PM VSD screw
Permanent-magnet variable speed screw compressor: flow turns down to 32 to 45% of rated depending on size, with no idle hours. IE4 motor (IE5 on request), multilingual touchscreen controller.
33 models in the catalogue, flow 0.95 - 44 m³/min, pressure 7 - 16 bar, noise level 60 - 85 dB(A).
How it works ↓
What is a variable speed screw compressor?
The same lubricated screw, run by a drive and a permanent magnet motor: the motor slows down when the workshop uses less air, instead of running off-load. On varying demand, that removes off-load hours; an off-load screw still draws 15 to 35% of its power while producing nothing, according to the US Department of Energy.
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Made for
- Consumption that varies with workstations, shifts or seasons
- Multi-station workshops, two- or three-shift production
- A stable network pressure
Not made for
- A flat load, always at full outputFixed-speed screw
- Oil-free airOil-free compressor
Two series side by side: CZ-SLT and CZ-SMART. Compare flow, footprint and weight row by row; the quote prices both.
| Reference | kW | HP | Flow by pressure (m³/min) | dB(A) | Outlet | L × W × H (mm) | Weight |
|---|---|---|---|---|---|---|---|
| CZ-SMART-7 | 5.5 | 8 | 8 bar0.95 | ||||
| CZ-SLT-7.5V | 7.5 | 10 | 8 bar0.49-1.110 bar0.4-0.913 bar0.28-0.63 | 60 | DN20 | 950 × 687 × 930 | 213 kg |
| CZ-OPP-10PV | 7.5 | 10 | 7 bar1.28 bar1.110 bar0.912 bar0.8 | 60 | DN15 | 930 × 620 × 820 | 185 kg |
| CZ-SLT-11V | 11 | 15 | 8 bar0.78-1.7510 bar0.74-1.6513 bar0.49-1.116 bar0.39-0.88 | 62 | DN20 | 1090 × 740 × 1085 | 317 kg |
| CZ-OPP-15PV | 11 | 15 | 7 bar1.68 bar1.510 bar1.312 bar1.1 | 62 | DN20 | 1080 × 700 × 1060 | 245 kg |
| CZ-SLT-15V | 15 | 20 | 8 bar1.1-2.4410 bar0.99-2.213 bar0.84-1.8716 bar0.49-1.1 | 62 | DN20 | 1090 × 740 × 1085 | 317 kg |
| CZ-OPP-20PV | 15 | 20 | 7 bar2.58 bar2.310 bar2.112 bar1.9 | 62 | DN20 | 1080 × 700 × 1060 | 245 kg |
| CZ-SLT-18.5V | 18.5 | 25 | 8 bar1.35-310 bar1.21-2.713 bar1.03-2.316 bar0.83-1.85 | 64 | DN25 | 1335 × 900 × 1170 | 470 kg |
| CZ-SLT-22V | 22 | 30 | 8 bar1.62-3.610 bar1.44-3.213 bar1.17-2.616 bar1.03-2.3 | 64 | DN25 | 1335 × 900 × 1170 | 470 kg |
| CZ-OPP-30PV | 22 | 30 | 7 bar3.88 bar3.610 bar3.212 bar2.7 | 64 | DN25 | 1300 × 850 × 1150 | 380 kg |
| CZ-SLT-30V | 30 | 40 | 8 bar2.25-510 bar2.02-4.513 bar1.62-3.616 bar1.23-2.94 | 66 | DN40 | 1510 × 1037 × 1275 | 645 kg |
| CZ-OPP-40PV | 30 | 40 | 7 bar5.38 bar510 bar4.512 bar4 | 66 | DN40 | 1390 × 950 × 1250 | 460 kg |
| CZ-SLT-37V | 37 | 50 | 8 bar2.83-6.310 bar2.52-5.613 bar2.07-4.6116 bar1.53-3.4 | 66 | DN40 | 1510 × 1037 × 1275 | 685 kg |
| CZ-OPP-50PV | 37 | 50 | 7 bar6.88 bar6.210 bar5.612 bar5 | 66 | DN40 | 1390 × 950 × 1250 | 460 kg |
| CZ-SLT-45V | 45 | 60 | 8 bar3.35-7.4610 bar2.81-6.2513 bar2.47-5.5116 bar2.34-5.22 | 66 | DN40 | 1510 × 1037 × 1275 | 712 kg |
| CZ-OPP-60PV | 45 | 60 | 7 bar7.48 bar710 bar6.212 bar5.6 | 66 | DN40 | 1500 × 950 × 1250 | 550 kg |
| CZ-SLT-55V | 55 | 75 | 8 bar4.17-9.2810 bar3.67-8.1713 bar3.26-7.2516 bar2.82-6.28 | 68 | DN50 | 1910 × 1270 × 1600 | 1,046 kg |
| CZ-OPP-75PV | 55 | 75 | 7 bar108 bar9.210 bar8.512 bar7.6 | 68 | DN50 | 1600 × 1170 × 1520 | 895 kg |
| CZ-SLT-75V | 75 | 100 | 8 bar5.55-12.3510 bar5.04-11.213 bar4.41-9.816 bar3.62-8.05 | 68 | DN50 | 1910 × 1270 × 1600 | 1,156 kg |
