Oil-Free Scroll
Compressor
CMW Series · ISO 8573-1 Class 0 Certified
100% oil-free compressed air from 2.2 to 27 kW, rated at 0.8–1.2 MPa (116–174 psi). No downstream oil filtration. No risk of product contamination. Noise floor from 49 dB(A).
2.2–27 kW
Installed Power
Single unit or tandem multi-compressor systems
0.8–1.2 MPa
Discharge Pressure
116 / 145 / 174 psi pressure classes
0.25–2.16 m³/min
Free Air Delivery (FAD)
7 to 87 cfm across model range
What Makes Scroll Technology Different
Zero Oil Carry-Over. By Design
— Not by Filtration.
Conventional rotary screw compressors inject oil into the compression chamber to seal the rotor clearance and manage heat. Even with coalescing filtration, trace oil aerosol (1–5 mg/m³ for Class 1) reaches your process. The CMW scroll design eliminates oil from the compression path entirely: fixed and orbiting scrolls compress air without lubricant contact.
The result is true ISO 8573-1 Class 0 air at the compressor outlet — not a filter-dependent Class 0 claim. For dental autoclaves, analytical instruments, cleanroom environments, and GMP pharmaceutical processes, this is the distinction that eliminates re-qualification risk.
Scroll geometry also eliminates the reciprocating mass that generates pulsation in piston compressors. Air delivery is continuous and near-pulsation-free, reducing downstream regulator hunting and instrument noise.
CMW Series: Class 0 at Outlet
ISO 8573-1 Class 0 requires total oil content below the detection limit specified by the equipment user — effectively 0.003 mg/m³ or below (lower than Class 1's 0.01 mg/m³ limit). The CMW achieves this without downstream oil-removal filtration.
Classification per ISO 8573-1:2010. Dew point achievable with matched compressed air dryer system.
Technical Specifications
CMW Series — Full Parameter Table
Three discharge pressure classes: 0.8 MPa (116 psi), 1.0 MPa (145 psi), 1.2 MPa (174 psi). Select by tab below.
| Model | Motor (kW) | Motor (HP) | Pressure (MPa) | Pressure (Psi) | FAD (L/min) | FAD (cfm) | Noise dB(A) | Outlet (inch) | Weight (kg) | L×W×H (mm) |
|---|---|---|---|---|---|---|---|---|---|---|
| CMW2.2-0.8 | 2.2 | 3 | 0.2–0.8 | 29–116 | 255 | 9 | 49±3 | 1/2" | 132 | 665×630×940 |
| CMW3.7-0.8 | 3.7 | 5 | 0.2–0.8 | 29–116 | 415 | 15 | 52±3 | 1/2" | 150 | 660×665×990 |
| CMW4.4-0.8 | 2.2×2 | 6 | 0.2–0.8 | 29–116 | 510 | 18 | 52±3 | 1/2" | 150 | 800×670×1190 |
| CMW7.4-0.8 | 3.7×2 | 10 | 0.2–0.8 | 29–116 | 830 | 29 | 55±3 | 1" | 185 | 880×670×1190 |
| CMW11-0.8 | 3.7×3 | 15 | 0.2–0.8 | 29–116 | 1245 | 44 | 58±3 | 1" | 300 | 1400×800×1280 |
| CMW15-0.8 | 3.7×4 | 20 | 0.2–0.8 | 29–116 | 1660 | 59 | 61±3 | 1" | 350 | 1400×800×1280 |
| CMW18.5-0.8 | 3.7×5 | 25 | 0.2–0.8 | 29–116 | 2075 | 73 | 63±3 | 1" | 600 | 1400×800×1870 |
| CMW22-0.8 | 3.7×6 | 30 | 0.2–0.8 | 29–116 | 2490 | 88 | 63±3 | 1" | 650 | 1400×800×1870 |
| Model | Motor (kW) | Motor (HP) | Pressure (MPa) | Pressure (Psi) | FAD (L/min) | FAD (cfm) | Noise dB(A) | Outlet (inch) | Weight (kg) | L×W×H (mm) |
|---|---|---|---|---|---|---|---|---|---|---|
| CMW2.2-1.0 | 2.2 | 3 | 0.2–1.0 | 29–145 | 215 | 8 | 49±3 | 1/2" | 132 | 665×630×940 |
| CMW4.5-1.0 | 4.5 | 6 | 0.2–1.0 | 29–145 | 410 | 14 | 52±3 | 1/2" | 150 | 660×665×990 |
| CMW4.4-1.0 | 2.2×2 | 6 | 0.2–1.0 | 29–145 | 430 | 15 | 52±3 | 1/2" | 150 | 800×670×1190 |
