Screw compressors WALTER SF KSP: inverter and direct drive

Screw compressor WALTER SF KSP with inverter in a soundproofed enclosure

7-year warranty

Compressors with inverter and direct drive 5.5–315 kW

The SF KSP range is the widest range of WALTER screw compressors: 19 models from 5.5 to 315 kW. Direct drive connects the screw airend to the motor without a belt, and the inverter continuously adjusts the speed to the current air consumption. With variable demand, the machine thus saves up to 35% of energy compared to a compressor with constant output. It is suitable for workshops and operations where consumption varies during a shift and the compressor should not run idle.

19models in the range

5.5–315 kWmotor input power

up to 35%energy savings with variable consumption

IE4synchronous motor, optionally IE5

All 19 models of WALTER SF KSP

Sorted by input power. Air delivery is stated at 8, 10, and 13 bar as a range from the lowest to the highest inverter speed. The largest model SF 315 KSP is manufactured for 8 and 10 bar.

Screw compressors WALTER SF KSP — all 19 variants
Model	Input power	Air delivery at 8 bar	Air delivery 10 bar	Air delivery 13 bar	Connection	Dimensions L × W × H	Weight	Noise level
SF 5,5 KSP	5.5 kW	0.42–0.95 m³/min	0.36–0.8 m³/min	0.36–0.64 m³/min	G ¾″	960 × 680 × 1,030 mm	227 kg	60 dB(A)
SF 7,5 KSP	7.5 kW	0.42–1.15 m³/min	0.36–1 m³/min	0.43–0.95 m³/min	G ¾″	960 × 680 × 1,030 mm	227 kg	60 dB(A)
SF 11 KSP	11 kW	0.67–1.65 m³/min	0.58–1.5 m³/min	0.74–1.3 m³/min	G ¾″	1,090 × 730 × 1,080 mm	243 kg	62 dB(A)
SF 15 KSP	15 kW	0.92–2.25 m³/min	0.74–2.15 m³/min	0.99–2.07 m³/min	G ¾″	1,090 × 730 × 1,080 mm	243 kg	62 dB(A)
SF 18,5 KSP	18.5 kW	1.1–3.2 m³/min	1–3 m³/min	1.1–2.6 m³/min	G 1″	1,300 × 880 × 1,170 mm	378 kg	64 dB(A)
SF 22 KSP	22 kW	1.44–4 m³/min	1.28–3.6 m³/min	1.2–3.3 m³/min	G 1″	1,300 × 880 × 1,170 mm	418 kg	64 dB(A)
SF 30 KSP	30 kW	2–5.21 m³/min	1.8–4.5 m³/min	1.21–4 m³/min	G 1½″	1,500 × 1,030 × 1,280 mm	518 kg	66 dB(A)
SF 37 KSP	37 kW	2.48–6.2 m³/min	2.24–5.6 m³/min	1.3–5 m³/min	G 1½″	1,500 × 1,030 × 1,280 mm	591 kg	66 dB(A)
SF 45 KSP	45 kW	2.95–7.51 m³/min	2.64–7.1 m³/min	1.2–5.9 m³/min	G 1½″	1,500 × 1,030 × 1,280 mm	690 kg	66 dB(A)
SF 55 KSP	55 kW	3.7–9.41 m³/min	3.4–8.7 m³/min	2.6–7.4 m³/min	G 2″	2,158 × 1,331 × 1,600 mm	1,128 kg	68 dB(A)
SF 75 KSP	75 kW	5.04–12.7 m³/min	4.48–11 m³/min	2.5–9.6 m³/min	G 2″	2,158 × 1,331 × 1,600 mm	1,225 kg	68 dB(A)
SF 90 KSP	90 kW	6–16 m³/min	5.2–13.7 m³/min	6.2–12.3 m³/min	DN 65	2,727 × 1,666 × 1,800 mm	1,795 kg	70 dB(A)
SF 110 KSP	110 kW	7.5–19.1 m³/min	6–17.9 m³/min	7.04–15 m³/min	DN 65	2,727 × 1,666 × 1,800 mm	2,124 kg	70 dB(A)
SF 132 KSP	132 kW	8.8–25 m³/min	7.48–20 m³/min	9.74–18.1 m³/min	DN 65	2,727 × 1,666 × 1,800 mm	2,281 kg	72 dB(A)
SF 160 KSP	160 kW	10.08–25.2 m³/min	9.48–23.7 m³/min	8.46–21.15 m³/min	DN 65	2,696 × 1,696 × 1,800 mm	3,300 kg	75 dB(A)
SF 185 KSP	185 kW	11.6–29 m³/min	11.2–28 m³/min	9.28–23.2 m³/min	DN 65	3,957 × 2,189 × 2,260 mm	4,000 kg	77 dB(A)
SF 200 KSP	200 kW	12.8–32 m³/min	11.48–28.7 m³/min	9.48–23.7 m³/min	DN 80	3,410 × 2,170 × 2,260 mm	4,400 kg	77 dB(A)
SF 220 KSP	220 kW	14.8–37 m³/min	12.8–32 m³/min	10.8–27 m³/min	DN 80	3,410 × 2,170 × 2,260 mm	4,500 kg	77 dB(A)
SF 315 KSP	315 kW	19.8–49.5 m³/min	18–45 m³/min	—	DN 125	3,900 × 2,170 × 2,260 mm	4,900 kg	80 dB(A)

Models SF 5.5 to 15 KSP can optionally be equipped with an air receiver and a dryer. Ready-made assemblies on the air tank can be found in the SFTG KSP range.