| CZ-OPP-100PV | 75 | 100 | 7 bar13.48 bar12.610 bar11.212 bar10 | 68 | DN50 | 1720 × 1220 × 1600 | 1,195 kg |
| CZ-SLT-90V | 90 | 120 | 8 bar6.84-15.210 bar5.98-13.313 bar5.4-12 | 70 | DN65 | 2460 × 1670 × 1700 | 1,775 kg |
| CZ-OPP-125PV | 90 | 125 | 7 bar16.28 bar1510 bar13.812 bar12.3 | 70 | DN50 | 2480 × 1460 × 1850 | 1,720 kg |
| CZ-SLT-110V | 110 | 150 | 8 bar8.91-19.810 bar7.42-16.513 bar5.94-13.2 | 70 | DN65 | 2460 × 1670 × 1700 | 2,104 kg |
| CZ-OPP-150PV | 110 | 150 | 7 bar218 bar19.810 bar17.412 bar14.8 | 70 | DN65 | 2480 × 1460 × 1850 | 1,960 kg |
| CZ-SLT-132V | 132 | 175 | 8 bar10.44-23.210 bar9.22-20.513 bar7.83-17.4 | 70 | DN65 | 2460 × 1670 × 1700 | 2,261 kg |
| CZ-OPP-175PV | 132 | 175 | 7 bar24.58 bar23.210 bar20.512 bar17.4 | 70 | DN65 | 2480 × 1460 × 1850 | 2,000 kg |
| CZ-SLT-160V | 160 | 215 | 8 bar12.73-28.310 bar11.25-2513 bar9.19-20.43 | 75 | DN65 | 2700 × 1700 × 1800 | 3,380 kg |
| CZ-OPP-220PV | 160 | 220 | 7 bar30.258 bar30.1510 bar26.912 bar23 | 75 | DN75 | 2970 × 1870 × 2350 | 2,150 kg |
| CZ-SLT-185V | 185 | 250 | 8 bar14.35-31.910 bar12.82-28.513 bar10.58-23.53 | 75 | DN100 | 3110 × 1940 × 2060 | 3,580 kg |
| CZ-OPP-250PV | 185 | 250 | 7 bar33.158 bar32.1510 bar30.112 bar24.32 | 85 | DN75 | 2970 × 1870 × 2350 | 2,800 kg |
| CZ-SLT-220V | 220 | 294 | 8 bar16.53-36.7410 bar14.92-33.1713 bar13.38-29.75 | 77 | DN100 | 3970 × 2190 × 2270 | 4,500 kg |
| CZ-SLT-250V | 250 | 335 | 8 bar19.8-4410 bar16.47-36.613 bar14.47-32.16 | 78 | DN100 | 4182 × 2240 × 2340 | 4,600 kg |
| CZ-OPP-350PV | 250 | 350 | 7 bar45.58 bar4310 bar38.912 bar36 | 85 | DN100 | 3350 × 1970 × 2440 | 4,500 kg |
Flows, pressures, noise levels and dimensions recorded model by model on the catalogue sheets. Flows given at 8 bar.
The permanent-magnet variable-speed screw follows demand: the motor slows down when the workshop consumes less, instead of running unloaded. On a varying load, that is as many idle hours removed: an unloaded fixed-speed screw still draws 15 to 35% of its power while producing nothing, according to the US Department of Energy Sourcebook.
It costs more to buy than the fixed-speed range and is not justified on a flat load. The speed floor depends on the model: in the catalogue, it runs from 32 to 45% of rated flow depending on size.
As in a conventional screw compressor, air is compressed between two oil-lubricated helical rotors. The difference lies in the motor: a permanent magnet (PM) motor controlled by a variable frequency drive (VSD, Variable Speed Drive) varies the rotational speed continuously.
The drive adjusts the motor speed in real time to match the network's air demand exactly, instead of working on an all-or-nothing basis like a fixed-speed compressor. The pressure follows a set point, without the load and unload cycles of a fixed-speed machine.
On a variable consumption profile, the gain is decisive: each 0.1 bar reduction in network pressure saves about 0.6 to 0.7% of energy, and the permanent magnet motor keeps a high efficiency at reduced speed.
The default choice as soon as air demand fluctuates: multi-station workshops, two-shift or three-shift production, sites where consumption varies by shift or by season. Electricity is by far the largest item in a compressor's cost of ownership: on a varying demand, the drive is the first lever compared with a fixed-speed machine.
