Roots pumps with bypass valve

These pumps work according to the classical “Roots” principle. Their application requires the pre-evacuation by a pre-vacuum pump (e.g., rotary vane vacuum pump, liquid ring vacuum pump or screw vacuum pump). They offer high suction property with low energy application. The lay out design of proper pre-vacuum pump / roots pump combination requires special know-how. If you, based on your experience or own engineer-technical considerations, can not exactly inform us which type of roots pump you need, give us please in your inquiry so much as possible data (e.g., volume to be evacuated, evacuation time, leakage streams to be expected, medium to be pumped off, availability of steams, if so which etc.).
Roots vacuum pumps are used mainly for works in low or fine vacuum area.
In this pressure area (from 80 to 0.01 mbar) they have a high compression ratio and at the same time big suction property.
These pumps cannot condense against atmosphere that is why they work only with a pre-vacuum pump. To exclude condensate formation in the pump, the conveyor stream is arranged vertically. The Roots pumps can be partially delivered with bypass. This is a mechanical discharge valve which prevents automatically the exceeding of the allowed difference pressure. If a Roots pump is used without this bypass, is this pressure control otherwise to be realized.