1. Classification by Working Principle
According to international vacuum industry standards, vacuum pumps are scientifically divided into two major categories: gas transfer pumps and gas capture pumps.
1.1 Gas Transfer Pumps
Gas transfer pumps continuously suck, compress and discharge gas without storing gas inside the pump body. Featuring stable operation and continuous air extraction, they dominate the industrial vacuum market. They are further divided into positive displacement pumps, momentum transfer pumps and jet pumps.
1.1.1 Positive Displacement Vacuum Pumps
These pumps change the internal chamber volume periodically through mechanical movement to complete air intake and exhaust processes. They are durable and highly popular in rough and low vacuum industries.
Rotary Vane Vacuum Pump: A classic oil-lubricated vacuum pump with single-stage and two-stage structures. It provides high ultimate vacuum with mature technology and affordable cost. However, it causes oil contamination and cannot handle corrosive gas. It is commonly used in laboratories, vacuum packaging and small vacuum coating.
Reciprocating Piston Vacuum Pump: Designed for large airflow and dust resistance with moderate vacuum performance. Mainly applied in chemical industry, sewage treatment and vacuum dehydration.
Roots Vacuum Pump: Characterized by high pumping speed and rapid pressure escalation. A backing pump is mandatory for operation. Widely used in chemical distillation, vacuum drying and lithium battery manufacturing.
Claw Vacuum Pump: Oil-free dry type vacuum pump with dual-claw rotors. It delivers clean vacuum and is preferred for pharmaceuticals, new energy and fine chemical processes.
Screw Vacuum Pump: Equipped with non-contact screw rotors. It performs excellently against water vapor and fine dust. It represents high-end dry vacuum equipment for industrial production.
1.1.2 Momentum Transfer Vacuum Pumps
By using high-speed rotating blades or gas jet flow to accelerate gas molecules, these pumps achieve high and ultra-high vacuum. They cannot operate independently and must be equipped with a fore pump.
Turbomolecular Pump: Running at an extremely high rotating speed, it provides oil-free ultra-high vacuum. Mainly used in semiconductors, aerospace and precision analytical instruments.
Diffusion Pump: Adopting high-temperature oil vapor jet flow for gas extraction. Cost-effective and technically mature, though limited by oil pollution. Mostly used in traditional vacuum coating and metallurgy.
1.1.3 Jet Vacuum Pumps
Jet pumps have no moving mechanical parts. Negative pressure is generated by high-speed fluid injection. Simple structure and maintenance-free performance ensure strong corrosion resistance.
Water Jet Vacuum Pump: Economical and durable with excellent water and corrosion resistance. Commonly used in chemical industry, sewage treatment and vacuum crystallization.
Steam Jet Vacuum Pump: Usually connected in multiple stages for large gas flow. Applied in petrochemical and large-scale distillation facilities.
1.2 Gas Capture Pumps
Instead of exhausting gas outward, gas capture pumps fix gas molecules inside the pump through adsorption, condensation and ionization. With zero vibration and ultra-clean performance, they are essential for ultra-high vacuum scenarios such as semiconductors and aerospace research.
Cryogenic Condensation Pump: Freezes and captures gas molecules at extremely low temperature to obtain extreme vacuum.
Sputter Ion Pump: Ionizes and absorbs residual gas to maintain stable ultra-high vacuum for a long time.
Adsorption Pump: Utilizes molecular sieve adsorption with simple structure and noise-free operation for laboratory miniature vacuum systems.
2. Classification by Vacuum Degree
According to international pressure division standards, vacuum pumps are categorized into four grades for industrial selection reference.
2.1 Rough Vacuum (10⁵ ~ 10³ Pa)
Representative pumps: Water ring pump, jet pump. Features: Large airflow, low vacuum tolerance, excellent water and dust resistance. Applications: Chemical dehydration, vacuum filtration and sewage treatment.
2.2 Low Vacuum (10³ ~ 10⁻¹ Pa)
Representative pumps: Single-stage rotary vane pump, claw pump. Features: High cost performance and strong universality. Applications: Vacuum defoaming, mould vacuuming and general negative pressure industries.
2.3 High Vacuum (10⁻¹ ~ 10⁻⁵ Pa)
Representative pumps: Two-stage rotary vane pump, Roots pump unit, diffusion pump. Features: High vacuum requiring fore pump cooperation. Applications: Vacuum coating, heat treatment and lithium battery production.
