1. Working Principle of Roots Blower
The Roots blower is a positive displacement blower, where the delivered air volume is proportional to its rotational speed. It is a rotary compressor that compresses and delivers gas by means of two rotors moving in opposite directions within a cylinder.
The rotors are kept in synchronous engagement by timing gears mounted at the rotor shaft ends. Each concave surface portion of the rotors and the cylinder wall forms a working chamber. During rotor rotation, the gas is drawn in from the inlet port, and when the chamber reaches the outlet side, it connects with the discharge port. At that moment, the pressure in the working chamber rises suddenly due to the backflow of the higher-pressure gas from the outlet, after which the gas is discharged into the exhaust passage.
The two rotors work alternately, but they do not touch each other. The sealing is maintained by the precisely controlled clearance between them, so the discharged gas is not contaminated by lubricating oil. Owing to its simple structure and ease of manufacturing, the Roots blower is suitable for low-pressure gas transmission and pressurization, and it can also be used as a vacuum pump.
However, due to the periodic suction and discharge as well as the instantaneous isochoric compression, the air velocity and pressure fluctuate, resulting in considerable aerodynamic noise.
2. Operating Characteristics of Roots Blower
- Three-lobe rotors perform three intake and exhaust cycles for every full rotation of two rotors.
- Compared with the two-lobe type, the three-lobe design reduces gas pulsation, vibration, and noise.
- During operation, the rotor lobes and the casing wall, the rotor end faces and end covers, as well as the gaps between rotors, always maintain a small clearance.
- Driven by synchronous gears, air is transported from the inlet along the inner casing wall to the outlet.
- The inner chamber of the blower requires no lubricating oil.
3. Product Features
- Positive displacement blower: Air volume is proportional to rotor speed.
- Simple structure: No internal lubrication needed, easy maintenance.
- Stable performance: Smooth operation with reduced pulsation.
- Low noise & vibration: Especially with three-lobe rotors compared to two-lobe types.
- Wide applicability: Used in gas delivery, low-pressure pressurization, and as a vacuum pump.
- Efficiency considerations: Small clearances between rotors and cylinder can cause air leakage, leading to efficiency reduction.
4. Application Fields
Roots vacuum blowers are widely used in various industries, including but not limited to:
- Environmental Protection:
For example, in wastewater treatment and waste incineration, their stable air delivery function supports processes such as aeration and combustion, thereby improving the efficiency and quality of environmental treatment.
- Power Industry:
In the power sector, Roots blowers are mainly used for fuel conveying and combustion air supply in thermal power plants. Their strong air delivery capacity meets the large air demand of power generation, ensuring stable operation.
- Chemical Industry:
During chemical production, Roots blowers are widely applied in gas conveying and mixing processes. Their reliable performance ensures stability and efficiency in chemical operations.
- Food Industry:
In food production, Roots blowers can be used in drying, ventilation, and mixing. Their low noise and low vibration features create a more comfortable production environment while enhancing product quality.
5. Operation and Maintenance Notes for Use
The inlet air temperature of the conveyed medium should not exceed 40 °C.
The dust content of the medium should not exceed 100 mg/m³, and particle size should not exceed half of the working clearance.
During operation, bearing temperature should not exceed 95 °C, and lubricating oil temperature should not exceed 65 °C.
Operating pressure should not exceed the boost range specified on the nameplate.
6.Maintenance Recommendations
Regularly check the fastening of all components and whether positioning pins are loose.
Monitor lubrication and cooling conditions, ensure lubricant quality, and listen for abnormal noises during operation.
Observe inlet/outlet pressure, bearing temperature, and motor current trends to determine if the blower is running normally.
Before disassembly, measure all fit dimensions, make records, and mark components to ensure original fit after reassembly.
For new or overhauled machines, clean the oil tank before use. After 8 hours of operation, replace the lubricating oil.
Establish a reasonable maintenance schedule according to actual operating conditions. Perform regular inspections and keep records. A major overhaul is recommended once a year, including replacing bearings and other wear parts.
7.Conclusion / Ending
With their stable performance, low noise, and wide applicability, Roots blowers have become an essential choice in multiple industries. By following proper operating conditions and regular maintenance, users can ensure long-term, reliable operation and maximize efficiency.
We are committed to providing high-quality Roots blowers and professional technical support to help our customers achieve sustainable and efficient solutions.
