A Roots blower (positive displacement air blower of the Roots type, known in Aerzen’s range as the Delta Blower) is a low-pressure air blower that uses two synchronized lobe rotors inside a compression chamber to deliver a large flow rate of air at differential pressures up to approximately 1 bar. Unlike high-pressure air compressors, a Roots blower does not compress air internally — instead, differential pressure is generated by backflow at the discharge side — resulting in simple mechanical construction, durable operation, and completely oil-free air delivery, making it suitable for wastewater treatment (aeration), pneumatic conveying, and numerous industrial processes.
- Roots blower = low-pressure positive displacement air blower with high flow rate
- Mechanism: synchronized lobe rotors, no internal compression — differential pressure generated at the discharge side
- Delta Blower series (Aerzen): differential pressure up to 1,000 mbar, flow rate 30–15,000 m³/h (depending on model)
- Oil-free air delivery, suitable for wastewater aeration & pneumatic conveying
- Advantages: durable, simple, easy to maintain; AERtronic demand-based control
What is a Roots Blower and How Does It Differ from an Air Compressor?
Distinguishing Positive Displacement Air Blowers from High-Pressure Air Compressors
A Roots blower belongs to the positive displacement blower category: with each rotation, the machine “captures” a fixed volume of air from the suction side and transfers it to the discharge side. This is a low-pressure machine — maximum working differential pressure is approximately 1 bar (1,000 mbar) — used to deliver large flow rates of air at moderate pressure, which is entirely different from screw or piston air compressors that generate high multi-bar pressures for storage in receivers.
The key point: a Roots blower has no internal compression process within the chamber. The two rotors only transport air; differential pressure forms when the air on the discharge side flows back against the volume of air just delivered by the rotors. This mechanism makes the machine mechanically simple, with few wear-prone parts, and delivers clean oil-free air — a critical factor in water treatment and food processing.
| Criterion | Roots Blower (Air Blower) | High-Pressure Air Compressor |
|---|---|---|
| Working Pressure | Low pressure, ≤ ~1 bar differential pressure | High pressure, multiple bars |
| Flow Rate | Very high, stable | Moderate, stored in receiver |
| Internal Chamber Compression | No (differential pressure at discharge side) | Yes |
| Typical Applications | Aeration, pneumatic conveying | Tool air, high-pressure process gas |
Construction of the Roots Delta Blower Air Blower
Lobe Rotors, Compression Chamber, and Silencer
The heart of a Roots air blower is a pair of synchronized lobe rotors housed in a cylindrical casing. On the Aerzen Delta Blower series, the rotors are three-lobe design, rotating in opposite directions and sweeping air progressively from the inlet port to the discharge port. The two rotors do not contact each other or the casing, thanks to timing gears, so the air chamber remains oil-free throughout operation.
A notable technical feature of the Delta Blower is integrated pulsation damping technology: two cast channels in the machine body regulate airflow direction, limiting backflow and compression pulses — thereby reducing noise and vibration. The reflective-type silencer uses no sound-absorbing material, preventing fibrous material from entering the delivered air and keeping pressure losses stable over time. The machine has a compact design, with anti-vibration mounts that isolate vibration and allow gear lubricant level inspection while running.
| Component | Role |
|---|---|
| Three-lobe rotor pair | Transports air from suction to discharge, without contact |
| Timing gears | Maintains rotor clearances, ensures oil-free operation inside the chamber |
| Integrated pulsation damping channels | Regulate airflow, reduce noise and vibration |
| Reflective silencer | Reduces noise, does not release sound-absorbing material into the air |
| Anti-vibration mounts | Isolate vibration, reduce transmission to foundation |
Technical Specifications & Operating Range
Pressure, Vacuum, and Flow Rate of the Delta Blower
According to Aerzen documentation, the new-generation Delta Blower series operates with a differential pressure range from -500 to 1,000 mbar — meaning it can be used for both positive-pressure air blowing and vacuum suction — and a volumetric flow rate of 30 to 15,000 m³/h. This is a wide coverage range, from smaller units for mid-scale aeration tanks to large blower packages for high-capacity water treatment plants. Specific figures for each machine depend on the model and operating conditions (temperature, altitude, actual back-pressure).
