Description
CMN/D Series Low Pressure Micro-Oil Screw Air Compressor
The CMN/D series covers low-pressure screw compressor applications where high airflow volume and straightforward operation take priority. Running at a fixed working pressure of 0.4 MPa (58 psi) across the full model range, these units deliver free air delivery from 4.92 m³/min on the CMN22D up to 42.88 m³/min on the CMN185D — a range that covers small aeration systems through to large-scale industrial pneumatic lines.
Micro-oil screw compression uses a small quantity of oil in the compression chamber to lubricate the rotors, remove heat, and seal the working clearances. This delivers reliable, efficient compression with established technology that is well-understood by maintenance teams. Oil content in the delivered air is rated at 2 PPM or below, and with appropriate downstream filtration this compressed air is suitable for a broad range of general industrial applications.
With thirteen models from 22 kW to 185 kW, the CMN/D series provides genuine granularity for matching compressor capacity to actual plant requirements. For applications where certified oil-free air is a firm requirement, or where variable demand makes fixed-speed operation less efficient, the oil-free CM/D and CM/DV series are worth reviewing alongside this product.
CMN/D Series Low Pressure Micro-Oil Screw Air Compressor Key Technical Features
Wide Power Range — 22 kW to 185 kW
Thirteen models spanning 22 kW (30 HP) to 185 kW (250 HP) give engineers precise control over compressor sizing. The CMN22D through CMN55D cover smaller flow requirements from under 200 cfm up to around 445 cfm, while the CMN75D through CMN185D handles the high-demand segment above 500 cfm. This range reduces the oversizing that is common when product lines have large gaps between models.
Consistent 0.4 MPa Operating Pressure
All CMN/D models operate at a single working pressure of 0.4 MPa (58 psi). This standardization simplifies plant design and piping layout when multiple units feed a common header. It also means that the entire model range can be compared on FAD and power alone, without the added variable of pressure rating affecting the selection process.
Low Oil Content in Delivered Air
Oil content in the compressed air supply is rated at 2 PPM or below. For general industrial applications — pneumatic conveying, wastewater aeration (non-contact), plant air systems, and similar uses — this level is acceptable and manageable with standard downstream coalescing filtration. This is micro-oil technology, not oil-free; applications requiring certified oil-free air should be directed to the CM/D or CM/DV series.
Air-Cooled Design Across Most Models
The CMN/D series uses air cooling as the primary heat rejection method, which removes the need for a separate cooling water supply and simplifies installation in locations where chilled water infrastructure is not available. Cooling fan power is clearly specified per model, from 0.45 kW on the CMN22D to 5.5 kW on the CMN185D. This self-contained cooling arrangement is one reason the CMN/D is commonly selected for greenfield installations or satellite facilities.
Mature Screw Air-End Technology
Micro-oil lubrication in the compression stage provides excellent rotor sealing and heat management, which contributes to stable long-term volumetric efficiency. The technology has a long service track record across industrial compressor applications and is supported by a well-established maintenance and spare parts supply chain. For maintenance teams that manage multiple pieces of rotating equipment, the CMN/D’s familiar design reduces the learning curve compared to more complex configurations.
Low Noise on Smaller Models
The CMN22D operates at 65 dB(A), which is notably quiet for an industrial screw compressor of this type. Noise levels rise progressively through the range, reaching 78 dB(A) on the larger models from CMN110D upward. For installations in or near occupied workspaces, the lower-power models in this series may reduce the need for acoustic enclosures or separate compressor rooms.
Technical Specifications — CMN/D Series
Working pressure: 0.4 MPa / 58 psi (all models) | Oil content in supply: ≤2 PPM | Supply temperature: ≤ambient +15 °C
| Model | Work Pressure MPa / Psi |
FAD m³/min / cfm |
Motor Power kW / HP |
Noise dB(A) |
Weight kg |
Cooling Fan Power kW |
Air Outlet Size |
Dimensions L×W×H mm |
| CMN22D | 0.4 / 58 | 4.92 / 174 | 22 / 30 | 65 | 770 | 0.45 | 1½” | 1500×950×1400 |
| CMN30D | 0.4 / 58 | 6.30 / 222 | 30 / 40 | 66 | 1250 | 1.8 | 2″ | 1850×1105×1600 |
| CMN37D | 0.4 / 58 | 7.50 / 265 | 37 / 50 | 67 | 1290 | 1.8 | 2″ | 1850×1105×1600 |
| CMN45D | 0.4 / 58 | 10.30 / 364 | 45 / 60 | 68 | 1476 | 3 | 2″ | 1900×1200×1660 |
| CMN55D | 0.4 / 58 | 12.60 / 445 | 55 / 75 | 70 | 1570 | 3 | 2″ | 1900×1200×1660 |
| CMN75D | 0.4 / 58 | 16.11 / 569 | 75 / 100 | 73 | 2250 | 0.37×1 / 4.0×1 | DN65 | 2000×1320×1980 |
| CMN90D | 0.4 / 58 | 20.10 / 710 | 90 / 125 | 73 | 2290 | 0.37×1 / 4.0×1 | DN65 | 2000×1370×1980 |
| CMN110D | 0.4 / 58 | 23.10 / 816 | 110 / 150 | 78 | 3700 | 0.37×1 / 4.0×1 | DN100 | 2830×1900×2325 |
| CMN132D | 0.4 / 58 | 28.85 / 1019 | 132 / 180 | 78 | 3760 | 3.5×2 | DN100 | 2830×1900×2325 |
| CMN160D | 0.4 / 58 | 36.63 / 1293 | 160 / 220 | 78 | 4430 | 3.5×2 | DN125 | 3200×2000×2530 |
| CMN185D | 0.4 / 58 | 42.88 / 1514 | 185 / 250 | 78 | 5000 | 5.5×2 | DN125 | 3200×2000×2530 |
Note: Specifications subject to change. Confirm final data with technical documentation before purchase.
