time. Now the large flow self-priming sewage pump is equipped with a vacuum auxiliary device. Instead of irrigation and diversion, start the vacuum pump to exhaust, and the suction head is increased to more than 8 meters. The large-scale self-priming sewage pump produced by our company uses the latest semi open impeller and spiral impeller, which have good anti blocking ability and strong cutting function. The precision CNC machining technology allows the clearance between the impeller and the inner wall of the pump body to be as small as possible (the impeller of the cutting self-priming sewage pump is embedded in the mouth ring). The self-priming sewage pump with proper suction head can not only save cost but also meet the actual demand.