MACHINE FAMILY
Roots Blowers & Boosters
Moves a lot of gas a little distance.
Two-lobe rotary machine with no internal compression — it moves a fixed volume against system pressure. The cheapest way to move a lot of gas a little distance, and a clean booster ahead of a higher-pressure machine.
The envelope
| Differential pressure | ≤ 1.0 bar single-stage · ≤ 2.0 bar two-stage |
|---|---|
| Suction flow window | 25–65,000 m³/h |
| Per-stage ratio / stages | 3:1 per stage · at most 2 stages on one crankshaft |
| Oil-free | Available / by design |
| Sealing | Shaft seals — piston-ring / labyrinth / mechanical; gear and bearing lubrication is segregated from the gas path on gas-service models |
| Wetted materials | Cast iron / ductile iron, Carbon steel, Stainless steel 316L |
| Design standards | No dedicated design standard — acceptance testing commonly agreed per ISO 1217 concepts; state the test method in the RFQ |
Where it is used
- Large-volume micro-boosting and circulation
- A clean booster stage ahead of a higher-pressure machine
Where it stops
- Differential pressure is the whole constraint: 1.0 bar single-stage, 2.0 bar two-stage
- Not a compressor in the pressure sense — if the duty needs real pressure, it needs another family
Chinese makers publish two-stage machines to 196 kPa differential.
Related reading
Running a duty point? The selector on the home page maps gas, pressures, flow and temperature to a machine family with its boundary conditions — free.
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