The cultural evolution of pumps and the development of various types of pumps

　　A pump is a machine that transports liquids or increases their pressure. It transfers mechanical energy from a prime mover or other external source to the liquid, thereby increasing the liquid’s energy. Pumps are primarily used to convey fluids such as water, oil, acidic and alkaline solutions, emulsions, suspensions, and even liquid metals; they can also handle mixtures of liquids and gases, as well as liquids containing suspended solids. The lifting of water has been of great importance to both human life and production. Even in ancient times, various water-lifting devices were employed, such as Egypt’s chain pump (17th century BC), China’s jie gao (17th century BC), the pulley (11th century BC), and the waterwheel (1st century AD). Furthermore, in the third century BC, Archimedes invented the screw pump, which could steadily and continuously lift water several meters high—a principle still utilized in modern screw pumps. Around 200 BC, the fire‑extinguishing pump invented by the ancient Greek engineer Ctesibius was a rudimentary piston pump, already incorporating the main components characteristic of piston pumps. However, piston pumps only experienced rapid development after the advent of the steam engine. Between 1840 and 1850, American inventor Worthington created a direct‑acting piston pump with opposed cylinder arrangements, marking the birth of the modern piston pump. The 19th century witnessed the peak of piston pump development, when they were widely employed in hydraulic presses and numerous other machines. Nevertheless, as water demand surged, starting in the 1920s, low‑speed piston pumps—limited in flow rate—gradually gave way to high‑speed centrifugal and rotary pumps. Nonetheless, reciprocating pumps continue to hold a dominant position in applications involving high pressure and low flow rates, particularly diaphragm and plunger pumps, whose advantages are increasingly recognized. The emergence of rotary pumps was closely linked to the growing diversity of industrial demands for fluid transport. As early as 1588, records exist of a four‑blade vane pump; subsequently, many other types of rotary pumps appeared. Yet until the 19th century, rotary pumps suffered from significant drawbacks, including substantial leakage, excessive wear, and low efficiency. In the early 20th century, advances in rotor lubrication and sealing technologies, coupled with the adoption of high‑speed electric motors, enabled the rapid development of rotary pumps suitable for higher pressures, moderate to small flow rates, and a wide range of viscous fluids. The variety of rotary pump designs and the breadth of fluids they can handle surpass those of other pump types. The concept of using centrifugal force to move water first appeared in sketches by Leonardo da Vinci. In 1689, French physicist Denis Papin invented a volute‑type centrifugal pump featuring a four‑blade impeller. However, the design most akin to modern centrifugal pumps emerged in the United States in 1818: the so‑called Massachusetts pump, equipped with radial straight blades, a semi‑open double‑suction impeller, and a volute casing. Between 1851 and 1875, multi‑stage centrifugal pumps with guide vanes were successively developed, paving the way for the creation of high‑head centrifugal pumps. Although Swiss mathematician Leonhard Euler proposed the fundamental equations governing impeller‑type hydraulic machinery as early as 1754—laying the theoretical groundwork for centrifugal pump design—it was not until the late 19th century, following the invention of the high‑speed electric motor—which provided an ideal power source—that the full potential of centrifugal pumps could be realized. Building on the theoretical research and practical contributions of scholars such as British scientist Osborne Reynolds and German engineer Ludwig Prandtl, centrifugal pump efficiency improved dramatically, expanding their performance range and areas of application. Today, centrifugal pumps are among the most widely used and mass‑produced pump types. Pumps are typically classified according to their operating principles into positive displacement pumps, dynamic pumps, and other specialized types, such as jet pumps, water hammer pumps, electromagnetic pumps, and gas‑lift pumps. Beyond classification by operating principle, pumps may also be categorized and named based on additional criteria. For example, by drive mechanism, they can be divided into electric pumps and waterwheel‑driven pumps; by construction, into single‑stage pumps and multi‑stage centrifugal pumps; by purpose, into boiler feed pumps and metering pumps; and by the nature of the conveyed fluid, into water pumps, oil pumps, and slurry pumps. Positive displacement pumps rely on working elements that perform reciprocating or rotary motion within the pump chamber, alternately increasing and decreasing the working volume to achieve suction and discharge. When the working element executes reciprocating motion, the pump is called a reciprocating pump; when it rotates, it is termed a rotary pump. In reciprocating pumps, suction and discharge occur sequentially within the same pump chamber, controlled by inlet and outlet valves. Rotary pumps, on the other hand, utilize the rotational action of gears, screws, blade‑shaped rotors, or vanes to propel liquid from the suction side to the discharge side. At a given speed or stroke frequency, positive displacement pumps deliver a relatively constant flow rate that remains nearly unaffected by changes in pressure. Reciprocating pumps, however, exhibit considerable pulsations in both flow and pressure, necessitating measures to mitigate these fluctuations. Rotary pumps generally show little or no pulsation. They possess self‑priming capability, enabling them to draw air out of the pipeline and begin pumping immediately upon startup. When starting such a pump, the discharge line valve must remain open. Reciprocating pumps are best suited for high pressure and low flow rates, while rotary pumps excel at medium to low flow rates under elevated pressures. Reciprocating pumps are particularly appropriate for conveying clean liquids or gas–liquid mixtures. Overall, positive displacement pumps tend to offer higher efficiency than dynamic pumps. Dynamic pumps operate by harnessing the kinetic energy generated through the rapid rotation of an impeller to impart momentum to the fluid, thereby increasing its kinetic and pressure energy. This energy is then transferred via the pump housing, where most of the kinetic energy is converted into pressure energy to facilitate fluid transport. Dynamic pumps are also known as impeller‑type or blade‑type pumps. Centrifugal pumps represent a common subtype of dynamic pumps. At a fixed rotational speed, dynamic pumps produce a limited head, with head varying according to flow rate. They operate stably, delivering continuous flow without pulsations in either flow or pressure. Typically lacking self‑priming ability, they require prior filling with liquid or vacuuming of the pipeline before operation. Their operational scope is broad, making them suitable for handling very low‑viscosity clean fluids; specially designed models can even handle sludge, wastewater, or solid‑laden fluids. Dynamic pumps are commonly employed for water supply, drainage, irrigation, process fluid transport, power‑station energy storage, hydraulic transmission, and ship propulsion systems. Other types of pumps refer to mechanisms that transfer energy through alternative means. For instance, jet pumps rely on high‑velocity jets of working fluid to draw the target fluid into the pump, achieving energy transfer through momentum exchange between two fluid streams. Water hammer pumps exploit the energy released when flowing water is abruptly halted, causing a portion of the water pressure to rise to a certain height. Electromagnetic pumps use electrically charged liquid metals, inducing motion under electromagnetic forces to accomplish fluid transport. Gas‑lift pumps channel compressed air or other compressed gases into the lower layers of a liquid, creating a lighter-than‑water gas–liquid mixture, which is then pushed upward by external liquid pressure. The key performance parameters of pumps include flow rate and head.