Pneumatic devices are various tools and instruments that generate and utilize compressed air.
The concept behind pneumatic tools has its origins in ancient times, but it was not until the last 500 years that it truly came to fruition.
The first compressors were probably bellows like devices developed sometime prior to 3000 B.C. They were used to provide small puffs of air to aid in fire starting. These evolved into larger, but not significantly more sophisticated, units used in basic metal smelting about 1500 B.C.
The hand bellows used by early smelters and blacksmiths for working iron and metals was a simple type of air compressor and the first pneumatic tool.
Greek mathematician Hero of Alexandria (c. 10 to 70 AD) is reputed to have thought of the field that gave birth to pneumatic tools (pneumatics) in the 1st century A.D. There is evidence of some of his inventions powered by steam and wind.
German physicist and engineer Otto von Guericke (1602 to 1686) is credited with having invented the air pump or compressor in 1650. The device sucked out air or gas from whatever vessel it was attached to. He experimented with copper enclosures called hemispheres, demonstrating that he could use the pump to pull apart the two halves. It could produce a partial vacuum and Guericke used it to study the phenomenon of vacuum and the role of air in combustion and respiration.
Two centuries after Guericke, pneumatic tools were developing beyond being mere exciting curiosities; they were now becoming practical.
Development of pneumatics remained relatively static until late in the 18th century when mechanical compressors achieved the capability of generating pressures as high as 15 psi. It was not until the 1800's that compressed air was seriously considered as an industrial energy transfer medium.
Once compressed air was commercially available, pneumatic devices were everywhere. The compressed air was used to power small air-powered electrical generators in restaurants, hospitals, and theaters. Engineers of the time proclaimed compressed air was the future in energy transmission and another emerging technology, electricity, had far too many technical shortcomings to ever be successful.
During the late 1800's, the use of compressed air and electricity expanded and each found its place; electricity being the most convenient form for large-scale energy transmission and pneumatics for specific industrial applications including power and process service and control functions.
In 1829, the first stage or compound air compressor was patented. A compound air compressor compresses air in successive cylinders.
By 1872, compressor efficiency was improved by having the cylinders cooled by water jets, which led to the invention of water-jacketed cylinders.
Pneumatics in the 19th century was dominated by the pneumatic tube, which was popularized by people in Victorian England using pipelines to transmit telegrams from one telegraph station to another. Also, John Wanamaker (1838 to 1922), an American merchant, introduced tube systems to the United States Post Office (when he was postmaster general) and department stores for transportation of mail items and money, respectively.
The best known pneumatic device is of course the pneumatic tube. A pneumatic tube is a method of transporting objects using compressed air. In the past, pneumatic tubes were often used in large office buildings to transport messages and objects from office to office.
The first documented genuine pneumatic tube in the United States is officially listed in a 1940 patent issued to Samuel Clegg and Jacob Selvan. This was a vehicle with wheels, on a track, positioned within a tube.
The most elaborate application of pneumatic tubes, however, was when Alfred Beach (1826 to 1896) built a pneumatic train subway in New York City based on his 1865 patent. The subway ran briefly in 1870 for one block west of City Hall. It was America's first subway. Alfred Beach practically invented the pneumatic subway line by demonstrating that a pipe was able to transport passengers. The Beach tunnel was constructed in only 58 days, starting under Warren Street and Broadway, directly across from City Hall. The station was under the south sidewalk of Warren Street just west of the Broadway corner. The single track tunnel ran east into Broadway, curved south, and ran down the middle of Broadway to Murray Street, a distance of one block, about 300 feet in all. The subway opened to the public on February 26, 1870.
Operated as a demonstration from 1870 to 1873, the short tunnel had only the one station and train car.
Tunnel portal Tunnel schematic
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The "cash carrier" invention sent money in little tubes traveling by air compression from location to location in department store so that change could be made. The first mechanical carriers used for store service was patented (#165,473) by D. Brown on July 13, 1875. However, it was not until 1882 when an inventor called Martin patented improvements in the system that the invention became widespread. Martin's patents were numbered 255,525 issued March 28, 1882, 276,441 issued April 24, 1883, and 284,456 issued on September 4, 1883.
The Chicago postal pneumatic tube service began between the post office and the Winslow rail road station on August 24, 1904. The service used miles of tube rented from the Chicago Pneumatic Tube Company.
Samuel Ingersoll invented the pneumatic drill in 1871.
Charles Brady King of Detroit invented the pneumatic hammer in 1890, and patented on January 28, 1894. Charles King exhibited two of his inventions at the 1893 Worlds Columbia Exposition; a pneumatic hammer for riveting and caulking and a steel brake beam for railroad road cars.
During the 20th century, use of compressed air and of compressed-air devices increased. Jet engines use centrifugal and axial-flow compressors. Automatic machinery, labor-saving devices, and automatic-control systems all use pneumatics.
Mass production on assembly lines as a standard industrial process increased the demand and application possibilities of compressed air. Today, the list of industrial applications is very long.
We use compressed air for:
MULTISPINDLE BARREL REAMING MACHINEreamer_off
Blowguns - Using their lungs, early hunters could develop 1 to 3 psi with a capacity of about 6000 cu. in/min.
Pneumatic rock drills - Early in the 19th century, compressors had been developed which were capable of producing 90 psi. A tunnel project was begun in Mt. Cenis, in the Alps, which was estimated to take 30 years to complete using manual drilling methods to cover 8 ½ miles. Using pneumatic rock drills, operating from over 4 miles of air lines, the tunnel was successfully completed in 14 years. It was open to traffic in 1871. This successful application attracted international interest leading many city governments to talk of building central compressor stations for citywide power.
Compressed air used in Paris - Paris, the city of lights, was actually the City of Air. In 1888, Paris installed a 65 HP compressor feeding 4 miles of mains with 30 miles of branches (a converted sewer system), delivering 90 psi. By 1891, the capacity was increased to 25,000 HP
Compressed air has been applied to control circuitry, dental drills, surgery, and many other industrial processes requiring high forces or impact blows. Light weight, durable and safe pneumatic tools such as pneumatic staplers and pneumatically powered impact wrenches are common.
There are a wide variety of pneumatic components available today.
Tubing today comes in a wide variety of sizes and can be made to the consumer's needs.
Components have long working life resulting in longer system reliability.
Safe to use
Only Semi-skilled manpower required for operation and maintenance
Best for use in inflammable area.
Far less moving parts inside, hence lower maintenance requirement.
Light in weight, yet sturdy in design.
Cheaper & lower technology options for control of speed.
Even considering investments on compressor, the pneumatic actuators are far more cost effective in terms of cost of ownership and return on investment.
If there is a power cut, pneumatic equipment will still function until the stored air in the compressor has been depleted.
As there are no fluids involved they can be used in a cleanroom environment.
Because air systems operate at relatively low pressure, the components can be made of relatively inexpensive materials.
Compressors and continuous compression can be expensive.
Air treatment is required to remove any oils, particulate and water vapour from the system.
The components are not reliable at slow speed.
Very low efficiency, less than 50% of input power is available at the work area.
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