| CMW9-1.0 | 4.5×2 | 12 | 0.2–1.0 | 29–145 | 820 | 29 | 58±3 | 1" | 185 | 880×670×1190 |
| CMW13.5-1.0 | 4.5×3 | 18 | 0.2–1.0 | 29–145 | 1230 | 43 | 61±3 | 1" | 300 | 1400×800×1280 |
| CMW18-1.0 | 4.5×4 | 25 | 0.2–1.0 | 29–145 | 1640 | 58 | 61±3 | 1" | 350 | 1400×800×1280 |
| CMW22.5-1.0 | 4.5×5 | 30 | 0.2–1.0 | 29–145 | 2050 | 72 | 63±3 | 1" | 600 | 1400×800×1870 |
| CMW27-1.0 | 4.5×6 | 36 | 0.2–1.0 | 29–145 | 2460 | 87 | 63±3 | 1" | 650 | 1400×800×1870 |
| Model | Motor (kW) | Motor (HP) | Pressure (MPa) | Pressure (Psi) | FAD (L/min) | FAD (cfm) | Noise dB(A) | Outlet (inch) | Weight (kg) | L×W×H (mm) |
|---|---|---|---|---|---|---|---|---|---|---|
| CMW3.0-1.2 | 3 | 5 | 0.2–1.2 | 29–174 | 210 | 7 | 49±3 | 1/2" | 132 | 665×630×940 |
| CMW4.5-1.2 | 4.5 | 6 | 0.2–1.2 | 29–174 | 360 | 13 | 52±3 | 1/2" | 150 | 660×665×990 |
| CMW6.0-1.2 | 3×2 | 8 | 0.2–1.2 | 29–174 | 420 | 15 | 52±3 | 1/2" | 150 | 800×670×1190 |
| CMW9-1.2 | 4.5×2 | 12 | 0.2–1.2 | 29–174 | 720 | 25 | 58±3 | 1" | 185 | 880×670×1190 |
| CMW13.5-1.2 | 4.5×3 | 18 | 0.2–1.2 | 29–174 | 1080 | 38 | 61±3 | 1" | 300 | 1400×800×1280 |
| CMW18-1.2 | 4.5×4 | 25 | 0.2–1.2 | 29–174 | 1440 | 51 | 61±3 | 1" | 350 | 1400×800×1280 |
| CMW22.5-1.2 | 4.5×5 | 30 | 0.2–1.2 | 29–174 | 1800 | 64 | 63±3 | 1" | 600 | 1400×800×1870 |
| CMW27-1.2 | 4.5×6 | 36 | 0.2–1.2 | 29–174 | 2160 | 76 | 63±3 | 1" | 650 | 1400×800×1870 |
Product Range
Industry Applications
Three pressure classes address the full range of B2B oil-free scroll compressor requirements from small dental clinics to hospital central air systems.
CMW-0.8 Series
CMW-1.0 Series
CMW-1.2 Series
Technical Advantages
Engineering Decisions That Define CMW Performance
Each feature below solves a real operational problem identified across dental, laboratory, and pharmaceutical installations.
Low-Noise Operation
The CMW2.2-0.8 measures 49±3 dB(A) — quieter than a normal conversation. Multi-unit tandem systems (CMW22 and above) remain under 65 dB(A). No vibration isolation pads required for most floor installations.
High-Rigidity Square Frame
The structural enclosure uses a square-section fabricated steel frame, not a sheet-metal cabinet. High geometric stiffness minimises resonance amplification and maintains scroll clearance tolerances over service life.
Soft-Start / No Impact Starting
Scroll compressors start unloaded and reach working pressure without the current surge or mechanical shock of direct-on-line piston or screw starts. This reduces electrical demand charges on shared supply circuits in dental and lab fit-outs.
Variable Frequency Drive (VFD) Option
CMW variable-speed models modulate motor RPM to match real-time air demand. Unlike fixed-speed machines that load/unload at rated pressure, VFD units hold pressure within ±0.1 bar and reduce energy consumption at part-load by 20–35%.
Tandem / Dual Scroll Configuration
From CMW4.4 onwards, units combine two scroll heads in one enclosure (e.g., CMW4.4-0.8 = 2 × 2.2 kW). For hospital central air or large dental group practices, multiple CMW units can be paralleled with automatic load-sharing and built-in redundancy.
Minimal Maintenance Schedule
No oil changes. No oil separator elements. No oil-lubricated gear stages. Service is limited to intake filter inspection and periodic tip seal/orbiting scroll replacement — intervals typically exceeding 8,000 operating hours depending on ambient conditions.