Selecting the Right CMN/D Model
Because every CMN/D model operates at the same 0.4 MPa working pressure, model selection in this series comes down to airflow requirements, physical footprint, and cooling arrangement.
Small installations under 300 cfm: The CMN22D (174 cfm) and CMN30D (222 cfm) cover smaller process lines, individual aeration zones, or secondary plant air supply points. Both models are notably compact and quiet at 65–66 dB(A), and their smaller footprint makes them practical for installations with limited floor space.
Medium installations 300–600 cfm: The CMN37D through CMN55D models cover this range with FAD outputs of 265–445 cfm. These are commonly selected for mid-scale fermentation tanks, pneumatic conveying lines, and plant air systems in light manufacturing facilities.
Large installations 600–1,000 cfm: The CMN75D (569 cfm) and CMN90D (710 cfm) are designed for higher-volume applications and transition to larger frame sizes with dual cooling fan configurations. They are commonly used in larger wastewater aeration installations, textile plants, and centralized compressed air headers serving multiple process points.
High-capacity installations above 1,000 cfm: The CMN110D through CMN185D serve large-scale industrial operations. The CMN132D at 1,019 cfm and CMN185D at 1,514 cfm are the highest-capacity models in the series. For facilities requiring more than 1,500 cfm from a single compressor, a dual-unit installation with one as standby is the standard approach. For applications at this scale where energy costs are significant, compare with the variable frequency low pressure air compressor options to evaluate whether VFD savings justify the higher capital cost.
Typical Applications of CMN/D Series Low Pressure Micro-Oil Screw Air Compressor
The CMN/D series is suitable for applications that require reliable large-volume low-pressure air and can work within the ≤2 PPM oil content specification with standard downstream filtration.
- Wastewater Treatment Aeration — Biological aeration tanks require sustained low-pressure airflow. The CMN/D’s high FAD output and air-cooled design make it practical for outdoor or semi-enclosed treatment plant installations where cooling water is not available.
- Pneumatic Conveying of Bulk Materials — Cement, grain, plastic pellets, and similar materials are transported at low pressure and high volume. Micro-oil compressed air with downstream filtration is acceptable for most dry-bulk conveying applications.
- Textile Manufacturing — Air-jet looms and associated handling equipment use compressed air at 3–4 bar. The CMN/D’s FAD range matches both small weaving operations and large integrated textile plants.
- Industrial Fermentation — Aerobic fermentation in brewing, bioprocessing, and chemical production requires consistent low-pressure aeration. The CMN/D provides stable continuous output for these processes.
- General Plant Air Supply — For manufacturing facilities with distributed pneumatic tooling, actuators, and instrument air requirements at low pressure, the CMN/D series provides a cost-effective centralized supply with a familiar maintenance profile.
- Mining and Mineral Processing — Material transport, dust suppression, and flotation processes use large volumes of low-pressure air. The robust screw air-end and straightforward air-cooled configuration suit the environmental conditions typical of mining operations.
- Paper and Pulp Processing — Drying air, pneumatic control systems, and process aeration in pulp mills are standard applications for this compressor type. The range of model sizes allows matching capacity to individual process zones.
Micro-Oil vs. Oil-Free vs. Variable Frequency: Which Type Fits Your Requirements?
