Oil free screw blowers

Screw compression at blower pressures. Up to 1.5 bar g, 22 to 180 kW.

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Technical data

Free air delivery: 15 – 98 m³/min (530 – 3,461 cfm)
Working pressure: 0.4 – 1.5 bar g
Motor power: 22 – 180 kW
Weight: 2,000 – 4,700 kg

Overview

Between the pressure a roots blower is efficient at and the pressure a compressor starts at, there is a band from roughly 0.5 to 1.5 bar where neither is a good answer. A roots blower is working hard there and a compressor is barely working at all.

A screw blower fills it. It uses a screw airend with internal compression — the air is actually squeezed inside the machine rather than pushed out against the discharge — which at those pressures is twenty to thirty five per cent more efficient than a roots blower doing the same duty.

Key benefits

Twenty to thirty five per cent less energy

Against a roots blower at the same duty. Internal compression is the reason.

Oil free air path

Timed rotors that never touch. Nothing in the air to reach the process or the tank.

No pulsation

Continuous compression rather than displacement, so no pulsation dampers and no noise from them.

Up to 1.5 bar g

The band where a roots blower struggles and a compressor is oversized.

Why internal compression matters at low pressure

A roots blower does not compress air inside itself. It moves a pocket of air to the discharge and the air in the discharge line pushes back into it — the compression happens abruptly, at the outlet, and abrupt compression is inefficient and noisy.

A screw blower squeezes the air progressively as it travels along the rotors, so by the time it reaches the discharge it is already at pressure. That is smoother, quieter and measurably less work.

The higher the pressure, the bigger the difference. At 0.3 bar there is little in it. At 1.0 bar and above, the screw blower is well ahead, which is why the changeover point in most aeration plants sits around there.

Internal compression, not displacement
Advantage grows with pressure
Oil free timed rotors
No pulsation dampers needed
Variable speed across the range
22 to 180 kW

Model range

Model	Motor power	Free air delivery	Working pressure	Connection	Weight	Dimensions L x W x H
GA-LG-22-04	22 kW	25 m³/min	40 kPa	DN150	2,000 kg	2100 × 1100 × 1600 mm
GA-LG-22-06	22 kW	16 m³/min	60 kPa	DN150	2,000 kg	2100 × 1100 × 1600 mm
GA-LG-22-08	22 kW	15 m³/min	80 kPa	DN150	2,000 kg	2100 × 1100 × 1600 mm
GA-LG-30-06	30 kW	25 m³/min	60 kPa	DN150	2,200 kg	2100 × 1100 × 1700 mm
GA-LG-30-08	30 kW	21 m³/min	80 kPa	DN150	2,200 kg	2100 × 1100 × 1700 mm
GA-LG-30-10	30 kW	15 m³/min	100 kPa	DN150	2,200 kg	2100 × 1100 × 1700 mm
GA-LG-37-04	37 kW	36 m³/min	40 kPa	DN150	2,300 kg	2300 × 1300 × 1900 mm
GA-LG-37-08	37 kW	25 m³/min	80 kPa	DN150	2,300 kg	2300 × 1300 × 1900 mm
GA-LG-37-10	37 kW	21 m³/min	100 kPa	DN150	2,300 kg	2300 × 1300 × 1900 mm
GA-LG-37-12	37 kW	16 m³/min	120 kPa	DN150	2,300 kg	2300 × 1300 × 1900 mm
GA-LG-37-15	37 kW	15 m³/min	150 kPa	DN150	2,300 kg	2300 × 1300 × 1900 mm
GA-LG-45-06	45 kW	36 m³/min	60 kPa	DN150	2,500 kg	2300 × 1300 × 2000 mm
GA-LG-45-10	45 kW	25 m³/min	100 kPa	DN150	2,500 kg	2300 × 1300 × 2000 mm
GA-LG-45-12	45 kW	24 m³/min	120 kPa	DN150	2,500 kg	2300 × 1300 × 2000 mm
GA-LG-55-04	55 kW	58 m³/min	40 kPa	DN200	2,900 kg	3000 × 1700 × 2300 mm
GA-LG-55-06	55 kW	43 m³/min	60 kPa	DN200	2,900 kg	3000 × 1700 × 2300 mm
GA-LG-55-15	55 kW	24 m³/min	150 kPa	DN200	2,900 kg	3000 × 1700 × 2300 mm
GA-LG-75-06	75 kW	58 m³/min	60 kPa	DN200	3,300 kg	3000 × 1700 × 2300 mm
GA-LG-75-08	75 kW	49 m³/min	80 kPa	DN200	3,300 kg	3000 × 1700 × 2300 mm
GA-LG-75-10	75 kW	42 m³/min	100 kPa	DN200	3,300 kg	3000 × 1700 × 2300 mm
GA-LG-75-12	75 kW	34 m³/min	120 kPa	DN200	3,300 kg	3000 × 1700 × 2300 mm
GA-LG-90-04	90 kW	89 m³/min	40 kPa		4,300 kg	3000 × 1900 × 2400 mm
GA-LG-90-06	90 kW	76 m³/min	60 kPa		4,300 kg	3000 × 1900 × 2400 mm
GA-LG-90-08	90 kW	58 m³/min	80 kPa		4,300 kg	3000 × 1900 × 2400 mm
GA-LG-90-10	90 kW	56 m³/min	100 kPa		4,300 kg	3000 × 1900 × 2400 mm
GA-LG-90-12	90 kW	47 m³/min	120 kPa		4,300 kg	3000 × 1900 × 2400 mm
GA-LG-90-15	90 kW	34 m³/min	150 kPa		4,300 kg	3000 × 1900 × 2400 mm
GA-LG-110-04	110 kW	98 m³/min	40 kPa		4,400 kg	3000 × 1900 × 2400 mm
GA-LG-110-06	110 kW	88 m³/min	60 kPa		4,400 kg	3000 × 1900 × 2400 mm
GA-LG-110-08	110 kW	75 m³/min	80 kPa		4,400 kg	3000 × 1900 × 2400 mm
GA-LG-110-10	110 kW	64 m³/min	100 kPa		4,400 kg	3000 × 1900 × 2400 mm
GA-LG-110-12	110 kW	56 m³/min	120 kPa		4,400 kg	3000 × 1900 × 2400 mm
GA-LG-110-15	110 kW	48 m³/min	150 kPa		4,400 kg	3000 × 1900 × 2400 mm
GA-LG-132-08	132 kW	88 m³/min	80 kPa		4,500 kg	3000 × 1900 × 2400 mm
GA-LG-132-10	132 kW	75 m³/min	100 kPa		4,500 kg	3000 × 1900 × 2400 mm
GA-LG-132-12	132 kW	64 m³/min	120 kPa		4,500 kg	3000 × 1900 × 2400 mm
GA-LG-132-15	132 kW	56 m³/min	150 kPa		4,500 kg	3000 × 1900 × 2400 mm
GA-LG-160-12	160 kW	86 m³/min	120 kPa	DN300	4,600 kg	3000 × 1900 × 2400 mm
GA-LG-160-15	160 kW	63 m³/min	150 kPa	DN300	4,600 kg	3000 × 1900 × 2400 mm
GA-LG-180-12	180 kW	90 m³/min	120 kPa	DN300	4,700 kg	3000 × 1900 × 2400 mm

