Description
CM/D Series Low Pressure Oil-Free Screw Air Compressor
The CM/D series is a fixed-speed, water-cooled, low pressure oil-free screw air compressor designed for continuous industrial operation where air quality and reliability are non-negotiable. With motor power ranging from 45 kW to 160 kW and working pressures between 0.12 MPa and 0.40 MPa (17–58 psi), this series covers the flow requirements of most large-scale low-pressure compressed air applications.
Because the screw air-end runs without any lubricating oil in the compression chamber, the delivered air is genuinely oil-free. There is no downstream oil separation, no oil carryover risk, and no oil filter maintenance to manage. For industries like wastewater treatment, food processing, pharmaceuticals, and electronics manufacturing, that distinction matters both for product quality and for regulatory compliance.
Across the CM/D lineup, discharge air temperature stays at or below 45 °C, noise levels range from 70 to 78 dB(A), and all models share a common water-cooled configuration that makes them well-suited to plant environments where heat rejection to ambient air is limited. If you are evaluating options for a new installation or replacing an aging low-pressure system, the medium and low pressure air compressor range provides a full picture of available configurations.
CM/D Series Low Pressure Oil-Free Screw Air Compressor Key Technical Features
Certified Oil-Free Compressed Air
There is no oil in the compression stage. The screw rotors operate on precision-engineered clearances without contact lubrication, which means no oil can enter the airstream. This makes the CM/D series appropriate for applications where oil contamination would damage product, spoil batch processes, or create compliance issues with food safety or pharmaceutical air quality standards.
High-Volume Low-Pressure Performance
The series is optimized for the 0.12–0.40 MPa pressure band, delivering free air delivery (FAD) from 13.60 m³/min up to 43.00 m³/min depending on model and operating pressure. This high-volume, low-pressure output makes the CM/D well-matched to aeration tanks, pneumatic conveying lines, and similar process applications that require consistent large-volume airflow rather than high pressure.
Low Discharge Temperature
All CM/D models maintain a supply gas temperature of 45 °C or below. In practice, this reduces thermal stress on downstream piping and connected equipment, and it also simplifies any downstream drying requirements. The water-cooled design is the primary reason this performance is consistent across the full operating range.
Straightforward Maintenance Structure
Without oil in the system, there is no oil filter to replace, no oil separator element to monitor, and no oil sampling schedule to maintain. Routine maintenance focuses on air-end inspection intervals, cooling water quality, and standard drive component checks. For operations running extended shifts, the lower maintenance overhead translates directly into higher availability.
Water-Cooled Configuration
The CM/D uses closed-loop water cooling with DN40 or DN80 cooling water connections depending on model size, and cooling water inlet temperature is referenced at 32 °C. Water flow requirements range from 12 T/h on the CM45D up to 35 T/h on the CM160D. This configuration makes the compressor independent of ambient temperature variation, supporting consistent performance year-round in enclosed plant environments.
Scalable Power Range
Six models spanning 45 kW to 160 kW (60 HP to 220 HP) allow plant engineers to match compressor capacity closely to actual demand. Smaller facilities typically start with the CM45D or CM55D, while large-scale continuous operations handling over 1,500 cfm of airflow are better served by the CM132D or CM160D.
Technical Specifications — CM/D Series (Fixed Speed)
Water-cooled | Supply gas temperature ≤45 °C | Cooling water inlet temperature reference: 32 °C
| Model | Work Pressure MPa / Psi |
FAD m³/min / cfm |
Motor Power kW / HP |
Noise dB(A) |
Weight kg |
Cooling Water Pipe Inlet/Outlet |
Cooling Water Qty T/h (32 °C) |
Dimensions L×W×H mm |
Air Outlet |
| CM45D | 0.12–0.25 / 17–36 | 13.80 / 487 | 45 / 60 | 70 | 1680 | DN40 | 12 | 2200×1350×1530 | DN65 |
| CM55D | 0.25–0.40 / 36–58 | 13.60 / 480 | 55 / 75 | 70 | 1700 | DN40 | 18 | 2200×1350×1530 | DN65 |
| CM75D | 0.25–0.40 / 36–58 | 20.10 / 710 | 75 / 100 | 72 | 2250 | DN40 | 20 | 2200×1350×1530 | DN65 |
| CM110D | 0.25–0.40 / 36–58 | 30.10 / 1063 | 110 / 150 | 78 | 3730 | DN80 | 24 | 3100×1700×2090 | DN125 |
| CM132D | 0.12–0.25 / 17–36 | 43.00 / 1518 | 132 / 180 | 78 | 3770 | DN80 | 30 | 3100×1700×2090 | DN125 |
| CM160D | 0.25–0.40 / 36–58 | 42.88 / 1514 | 160 / 220 | 78 | 3830 | DN80 | 35 | 3100×1700×2090 | DN125 |
How to Select the Right CM/D Model
Start with two numbers: the airflow you need at your operating pressure, and how many hours per day the compressor will run. Those two figures narrow the selection quickly.
