Industrial Process Air / 17–580 PSI
Medium & Low Pressure Air Compressors
Purpose-built screw air compressors for two specialised pressure bands: 1.2–4 bar (17–58 psi) low-pressure process air and 20–40 bar (290–580 psi) medium-pressure air. Select oil-free or oil-injected compression according to pressure, air-purity requirements and process demand.
Compressor Selection
Choose by Pressure and Air Purity
Both share the identical water-lubricated 316L stainless air end, TÜV Class 0 certification, and core architecture. Select by demand profile and energy strategy.
| Pressure Range |
Oil-Free Air
No lubricating oil introduced into the compression chamber. |
Oil-Injected Air
Industrial screw compression where Class 0 oil-free air is not required. |
|---|---|---|
|
Low Pressure 1.2–4 bar |
Select CM/D for relatively stable base-load demand. Select CM/DV where process-air demand changes significantly during operation. |
Low-pressure oil-injected screw compressor for high-volume industrial process air where oil-free compression is not mandatory. |
|
Medium Pressure 20–40 bar |
Medium-pressure oil-free process air, with particular relevance to PET bottle blowing and contamination-sensitive applications. |
Oil-injected medium-pressure compression for industrial processes where downstream air quality requirements permit this technology. |
No lubricating oil introduced into the compression chamber.
Select CM/D for relatively stable base-load demand. Select CM/DV where process-air demand changes significantly during operation.
Industrial screw compression where Class 0 oil-free air is not required.
Low-pressure oil-injected screw compressor for high-volume industrial process air where oil-free compression is not mandatory.
No lubricating oil introduced into the compression chamber.
Medium-pressure oil-free process air, with particular relevance to PET bottle blowing and contamination-sensitive applications.
Industrial screw compression where Class 0 oil-free air is not required.
Oil-injected medium-pressure compression for industrial processes where downstream air quality requirements permit this technology.
Pressure Architecture
Where These Compressors Fit in Your Air System
The Medium & Low Pressure range is not intended to replace standard 8–16 bar plant-air compressors. It covers two pressure bands that benefit from compressors engineered specifically for the process pressure.
Low Pressure
CM/D · CM/DV · CMN/D
1.2–4 bar process air
Standard Plant Air
CM/B · CM/PV · CMN/A · CMN/PV · CMW
Explore our standard-pressure compressor ranges.
Medium Pressure
CM/G · CMN/G
20–40 bar industrial and PET process air
bar 17–58 PSI
Low-Pressure Screw Air Compressors
Low-pressure systems are designed for processes requiring large air volume at relatively low discharge pressure. Matching compressor pressure to the actual process requirement can avoid unnecessary compression to standard plant-air pressure followed by pressure reduction.
Oil-Free · Fixed Speed
CM/D Series
Low-Pressure Fixed-Speed Oil-Free Screw Air Compressor
CM/D Series
Continuous processes with relatively stable low-pressure air demand, especially where oil-free compression is required.
Oil-Free · PM VSD
CM/DV Series
Low-Pressure Variable-Speed Oil-Free Screw Air Compressor
CM/DV Series
Production lines with changing air demand where motor speed adjusts automatically according to compressed air requirements.
Oil-Injected · Micro-Oil
CMN/D Series
Low-Pressure Micro-Oil Screw Air Compressor
CMN/D Series
General industrial compressed air applications requiring reliable low-pressure airflow where oil-free air is not a process requirement.
CM/D vs CM/DV
Fixed Speed or VSD for Low-Pressure Air?
VSD is most useful when process demand changes substantially. Where air consumption remains near a consistent base load, a fixed-speed compressor can remain the simpler option.
Diagram illustrates control principle only. Actual operating efficiency depends on model, pressure, load profile and site conditions.
| Selection Factor | CM/D Fixed Speed | CM/DV PM VSD |
|---|---|---|
| Demand profile | Relatively stable | Variable through the shift |
| Motor control | Fixed rotational speed | Permanent-magnet motor with variable-speed control |
| Flow adjustment | Conventional capacity control | Output adjusted through compressor speed |
| Best operating case | Continuous base-load operation | Frequent changes in production-air requirement |
| Initial configuration | Simpler | More advanced drive and control system |
| Selection priority | Stable demand and straightforward operation | Closer supply-demand matching at part load |
Pressure Matching
Why Use a Compressor Designed for Low Pressure?
