A fan is a device to agitate or move air or gas. It is basically a device for creating a current of air by movement of a surface or surfaces. It is used to move air or gas from one location to another, within or between spaces, for industrial reasons, or for residential use, for ventilation purposes or to increase the circulation of air in a living space. Fans have broad surfaces that usually revolve in motion.
Leaves or flat objects, waved to produce a more comfortable atmosphere, have not entirely given way to variable-speed electromechanical devices. In the course of their development, fans have exhibited a great variety of materials, a richness of decorative artwork, and associations with sophisticated milieus that belie the origins of this humble and apparently universal tool.
Applications include ornamental decorations, climate control, cooling system, refreshing air, personal wind-generation (e.g., an electric table fan), ventilation (e.g., an exhaust fan), winnowing (e.g., separating chaff of grain), removing dust (e.g., sucking as in a vacuum cleaner), cuttings, and to provide draft for a fire.
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The fan has an ancient history. Fan history stretches back thousands of years. Since antiquity, fans have possessed a dual function, one as a status symbol and the other as useful ornament. In the course of their development, fans have been made of a variety of materials, have included decorative artwork, and been a universal tool. The simplest kinds are leaves or flat objects, waved to produce a more comfortable atmosphere. These rigid or folding hand-held device has been used for cooling, air circulation, ceremonial device, and a sartorial accessory throughout the world from ancient times. They are still used.
The fan may have had tropical origins. The earliest known fans are called 'screen fans' or 'fixed leaf fans'. These instruments were manipulated by hand to cool the body, to produced a breeze, and ward off insects. Such early fans usually took the form of palm leaves. Some of the earliest known fans have came from Egyptian tombs. Early Assyria and Egypt employed slaves and servants to manipulate these instruments. In Egyptian reliefs, fans were of the rigid type. Tutankhamum's tomb possessed gold fans with ostrich feathers, matching depictations on tomb walls. Long-handled, disk-shaped fans were carried by attendants in ancient times and were associated with regal and religious ceremonies. They had handles or sticks attached to a rigid leaf or to feathers. Plumage of birds were used in fans, such as the Egyptians and Native American Indians, that had both practical and ceremonial uses.
In the ancient Americas, the Aztec, Maya, and South American cultures used bird feathers in their fans. This had a religious connotation. In India, the Hindi term for a fan is 'pankha' (a derivative of "a feather" or "a bird's wing"). Pictorial evidence records that the Greekss, the Etruscans, and Romans used fans as cooling and ceremonial devices. In Greece, linen was stretched over leaf-shaped frames. In Rome, gilded and painted wooden fans were used. Roman ladies throughout the empire used circular fans. Chinese sources link the fan with mythical and historical characters.
In China, screen fans were used throughout society. The earliest known Chinese fans are a pair of woven bamboo side-mounted fans from the second century BC. In ancient China, the symbol for a fan means 'a bird's wing' and looks like a wing. In modern China, the symbol for a fan, 'shan', means 'feathers under a roof'. The Chinese fixed fan, pien-mien, means 'to agitate the air'. The Japanese language's symbol for a fan is related to birds. Fans entailed certain regulations of societal norms for the Chinese people. A particular status and gender would accord a specific type of fan to an individual. The first folding fans were developed in medieval Japan and China. The folding fan was invented in Japan and taken to China in the 9th century. The Akomeogi (or Japanese folding fan; 衵扇; Hiôgi) originated in the sixth century. These were fans held by aristocrats of the Heian period when formally dressed. They were made by tying thin stripes of hinoki (or Japanese cypress) together with thread. The number of strips of wood differed according to the person's rank. They are used today by Shinto priests in formal costume and are brightly painted. The Chinese dancing fan was developed in the seventh century. The Chinese form of the hand fan was a row of feathers mounted in the end of a handle. In China, the folding fan came into fashion during the Ming dynasty between the years of 1368 and 1644. The Mai Ogi (or Chinese dancing fan) has ten sticks and a thick paper mount showing the family crest. Chinese painters crafted many fan decoration designs. The slats, of ivory, bone, mica, mother of pearl, or tortoise shell, were carved and covered with paper or fabric. Folding fans have "montures" which are the sticks and guards. The leaves are usually painted by craftsman. Social significance was attached to the fan in the Far East. The management of the fan became a highly regarded feminine art. The function and employment of the fan reached its high point of social significance in Japan (the japanese even used fans as a weapon [called the tessen]).
Printed fan leaves and painted fans are done on a paper ground. The paper was originally hand made and displayed the characteristic watermarks. Machine made paper fans, introduced in the 19th century, are smoother with an even texture.
In Europe, during the Middle Ages, the fans were absent. The West's earliest fan is a flabellum (or ceremonial fan), which dates to the 6th century. Hand fans were reintroduced to Europe in the 13th century and 14th century. Fans from the Middle East were brought back by Crusaders. In the 15th century, Portuguese traders brought fans to Europe from China and Japan. Fans became generally popular. In the 1600s, the folding fan, introduced from China, became popular in Europe. In the 17th century and 18th century, fans reached a high degree of artistry and were being made throughout Europe. Folded fans of lace, silk, or parchment were decorated and painted by artists. Fans were imported from China by the East India Companies at this time, also. Around the middle 1700s, inventors started designing mechanical fans. Wind-up fans (similar to wind-up clocks) were popular in the 1700s. In the 19th century in the West, European fashion caused fan decoration and size to vary.
