Oil free dry vacuum pump (also referred to as dry mechanical pump) refers to the pump can began under atmospheric pressure extraction, but also will be pumping gas directly into the atmosphere, the pump cavity without oil or other work medium, and the ultimate pressure of the pump and oil seal type rotary vane vacuum pump the same order of magnitude or close to the mechanical vacuum pump.
At present, the vacuum industry use of most mechanical vacuum pump oil, water or other polymer fluid ACTS as the working medium of the pump, the pump in cooling, sealing, lubrication, etc.With the development of science and technology and expansion of the vacuum application domain of the original mechanical vacuum pump and its extraction system appeared two urgent problems: one is the working medium pump reflux pollution is pumped container, and this kind of reflux in many cases influence the quality of the products, quantity, increase the cost of equipment maintenance.Second, due to some process in the process of material make the medium inside the vacuum pump serious metamorphic reaction, make the pump does not work.
For ordinary oil free vacuum system, although the available oil seal type vacuum pump with cold trap or adsorption trap such as attachments to prevent reflux, but cannot completely solve the problem, and make the system appear complex.And using the appropriate type of dry vacuum pump, can achieve the ideal use effect.;Dry vacuum pump application is broad, mainly has the following several aspects:
1) low pressure chemical vapor deposition of polysilicon preparation process;
2) semiconductor etching process.Often used in the production process or generated corrosive gas and abrasive particles;
3) in addition to the semiconductor process some of the particles in the producing process, do not want to particle mixed in the oil pump, and hoping to particle discharge pump, with a certain type of dry vacuum pump can meet the requirements;
4) in the chemical industry, pharmaceutical industry, food industry in distillation, drying, deaeration, packaging, etc., to prevent the pollution caused by organic solvent, suitable for dry vacuum pump;
5) used as a general without oil pump before clean vacuum system, in order to prevent oil pollution.
In recent years, the dry vacuum pump get rapid development, many large vacuum companies abroad have developed a new type of dry scroll vacuum pump.Many domestic units for dry vacuum pump has been developed, such as the northeastern university, shenyang vacuum technology research institute, Shanghai vacuum pump factory, etc.At present, the dry vacuum pump consists of contact type and non-contact type.Contact type dry pump vane type, CAM type, reciprocating piston, diaphragm and so on, this kind of pump speed is low, suitable for small capacity, high compression ratio (single stage compression ratio).Non-contact type dry pumps have roots type, claw type, screw type, vortex type, etc., its speed is high, suitable for large capacity, low compression ratio (refers to the single stage compression ratio).Different types of dry type pump has the characteristics of each.When used according to different USES to choose.