By vacuum pump works, pump basically be divided into two types, namely gas transmission pump and pump gas trap. With the application of technology in the field of vacuum production and scientific research in the application of the requirements of its increasingly wide pressure range, mostly required by vacuum extraction system consisting of several vacuum pumping after joint production and scientific research in order to meet the requirements of the process, so many cases the choice of different types of vacuum pumps vacuum pumping units were pumping. For convenience, these pumps according to their works or structural characteristics of specific detailed classification is necessary. Are described below:
Gas transmission pump
Gas transfer pump is a gas constant to make the suction and discharge, in order to achieve the purpose of the vacuum pump, such pumps are basically two types:
1) displacement pumps
Displacement pumps is to use periodically varying volume of the chamber to accomplish a vacuum pump suction and discharge processes. Gas is compressed before it is discharged. This reciprocating and rotary pumps into two categories:
⑴ reciprocating pump: The use of the pump chamber of the piston reciprocating motion, the gas is sucked, compressed and discharged. Therefore, also known as a piston pump.
⑵ rotary vacuum pump: is the use of rotary motion of the piston pump chamber, the gas is sucked, compressed and discharged. Rotary vacuum pump there are several types:
① oil-sealed vacuum pump: It is the use of oil seal gap between the moving parts, reducing the space of a harmful rotary displacement pumps. This pump is usually with gas ballast device, so called gas ballast vacuum pumps. Its structure is divided into the following five types of characteristics.
a) rotary vane vacuum pump: a certain eccentricity rotor mounted in the pump casing and pump housing with a fixed surface near the surface of the rotor slots with two (or more) rotary vane, when the rotor rotates spin tablet can reciprocally slide along its radial slot and is always in contact with the inner wall of the pump housing, this rotation plate rotate together with the rotor, can be divided into several variable volume pump chamber.
b) slide valve vacuum pump: the eccentric outer rotor is provided with a slide valve, a rotor driven rotary slide valve sliding along the inner wall of the pump housing and rolling, sliding the slide valve stem can slide in the upper portion of the swingable rail slide valve, and the divided into two variable volume pump chamber.
c) fixed vane vacuum pump: the pump housing and the pump is provided with a surface close to the eccentric rotor, equipped with a radial vane is always in contact with the upper surface of the rotor casing, the rotor rotates, the vane can, lower sliding will be divided into two variable volume pump chamber.
d) trochoidal vacuum pump: The pump chamber is equipped with a type of eccentric line trochoidal rotor, which rotates in the pump chamber and the inner wall into two variable volume pump chamber.
e) multi-chamber rotary vane vacuum pump: a pump housing in parallel equipped with an electric motor driven by multiple independent studio rotary vane vacuum pump.
② dry vacuum pump: It is a no oil (or liquid) sealed displacement pumps.
③ liquid ring vacuum pump: a rotor with multiple blades mounted eccentrically in the pump housing, when it rotates, the liquid (usually water or oil) is thrown to the pump housing forms a liquid ring pump casing concentric liquid ring and the rotor blade forming a volume cycle of several small volumes, it is also known rotary positive displacement pumps.
④ Roots vacuum pump: pump built with two opposite directions of rotation of the rotor synchronous dual-leaf or leaf, and intertrochanteric, have maintained a certain gap between the rotor with the inner wall of the pump casing. It belongs to the rotational pump. This is the type of mechanical booster pumps.
2) momentum transfer pump
This pump is to rely on the blades rotating at high speed or high-speed jet, to transfer momentum to the gas or gas molecules, so that continuously transferred from the gas inlet to the pump outlet. Concrete can be divided into the following types.
⑴ molecular vacuum pump: It is the use of high-speed rotation of the rotor to transfer energy to the gas molecules, so that the compression, a vacuum pump exhaust. There are several types of it:
① traction molecular pumps: rotor speed movement of gas molecules collide and get momentum, was sent to export, therefore, is a momentum transfer pump.
② turbo molecular pump: pump contains a disk or tape slotted rotor blades, which rotate in the stator disc (or piece) rooms. High linear velocity of the rotor periphery. Such pumps are typically operate at the molecular flow state.
③ complex molecular pump: it is towed by the turbine and pump series combination of two molecules together a composite molecular pump.
⑵ jet vacuum pump: it is the use of pressure venturi (Venturi) to produce the effect of lowering the high speed jet to export gas to a momentum transfer pump, suitable for working in the viscous flow and transition flow state. The pump can be divided into the following detail:
① liquid jet pump: a liquid (usually water) for injection pump working medium.
② gas injection pump: a non-condensable gas injection pump as working medium.
③ vapor jet vacuum: the vapor (water, oil, or mercury vapor) as a jet pump working medium.
⑶ diffusion pump: A high-speed low-pressure vapor stream (oil or mercury vapor) as a jet pump working medium. Gas molecules diffuse into the vapor jet, was sent for export. The density of gas molecules in the jet is always very low, the pump adapted to operate in molecular flow state. Can be divided into:
① self-cleaning diffusion pump: pump liquid volatile impurities by specialized machinery delivered to export back to the boiler without an oil diffusion pump.
② fractionating diffusion pump: such a pump having a fractionation unit, so that the lower vapor pressure of the working fluid vapor into a high vacuum working nozzle, and a higher vapor pressure of the working fluid vapor enters a low vacuum working nozzle, it is a multi-grade oil diffusion pump.
⑷ diffusion ejector pump: It is a characteristic of a diffusion pump or a single-stage or multi-stage nozzle with a single or multistage jet vacuum nozzle having a characteristic of the concatenation of the momentum transfer pump. Oil booster that belong to this type.
⑸ ion transfer pump: It is to be ionized gas under the action of an electromagnetic field or an electric field, transported to a momentum transfer pump outlet.
trapping gas pump
This pump is a gas molecules are adsorbed or condensed on the inner surface of the pump, thereby reducing the number of gas molecules within the vessel to achieve the purpose of the vacuum pump, there are several types.
1) adsorption pump
It mainly depends on the physical adsorption of the adsorbent (e.g., porous material) having a large surface to a trapping type exhaust vacuum pump.
2) getter pump
It is a way to capture chemically combined use of vacuum gas getter. The getter usually massive or film form of freshly deposited metal or alloy. Sublimation pump that belong to this type.
3) getter ion pump
It is so by the action of electromagnetic or electrical field have adsorbed on the surface of the getter material, in order to achieve the purpose of the exhaust gas to be ionized. There are several types of it.
⑴ evaporation ion pump: pump ionized gas adsorbed on an intermittent or continuous manner sublimation (or evaporation) and the inner wall of the cover on the pump getter material, in order to realize a vacuum pumping.
⑵ sputter ion pump: pump ionized gas adsorbed on the cathode by continuous sputtering comes out of the getter material, a vacuum pump in order to achieve the purpose.
4) cryogenic pump
Using low-temperature surface trapping gas pump