Industry Applications
Where CMW Series Oil-Free Scroll Compressors Are Specified
Low demand-volume, critical air-purity environments where contamination cannot be tolerated and quiet operation is a facility requirement.
Product Range
Industry Applications
Three pressure classes address the full range of B2B oil-free scroll compressor requirements from small dental clinics to hospital central air systems.
Air Intake at Scroll Periphery
Ambient air enters through an intake filter at the outer periphery of two mating scroll elements — one fixed to the housing (stator scroll), one mounted eccentrically to the crankshaft (orbiting scroll). No inlet valve is required: the geometry controls flow.
Progressive Compression Toward Centre
As the orbiting scroll moves in a circular path (it does not rotate — it orbits), a series of crescent-shaped air pockets form between the scroll flanks and migrate inward. Pocket volume decreases continuously as they move toward the discharge port at the scroll centre. Compression is smooth and continuous — there is no discrete compression event, no valve slamming, and no pressure pulse.
Discharge at Centre — No Oil Contact
Compressed air exits through the centre discharge port. At no point does lubricating oil contact the air stream. Scroll tip seals (PTFE-based) maintain the clearance between orbiting and fixed scroll, handling the minor leakage that oil would otherwise manage in lubricated designs. This is why tip seal replacement — not oil changes — defines the CMW’s service cycle.
Tandem Scroll Heads for Higher Capacity
CMW models above 3.7 kW stack two or more scroll pairs in a common housing on a shared drive shaft. Each scroll pair operates independently, and the combined discharge feeds a common outlet. This is mechanically simpler than scaling a single scroll — it also means that if one scroll pair reaches service life, the unit continues to run at reduced output rather than failing completely.
Oil-Free Scroll vs. Alternatives — Direct Comparison
| Criteria | Scroll (CMW) | Dry Screw / Piston |
|---|---|---|
| Oil in air stream | None (Class 0) | Class 1 possible* |
| Noise level | 49–63 dB(A) | 65–80+ dB(A) |
| Air pulsation | Near-zero | Significant |
| Start-up shock | None | Moderate |
| Service interval | >8,000 hr (tip seal) | 4,000–6,000 hr (oil) |
| Part-load efficiency | High (VFD option) | Moderate |
| Vibration | Very low | High (piston) |
| Capacity ceiling | Up to 27 kW / unit | Unlimited (screw) |
Sizing Guidance
- Dental: Allow 50–70 L/min FAD per dental chair at 0.8 MPa. A CMW2.2-0.8 (255 L/min) covers 3–4 chairs. CMW7.4-0.8 (830 L/min) covers 10–12 chairs.
- Laboratory: Instrument air headers typically run at 0.6–0.8 MPa, 100–600 L/min. A CMW3.7-0.8 or CMW4.4-0.8 covers most single-lab environments.
- Hospital central air: ISO 7396-1 requires N+1 redundancy. Specify two CMW tandem units with automatic failover control — one as duty, one as standby.
Technical FAQ
Common Questions from Engineers and Procurement Managers
Answers to the questions asked most frequently before specifying or purchasing oil-free scroll compressors.
How does an oil-free scroll compressor work?
A scroll compressor uses two interleaved spiral elements — one fixed, one orbiting eccentrically on a crankshaft — to trap and compress air in progressively smaller crescent-shaped pockets as they migrate from the outer periphery toward the central discharge port. Because the scrolls seal against each other with PTFE-based tip seals (not oil films), no lubricant enters the air stream.
This is mechanically different from rotary screw compressors, where oil is injected into the male-female rotor mesh to provide sealing and cooling. Scroll compression is a continuous process with no valves and no reciprocating mass, which explains both the low noise level and near-absence of pressure pulsation at the outlet.
What is ISO 8573-1 Class 0 oil-free, and does the CMW series meet it?
ISO 8573-1:2010 classifies compressed air purity across three contaminant categories: solid particles, water, and oil. Class 0 for oil means the total oil content (aerosol + vapour + liquid) must not exceed the limit agreed between user and supplier — in practice this is typically stated as ≤ 0.003 mg/m³ or below the instrument detection limit of an appropriate oil-vapor analyser.
The CMW series achieves Class 0 oil content at the compressor outlet without downstream filtration, because oil never contacts the compression chamber. This is a structurally different claim from an oiled compressor with a downstream Class 0 filter — where the classification depends on the filter integrity, not the compressor design.
Oil-free scroll compressor vs. oil-free screw compressor — which is right for my application?
Scroll compressors (like the CMW series) are the right choice for applications requiring: quiet operation (sub-65 dB(A)), low to medium air demand (up to ~2.5 m³/min), minimal vibration, and a small installation footprint. Dental clinics, laboratories, medical suites, and light semiconductor processes are the natural fit.