GA-LG-22-0422 kW

40 kPa: 25 m³/min

Connection: DN150
Weight: 2,000 kg
Dimensions L x W x H: 2100 × 1100 × 1600 mm

GA-LG-22-0622 kW

60 kPa: 16 m³/min

Connection: DN150
Weight: 2,000 kg
Dimensions L x W x H: 2100 × 1100 × 1600 mm

GA-LG-22-0822 kW

80 kPa: 15 m³/min

Connection: DN150
Weight: 2,000 kg
Dimensions L x W x H: 2100 × 1100 × 1600 mm

GA-LG-30-0630 kW

60 kPa: 25 m³/min

Connection: DN150
Weight: 2,200 kg
Dimensions L x W x H: 2100 × 1100 × 1700 mm

GA-LG-30-0830 kW

80 kPa: 21 m³/min

Connection: DN150
Weight: 2,200 kg
Dimensions L x W x H: 2100 × 1100 × 1700 mm

GA-LG-30-1030 kW

100 kPa: 15 m³/min

Connection: DN150
Weight: 2,200 kg
Dimensions L x W x H: 2100 × 1100 × 1700 mm

GA-LG-37-0437 kW

40 kPa: 36 m³/min

Connection: DN150
Weight: 2,300 kg
Dimensions L x W x H: 2300 × 1300 × 1900 mm

GA-LG-37-0837 kW

80 kPa: 25 m³/min

Connection: DN150
Weight: 2,300 kg
Dimensions L x W x H: 2300 × 1300 × 1900 mm

GA-LG-37-1037 kW

100 kPa: 21 m³/min

Connection: DN150
Weight: 2,300 kg
Dimensions L x W x H: 2300 × 1300 × 1900 mm

GA-LG-37-1237 kW

120 kPa: 16 m³/min

Connection: DN150
Weight: 2,300 kg
Dimensions L x W x H: 2300 × 1300 × 1900 mm

GA-LG-37-1537 kW

150 kPa: 15 m³/min

Connection: DN150
Weight: 2,300 kg
Dimensions L x W x H: 2300 × 1300 × 1900 mm

GA-LG-45-0645 kW

60 kPa: 36 m³/min

Connection: DN150
Weight: 2,500 kg
Dimensions L x W x H: 2300 × 1300 × 2000 mm

GA-LG-45-1045 kW

100 kPa: 25 m³/min

Connection: DN150
Weight: 2,500 kg
Dimensions L x W x H: 2300 × 1300 × 2000 mm

GA-LG-45-1245 kW

120 kPa: 24 m³/min

Connection: DN150
Weight: 2,500 kg
Dimensions L x W x H: 2300 × 1300 × 2000 mm

GA-LG-55-0455 kW

40 kPa: 58 m³/min

Connection: DN200
Weight: 2,900 kg
Dimensions L x W x H: 3000 × 1700 × 2300 mm

GA-LG-55-0655 kW

60 kPa: 43 m³/min

Connection: DN200
Weight: 2,900 kg
Dimensions L x W x H: 3000 × 1700 × 2300 mm

GA-LG-55-1555 kW

150 kPa: 24 m³/min

Connection: DN200
Weight: 2,900 kg
Dimensions L x W x H: 3000 × 1700 × 2300 mm

GA-LG-75-0675 kW

60 kPa: 58 m³/min

Connection: DN200
Weight: 3,300 kg
Dimensions L x W x H: 3000 × 1700 × 2300 mm

GA-LG-75-0875 kW

80 kPa: 49 m³/min

Connection: DN200
Weight: 3,300 kg
Dimensions L x W x H: 3000 × 1700 × 2300 mm

GA-LG-75-1075 kW

100 kPa: 42 m³/min

Connection: DN200
Weight: 3,300 kg
Dimensions L x W x H: 3000 × 1700 × 2300 mm

GA-LG-75-1275 kW

120 kPa: 34 m³/min

Connection: DN200
Weight: 3,300 kg
Dimensions L x W x H: 3000 × 1700 × 2300 mm

GA-LG-90-0490 kW

40 kPa: 89 m³/min

Weight: 4,300 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-90-0690 kW

60 kPa: 76 m³/min

Weight: 4,300 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-90-0890 kW

80 kPa: 58 m³/min

Weight: 4,300 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-90-1090 kW

100 kPa: 56 m³/min

Weight: 4,300 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-90-1290 kW

120 kPa: 47 m³/min

Weight: 4,300 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-90-1590 kW

150 kPa: 34 m³/min

Weight: 4,300 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-110-04110 kW

40 kPa: 98 m³/min

Weight: 4,400 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-110-06110 kW

60 kPa: 88 m³/min

Weight: 4,400 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-110-08110 kW

80 kPa: 75 m³/min

Weight: 4,400 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-110-10110 kW