2.4 Ultra-High Vacuum (< 10⁻⁵ Pa)
Representative pumps: Molecular pump, cryogenic pump, ion pump. Features: Ultra-clean and oil-free for precision manufacturing. Applications: Semiconductor chips, optical coating and aerospace testing.
3. Classification by Lubrication & Cleanliness
3.1 Oil-Lubricated Vacuum Pumps
Advantages: Tight sealing, high ultimate vacuum and low manufacturing cost. Disadvantages: Oil vapor contamination, poor chemical resistance and regular oil maintenance. Suitable for common industrial fields without strict cleanliness requirements.
3.2 Dry Vacuum Pumps
Representative types: Claw pump, screw pump, scroll pump and diaphragm pump. Advantages: Oil-free cavity, clean vacuum, water vapor and mild corrosion resistance. Disadvantages: High production cost and high machining precision requirement. Widely adopted in pharmaceuticals, food processing, semiconductors and new energy industries.
4. Classification by Mechanical Motion Structure
4.1 Rotary Vacuum Pumps
Gas extraction is completed by continuous rotor rotation with smooth operation and low vibration, including rotary vane pump, screw pump, claw pump, Roots pump and molecular pump.
4.2 Reciprocating Vacuum Pumps
Adopting piston reciprocating compression. Large vibration and noise limit its application, only reserved for heavy-duty rough vacuum working conditions.
4.3 Fluid Jet Vacuum Pumps
No moving parts. Depend on high-speed fluid jet to form negative pressure with maintenance-free and corrosion-resistant characteristics.
5. Classification by Corrosion Resistance
5.1 Carbon Steel Vacuum Pumps
Applied for dry and clean air without corrosive medium, commonly used in general mechanical processing.
5.2 Stainless Steel Anti-Corrosion Pumps
Made of 304/316 stainless steel to resist weak acid, weak alkali and water vapor, suitable for chemical and pharmaceutical industries.
5.3 PTFE Lined Anti-Corrosion Pumps
With internal Teflon coating, it withstands strong acid, strong alkali and organic solvents for fine chemical and electroplating waste gas treatment.
6. Comparison of Mainstream Vacuum Pumps
6.1 Water Ring Vacuum Pump
Advantages: Water resistance, dust resistance, explosion-proof performance and low cost. Disadvantages: Limited vacuum degree and high water consumption. Applications: Chemical industry, mining, papermaking and sewage treatment.
6.2 Rotary Vane Vacuum Pump
Advantages: High vacuum performance, low noise emission and mature technological structure. Disadvantages: Oil pollution and poor corrosion resistance. Applications: Laboratory research, vacuum packaging and miniature vacuum coating processes.
6.3 Roots Vacuum Pump
Advantages: High pumping speed and rapid pressure rise. Disadvantages: Mandatory backing pump and high operating temperature. Applications: Chemical rectification, vacuum drying, lithium battery manufacturing and vacuum metallurgy.
6.4 Screw Vacuum Pump
Advantages: Dry oil-free structure, excellent vapor resistance and long service lifespan. Disadvantages: High unit purchasing cost. Applications: Pharmaceutical production, new energy materials and fine chemical engineering.
6.5 Molecular Pump
Advantages: Ultra-high vacuum performance and oil-free cleanness. Disadvantages: Expensive investment and poor dust tolerance. Applications: Semiconductor manufacturing, optical industry and aerospace engineering.
6.6 Jet Pump
Advantages: Zero daily maintenance and extreme corrosion resistance. Disadvantages: High energy consumption and low ultimate vacuum. Applications: Large-scale chemical plants and petroleum distillation processes.
7. Development Trend of Vacuum Pump Industry
Driven by China’s manufacturing upgrading, rapid expansion of new energy sectors and semiconductor localization, the vacuum pump industry presents five major development directions: dry oil-free pumps replacing traditional oil pumps, upgraded anti-corrosion materials, intelligent frequency conversion control, low noise and low energy consumption, and domestic substitution of imported vacuum equipment. In the past, high-end vacuum pumps were heavily dependent on European, American and Japanese suppliers. Currently, domestic screw pumps, claw pumps and molecular pumps are achieving rapid import substitution through continuous technological breakthroughs.