An electric pump is a machine that uses electrical power to increase the pressure of a liquid through centrifugal force. Though liquids cannot truly be compressed and pressurized, they can be imparted with kinetic energy and undergo pressure to follow a certain course.
Centrifugal force is the force that causes substances to move away from their center of rotation, and electric pumps use that force to lift and transport liquids. They are constructed from stainless steel, aluminum or cast iron and consist of an impeller, a volute (casing) and a motor. Electric pumps require electricity to run and therefore have power cords to keep them connected. Centrifugal pumps are used in commercial, industrial, general purpose and residential applications, most commonly with water. Electric pumps remove water from flooded areas and help facilitate proper drainage around buildings and roads. Some are small and light enough to be portable, such as those found to bail out boats or basements. Some heavy duty electric pumps are able to handle mixtures of solids and liquids such as water polluted with garbage. Wastewater and sewage treatment plants benefit from use of electric pumps as well. Besides trash, centrifugal pumps also transport chemicals to and from multiple processing containers. Harsh or hazardous chemicals require high grade metals that will not corrode or cause impurities in the product.
Electric pumps are relatively simple machines that accomplish massive amounts of work. A casing called a volute contains an impeller mounted on a rotating shaft. The electric motor uses its mechanical energy to turn the impeller whose blades then impart kinetic energy to the liquid as it begins to rotate along the casing. Momentum and pressure carry the water through the expanding volute until it exits through a discharge opening. The force can lift the liquid over 500 feet in the air or at a rate of 40,000 gallons per minute for industrial pumps. Small 12 volt pumps have a maximum of around 30 feet of lift or 10 gallons per minute. Electric motors are more commonly used than gas powered models because gas tanks add weight and bulk and also require refilling. In the case of vertical or submersible pumps, which are located underground or in the source of liquid, this is not a plausible option. For electric pumps, the power cords are carefully wrapped in a strong protective casing to prevent any leaks or damage. The three main kinds of flow that electric pumps produce are radial, mixed and axial; the differences come from the shape of the impeller and its affect on how the liquid is moved.
