The "Core Magic" of Four Vacuum Pumps?

The essence of a vacuum pump is to evacuate gas from a sealed space through various methods, thereby reducing pressure (creating a vacuum). Based on the different "evacuation methods," they are primarily classified into four categories:

vacuum displacement pump

Principle: The pump chamber volume is altered through mechanical motion to draw gas into the 'suction port' and then compress it for discharge through the 'exhaust port' (similar to the reverse operation of a pump).

Representative model：

Vane Pump (Preferred for Laboratory/Small-Scale Applications): This pump features a rotating rotor with 2-3 sliding vanes. During rotation, the vanes divide the pump chamber into two sections—the suction side (increased volume for gas intake) and the discharge side (decreased volume for gas expulsion). Key advantages include low cost and easy maintenance, while drawbacks include oil consumption (requiring regular oil changes) and limited vacuum capability (approximately 10⁻² Pa).

Roots Pump (Industrial High-Flow Preferred): Two "8-shaped" rotors rotate in opposite directions, meshing like gears to "push" gas from the suction port to the exhaust port (without compression, relying on volume change). Its advantages include high flow rate (up to 10^5 m³/h) and high efficiency, while the disadvantage is that it cannot be used alone (requires a pre-stage pump, such as a rotary vane pump). It is suitable for large-scale vacuum systems in industries like steel and chemical processing.

Pneumatic slide valve pump (heavy-duty application): The pump chamber volume is adjusted by the reciprocating motion of the slide valve. It exhibits superior wear resistance compared to rotary vane pumps, making it ideal for industrial vacuum drying, distillation, and other heavy-duty applications.

dynamic vacuum pump

Principle: High-speed moving components (blades/fluid) propel gas molecules toward the exhaust port, utilizing kinetic energy transfer (similar to how a fan circulates air).

Representative model

Turbomolecular Pump (a semiconductor/research "ultra-high vacuum marvel"): The pump chamber contains multiple inclined blades (rotating at high speeds, reaching 30,000-100,000 rpm). When gas molecules collide with the blades, they are "flung" toward the exhaust port (similar to a tennis ball being struck by a racket). Its advantages include extremely high vacuum levels (up to 10^-10 Pa) and oil-free operation. Disadvantages include high cost (ranging from tens of thousands to hundreds of thousands) and sensitivity to particulate matter (cannot handle dusty gases). It is primarily used in high-end applications such as chip manufacturing and electron microscopy.

Jet Pump (Low-Cost "Flow Champion"): High-pressure fluid (water/steam/air) is ejected from the nozzle to form a high-speed jet, driving surrounding gas out together (similar to the "Venturi effect"). Its advantages include no moving parts (maintenance-free) and low cost, while the disadvantages are low vacuum (approximately 10⁻¹ Pa) and high energy consumption. It is suitable for rough vacuum applications such as metallurgy and papermaking.

adsorption vacuum pump

Principle: Utilizing adsorbent materials (such as molecular sieves or activated carbon) or electric/magnetic fields to "fix" gas molecules within the pump (instead of discharging them, they are "stored").

Representative model

Molecular sieve pump (oil-free/ultra-high vacuum preferred): Utilizes zeolite molecular sieves (a porous material) to adsorb gas molecules (adsorption at low temperatures, desorption and regeneration at high temperatures). The advantages include oil-free operation and high vacuum levels (up to 10⁻⁸ Pa), while the disadvantages involve the need for alternating cooling/heating (regeneration is cumbersome). It is suitable for extreme environments such as space exploration and quantum computing

Ion pump (lab-grade ultra-high vacuum): Ionizes gas molecules into ions through an electric field, then adsorbs them onto a negative electrode (titanium plate) (ions collide with and are "fixed" on the titanium plate). Advantages include extremely high vacuum levels (above 10⁻¹⁰ Pa) and vibration-free operation. Disadvantages include high cost and limited applicability to inert gas extraction, primarily used in particle accelerators and semiconductor research.

Other types

Diffusion pump (traditional high vacuum): Utilizes high-temperature oil vapor injection to drive gas molecules toward the exhaust port (similar to an ejector pump but employing oil vapor). Its advantages include high vacuum levels (10⁻⁶ Pa) and large flow rates, while the disadvantages are oil contamination and the requirement for water cooling. It is now gradually being replaced by turbomolecular pumps.

Dry vacuum pumps (oil-free scenarios): Examples include screw pumps (using two rotating screws without oil) and claw pumps (with two claw-shaped rotors meshing without oil), suitable for medical equipment, food packaging, and other applications requiring high oil-free performance.