Vacuum Pump Working and Type

About Vacuum Pump

vacuum pump

A vacuum pump is a type of system that is used to reduce fluid pressure, compared to limiting pressure, and is achieved through a vacuum system often used to remove surplus air and its elements. Additional reactants otherwise unnecessary by-products; Reducing the boiling point, etc. In many development industries, the concern is the degree of migration required to override. These pumps are classified into different types and are used by different requirements of vacuum and displacement levels in different processes.

Simply put, a vacuum pump is used to reduce the pressure in a closed container in caparison to atmospheric pressure. in simple word,  vacuum means blew atmospheric pressure
Vacuum pump efficiency mainly depends on various parameters such as pumping speed and throughput. The amplitude factors for both are different. Some corporations also calculate the capacity of the pump in terms of suction capacity and capacity to produce vacuum in Hg.

The first vacuum pump was invented in 1650 by Otto von Guericke, and was preceded by the suction pump, which dates to antiquity.

Working of Vacuum Pump

Vacuum is the function of the pump, it eliminates the air from the closed system by means of suction so that the density of air in the restricted space is gradually reduced so that vacuum can be created. This removes air in a closed system as the mechanical effort energy of a revolving shaft is converted to pneumatic power.

The force level within a protected volume decreases compared to the external environment. The amount of energy generated depends mainly on the amount of gas otherwise the air is exhausted and the pressure dissatisfaction generated between the inside and outside atmosphere

Type of  Vacuum Pump

classification of vacuum pump
PV=nRT
P=  pressure
V=  volume
n = amount of substance
R= ideal gas constant
T=  temperature
As per ideal gas equation  
Gas Transfer vacuum pump
P=1/V
Pressure is inversely propositional of volume 
we want create vacuum to the increase the volume and hence pressure is decrease 
Gas capture vacuum pump 
P=T
Pressure is directly propositional to temperature 
and to create vacuum decrease the temperature and hence pressure also decrease
The two technologies used by vacuum pumps are gas transfer and gas capture.
Transfer pumps operate by either moving gas molecules by momentum exchange (kinetic action) or by positive displacement. The same number of molecules is discharged from the pump as it enters and when expelled the gas is slightly above atmospheric pressure. The ratio of the exhaust pressure (outlet) to the lowest pressure (inlet) is known as the compression ratio.

Kinetic transfer pumps work on the principle of transfer of momentum, providing the probability of the molecule moving towards the outlet using a high-speed blade or initiated vapor directing the gas towards the pump outlet. Kinetic pumps typically do not have seal segments, but can achieve high compression ratios at low pressures.

Positive displacement transfer pumps work by mechanically trapped the amount of gas and transferring it through the pump. They are often designed in multiple stages on a common drive shaft. The isolated volume is compressed into a small volume at a high pressure, and finally, the compressed gas is expelled to the atmosphere (or the next pump). It is common to use two transfer pumps in series to provide high vacuum and flow rates. For example, a turbomolecular (kinetic) pump can be purchased in series with a scroll (positive displacement) pump as a packet system.

Positive displacement Vacuum Pump

Positive displacement Vacuum Pump

 A partial vacuum can be generated by increasing the volume of the container. To evacuate a chamber indefinitely without the need for infinite growth, a box of vacuum can be repeatedly closed, abolished and re-expanded. This is the principle behind a positive displacement pump, for example a manual water pump. Inside the pump, a mechanism expands a small seal cavity to reduce its pressure below the atmosphere. Due to the pressure difference, some fluid (or wells in our example) from the chamber is pushed into the small cavity of the pump. The cavity of the pump is then sealed from the chamber, opened into the atmosphere, and squeezed back into a minute shape.

Momentum transfer Vacuum Pump

Momentum transfer Vacuum Pump

In a speed transfer pump, the gas molecules are accelerated from the vacuum side to the exhaust side (which is usually maintained under low pressure by a positive displacement pump). Momentum transfer pumping is possible only after pressures of 0.1 kPa. The fluid flows at different pressures depending on the laws of fluid dynamics. At atmospheric pressure and light vacuoles, the molecules make contact with each other and their neighboring molecules are known as viscous flows. When the distance between molecules increases, the molecules interact with the chamber walls more often than other molecules, and molecular pumps become more effective than positive displacement pumping. This regime is generally called high vacuum.

Regenerative Vacuum Pump

Regenerative pumps use the vortex behavior of the fluid (air). The construction is based on the hybrid concept of centrifugal pumps and turbopumps. It usually consists of several sets of teeth perpendicular to the air molecules moving inside a stable hollow groove, such as a multistage centrifuge pump. This is sometimes referred to as a side channel pump. Since the high pumping rate due to high vacuum and low contamination from the atmosphere can be installed on the exhaust side, these types of pumps are used in the load lock in semiconductor manufacturing processes.

 Entrapment Vacuum Pump

Such a pump is probably a cryopump, and it uses cold temperatures to compress gases into a hard state. A chemical pump reacts with gases to produce a hard residue, otherwise, the ion pump uses hard electric fields to push ions as well as ions into a hard substrate. A cryomodule employs cryopumping. Such pumps are sorption, titanium sublimation, non-evaporative gutter pumps.

Diaphram Vacuum Pump

Diaphram Vacuum Pump

A diaphragm is rapidly flexed by a rod riding on a cam rotated by a motor, causing gas transfer in one valve and exiting the other. It is compact and low maintenance. The lifespan of the diaphragm and valve is typically more than 10,000 operating hours. Diaphragm pumps (Fig. 5) are used to support small compound turbo-molecular pumps in clean, high vacuum applications. It is a small capacity pump widely used in R&D laboratories for sample preparation. A specific final pressure of 5 x 10–8 mbar can be achieved when using a diaphragm pump to return a compound turbo-molecular pump. It has a pumping speed range of 0.6 to 10 m3 / h (0.35 to 5.9 ft3 / min). 

Piston Vacuum Pump 


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