The first recorded mechanical fan was the punkah fan used in the Middle East in the 1500s. It had a canvas covered frame that was suspended from the ceiling. Servants, known as punkah wallahs, pulled a rope connected to the frame to move the fan back and forth.
The Industrial Revolution in the late 1800s introduced belt-driven fans powered by factory waterwheels. Attaching wooden or metal blades to shafts overhead that were used to drive the machinery, the first industrial fans were developed. When Thomas Edison and Nikola Tesla introduced electrical power in the late 1800s and early 1900s for the public, the personal electrical fan was introduced. Between 1882 and 1886, Dr. Schuyler Skaats Wheeler developed the two-bladed desk fan, a type of personal electric fan. It was commercially marketed by the American firm Crocker & Curtis. In 1882, Philip H. Diehl introduced the electric ceiling fan. Diehl is considered the father of the modern electric fan. In the late 1900s, electric fans were used only in commercial establishments or in well-to-do households. Heat-convection fans fueled by alcohol, oil, or kerosene were common around the turn of the 20th century.
In the 1920s, industrial advances allowed steel to be mass-produced in different shapes, bringing fan prices down and allowing more homeowners to afford them. In the 1930s, the first art deco fan was designed. Before this fan, called the Silver Swan, most household fans were fairly plain. In the 1950s, fans were manufactured in colors that were bright and eyecatching. Central air-conditioning in the 1960s brought an end to the golden age of electric fan. In the 1970s, Victorian-style ceiling fans became popular.
In the twentieth century, fans have become utilitarian following the social and economic trends of society. During the 2000s, fan aesthetics have become a concern to fan buyers. The fan is part of everyday life in the Far East, Japan, and Spain (among other places).
Mechanically, a fan can be any revolving vane or vanes used for producing currents of air, in winnowing grain, blowing a fire, or for ventilation. A fan can also be used for checking rapid motion by the resistance of the air; e.g., a fan blower or a fan wheel.
Mechanical revolving blade fans are put on the floor or a table, or hung from the ceiling, or are built into a window, wall, roof, chimney, etc., and also into instruments, e.g. a computer. They are also used to move air for cooling purposes, as in automotive engines and air-conditioning systems, and are driven by belts or by direct motor. Fans create a wind chill but do not lower temperatures directly.
Fans usually use electric power. Electric fans generally consist of a set of rotating blades that are placed in a protective housing that permits air to flow through it. The blades are rotated by an electric motor that is either AC-powered or battery-powered.
Fans used in industry come in two main types, axial and centrifugal. The axial-flow fans have blades that force air to move parallel to the shaft about which the blades rotate. Axial fans blow air across the axis of the fan, linearly, hence their name. The centrifugal fan has a moving component (called an impeller) that consists of a central shaft about which a set of blades form a spiral pattern. Centrifugal fans blow air at right angles to the intake of the fan, and spin (centrifugally) the air outwards to the outlet. An impeller rotates, causing air to enter the fan near the shaft and move perpendicularly from the shaft to the opening in the scroll-shaped fan casing. The action of a fan or blower causes pressures slightly above atmospheric, which are called Plenums.
Basic elements of most electrical mechanical fans include the fan blade, base, stator with armature and lead wires, blade guard, motor housing, oscillator gearbox, a badge, rotor, and oscillator shaft. The oscillator is a mechanism that motions the fan from side to side. The rotor goes inside a stator. Current comes through the lead wires and flows into the armature, which is a series of electromagnets. The rotor makes and breaks contacts turning on (or off) each of the electromagnets. These pull the rotor around. One end of the rotor is attached to the blade and the other is attached to the oscillator gearbox. The motor case joins to the gearbox to contain the rotor and stator. The oscillator shaft combines to the weighted base and the gearbox. A motor housing covers the oscillator mechanism. The blade guard joins to the motor case for safety. The badge is a logo nameplate. Electric fans are powered by standard electrical lines.
Electro-mechanical fans, among collectors, are rated according to their condition, size, age, and number of blades. Four-blade designs are the most common. Five-blade or six-blade designs are rare. The materials from which the components are made, such as brass, are important factors in fan desirability.
A fan suspended from the ceiling of a room is a ceiling fan. It usually has a light associated with it to replace any displaced light. These devices are generally used in homes without central air conditioning. Ceiling fan controls usually include one for speed (slow, medium, and fast), one for the light (on and off), and one for directional control of the fan blades (clockwise and counterclockwise). Ceiling fans can be used as a cooling device in warm months (pulling air up) and a heat transferer (pushing air down) in colder months.
In a fan heater, a fan (or blower) blows cool air past a heating element, heating the air (forced convection). It has a fan wheel with vanes fixed on a rotating shaft inclosed in a case or chamber, to create a blast of air (i.e., the fan blast) for forge purposes.
A fan is also a small vane or sail that is used to keep the large sail of a smock windmill always in the direction of the wind.
See also: Turbine, Wind turbine, Windmill
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