In recent decades, there has been more and more research on the oil-free screw air compressor. According to the type of lubrication, the Screw type air compressor has two kinds: the water-lubricated single-screw type and the dry twin-screw type.
For the Dry oil-free screw air compressor, most are twin-screw air compressors. Water-lubricated oil-free screw air compressor is also called a water-injected screw air compressor, most are single screw air compressors. The following analyze their differences:
COMPARISONS
VS
Double Screw Air Compressor
Working Principle
| Comparison | Water-lubricated Oil-free Single Screw | Dry Oil-free Double Screw |
|---|---|---|
Air Quality |
100% Oil-Free | Oil in the gear |
Air Purity |
Clear air after purified by water | Contain dust and oil stain |
Lubrication Media |
Pure Water | Dry |
Air Temp |
Less than 55℃ | About 180~200℃ |
Compression |
Single-Stage | Two-stage |
Cooling method |
Don’t need a cooling system | Need interstage and after Cooling system |
Structure |
Simple and Balanced Structure | Radial load is not balance |
Vibration and Noise |
Low vibration and noise | High-frequency noise due to the two screws |
Durability |
Ideal Rotation speed 3000r/min, theoretically zero loads.
Long lifetime of the screw (30000h) and star wheel (50000h) |
Rotation speed 18000r/min, high loads on screws.
The short lifetime of the screw (8000~18000h) |
Maintenance |
Only air and water filter elements | More spare parts |
Different principles
- The dry oil-free screw air compressor means that the coating on the surface of the rotor teeth will play the role of lubrication and sealing. There is no lubrication medium in the compression chamber. But there is lubricating oil in the gearbox;
- But for the Water-lubricated oil-free type means that the water and air are mixed and compressed. Water plays the role of lubricating, sealing, cooling, and denoising
Different Prices
- Water-lubricated oil-free type is mostly single-screw air compressors. The price is generally lower than the dry oil-free type. The maintenance cost is also lower. Only air filter elements and water filter elements.
- But for the dry oil-free air compressor, except for the spare parts, the coating also needs to be replaced regularly.
Different Losses
- Water-injected oil-free single screw type: ideal isothermal compression, no heat loss.
- Dry oil-free double screw type: energy lost due to hot air discharge
Water-injected Oil-free Screw Air Compressor
The Rotary Compression Cycle
The rotary compression cycle is an engine that uses a
Variable Speed Air Compressor
A Variable Speed Rotary Screw Air Compressor is a type
Benefits of Variable Speed Drives
An immense measure of the energy lost in a manufacturing
Air System Heat Recovery from Air Compressors
Almost all air compressor setups have considerable and often unused
How much will compressed air cost you?
Whenever any industry is planned to run, its budget is
How to calculate your current air demand
Air demand is usually measured to assess your cost and
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