There are many types of pumping machines, and the principles used are also different. However, the two more popular types of pumps on the market, piston pumps and centrifugal pumps, both use atmospheric pressure to pump water.
The use of atmospheric pressure to pump water abounds in daily life. When we use a straw to suck a drink, we suck most of the air out of the straw, so that the pressure inside the straw is reduced, and the drink flows down the straw to our mouth under the action of the external pressure.
Piston pumps and centrifugal pumps, although they are very different in terms of technical details, the physics of pumping water is based on atmospheric pressure. The piston pumping machine has a simple structure, and there is a piston in the suction pipe, and there are valves in the piston and the pipe (as shown in the figure below). When the piston moves downward, the valve on the piston opens, the valve in the pipe closes, and the water flows to the piston;When the piston moves upward, the valve on the piston is closed, and the piston moves upwards to lift the water, and at the same time, the pressure in the pipeline decreases, and the water (or groundwater) in the pool pushes open the piston in the pipe under the action of atmospheric pressure and enters the pipeline. Most of the early pumping machines were piston type.
The centrifugal pump uses spiral fan blades instead of pistons, relying on the fan blades to "throw out" the water, causing the pressure in the pipeline to decrease and make the water move along the pipeline. Most of the centrifugal pumps on the market are now seen.
Both types of pumps need to be filled with water before working in order to create a better sealing environment.