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Pumps are mechanical devices designed to move fluids or increase their pressure. They transfer energy—either from a prime mover or an external source—to the fluid, thereby increasing its energy level. These machines are widely used to transport various types of liquids, including water, oils, acids, bases, emulsions, suspensions, and even liquid metals. Pumps can also handle gas-liquid mixtures and fluids containing solid particles.
Water lifting has always been essential for human survival and industrial progress. In ancient times, many early water-lifting devices were developed. For example, in Egypt around 1700 BC, chain pumps were used, while in China, similar mechanisms called "tangerines" appeared at the same time. Later, in 1100 BC, pot and lantern pumps were used, and by the first century AD, water tankers became common. One of the most famous early inventions was the Archimedean screw, created around 250 BC in Greece. It could lift water smoothly and continuously to a height of several meters, and its principle is still used in modern screw pumps.
Around 200 BC, a fire pump was invented by the Greek engineer Ctesibius, which was one of the earliest forms of a piston pump. Although it had the basic components of a modern piston pump, it wasn't until the invention of the steam engine that this type of pump really took off. In the 1840s and 1850s, the United States saw the development of the Worthington pump, a direct-acting steam-driven piston pump, marking the birth of the modern piston pump.
During the 19th century, piston pumps reached their peak in development and were widely used in hydraulic presses and other machinery. However, as water demand grew, low-speed, heavy-duty piston pumps gradually gave way to high-speed centrifugal and rotary pumps after the 1920s. Despite this, reciprocating pumps still play a major role in high-pressure, low-flow applications. Diaphragm and plunger pumps, in particular, have unique advantages and are increasingly used in specialized industries.
Rotary pumps emerged alongside the growing need for more diverse liquid transportation solutions. The earliest known record of a four-blade vane pump dates back to 1588, and various rotary pump designs followed. However, these pumps suffered from issues like leakage, wear, and inefficiency until the early 20th century, when improvements in rotor lubrication and sealing allowed them to become more efficient. With the introduction of high-speed motors, rotary pumps capable of handling higher pressures and viscous liquids began to develop rapidly.
The concept of using centrifugal force to move water first appeared in sketches by Leonardo da Vinci. In 1689, the French physicist Denis Papin invented a four-bladed impeller volute centrifugal pump. Later, in 1818, the so-called Massachusetts pumps with radial straight blades and half-open double-suction impellers appeared in the U.S., bringing the design closer to modern centrifugal pumps. From 1851 to 1875, multi-stage centrifugal pumps were developed, enabling the creation of high-head pumps. The theoretical foundation for centrifugal pump design was laid during this period.
It wasn’t until the late 19th century, with the invention of high-speed motors, that centrifugal pumps found their ideal power source and became widely adopted. Through the work of scholars like Reynolds in Britain and Pfrederick in Germany, the efficiency of centrifugal pumps improved significantly, expanding their performance range and application areas. Today, they are the most commonly used pumps, with the largest output volume.
Pumps can be classified in various ways, such as by their operating principles: positive displacement pumps, power pumps (like centrifugal pumps), and others such as jet pumps, water hammer pumps, electromagnetic pumps, and gas lift pumps. They can also be categorized based on driving methods (electric or water-driven), structure (single-stage or multi-stage), use (boiler feed or metering pumps), and the type of liquid being handled (clean, corrosive, or slurry pumps).
Positive displacement pumps operate by changing the volume within a chamber through reciprocating or rotating motion, allowing for suction and discharge. Reciprocating pumps use linear motion, while rotary pumps rely on rotational elements like gears, screws, or vanes. Positive displacement pumps typically provide a constant flow rate regardless of pressure, whereas power pumps depend on impeller speed and may exhibit pulsations in flow.
Centrifugal pumps, a type of power pump, are the most common. They convert kinetic energy into pressure energy, offering stable and continuous flow but generally lacking self-priming capability. Their performance parameters include flow, head, power, speed, and net positive suction head (NPSH). These parameters are interrelated and often represented on characteristic curves, which help determine the optimal operating point.
In practice, pump selection involves ensuring the operating point falls within the recommended working range provided by the manufacturer. Additionally, factors like liquid viscosity affect pump performance, so heating may be necessary to reduce viscosity and improve efficiency.