Dry oil-free screw compressors are appropriate when compressed air demand exceeds the scroll range (typically above 30 kW / 5+ m³/min), where capital cost per kW is a priority at larger scales, and where noise levels above 70 dB(A) are acceptable with acoustic enclosures. They are also oil-free Class 0 at the outlet — but at roughly 2–3× the capital cost of a scroll for equivalent output in the overlap range, and with significantly higher noise.
There is a genuine break-even point around 18–27 kW where the CMW tandem scroll and an equivalent small dry screw overlap in price and performance. For installations in that range, the decision usually comes down to noise constraints and whether the facility has existing acoustic enclosures.
What is the noise level of an oil-free scroll compressor?
The CMW2.2-0.8 and CMW3.0-1.2 measure 49±3 dB(A) at 1 m in free field — comparable to a quiet library or a normal conversation at 2 m distance. Models with 2-scroll tandem heads (CMW4.4 and above) measure 52±3 dB(A). The largest 6-scroll tandem units (CMW22–CMW27) measure 63±3 dB(A).
For comparison: a typical oil-lubricated rotary screw compressor of equivalent output runs at 68–76 dB(A). A reciprocating (piston) oil-free compressor in the same power range typically generates 72–80 dB(A) plus significant vibration transmitted through the floor. The CMW series is the only configuration in this power class that can reasonably be installed in or adjacent to occupied clinical or research spaces without acoustic treatment.
Scroll compressor vs. piston compressor for dental or laboratory use?
Piston (reciprocating) oil-free compressors are common in entry-level dental and lab installations due to lower initial purchase cost. Their drawbacks at a technical level: significant pressure pulsation (causing regulator hunting on precision instruments), high noise (72–80 dB(A)), high vibration, high heat output per unit of FAD, and shorter service intervals (piston ring and valve replacement typically every 2,000–4,000 hours).
Scroll compressors deliver near-pulsation-free air, operate at 49–52 dB(A) for comparable outputs, generate less heat, and require substantially less maintenance intervention. For dental group practices or laboratories where compressor uptime is critical and technician access for maintenance carries a cost, the total cost of ownership over a 10-year period typically favours the scroll — even when the initial capital cost is 30–50% higher than an equivalent piston unit.
What is the maintenance cost and service life of a scroll compressor?
The primary consumable is the orbiting scroll tip seal, a PTFE-based component that maintains compression clearance. Replacement intervals depend on ambient conditions and duty cycle, but are typically rated beyond 8,000 operating hours under normal conditions. This compares to 4,000-hour oil and separator element changes on lubricated screw compressors.
There are no oil changes, no oil separator elements, no oil coolers, and no oil system maintenance costs. Annual maintenance typically consists of intake filter inspection, condensate drain check, and a visual inspection. Major service (tip seal replacement) is a planned, scheduled event — not an emergency arising from oil degradation or separator failure.
Expected service life for the scroll assembly exceeds 40,000 hours with proper maintenance, depending on installation conditions. CMW tandem units (multiple scroll pairs in one housing) continue operating at reduced output if one scroll pair reaches service life ahead of schedule — a resilience advantage over single-head designs.
Can oil-free scroll compressors be used for breathing air or medical air applications?
The CMW series provides oil-free compressed air at the compressor outlet that is suitable as the source for medical air systems when the complete installation (compressor, dryer, filtration, receiver, distribution) meets ISO 7396-1 (Medical Gas Pipeline Systems) and relevant regional standards (e.g., HTM 02-01 in the UK, NFPA 99 in the US).
Breathing air (for personal protective equipment / SCBA) requires additional purity standards (typically EN 12021 or CGA Grade D/E) covering CO, CO₂, and moisture — these require a complete system design, not just an oil-free compressor. The CMW provides the oil-free source; downstream dryers, carbon filters, and monitoring complete the system. Contact us to discuss your specific medical or breathing air system design requirements.
What pressure does a scroll compressor deliver? Can it reach 10 bar or 12 bar?
The CMW series covers three pressure classes: 0.8 MPa (116 psi / approximately 8 bar), 1.0 MPa (145 psi / approximately 10 bar), and 1.2 MPa (174 psi / approximately 12 bar). Each model’s designation indicates its pressure class — CMW9-1.0 delivers up to 1.0 MPa; CMW27-1.2 delivers up to 1.2 MPa.
All CMW units are variable-pressure: the low end of the range is 0.2 MPa (29 psi), so the compressor can supply lower pressures by adjusting the pressure regulator setting. FAD (free air delivery) decreases as working pressure increases within the rated range, which is why the 1.2 MPa variants show lower L/min figures than their 0.8 MPa counterparts at the same motor power.