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Hokaido Vacuum Technology (Int'l) Group Limited

Oil Vacuum Pump, Oil Free Air Compressor, Vane Pump manufacturer / supplier in China, offering Rh Series Rotary Vane Energy Saving Hospital Vacuum Pump (RH0063), System One Single Stage Oil Lubricated Rotary Vane Vacuum Pump (RH0200), Lower Cost Oil Lubricated Rotary Vane Vacuum Pump (RH0250) and so on.

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Supplier Homepage Company Show Bulletin Board Hokaido Vacuum Pump Exhibition is on the Way

Bulletin Board

Hokaido Vacuum Pump Exhibition is on the Way [Jun 01,2015]
Hokaido Vacuum Pump Exhibition is on the Way
Hokaido Vacuum Pump Exhibition is On the Way

The
time goes fast, Hokaido exhibition are coming again, welcome all of you come to our booth to see our succeed after one year trying,we are ready for your checking.

Vacuum pumps are combined with chambers and operational procedures into a wide variety of vacuum systems. Sometimes more than one pump will be used (in series or in parallel) in a single application. A partial vacuum, or rough vacuum, can be created using a positive displacement pump that transports a gas load from an inlet port to an outlet (exhaust) port. Because of their mechanical limitations, such pumps can only achieve a low vacuum. To achieve a higher vacuum, other techniques must then be used, typically in series (usually following an initial fast pump down with a positive displacement pump). Some examples might be use of an oil sealed rotary vane pump (the most common positive displacement pump) backing a diffusion pump, or a dry scroll pump backing a turbomolecular pump. There are other combinations depending on the level of vacuum being sought.
 
Achieving high vacuum is difficult because all of the materials exposed to the vacuum must be carefully evaluated for their outgassing and vapor pressure properties. For example, oils, and greases, and rubber, or plastic gaskets used as seals for the vacuum chamber must not boil off when exposed to the vacuum, or the gases they produce would prevent the creation of the desired degree of vacuum. Often, all of the surfaces exposed to the vacuum must be baked at high temperature to drive off adsorbed gases.

Ultra high vacuum generally requires custom-built equipment, strict operational procedures, and a fair amount of trial-and-error. Ultra-high vacuum systems are usually made of stainless steel with metal-gasketed ConFlat® flanges. The system is usually baked, preferably under vacuum, to temporarily raise the vapour pressure of all outgassing materials in the system and boil them off. If necessary, this outgassing of the system can also be performed at room temperature, but this takes much more time. Once the bulk of the outgassing materials are boiled off and evacuated, the system may be cooled to lower vapour pressures to minimize residual outgassing during actual operation. Some systems are cooled well below room temperature by liquid nitrogen to shut down residual outgassing and simultaneously cryopump the system.