8 Best Vacuum Pumps | April 2017
- 4 cfm air displacement
- includes bottle of oil
- limited included fittings
|Rating||4.0 / 5.0|
- exhaust port with cap
- lines are color-coded
- poorly written instructions
|Rating||3.9 / 5.0|
- clear built-in gauge
- made in the united states
- overheats quickly when oil gets low
|Rating||4.0 / 5.0|
- aluminum alloy casing
- anti-vibration coupling
- makes a lot of noise
|Rating||4.0 / 5.0|
- industrial strength
- perfect for hvac maintenance
- requires separate gauge
|Rating||3.9 / 5.0|
- tethered caps on oil drain
- comes with two-year warranty
- gas ballast vapor exhaust
|Rating||4.7 / 5.0|
- more than one meter of hose
- very easy to start
- high-volume cooling fan
|Rating||5.0 / 5.0|
- economical 7-cfm airflow
- 28-ounce lubricant capacity
- sturdy steel handle
|Rating||4.6 / 5.0|
A Brief History Of The Vacuum Pump
The suction pump was the precursor of the vacuum pump and is responsible for prompting the research that led to its development. The invention of the suction pump dates all the way back to the ancient city of Pompeii, which was founded in in the sixth or seventh century B.C. Suction pumps were also used in Arabia in the 13th century and later in Europe during the 15th century.
In the 17th century, as suction pumps become more and more powerful, scientist began to look at what was happening to the air after water was sucked out. All they knew at the time was that pulling water beyond a certain height with suction pumps was impossible. This limit, which was roughly 25 to 30 feet, was causing considerable problems for mine drainage, irrigation projects, and decorative water fountains that the Duke of Tuscany was planning. He commissioned Galileo to explore the problem and, hopefully, find a way to solve it.
It took the input of various other scientist to get to the bottom of what was happening. The first step was for Gasper Berti to reproduce the problem in 1639 using the first water barometer. Unfortunately, while he could reproduce it, he couldn't explain it. Four years later in 1643, a breakthrough was made by Evangelista Torricelli. He built the world's first mercury barometer and argued that the space left after the mercury was pumped out was a vacuum.
The first actual vacuum pump was created in 1654 by Otto von Guricke, and he used it to conduct the famous Magdeburg hemispheres experiment. In it, he demonstrated the power of atmospheric pressure by showing that two hemispheres, which had their air evacuated, could not be pulled apart no matter how much force was applied. He used two teams of horses pulling in opposite directions to illustrate his point.
Von Guricke's vacuum pump didn't capture the imagination of scientists, and the technology wasn't pursued until much later in 1855, when Heinrich Geissler invented the mercury displacement pump. His displacement pump created a record vacuum of roughly 10 Pascal units (Pa) and spurred renewed interest in vacuum pump technology, which led to the creation of the vacuum tube.
Understanding The Types Of Vacuum Pumps
While there are many different designs of vacuum pumps, they can be broadly categorized by the principle they make use of: positive displacement, momentum transfer, or entrapment.
The principle behind a positive displacement pump is that increasing the volume of a container can create a partial vacuum. One can then continue to evacuate the chamber without having to continually grow the container in size, by closing off the suction section of the chamber, evacuating the air, and then expanding it again. This creates a pressure differential which sucks air or gas in to fill the void.
Momentum transfer pumps make use of positive displacement pumps, but add momentum to the mix. Inside of a momentum transfer pump, gas molecules are accelerated as they travel from the vacuum side to the exhaust side. The exhaust side will often have a positive displacement pump maintaining the air at a reduced pressure. Momentum transfer pumps are best used at specific pressures and are not possible below pressures of 0.1 kPa. They are governed by the laws of fluid dynamics and their functionality is dependent on how molecules interact with each other. At atmospheric pressures, or in very mild vacuums, molecular pumping is more effective than positive displacement pumping.
Entrapment pumps work by using chemical reactions to create vacuums. Since the entire process takes place inside the area being vacuumed, they can be more effective. Entrapment pumps remove a thin film that is created by molecules in the air when they chemically react to some of the pump's internal surfaces. They are often used in conjunction with momentum transfer and positive displacement pumps to create ultra high vacuum chambers.
The Many Uses For Vacuum Pumps
Vacuum pumps may seem like something that only scientists and those working in certain industrial applications make use of, but this is entirely untrue. You probably interact with over a dozen mechanisms making use of some kind of vacuum pump each day without knowing it. Your car's door locks make use of a vacuum-based functionality as do hydraulic brakes. As you probably guessed, your vacuum cleaner has a vacuum pump inside, which is what is responsible for creating the suction.
Vacuum pumps are used in a number of different medical procedures such as pharyngeal aspiration, pleural suctioning, and subglottic secretion removal. They can be used in variety of automobile applications where they can help to add horsepower, keep oil cleaner, and increase the life of an engine.
You'll often find them in laboratory settings where they may be used to evaporate and condense solvents from biological samples, vacuum concentrated samples for research or aid in cell harvesting, tissue culture and freeze drying.
While the vacuum pump may have originally been intended to aid in the movement of water and overcome the limitations opposed by atmospheric pressure, it has become an essential piece of equipment in thousands of other applications.