The three low-pressure screw compressor types in the CM/D product family address different priorities. Here is a practical comparison to help guide selection.
| Type | Key Advantages | Best Suited For |
| Micro-Oil Screw Compressor CMN/D Series |
Proven screw compression technology. Higher volumetric efficiency due to oil sealing. Air-cooled — no cooling water supply required. Broader model range from 22 kW. Lower capital cost compared to oil-free equivalents. | General industrial pneumatics, wastewater aeration, pneumatic conveying, bulk material handling, and applications where ≤2 PPM oil content is acceptable with standard filtration. |
| Oil-Free Screw Compressor CM/D Series |
Zero oil in the compression stage. No oil maintenance tasks (filters, separators, sampling). Eliminates any risk of oil contamination in the product stream. Water-cooled for consistent performance. | Food and beverage, pharmaceutical, electronics, cleanroom environments, fermentation, and any application with regulatory or product quality requirements for oil-free compressed air. |
| Variable Frequency Oil-Free CM/DV Series |
Permanent magnet VFD motor adjusts output to match demand. Energy savings of 15–30% in variable-load operations. Stable supply pressure with narrow pressure band. Oil-free air quality. | Applications with fluctuating demand across shifts, facilities targeting energy cost reduction, and any oil-free application where variable load makes fixed-speed operation inefficient. |
Review the full range of medium and low pressure air compressors to compare all available series.
Frequently Asked Questions
What is a micro-oil screw air compressor?
A micro-oil screw compressor uses a small quantity of lubricating oil inside the compression chamber to seal the rotor clearances, reduce friction, and remove compression heat. The oil is separated from the compressed air downstream, resulting in a residual oil content of 2 PPM or below in the delivered air. This is distinct from oil-free compressors, where no oil enters the compression stage at all. Micro-oil technology is well-established and widely used in general industrial compressed air systems.
What working pressure does the CMN/D series operate at?
All CMN/D models operate at a fixed working pressure of 0.4 MPa (58 psi, approximately 4 bar). This is consistent across the full range from CMN22D to CMN185D. If your application requires pressures below 0.4 MPa — for example, 0.12–0.25 MPa for biological aeration — the oil-free CM/D or CM/DV series covers those lower pressure ranges and should be considered instead.
Is 2 PPM oil content acceptable for my application?
For most general industrial applications — pneumatic conveying of non-food materials, wastewater aeration, plant tool air, and similar uses — 2 PPM oil content with standard downstream coalescing filtration is acceptable. However, for food contact air, pharmaceutical production, electronics manufacturing, and applications governed by air quality regulations (such as ISO 8573-1 Class 1), 2 PPM is not sufficient. Those applications require certified oil-free compression from the CM/D or CM/DV series.
Does the CMN/D series require cooling water?
No. The CMN/D series uses air cooling, not water cooling. Cooling fans are integrated into the compressor package — cooling fan power is specified for each model in the technical table above. This air-cooled design simplifies installation significantly, as no cooling water supply, return piping, or water treatment system is required. It also makes the CMN/D practical for outdoor installations or locations where water infrastructure is limited or unavailable.
How do I select between the CMN/D and CM/D series?
The primary decision factor is air quality. If your process requires oil-free compressed air — due to product contact, regulatory compliance, or contamination sensitivity — specify the CM/D (fixed speed) or CM/DV (variable frequency) oil-free series. If your application can operate with ≤2 PPM oil content and you prefer a simpler installation without cooling water requirements, the CMN/D offers a cost-effective and reliable alternative. The CMN/D also covers a broader power range starting at 22 kW versus 45 kW for the CM/D.
What routine maintenance does the CMN/D require?
Routine maintenance on micro-oil screw compressors covers oil level checks and oil changes at manufacturer-recommended intervals, air filter and oil filter replacement, oil separator element monitoring, and cooling fan inspection. Compared to larger rotary or reciprocating compressors, screw compressor maintenance is generally less intensive, and the CMN/D’s modular design supports straightforward access to serviceable components. Establishing a maintenance schedule based on actual running hours rather than calendar time is the most effective approach for compressors running variable-length shifts.
Can CMN/D units be run in parallel for larger flow requirements?
Yes. Multiple CMN/D units can operate in parallel on a common header to achieve higher combined FAD than a single unit can provide, or to provide operational redundancy. Running two or more units in parallel also allows partial-load operation by shutting down one unit during periods of reduced demand — a practical way to manage energy costs without a variable frequency drive. If your flow requirements exceed the capacity of a single CMN185D (1,514 cfm), a parallel configuration or a discussion with our engineering team about large-capacity solutions is the appropriate next step.
Discuss Your Low Pressure Compressed Air Requirements
To confirm the right CMN/D model for your application, share your required FAD (m³/min or cfm), working pressure, operating hours per day, and whether your process has specific air quality requirements. Our engineering team can recommend the appropriate model and advise on installation, cooling, and downstream filtration needs.
You can also review the full medium and low pressure air compressor range to compare available series side by side.
