Similar to rotary vane vacuum pumps, rotary piston vacuum pumps are volumetric pumps with almost the same applications and working conditions. The pump is used for industries like aerospace, vacuum impregnation, vacuum coating, metal drying, etc.
Due to its big volume, rotary piston pump is often used in large-sized vacuum equipment. Like some other vacuum pumps, the rotary piston pump has also two basic types: single stage and dual stage.
The ultimate pressure of small sized single-stage pumps is generally not more than 0.6 Pa, and that of large sized pumps is not more than 1.3 Pa (gas ballast closed). The ultimate pressure of dual stage pumps is not more than 0.06 Pa (gas ballast closed). The rotary piston vacuum pumps with pumping speed greater than 150 L/s are mostly single stage ones.
How the Rotary Piston Vacuum Pumps Work
The rotary piston pump consists of pump body, eccentric wheel, piston parts, arch track, etc. The chamber is divided by the piston to Section A and Section B.
When the drive shaft rotates clockwise, the volume of Section A is increased with reducing pressure. Gas is drawn into the chamber through inlet and shaft. The piston moves to the left till the volume of Section A is maximized, the inlet is closed.
Meanwhile, the volume of Section B keeps reducing and the gas is compressed. When the pressure in Section B is increased slight above atmospheric, the gas is discharged out of the outlet and vacuum is created.
Limitations of the Pump: Vibration and Noise
The rotary piston pumps have usually large vibration because it’s difficult for the eccentricity of the rotating mass and inertia forces to achieve complete balance. Therefore, the pumping speed of most models has to be maintained at 350 – 600 rpm.
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Coolink, a TOP 3 Global HVAC Vacuum Pump Manufacturer & Quality Industrial Vacuum Pump Supplier from China