Dual lobe blowers operating on the Roots principle produce conveying pulsations due to their design, which can be detrimental not only to the blower itself but also to the conveying pipe work.
Aerzener Maschinenfabrik have developed a system that has almost eliminated these pulsations at source. To achieve this a three lobe blower having two channels cast into the cylinder wall controls the backstream of gas into the cylinder. Sound waves produced by the backstream cancel most of those produced by the blower.