#showmore#

Why inverter and direct drive

A compressor with fixed speed, under low demand, either runs idle or stops and restarts. An inverter solves this differently: the motor speed continuously follows the demand, so the machine produces only as much air as is currently being consumed.

Up to 35% less energy

The savings apply under variable air consumption compared to a compressor with constant output. Under steady demand, the difference is smaller.

Stable pressure

The inverter keeps the pressure in the distribution system at the set value, even when demand fluctuates. The operating pressure can be set within a wide range of 5–13 bar.

Soft start

The current at startup increases gradually, so the motor starts up without a current surge to the mains.

Protection against current spikes

The electronics protect the motor and the power supply against the adverse effects of peak currents. The motor winding is monitored by thermal protection.

IE4 motor, optionally IE5

The high-efficiency synchronous motor is connected directly to the screw element with a 1:1 ratio, without a belt.

Which models share a housing

Models with adjacent power inputs share the same housing. Switching to a higher power input therefore often does not change the footprint or the connection, which is useful when planning a compressor room with reserve capacity.

Housings of WALTER SF KSP screw compressors
Housing L × W × H	Models	Connection	Weight
960 × 680 × 1,030 mm	SF 5,5 KSP, SF 7,5 KSP	G ¾″	227 kg
1,090 × 730 × 1,080 mm	SF 11 KSP, SF 15 KSP	G ¾″	243 kg
1,300 × 880 × 1,170 mm	SF 18,5 KSP, SF 22 KSP	G 1″	378–418 kg
1,500 × 1,030 × 1,280 mm	SF 30 KSP, SF 37 KSP, SF 45 KSP	G 1½″	518–690 kg
2,158 × 1,331 × 1,600 mm	SF 55 KSP, SF 75 KSP	G 2″	1,128–1,225 kg
2,727 × 1,666 × 1,800 mm	SF 90 KSP, SF 110 KSP, SF 132 KSP	DN 65	1,795–2,281 kg
2,696 × 1,696 × 1,800 mm	SF 160 KSP	DN 65	3,300 kg
3,957 × 2,189 × 2,260 mm	SF 185 KSP	DN 65	4,000 kg
3,410 × 2,170 × 2,260 mm	SF 200 KSP, SF 220 KSP	DN 80	4,400–4,500 kg
3,900 × 2,170 × 2,260 mm	SF 315 KSP	DN 125	4,900 kg

What's inside the housing

Direct drive 1:1 — the screw block is connected directly to the motor, so no power is lost in the transmission.
Synchronous motor IE4 — optionally IE5. Soft start is ensured by the inverter, the winding is protected by thermal protection.
Oil separation — SF 5,5 and 7,5 KSP use a screw-in separator, which is easy to service, while SF 11 to 315 KSP use a highly efficient immersion separator with a long service life.
Cooling — an efficient fan controlled according to temperature. The algorithm runs in the WALTER CONTROLLER control unit.

WALTER SF KSP screw compressor in a soundproofed enclosure — Housing of SF KSP and SK KSP compressors

Separation tank and screw block of the WALTER SF KSP compressor — Oil separator tank and screw airend

Axial cooling fan of the WALTER SF KSP compressor — Axial cooling fan

SF KSP, SK KSP or SF DSP?

The three related ranges have direct drive without a belt. They differ in how they control output and how many compression stages they have.

Direct drive ranges side by side
Range	SF KSP	SK KSP	SF DSP
Power control	inverter	fixed speed	inverter
Compression	single-stage	single-stage	two-stage
Input power	5.5–315 kW	11–315 kW	22–315 kW
Number of models	19	17	13
Suitable for	fluctuating air consumption	constant demand	long operation where electricity costs are decisive

Ventilek advises

An inverter pays off where demand varies.

Note down how much air you draw in the morning, at midday, and at peak demand. If the difference is large, you will make full use of the inverter's control range and save the most. If demand stays at the same value throughout the shift, the SK KSP range with fixed speed is sufficient. And if the machine runs almost continuously, also compare the two-stage SF DSP range.

Efficient operation of screw compressors

Frequently Asked Questions

How does SF KSP differ from SK KSP?: Both machines have direct drive. SF KSP additionally has an inverter, so the air delivery continuously follows demand. SK KSP has a fixed speed and delivers a constant amount of air. SF KSP is therefore the range for fluctuating consumption, SK KSP for constant demand.
What pressure do the SF KSP models have?: Each model is produced in variants for 8, 10, and 13 bar, with only the SF 315 KSP available for 8 and 10 bar. The inverter allows an operating pressure from 5 to 13 bar. Choose according to the most demanding consumer and add a reserve for losses in the distribution system.
Can an air receiver and dryer be added to a standalone machine?: For models SF 5.5 to 15 KSP, yes, the air receiver and dryer can optionally be added. If you want a complete assembly, select the SFTG KSP series.
What connections do they have and how loud are they?: Up to 15 kW the connection is G ¾″, for 18.5 and 22 kW G 1″, for 30 to 45 kW G 1½″, and for 55 and 75 kW G 2″. From 90 kW the connection is DN 65, for SF 200 and 220 KSP DN 80, and for SF 315 KSP DN 125. Noise level ranges from 60 dB(A) for the smallest models up to 80 dB(A) for the largest.
How often is service needed?: For all WALTER screw compressors, every 2,000 motor hours. Regular maintenance is also a condition for 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).