Pressure range first. The CM45D and CM132D cover the lower band of 0.12–0.25 MPa (17–36 psi), which is typical for coarse-bubble aeration in wastewater treatment or low-pressure pneumatic conveying. The CM55D, CM75D, CM110D, and CM160D operate at 0.25–0.40 MPa (36–58 psi), the more common range for textile processing, fermentation, and general industrial blow-off.
Airflow next. If your process requires up to 500 cfm (roughly 14 m³/min), the CM45D or CM55D is the starting point. Applications in the 500–750 cfm range are a match for the CM75D. For continuous-duty operations drawing 1,000 cfm or more — large aeration tanks, centralized plant air systems — the CM110D, CM132D, or CM160D provides the necessary capacity. The CM132D at 1,518 cfm and CM160D at 1,514 cfm are functionally equivalent on airflow; the CM160D runs at higher pressure and draws slightly more power.
Cooling water availability. All models are water-cooled. Before finalizing model selection, confirm that your cooling water system can supply the required flow — 12 T/h for the CM45D, scaling up to 35 T/h for the CM160D — at an inlet temperature at or below 32 °C. If your facility has limited cooling water capacity, that constraint may influence the model or require additional cooling infrastructure.
For continuous 24/7 operation, there is no penalty on these fixed-speed models beyond the operating cost of running at full load. If your demand varies significantly across shifts, consider reviewing the CM/DV variable frequency series, which can reduce energy consumption during partial-load periods.
Typical Applications of CM/D Series Low Pressure Oil-Free Screw Air Compressor
The CM/D series is commonly used in processes that require large-volume, oil-free compressed air at low to medium pressure on a continuous basis.
- Wastewater Treatment — Aeration basins require sustained low-pressure airflow over extended periods. Oil-free air eliminates any risk of contaminating the biological treatment process, and the high FAD of the CM110D through CM160D matches large municipal or industrial plant requirements.
- Textile Manufacturing — Air-jet looms and fiber transport systems operate at pressures in the 3–4 bar range. Oil contamination at this stage can damage yarn and cause production rejects. The CM/D delivers the required volume reliably without oil carryover.
- Food and Beverage Processing — Pneumatic conveying of dry ingredients, packaging line actuation, and fermentation aeration all benefit from confirmed oil-free air. Regulatory frameworks for food contact air typically require oil-free compression as a baseline.
- Pharmaceutical Manufacturing — Fermentation, tablet coating, and clean room pressurization require air that meets strict purity standards. Oil-free screw compression at the source simplifies the overall air treatment system design.
- Electronics Manufacturing — Circuit board assembly, component handling, and cleanroom environments cannot tolerate oil aerosol contamination. Low-pressure oil-free air from the CM/D series supports these processes without the risks associated with oil-injected compressors.
- Chemical and Petrochemical Processing — Instrument air and process air in chemical plants often require confirmed oil-free status to prevent catalyst contamination or reaction interference. The CM/D covers the low-pressure segment of these requirements.
- Pneumatic Conveying Systems — Bulk powder and granule transport systems commonly run at 2–4 bar. The CM/D’s high FAD output supports medium and large conveying lines with stable pressure delivery.
Oil-Free vs. Micro-Oil vs. Variable Frequency: Choosing the Right Type
All three types of low-pressure screw compressor are available in the CM/D product family. The right choice depends on your air quality requirements, operating pattern, and budget priorities.
