The goal of a vacuum pump is to extract the air or another gas contained in an enclosure in order to decrease the Pression by it.

The gases to be evacuated are on the one hand those present at the beginning of the vacuum setting (generally with the atmospheric pressure) and on the other hand those emanating from phenomena such as the natural degasification of the vacuum walls (even of zones which are heated), of the possible escapes (real or virtual), of the permeation of the joined or the walls or voluntary gas introduction (manufactoring process or of treatment, in the field of the Semi-conducteur S for example), of the evaporation of grease.

The “perfect” Vide does not exist, there is acted in fact of very a low pressure; a vacuum considered as excellent (10^-8 Pa) contains 2 more million molecules per cubic centimeter.

There exist various types of vacuum pumps, to reach various ranges of pressure. To describe the quality of the vacuum, one distinguishes 4 fields which characterize the quantity of remaining matter compared to a volume. To each one of these fields a range of apparatuses corresponds.

The vacuum is measured in Pascal (Pa, unit of the international system) or more usually in industry in Millibar (mbar) or in Torr.

The most current technologies for the vacuum pumps are:

• vane pumps (lubricated or dry), for primary education vacuum,
• Piston pump, for primary education vacuum,
• Pump with liquid ring, for primary education vacuum,
• Diaphragm pump, for primary education vacuum,
• ejector S with vacuum, for the coarse vacuum, using the vapor or a compressed gas,
• pumps turbomoléculaires, molecular and hybrid, for secondary vacuum, it can be conventional on rolls of the dice or without contact on magnetic bearings,
• pumps diffusion, for secondary vacuum,
• Pompe Roots , for primary education vacuum, cryogenic
• cold trap, or pumps.
• Pompe dries (without lubricant), for primary education vacuum.
• ionic Pump, for the Ultra-high vacuum.

Vane pumps

They comprise a excentré stator and rotor compared to the stator. The rotor is equipped with longitudinal grooves where pallets are placed radially, generally out of bakelite.

History

• 1659 : Air pump of Robert Boyle

See too

• Lyophilisateur

External bonds

• www.vide.org Site of the French company of the Vacuum

• turbo Pumps and * diffusion pumps