A high-pressure oil-injected screw air compressor delivers 15-40 bar compressed air using a two-stage compression design. Air passes through a first-stage screw air end to reach an intermediate pressure, is cooled and dried through oil-gas separation, then enters a second-stage air end for final compression to 15-40 bar. Oil lubricates both compression chambers, sealing the rotor clearances and preventing metal-to-metal contact — so the air end has no wearing parts. This design replaces traditional high-pressure piston compressors with far lower noise, higher efficiency, and simpler maintenance.
A single-stage screw compressor efficiently reaches only ~7-10 bar. Beyond that, the compression ratio becomes too high — discharge temperature rises, efficiency drops, and rotor life shortens. The RD-HPI series splits the compression into two stages: first stage to an intermediate pressure, then second stage to the final 15-40 bar. This keeps the compression ratio per stage manageable, discharge temperature low, and overall efficiency high.
The working principle applies to both fixed-frequency and variable-frequency configurations. The difference is in how the motor drives the air ends and how the speed adjusts to air demand.
Ambient air passes through the intake filter and enters the first-stage screw air end. The rotor compresses air to an intermediate pressure — typically 2-5 bar depending on the final target — while oil injection cools the compression chamber and seals the rotor clearances.
The compressed air-oil mixture enters the first-stage oil-gas separator. Oil returns to the lubricating circuit, while the compressed air passes through an intermediate cooler to remove the heat of first-stage compression. This intercooling step is critical: it lowers the air temperature entering stage 2, which reduces the second-stage compression work and extends rotor life.
The cooled intermediate-pressure air enters the second-stage screw air end, where it is compressed to the target 15-40 bar. Oil injection provides cooling and sealing throughout, keeping the discharge temperature within safe operating limits.
The second-stage air-oil mixture passes through a final oil-gas separator to remove residual oil, then through the aftercooler before discharging to downstream dryers, filters, or the user's high-pressure network.
RAYDAFON offers two drive configurations for the RD-HPI series. The choice depends on whether your air demand is steady or fluctuates during the working day.
Traditional high-pressure piston compressors suffer from high noise, high energy consumption, and efficiency loss due to piston ring wear. The RD-HPI two-stage oil-injected screw design addresses each of these problems.
The screw and star wheel never touch directly — an oil film separates them at operating speed. No piston rings, no valves, no wearing components to replace on a schedule.
The air end itself requires no periodic service. Daily maintenance is limited to replacing the oil filter, air filter, oil-gas separation core, and compressor oil — on a 3,000-hour cycle.
The screw compression principle generates far less noise and vibration than reciprocating pistons. No dedicated compressor room is required — the RD-HPI can be installed near the production line.
The continuous screw compression produces smooth, pulse-free air. This eliminates the pressure pulsation that affects downstream PET bottle wall thickness and sandblasting surface quality.
Higher efficiency, lower maintenance frequency, and longer air end life translate to a lower total cost of ownership over 10-15 years compared to traditional high-pressure piston machines.
Intercooling between stages reduces second-stage work and rotor thermal load. The result is higher compression efficiency at 15-40 bar than any single-stage design can achieve.
| Parameter | Specification |
|---|---|
| Working Pressure | 15-40 bar (1.5-4.0 MPa) |
| Compression Type | Two-stage oil-injected screw |
| Drive Configuration | Fixed-frequency or dual PM VSD |
| Air End Lubrication | High-quality synthetic compressor oil |
| Maintenance Interval | 3,000 hours |
| Maintenance Parts | Oil filter, air filter, oil-gas separator, compressor oil |
| Noise Level | 30%+ lower than traditional piston high-pressure machines |
| Vibration | Low; no independent compressor room required |
| Voltage | 380V / 440V (customizable) |
| Certifications | CE, PED, ISO 9001 |
High-pressure oil-injected screw compressors serve industries where standard 7-10 bar air is insufficient, and where the reliability and efficiency of screw compression matter more than oil-free purity.
Stretch blow molding of beverage, cosmetic, and pharmaceutical containers requires 25-35 bar clean, dry air. The RD-HPI delivers stable pressure for consistent bottle wall thickness. See PET blowing applications →
Industrial sandblasting, shot blasting, and surface preparation require high-pressure air to propel abrasive media. The two-stage design delivers stable pressure without piston pulsation.
Hydraulic and pneumatic valve testing, pressure vessel certification, and research laboratories require precise high-pressure air. Variable-frequency control maintains stable test pressure.
Hydropower stations, industrial cleaning, and high-pressure pneumatic actuation systems rely on continuous high-pressure air supply. Screw compression provides the reliability these applications demand.
High-pressure air is used as assist gas for laser cutting of stainless steel, aluminum, and non-ferrous metals. Stable 20-30 bar pressure ensures clean, dross-free cuts. See laser cutting applications →
High-pressure air cleaning and descaling operations in chemical plants, refineries, and power stations require a reliable high-pressure air source with low maintenance downtime.
| Application | Recommended Pressure | Drive Configuration |
|---|---|---|
| Beverage PET bottle blowing | 25-35 bar | Fixed-frequency or PM VSD |
| Cosmetic container molding | 20-30 bar | PM VSD for multi-line production |
| Pharmaceutical infusion packaging | 25-40 bar | Fixed-frequency for continuous duty |
| Industrial sandblasting | 15-25 bar | Fixed-frequency |
| Valve & pressure testing | 20-40 bar | PM VSD for variable test cycles |
| Laser cutting assist gas | 20-30 bar | PM VSD |
| Hydropower & industrial | 15-40 bar | Fixed-frequency |
Pricing depends on working pressure, flow capacity, drive configuration, and optional equipment such as high-pressure dryers, filters, and air receiver tanks. Share your application parameters and RAYDAFON will respond with a factory-direct quote within 12 hours.
High-pressure oil-injected screw compressors deliver 15-40 bar compressed air for PET bottle blowing, sandblasting, industrial cleaning, valve pressure testing, scientific research, hydropower station equipment, and high-pressure pneumatic systems where standard 7-10 bar pressure is insufficient.
Air enters the first-stage air end and is compressed to an intermediate pressure, then passes through oil-gas separation and an intermediate dryer. The compressed air enters the second-stage air end for further compression to 15-40 bar, then post-treatment before reaching the user.
The fixed-frequency model uses a fixed-speed motor driving two air ends — suitable for steady demand. The variable-frequency model uses two PM variable-frequency motors driving two air ends, automatically adjusting speed to match air consumption and reducing energy use when load fluctuates.
Maintenance is simple and infrequent. The air end has no wearing parts and requires no major service. Daily maintenance is limited to replacing the oil filter, air filter, oil-gas separation core, and compressor oil — with a replacement cycle of approximately 3,000 hours.
Yes. RAYDAFON supplies complete high-pressure air treatment packages including high-pressure refrigerated dryers, desiccant dryers, coalescing filters, and high-pressure air receiver tanks. See after-treatment range →
Standard configurations ship within 30-50 days from order confirmation. MOQ is 1 unit. Custom pressure, flow, or cooling configurations may require 55-75 days. We accept sample orders for validation testing.
For a complete high-pressure compressed air system, pair your RD-HPI compressor with:
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