| Type | Key Advantages | Best Suited For |
| Oil-Free Screw Compressor CM/D Series |
No oil in the compression chamber. Zero oil carryover into the airstream. Eliminates oil-related maintenance tasks. Simplifies downstream air treatment. | Food processing, pharmaceuticals, electronics, fermentation, cleanroom environments, and any application where oil contamination creates product or compliance risk. |
| Micro-Oil Screw Compressor CMN/D Series |
Oil lubrication improves rotor sealing efficiency, resulting in higher volumetric output per unit of power. Lower capital cost than oil-free equivalents. Mature, well-understood technology. | General industrial pneumatics, wastewater aeration (non-contact air), pneumatic conveying of non-food materials, and any application where downstream filtration can adequately manage residual oil content. |
| Variable Frequency Oil-Free CM/DV Series |
Permanent magnet motor with inverter drive adjusts compressor speed to match actual demand. Reduces energy consumption by 15–30% in variable-load operations. Stable output pressure with lower pressure band variation. | Applications with fluctuating air demand across shifts or seasons. Facilities targeting energy cost reduction. Any oil-free application where load factor varies and energy efficiency is a priority. |
For a complete overview of available configurations, visit the medium and low pressure air compressor series page.
Frequently Asked Questions
What is a low pressure oil-free screw air compressor used for?
Low pressure oil-free screw compressors are designed for applications that need large volumes of clean air at pressures below 0.4 MPa (58 psi). Common uses include biological aeration in wastewater treatment plants, air-jet loom systems in textile mills, fermentation aeration in food and pharmaceutical production, pneumatic conveying of dry bulk materials, and instrument air systems in processing plants. The oil-free designation is critical in any process where oil contamination would affect product quality or violate safety regulations.
What pressure range does the CM/D series operate at?
The CM/D series covers two working pressure ranges. The CM45D and CM132D are rated at 0.12–0.25 MPa (17–36 psi), suitable for very low pressure aeration and similar applications. The CM55D, CM75D, CM110D, and CM160D operate at 0.25–0.40 MPa (36–58 psi), covering the broader band of industrial low-pressure requirements. All models are fixed-speed, meaning they run at rated output when in operation.
How do I choose the right CM/D model for my application?
Begin with your required FAD (free air delivery) at your operating pressure, then verify that your cooling water system can support the required flow rate for that model. For flows up to approximately 500 cfm, the CM45D or CM55D is appropriate. Between 500–750 cfm, look at the CM75D. For large installations requiring 1,000 cfm or more, the CM110D through CM160D covers that range. If your demand fluctuates significantly, the variable frequency CM/DV series is worth evaluating alongside the fixed-speed CM/D.
What is the difference between oil-free and oil-injected screw compressors?
In an oil-injected screw compressor, oil is circulated through the compression chamber to lubricate the rotors, seal clearances, and remove heat. This oil is separated downstream, but trace quantities remain in the compressed air. In an oil-free screw compressor like the CM/D, the rotors operate without oil in the compression stage, and the delivered air contains no oil carryover. Oil-free compressors are typically specified where air purity is regulated or where oil contamination would damage downstream processes. Oil-injected models are often lower cost and have slightly higher volumetric efficiency.
What cooling water supply does the CM/D require?
All CM/D models are water-cooled. Cooling water inlet and outlet connections are DN40 for the CM45D through CM75D, and DN80 for the CM110D through CM160D. Cooling water flow requirements range from 12 T/h on the CM45D to 35 T/h on the CM160D, referenced at 32 °C inlet temperature. Before installation, confirm that your plant cooling water system can sustain these flow rates. If cooling water availability is limited, discuss alternative cooling configurations with our engineering team.
What maintenance does an oil-free screw compressor require?
Without oil in the compression stage, the maintenance schedule for the CM/D is simpler than for oil-injected units. There are no oil filters, oil separators, or oil sampling intervals to manage. Routine maintenance covers air filter inspection and replacement, cooling water quality monitoring and treatment, drive belt or coupling checks, and periodic air-end inspection at manufacturer-recommended intervals. For high-availability operations, a planned maintenance schedule based on actual running hours is the most effective approach.
Can the CM/D series support 24/7 continuous operation?
Yes. The CM/D series is designed for continuous industrial operation. The water-cooled configuration supports sustained full-load running without the thermal limitations that can affect air-cooled units in warm environments. For operations requiring uninterrupted airflow — such as wastewater aeration or continuous process lines — specifying a standby unit alongside the primary compressor is standard practice to ensure zero-interruption capability during scheduled maintenance.
Get Engineering Support for Your Application
Need help selecting the right low pressure oil-free compressor? Share your required airflow (m³/min or cfm), working pressure (MPa or bar), daily operating hours, and whether your application has specific air purity requirements. Our engineering team can confirm model selection, review cooling water compatibility, and advise on installation requirements.
You can also review the full medium and low pressure air compressor range to compare available series before reaching out.
