WALTER SF DSP screw compressors: two-stage compression
7-year warrantyTwo-stage compressors with inverter 22–315 kW
The SF DSP range compresses air in two stages and delivers on average 12% more compressed air than a single-stage machine. The IE5 magnetic motor with inverter maintains efficiency across a wide load range, making the compressor suitable for applications with long running times where electricity is the largest cost item. The range includes 13 models from 22 to 315 kW.
All 13 WALTER SF DSP models
Sorted by power input. Air delivery is stated at 8, 10, and 13 bar as a range from the lowest to the highest inverter speed. The SF 22 DSP and SF 30 DSP models are manufactured for 8 and 10 bar.
| WALTER SF DSP screw compressors — all 13 versions | ||||||||
|---|---|---|---|---|---|---|---|---|
| Model | Power input | Air delivery 8 bar | Air delivery 10 bar | Air delivery 13 bar | Connection | Dimensions L × W × H | Weight | Noise level |
| SF 22 DSP | 22 kW | 1.68–4.2 m³/min | 1.52–3.8 m³/min | — | G 1½″ | 1,500 × 1,037 × 1,273 mm | 738 kg | 63 dB(A) |
| SF 30 DSP | 30 kW | 2.34–5.86 m³/min | 2.21–5.53 m³/min | — | G 1½″ | 1,610 × 1,043 × 1,380 mm | 826 kg | 65 dB(A) |
| SF 37 DSP | 37 kW | 3–7.5 m³/min | 2.69–6.72 m³/min | 2.26–5.65 m³/min | G 1½″ | 1,610 × 1,043 × 1,380 mm | 841 kg | 65 dB(A) |
| SF 45 DSP | 45 kW | 3.66–9.14 m³/min | 3.24–8.11 m³/min | 2.6–6.52 m³/min | G 2″ | 2,132 × 1,318 × 1,600 mm | 1,144 kg | 65 dB(A) |
| SF 55 DSP | 55 kW | 4.74–11.86 m³/min | 4.23–10.58 m³/min | 3.2–7.99 m³/min | G 2″ | 2,132 × 1,318 × 1,600 mm | 1,663 kg | 65 dB(A) |
| SF 75 DSP | 75 kW | 6.28–15.7 m³/min | 5.82–14.56 m³/min | 4.59–11.48 m³/min | G 2″ | 2,256 × 1,469 × 1,700 mm | 1,861 kg | 68 dB(A) |
| SF 90 DSP | 90 kW | 7.64–19.1 m³/min | 6.7–16.76 m³/min | 5.736–14.34 m³/min | DN 65 | 2,656 × 1,698 × 1,800 mm | 3,300 kg | 70 dB(A) |
| SF 110 DSP | 110 kW | 9.28–23.2 m³/min | 8.21–20.53 m³/min | 6.852–17.13 m³/min | DN 80 | 2,656 × 1,698 × 1,800 mm | 3,600 kg | 72 dB(A) |
| SF 132 DSP | 132 kW | 11.2–27.4 m³/min | 10.2–25.5 m³/min | 8.38–20.96 m³/min | DN 80 | 2,656 × 1,698 × 1,800 mm | 3,900 kg | 74 dB(A) |
| SF 160 DSP | 160 kW | 13.2–33.3 m³/min | 12.4–31 m³/min | 9.84–24.6 m³/min | DN 100 | 3,108 × 1,940 × 2,060 mm | 4,250 kg | 76 dB(A) |
| SF 185 DSP | 185 kW | 15–36.6 m³/min | 13–32.9 m³/min | 10.6–26.71 m³/min | DN 100 | 3,970 × 2,190 × 2,265 mm | 4,650 kg | 76 dB(A) |
| SF 250 DSP | 250 kW | 20.5–51.4 m³/min | 18–45.3 m³/min | 15.6–39.01 m³/min | DN 100 | 4,400 × 2,240 × 2,340 mm | 6,450 kg | 78 dB(A) |
| SF 315 DSP | 315 kW | 19.86–66.2 m³/min | 17.43–58.1 m³/min | 15.21–50.7 m³/min | DN 125 | 3,700 × 2,400 × 2,300 mm | 7,800 kg | 86 dB(A) |
Electricity accounts for more than 80% of the costs of producing compressed air over the compressor's lifetime. That's why with a two-stage machine, you save where it matters most.
#showmore#
Why two-stage compression
A single-stage block compresses air from 1 to 8 bar in one step. Two-stage compression splits this into two steps, so it runs cooler, with lower leakage and less load on the bearings.
Lower temperature during compression
Compression takes place at a lower temperature than in a single-stage block, resulting in a more efficient isothermal conversion.
