Suction cup

A suction cup, also known as a sucker, is an object that uses the negative fluid pressure of air or water to adhere to nonporous surfaces, creating a partial vacuum.

Suction cups are anatomical traits of some animals such as octopuses and squids, and have been reproduced artificially for numerous purposes.

Theory

The working face of the suction cup is made of elastic, flexible material and has a curved surface. When the center of the suction cup is pressed against a flat, non-porous surface, the volume of the space between the suction cup and the flat surface is reduced, which causes the air or water between the cup and the surface to be expelled past the rim of the circular cup. The cavity which develops between the cup and the flat surface has little to no air or water in it because most of the fluid has already been forced out of the inside of the cup, causing a lack of pressure. The pressure difference between the atmosphere on the outside of the cup and the low-pressure cavity on the inside of the cup keeps the cup adhered to the surface.

Hydraulic press

A hydraulic press is a device (see machine press) using a hydraulic cylinder to generate a compressive force. It uses the hydraulic equivalent of a mechanical lever, and was also known as a Bramah press after the inventor, Joseph Bramah, of England. He invented and was issued a patent on this press in 1795. As Bramah (who is also known for his development of the flush toilet) installed toilets, he studied the existing literature on the motion of fluids and put this knowledge into the development of the press.

Principle

The hydraulic press depends on Pascal's principle: the pressure throughout a closed system is constant. One part of the system is a piston acting as a pump, with a modest mechanical force acting on a small cross-sectional area; the other part is a piston with a larger area which generates a correspondingly large mechanical force. Only small-diameter tubing (which more easily resists pressure) is needed if the pump is separated from the press cylinder.

Pascal's law: Pressure on a confined fluid is transmitted undiminished and acts with equal force on equal areas and at 90 degrees to the container wall.

Suction

Suction is the flow of a fluid into a partial vacuum, or region of low pressure. The pressure gradient between this region and the ambient pressure will propel matter toward the low pressure area. Suction is popularly thought of as an attractive effect, which is incorrect since vacuums do not innately attract matter. Dust is "sucked" into a vacuum cleaner when it is pushed in by the higher pressure air on the outside of the cleaner. The higher pressure of the surrounding fluid can push matter into a vacuum but a vacuum cannot attract matter.

Humans can create a sucking effect with the use of the lips, as in the case of drinking through a straw[class-7].

Pumps

Pumps typically have an inlet where the fluid enters the pump and an outlet where the fluid comes out. The inlet location is said to be at the suction side of the pump. The outlet location is said to be at the discharge side of the pump. Operation of the pump creates suction (a lower pressure) at the suction side so that fluid can enter the pump through the inlet. Pump operation also causes higher pressure at the discharge side by forcing the fluid out at the outlet. There may be pressure sensing devices at the pump's suction and/or discharge sides which control the operation of the pump. For example, if the suction pressure of a centrifugal pump is too low, a device may trigger the pump to shut off to keep it from running dry; i. e. with no fluid entering.

Vacuum

Vacuum is space void of matter. The word stems from the Latin adjective vacuus for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is lower than atmospheric pressure. The Latin term in vacuo is used to describe an object as being in what would otherwise be a vacuum.

The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. Much higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10⁻¹²) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm³.Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average. According to modern understanding, even if all matter could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, transiting gamma rays, cosmic rays, neutrinos, and other phenomena in quantum physics. In the electromagnetism in the 19th century, vacuum was thought to be filled with a medium called aether. In modern particle physics, the vacuum state is considered the ground state of matter.

Cupping therapy

Cupping therapy is an ancient form of alternative medicine in which a local suction is created on the skin; practitioners believe this mobilizes blood flow in order to promote healing. Suction is created using heat (fire) or mechanical devices (hand or electrical pumps).

Description

Through either heat or suction, the skin is gently drawn upwards by creating a vacuum in a cup over the target area of the skin. The cup stays in place for five to fifteen minutes. It is believed by some to help treat pain, deep scar tissues in the muscles and connective tissue, muscle knots, and swelling, however the efficacy of this has been questioned.

History

There is reason to believe the practice dates from as early as 3000 BC. The Ebers Papyrus, written c. 1550 BC and one of the oldest medical textbooks in the world, describes the Egyptians' use of cupping. Archaeologists have found evidence in China of cupping dating back to 1000 BC. In ancient Greece, Hippocrates (c. 400 BC) used cupping for internal disease and structural problems. This method in multiple forms spread into medicine throughout Asian and European civilizations. In 1465, cupping was recommended Serefeddin Sabuncuoglu, a Turkish surgeon, and called it mihceme.