Vacuum pumps are used in various methods to produce a closed space , which means to improve and maintain the vacuum .
Vacuum pumps can be defined as the device or equipment , By use of mechanical, physical , chemical or physical chemistry methods have been drawn container extraction to obtain a vacuum , With the development of vacuum widely applications , vacuum pumps have been developed all kinds of types , such as oil diffuison vacuum pump and so on ,and its pumping speed from zero a few liters per second per second, hundreds of thousands , millions of liters. Extreme pressure ( maximum vacuum ) from rough vacuum to 10-12Pa over ultra-high vacuum range .
Because vacuum applications department involved working pressure range is very wide, so any type of the vacuum pump can not fully applicable to all operating pressure range, only depending on the operating pressure range and different working way requirements , the use of different types of vacuum pump . For ease of use and the need for various vacuum processes , A lot of vacuum pumps may be combined togetheraccording to their performance in the unit type of application .
Any use of mechanical motion ( rotating or sliding ) to obtain a vacuum pump , called the mechanical vacuum pump . Mechanical vacuum pumps according to their works and structural characteristics are divided into as follows :
1 . Displacement pumps
It is the use of periodic variation of the pump chamber volume to complete the suction and discharge pumps to achieve the purpose of extraction . Gas discharge pump chamber before being compressed. This pump is divided into two kinds of reciprocating and rotary .
( A ) reciprocating pump
Reciprocation of the vacuum pump piston chamber , the gas suction, compression and discharge. Also known as rotary piston vacuum pump.
2 . Momentum transfer pump
It relies on high speed rotating blades or a high velocity jet , the momentum transfer to a gas or gas molecules , the gas continuously transferred from the pump inlet to the outlet . These pumps can be divided into the following forms:
( 1 ) molecular vacuum pump
It is the use of high-speed rotation of the rotor of the momentum transfer to the gas molecules , so as to obtain the orientation speed , so as to be compressed , the exhaust port is driven after a pre- pumped vacuum . The vacuum pump can be divided :
1 ) Traction molecular pump gas molecules with high-speed movement of the rotor relative to the collision to get momentum , to be driven to the pump outlet .
2 ) turbo molecular pump by high-speed rotation of the rotor blades and stationary vanes cooperate with each other to achieve the fixed pumping . This pump is usually in the molecular flow mode of operation .
3 ) It is composed of complex molecular pump turbo molecular pump and traction type two series combined elements of a composite type vacuum pump .
Mechanical vacuum pump is a vacuum applications most commonly used in the field of a class of pumps , vacuum equipment which is an important component .
3 rotary vacuum pump
The pump chamber rotary motion of the rotor components of the gas suction, compression and discharge. It roughly follows several classification :
1 ) It is the use of oil-sealed vacuum pump oil pump seal the gap between the moving parts , reducing harmful pump space a rotary displacement pump . This pump is usually with gas ballast device . It mainly consists of rotary vane vacuum pumps , fixed vane vacuum pumps , rotary piston vacuum pumps, vacuum pumps and other trochoidal .
2 ) liquid ring vacuum pump with a multi-bladed rotor eccentrically mounted on the pump housing . As it rotates , the working fluid thrown pump casing is formed concentric with the liquid ring pump housing , the liquid ring formed with the rotor blades cycle several small volume of the suction and discharge chambers rotational capacity . The working fluid , usually water or oil , so it is also called water ring vacuum pump or oil ring vacuum pump .
3 ) It is a dry vacuum pump without oil ( or liquid ) sealed displacement pumps . Because dry vacuum pump chamber without working fluid , therefore , for the semiconductor industry , chemical industry, pharmaceutical industry and food industries that require no oil vacuum cleaner process applications.
4 ) Roots vacuum pump is built with two opposite directions simultaneously rotating twin- leaf or leaf of the rotor. Rotor , the rotor with the inner wall of the pump housing to maintain a certain gap between both.