If a process requires approximately 3–4 bar, compressing all air to a substantially higher plant pressure and then throttling it down can create unnecessary compression work. A dedicated low-pressure compressor allows the compression ratio to be selected around the actual process requirement.
Compressor
7–10 bar
Receiver
Pressure
Reducing Valve
Process
3–4 bar
The pressure-reducing valve lowers pressure at the point of use, but it does not recover the additional compression work already performed upstream.
Low-Pressure
Compressor
3–4 bar
Receiver
Process
3–4 bar
Compressor discharge pressure is selected around the actual process requirement, subject to piping losses and the minimum pressure needed at the point of use.
bar 290–580 PSI
Medium-Pressure Screw Air Compressors
The 20–40 bar range serves processes that operate above conventional plant-air pressure. In PET manufacturing, this pressure class is commonly associated with the higher-pressure air required by stretch blow-molding equipment.
Oil-Free · Medium Pressure
CM/G Series
20–40 Bar Oil-Free Screw Air Compressor
CM/G Series
PET bottle blowing and other 20–40 bar processes requiring oil-free compression or strict contamination control.
Oil-Injected / Micro-Oil
CMN/G Series
20–40 Bar Oil-Injected Screw Air Compressor
CMN/G Series
Medium-pressure industrial processes where oil-injected compression is technically acceptable and downstream air treatment is designed accordingly.
Application Selection
Match Pressure and Air Quality to the Process
Similar air volumes can require very different compressor configurations. Process pressure, allowable contamination, load profile and downstream air treatment should be assessed together.
—— PET Process Air
20–40 Bar Compressed Air for PET Bottle Blowing
PET stretch blow molding is one of the most important applications for the CM/G medium-pressure oil-free range. Required pressure and FAD depend on bottle volume, bottle geometry, machine output, number of blow molders and the plant’s air-recovery strategy.
PET PROCESS CONSIDERATIONS
A useful compressor recommendation starts with the blow-molding process data rather than a target motor size.
Application Selection
Match Pressure and Air Quality to the Process
Similar air volumes can require very different compressor configurations. Process pressure, allowable contamination, load profile and downstream air treatment should be assessed together.
Oil-Free Compression
Lubricating oil is not introduced into the compression chamber. On applicable water-lubricated models, purified water provides cooling, sealing and lubrication functions.
- Lower process risk from compressor lubricant carryover
- Suitable for contamination-sensitive air applications
- CM/D and CM/DV for low pressure
- CM/G for 20–40 bar medium pressure
- Class 0 claims should follow applicable model certification
Oil-Injected Compression
Oil is introduced into the compression process for lubrication, sealing and heat control. Downstream treatment should be specified according to the required air quality.
- Appropriate for many general industrial process-air duties
- Air treatment selected according to contamination tolerance
- CMN/D provides low-pressure oil-injected air
- CMN/G covers the 20–40 bar pressure class
- Often selected where Class 0 oil-free air is unnecessary
Medium & Low Pressure Compressor Series
Select the appropriate compressor series according to pressure range, air purity requirements and operating conditions. Detailed model specifications are available below.
Detailed Model Specifications
CM/D Series — Low Pressure Fixed Speed Models
| Model | Pressure | FAD | Power | Noise |
|---|---|---|---|---|
| CM45D | 1.2–2.5 bar | 13.8 m³/min | 45 kW | 70 dB(A) |
| CM75D | 2.5–4 bar | 20.1 m³/min | 75 kW | 72 dB(A) |
| CM160D | 2.5–4 bar | 42.88 m³/min | 160 kW | 78 dB(A) |
CM/DV Series — PM Variable Speed Models
| Model | Pressure | Variable FAD | Power |
|---|---|---|---|
| CM45DV | 1.2–2.5 bar | 5.5–13.8 m³/min | 45 kW |
| CM160DV | 2.5–4 bar | 17.1–42.88 m³/min | 160 kW |
CM/G Series — 20–40 Bar Oil-Free Models
| Pressure | Power | Application |
|---|---|---|
| 20–40 bar | 75–320 kW | PET / Clean Process Air |
Application Selection
Match Pressure and Air Quality to the Process
Similar air volumes can require very different compressor configurations. Process pressure, allowable contamination, load profile and downstream air treatment should be assessed together.
