Five Tips for Working with Turbine Pumps

Turbine pumps work by moving gas molecules into a specific direction by colliding with a moving solid surface. The rapidly rotating fan rotor strikes gas molecules and blows them from the pump inlet to the outlet to form and maintain a vacuum. Here are five tips for understanding how turbo pumps work.

Most turbo pumps use multistage pumps. Each stage has a rotor blade and stator blades that rotate rapidly.The pump works like a compressor, giving energy to the gas instead of discharging it.

When gas molecules enter the inlet of the pump, they are struck by the rotor blades, and the mechanical energy of the blades is transferred to the gas molecules, thereby imparting kinetic energy.

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Gas molecules use this kinetic energy to enter the gas transfer holes in the stator. The gas molecules collide with the rotor surface again and move outward to the outlet.

When installing a turbo pump rotor shaft through two ball bearings, both bearings need to be placed on the front vacuum side due to the presence of lubricating oil in the bearing. The rotor is of high mass and can be supported on one side.

From the perspective of rotor dynamics, it is advantageous to use hybrid bearing support. Hybrid bearings require a two-bearing concept.

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Install an oil-lubricated ball bearing on the shaft end of the vacuum side of the front stage. The other end of the vacuum side is fitted with a maintenance-free, wear-free permanent magnet bearing that centers the rotor radially.

A brushless DC motor capable of supporting a rotational frequency of up to 1500 Hz is ideal for driving a rotor.Such frequencies allow the blades to reach the speed required to pump the gas.

The drive is connected directly to the pump and should be powered by 24V, 48V or 72V DC. Either an external power supply or a power supply unit integrated with the pump's electronics unit can be used.

Forming a clean vacuum

The turbo pump produces a clean vacuum within 10 hPa. Due to its high compression ratio, oil can be prevented from entering the inlet area.

Stainless steel covers can be used to make these pumps more suitable for R&D applications. It is also possible to use a turbo pump to evacuate a large container and a rotary vane pump as a backup pump.

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If a turbo tow pump is involved, a two-stage diaphragm pump must be used as a backup pump. However, due to the low pumping speed, it takes a long time to empty a large container.

When handling the transport material in a vacuum process, the vacuum load lock chamber must be cleaned. If you choose to transfer at atmospheric pressure, the chamber should be pre-vacued through a bypass line.

Finally, a valve is used to connect the running turbo pump to the backup pump and the chamber.