无油螺杆鼓风机

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.

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.

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.

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.

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

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.

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

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.

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.

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