100 kPa: 64 m³/min

Weight: 4,400 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-110-12110 kW

120 kPa: 56 m³/min

Weight: 4,400 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-110-15110 kW

150 kPa: 48 m³/min

Weight: 4,400 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-132-08132 kW

80 kPa: 88 m³/min

Weight: 4,500 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-132-10132 kW

100 kPa: 75 m³/min

Weight: 4,500 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-132-12132 kW

120 kPa: 64 m³/min

Weight: 4,500 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-132-15132 kW

150 kPa: 56 m³/min

Weight: 4,500 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-160-12160 kW

120 kPa: 86 m³/min

Connection: DN300
Weight: 4,600 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-160-15160 kW

150 kPa: 63 m³/min

Connection: DN300
Weight: 4,600 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

GA-LG-180-12180 kW

120 kPa: 90 m³/min

Connection: DN300
Weight: 4,700 kg
Dimensions L x W x H: 3000 × 1900 × 2400 mm

FAD measured to ISO 1217 Edition 4, Annex C and E at 1 bar a intake, 20°C, 0% humidity. Noise measured to ISO 2151 in free field conditions, tolerance ± 3 dB(A). Water-cooled versions of every model are available. Ask us for their sheet.

Frequently asked questions

When should I choose this over a roots blower?

Above about 0.7 bar g and on continuous duty. Below that, and on intermittent duty, a roots blower is cheaper and the energy saving will not repay the difference.

And over a magnetic levitation blower?

Screw blowers go higher in pressure; magnetic levitation machines go higher in flow at low pressure. Tell us the duty and the answer is usually clear cut.

Is it genuinely oil free?

In the air path, yes. The rotors are timed by gears which run in oil, but that oil is sealed away from the air and never reaches it.

What is internal compression?

The air is squeezed progressively along the rotors so it reaches the discharge already at pressure. A roots blower compresses abruptly at the outlet, which is inefficient and noisy.

How much energy does it save?

Twenty to thirty five per cent against a roots blower at the same duty, and the advantage grows with pressure.

Does it need pulsation dampers?

No, and that is a real saving in cost, space and noise. Compression is continuous rather than displacement, so there is no pulse to damp.

What maximum pressure does it reach?

Up to about 1.5 bar g. Above that you are into compressor territory and we would size a low pressure screw compressor instead.

Can it be variable speed?

Yes, and on a wastewater aeration duty it should be. The dissolved oxygen demand swings through the day and a fixed speed blower simply wastes the difference.

What is the routine maintenance?

Air filter, gear oil at its interval and a drive belt check where one is fitted. It is simpler than a compressor of the same power.

Can it replace a roots blower in the same footprint?

Usually, and often with a smaller machine because roots blowers are frequently installed oversized. We check the actual duty point rather than the nameplate.

Not sure which model you need?

Send us your air demand, working pressure and running hours. Our engineers will size the machine and send a written recommendation, no cost, no obligation.

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