Lower internal leakage
The lower compression ratio of each stage reduces internal leakage to a quarter and increases volumetric efficiency by 5–10%.
Bearings last up to four times longer
The forces acting on the bearings in a two-stage block are half as much, extending their service life by up to four times.
Optimal rotor speed
The block design allows the linear speed of each rotor to be set to the optimal value of 25–35 m/s.
IE5 magnetic motor
The IE5 synchronous motor has the highest efficiency and maintains it over a wide load range, making it worthwhile even with variable demand.
At a working pressure of 8 bar, the first stage compresses at a ratio of 2.8:1 and the second stage also at 2.8:1. The single-stage block compresses at a ratio of 8:1.
What's inside the housing
- Three-stage oil separation — high air quality with lower noise and smaller pressure loss, at most 3 ppm of oil mist in the output air.
- Cooling — efficient axial fan and temperature-controlled motor.
- Direct 1:1 drive — the block is connected directly to the motor, without a belt.
- Inverter — the built-in inverter continuously regulates output according to demand.
Ventilek’s advice
A two-stage machine pays off through electricity, not through output.
Add up what will run at the same time, and look for the row where your typical consumption falls in the middle of the air delivery range. That's where the inverter works best. If your consumption varies only a little during the day, also check out the single-stage SF KSP series; two-stage compression pays off the most for machines that run entire shifts.
Frequently asked questions
- How does SF DSP differ from SF KSP?
- Both have direct drive and an inverter. SF DSP compresses air in two stages and has an IE5 magnetic motor, SF KSP is single-stage with an IE4 motor (optionally IE5). With the same power input, it therefore delivers more air — for 45 kW this is up to 9.14 m³/min at 8 bar compared to 7.51 m³/min.
- What pressure do the SF DSP models have?
- The working pressure is 8, 10 or 13 bar. The SF 22 DSP and SF 30 DSP models are manufactured for 8 and 10 bar. Choose the pressure according to the most demanding consumer.
- What connections do they have?
- Up to 37 kW, a G 1½″ thread; for 45–75 kW models, a G 2″ thread. From 90 kW, the connection is DN 65, and up to DN 125 for the largest machines.
- How often is service needed?
- Every 2,000 engine hours, the same as for all WALTER screw compressors. Regular maintenance is also a condition of the seven-year warranty.
All models are covered by a 7-year warranty on the entire machine. Warranty and service conditions can be found on the page Šroubové kompresory WALTER. Air delivery is stated according to ISO 1217:2009, Annex C, sound pressure level with a tolerance of ±3 dB(A).
Bestsellers
Product sorting
List of products
The smallest two-stage WALTER for operation that runs full shifts and doesn't want to waste electricity. The housing with a footprint of 1.5 × 1.04 m weighs 738 kg and the...
The smallest two-stage WALTER, capable of handling up to 13 bar. It shares a housing with the SF 30 DSP and weighs 841 kg. Connection G 1½″, noise level 65 dB(A).
The more powerful of the pair of two-stage machines in a shared housing with the SF 45 DSP, for operation with several larger consumers at the same time. It weighs 1,663 kg,...
A two-stage WALTER with its own housing, designed for larger operations with continuous running. It weighs 1,861 kg and the connection is G 2″. Noise level 68 dB(A).
Two-stage WALTER for industrial operation with continuous draw-off, the first model in a large housing with a DN 65 connection. It weighs 3,300 kg. Noise level 70 dB(A).
The mid-sized model of the large two-stage housing, for operations that need reserve capacity and do not want to change the footprint. It weighs 3,600 kg, has a DN 80...
The most powerful model of the large two-stage casing for continuous industrial operation. It weighs 3,900 kg and the connection is DN 80. Noise level 74 dB(A).
Two-stage WALTER in its own enclosure for large-scale production with continuous operation. It weighs 4,250 kg, connection DN 100. Noise level 76 dB(A).
Two-stage WALTER for large industrial operation with continuous consumption. It weighs 4,650 kg and has the same DN 100 connection as the SF 160 DSP. Noise level 76 dB(A).
A two-stage WALTER for large operations with fluctuating demand that requires an inverter as well as high efficiency. It weighs 6,450 kg and the connection is DN 100. Noise...
The second smallest two-stage WALTER, in a housing shared with the SF 37 DSP. Suitable for applications where the compressor runs for long periods and demand fluctuates. It...
The largest two-stage WALTER for the most demanding industrial operations with continuous consumption. It weighs 7,800 kg and the connection is DN 125. Noise level 86 dB(A).
The first two-stage WALTER in a larger cabinet, designed for medium operation with multiple consumers at the same time. It weighs 1,144 kg and the connection is G 2″. Noise...