Flow follows the workshop
The drive sets the motor speed to what the workshop consumes. Depending on size, flow turns down to 32 to 45% of rated: the 75 kW modulates from 5.55 to 12.35 m³/min.
No more idle hours
At fixed speed, a screw with no demand left runs unloaded and still draws 15 to 35% of its power while producing nothing, according to the US Department of Energy's Sourcebook. The drive slows the motor down instead.
IE4 permanent magnet motor
IE4 class synchronous motor (IE5 on request), whose efficiency stays high at reduced speed.
Pressure held on set point
The pressure follows a set point instead of swinging between a load threshold and an unload threshold: the network can be set as tightly as possible, and each bar avoided is worth about 7% of energy (DOE Sourcebook).
Soft start
The drive ramps up speed smoothly: inrush current stays limited to the rated current, with no peak on the electrical supply and no shock to the mechanics.
SKF bearings, 80,000 to 100,000 h
Same 3rd-generation air-end as the fixed-speed range, on reinforced SKF bearings rated for 80,000 to 100,000 hours.
Our order of preference for Class 0
When a specification says Class 0, CEZIUM quotes an oil-free machine, as the trade understands it: scroll compressor up to 5 m³/min, rotary tooth compressor from 2.3 to 8.6 m³/min, dry screw or centrifugal beyond that. We also point out the alternative few suppliers mention: a lubricated screw followed by a treatment chain delivers oil-free air for a markedly lower purchase price, without carrying the Class 0 label.
In this trade, Class 0 means an oil-free machine. That is the convention, and it is what a specification expects when it writes Class 0, so that is what we quote. Technically, ISO 8573-1 classifies air at the point of use rather than the compressor, so a lubricated screw followed by multi-stage filtration and an adsorption dryer delivers oil-free air measured on acceptance. That is a genuine alternative, cheaper to buy and far better at heat recovery, but it does not give you a Class 0 certified machine. Both are worth knowing; your own documents decide.
| Rank | Technology | Catalogue flow | Power | Class 0 | Recoverable heat | Purchase cost |
|---|---|---|---|---|---|---|
| 01 | Scroll compressor | 0.3 to 4.96 m³/min | 2.2 to 45 kW | Oil-free machine | Low | Moderate |
| 02 | Rotary tooth compressor | 2.3 to 8.6 m³/min | 15 to 55 kW | Oil-free machine | Low | High |
| 03 | Dry screw compressor | 6.8 to 43 m³/min | 45 to 250 kW | Oil-free machine | Limited | Very high |
| 04 | Centrifugal compressor | 48 to 3,000 m³/min | 198 to 12,055 kW | Oil-free machine | High | Very high |
| 05 | Lubricated screw + treatment chainthis page | 0.95 to 44 m³/min | 5.5 to 250 kW | Treated air, no label | High | Low |
Flow rates and power ratings taken from the CEZIUM catalogue, oil-free technologies and variable-speed lubricated screw. Purchase cost is given in relative ranks, at comparable flow.
- 01
Scroll compressor
Up to 5 m³/minThe first choice below 5 m³/min: oil-free by design, quiet, compact. The right format for a laboratory, a dental practice or a small production line.
See the 13 catalogue models - 02
Rotary tooth compressor
2.3 to 8.6 m³/minAbove the scroll range and up to 8.6 m³/min. The rotors never touch: no friction inside the chamber, minimal wear, TÜV-certified Class 0. Beyond that flow, several units run in parallel.
See the 14 catalogue models - 03
Dry screw compressor
7.8 to 46 m³/minThe answer at high flow when the specification says Class 0. We also state its downside: it costs a great deal to buy and lends itself poorly to heat recovery. If your documents ask for oil-free air rather than a certified machine, the previous step is worth quoting alongside.
See the 20 catalogue models - 04
Centrifugal compressor
From 48 m³/minReserved for the continuous base load of very large sites, where no screw compressor can carry the flow in a single machine.
See the 11 catalogue models - 05
Lubricated screw + treatment chain
Alternative, above 8.6 m³/minThe alternative, when your specification asks for oil-free air rather than a certified machine: multi-stage filtration and an adsorption dryer behind a lubricated screw, with acceptance measurement at the point of use. Markedly lower purchase price, and compression heat is recovered from the oil circuit, which a dry machine does poorly. Rule it out if your documents say Class 0.
See the 33 catalogue models
Worth reading on this technology
Permanent magnet VSD: what the drive really saves
What a permanent magnet drive changes on a varying load: idle hours removed, and the annual gain to be worked out from your own load profile, across 6 typical power ratings.
Two-stage screw compressor: around 10% less energy than a standard screw
A two-stage screw compressor compresses air in two steps with intercooling in between, close to the theoretical isothermal cycle. Around 10% less energy than a standard screw at constant load; with a permanent magnet drive, on a variable load, the two gains combine.