The process medium is air and neutral gases; with certified oil-free process gas configuration, the machine meets the requirements of sensitive processes. When required, the machine can be equipped with special motors, corrosion-resistant coatings, ATEX-certified versions for hazardous areas, sand filters, or acoustic enclosures for seismic zones — options available according to project requirements.
| Parameter | Value (depending on model) |
|---|---|
| Working differential pressure | -500 to 1,000 mbar |
| Volumetric flow rate | 30 – 15,000 m³/h |
| Process medium | Air & neutral gases, oil-free delivery |
| Options | ATEX, special coatings, acoustic enclosure, sand filter |
Applications & Control Options
Wastewater Aeration, Pneumatic Conveying, and Energy Efficiency
The most common application of a Roots blower is supplying air to aerobic tanks (aeration) in wastewater treatment: the machine pumps air to the bottom of the tank to support microorganisms that decompose organic matter. The machine is also used for pneumatic conveying of bulk materials (flour, plastic pellets, cement, wheat flour), in food processing, and in various chemical processes. Because it delivers oil-free air, the Roots air blower is suitable for production lines with high hygiene requirements.
In water treatment plants, the blower system is typically a major electricity consumer, so the control approach largely determines operating costs. Aerzen provides the AERtronic controller for each machine, combined with a variable frequency drive (VFD) to adjust speed according to load. When operating multiple machines in parallel, the AERsmart coordination system distributes load according to the actual dissolved oxygen (DO) demand of the tank — running the right number of machines at the right speed, reducing electricity consumption significantly compared to fixed-speed operation. The specific level of savings depends on tank scale and organic load.
| Control Option | Applicable When |
|---|---|
| AERtronic | Control and monitoring of individual blowers |
| Variable Frequency Drive (VFD) | Adjusts speed according to load, prevents excess air delivery |
| AERsmart | Coordinates multiple machines according to tank DO demand |
If you are evaluating different technologies, you may refer to the article on comparison of Roots, screw, and turbo air blowers to select the right option based on flow rate and energy savings goals, or view the overview of industrial air blowers.
AERZEN · GERMANY Delta Blower — Roots Positive Displacement Air Blower
Aerzen (Germany) is a brand specializing in air blowers and air compressors with established expertise in low-pressure air delivery. The Roots-type Delta Blower series features integrated pulsation damping design, oil-free operation, and a wide flow rate range, combined with AERtronic/AERsmart control systems to optimize energy consumption at aeration stations. TKT Pumps is an authorized Aerzen distributor in Vietnam, providing technical consultation on configuration selection, installation, and genuine spare parts.
Frequently Asked Questions About Roots Blowers
How does a Roots blower differ from an air compressor?
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A Roots blower is a low-pressure air blower (differential pressure up to approximately 1 bar), delivering high flow rates without internal compression inside the chamber — differential pressure is generated at the discharge side. A high-pressure air compressor generates multi-bar pressures with an internal compression process, used for tool air or process gas stored in receivers.
What are the flow rate and pressure ranges of the Aerzen Delta Blower?
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According to Aerzen documentation, the new-generation Delta Blower operates with a differential pressure of -500 to 1,000 mbar and a volumetric flow rate of 30 to 15,000 m³/h. Specific values depend on the individual model and actual operating conditions.
What applications is a Roots air blower used for?
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The most common use is supplying air to aerobic tanks (aeration) in wastewater treatment. The machine is also used for pneumatic conveying of bulk materials (flour, plastic pellets, cement), in food processing, and in chemical processes thanks to its oil-free air delivery capability.
Why does a Roots blower deliver oil-free air?
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The two rotors do not contact each other or the casing, thanks to timing gears, so the air chamber requires no lubrication. Oil is used only for the gear housing, which is isolated from the air path — therefore the delivered air is completely free of oil.
How can a Roots air blower save energy at an aeration station?
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By combining a variable frequency drive (VFD) to adjust speed according to load and the AERsmart coordination system to run the right number of machines according to the tank’s dissolved oxygen (DO) demand. This approach avoids over-supplying air and reduces electricity consumption significantly compared to fixed-speed operation; savings levels depend on scale and organic load.
Can a Roots blower operate in vacuum mode?
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Yes. The Delta Blower’s differential pressure range extends from -500 mbar (vacuum suction) to +1,000 mbar (positive pressure blowing), so the same machine series can be configured for both air blowing and vacuum applications depending on the model.
Need to select the right Roots air blower flow rate and energy-efficient control approach for your project? The TKT Pumps technical team provides consultation on Aerzen Delta Blower configuration, installation support, and genuine spare parts.
Submit a Consultation Request or hotline 0941.400.488
Source: Aerzen technical documentation (Delta Blower series for air and neutral gases) combined with industry knowledge; compiled by TKT Pumps.
