Three Types of Vacuum Pumps
July 23rd, 2009. Published under Technology. No Comments.
In 1650, Otto von Guericke invented the vacuum pump. The vacuum pump was designed to remove gas molecules from a sealed volume so that it would leave behind a partial vacuum.
They are categorized into three main groups. The three main groups are positive displacement, entrapment and momentum transfer. The positive displacement pump uses a technique that repeatedly expands the cavity. In doing this it allows the gases to flow in from the chamber then seal off the cavity, and then it disperses it into the air.
The principal behind a positive displacement pump is that is the easiest way to make an artificial vacuum to expand the volume of a container. The need for this type of pump was because liquids cannot be pulled so it is impossible to create a vacuum by suction. The best example of this type of pump is the diaphragm muscle. It works just like a positive displacement pump; it expands the chest cavity, which causes the volume of the lungs to increase.
The entrapment pump works differently. It uses cold temperatures condense gases to a solid or adsorbed state. The pump works by trapping the molecules in a confined space. It works like a cryopump. They trap the liquefied gas molecules in a cold trap and then the ion pump uses the ionized gas that is magnetically confined.
The last category is the momentum transfer pump, which is also called molecular pump.This type works by using a high-speed jet of dense fluid or a high -speed rotating blade that knocks the gaseous molecules out of the chamber. With this type of pump the gas molecules are increased from the vacuum side to the exhaust side. This kind of pump can only work at pressures below of 1kPa. The matter moves differently depending on the pressure that is flowing thru the pump. This is based on the laws of fluid dynamics.
There are two main types of momentum transfer pumps. They are diffusion pump and turbo molecular pump. These two kinds of pumps blow out the gas molecules that spread out into the pump by giving momentum to the gas molecules.
The turbo molecular uses a high -speed fan to push the gases. But the diffusion pump works differently it blows out the gas molecules with a jet of oil or mercury. But both of these kinds of pumps will stall and fail to pump if they are exhausted directly to atmospheric pressure. They must be exhausted to a lower grade vacuum that is created by a mechanical pump.
There are different types of vacuum pumps, but they all a very specific purpose.
Matthew McKernan is an expert in the chiller and HVAC industry with over 20 years of experience. http://www.loikits.com