Required Working Pressure
Pressure required at the point of use, not only compressor discharge.
Required FAD
m³/min or cfm at stated reference conditions.
Air Purity
Oil-free requirement, filtration and any ISO 8573-1 target.
Demand Profile
Stable base load or significant production fluctuations.
Operating Hours
Hours/day and expected annual running hours.
Ambient Temperature
Maximum compressor-room or outdoor ambient condition.
Site Altitude
Required for inlet-air density and performance correction.
Electrical Supply
Voltage, frequency and phase; especially 60 Hz projects in North America.
Cooling Conditions
Available cooling water, temperature and quality where applicable.
Installation Location
Indoor/outdoor, ventilation, service clearance and available footprint.
Redundancy
Single compressor, duty/standby or multiple-machine sequencing.
Future Expansion
Expected increase in production or compressed-air consumption.
System Engineering
Compressor Selection Is Only Part of the Air System
Receiver volume, drying, filtration, cooling and piping pressure loss should be designed around the required air quality and pressure at the actual point of use.
Air Intake
Ambient condition
Compressor
Pressure + FAD
Receiver
System stability
Drying
Dew-point requirement
Filtration
Air-quality requirement
Process
Required point-of-use pressure
Engineering Questions
Frequently Asked Questions
What is a low-pressure air compressor?
n this product range, low-pressure compressors are purpose-built machines operating in the 1.2–4 bar(g) / 17–58 psi range. They are intended for high-volume processes such as pneumatic conveying, fermentation and other applications that do not require conventional 7–10 bar plant air.
Why use a 4 bar compressor instead of compressing to 8 bar and reducing the pressure?
Compressing air to a pressure substantially above the process requirement increases the pressure ratio and compression work. A pressure-reducing valve can lower the downstream pressure but cannot recover the compression energy already used. The correct comparison should use compressor specific power, required FAD, pressure losses and the actual operating profile.
What is the difference between CM/D and CM/DV?
Both are low-pressure oil-free screw compressor series. CM/D uses fixed-speed operation, while CM/DV uses a permanent-magnet motor with variable-speed control. CM/D is generally suited to stable base-load demand; CM/DV is intended for processes where the required air volume changes significantly during operation.
Which compressor series is recommended for PET bottle blowing?
CM/G is the primary oil-free series in the 20–40 bar pressure class for PET-related compressed-air systems. Final compressor sizing must use the actual blow-molder pressure, required FAD, bottle output, receiver arrangement and any air-recovery system.
Is 40 bar considered medium pressure or high pressure?
This product family uses “medium pressure” as its manufacturer classification for the 20–40 bar range. In PET industry search terminology, 30–40 bar compressed air is also frequently described as high-pressure blowing air. Both terms can therefore appear depending on engineering and application context.
What is the difference between fixed-speed and VSD rotary screw compressors?
A fixed-speed compressor runs its motor at a single constant speed. Air delivery is regulated by an inlet valve and load/unload cycling. When demand drops below the compressor’s output, the machine unloads — the motor continues running at full speed, but no useful air is produced. A VSD (variable speed drive) compressor adjusts motor speed continuously to match actual demand. When demand decreases, the motor slows and power consumption reduces proportionally. The trade-off is higher initial cost and more complex electronics. Fixed-speed is often cost-effective when demand stays consistently near full capacity; VSD typically shows greater energy benefit when the compressor runs at partial load for extended periods.
Should I select an oil-free or oil-injected compressor?
Select oil-free compression where compressor lubricant carryover creates unacceptable process or product risk. Oil-injected compression may be suitable for general industrial duties where the process permits it and the downstream treatment system is designed for the required air quality.
Can a low-pressure screw compressor replace a blower?
Not automatically. Blowers and low-pressure compressors overlap in some applications, but selection depends on discharge pressure, pressure ratio, required flow, process stability, specific power and operating range. Compare equipment at the actual required operating point rather than by nominal motor size.
What information is needed to size a compressor for North America?
Provide required pressure and FAD, air-quality requirement, site altitude, maximum ambient temperature, operating profile, cooling conditions, installation location and electrical supply including voltage and 60 Hz frequency where applicable.