There are essential differences between Roots blowers and conventional blowers (represented by centrifugal blowers) in terms of working principles, performance characteristics, and application scenarios. The following is a detailed comparative analysis:
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**1、 Overview of Core Differences**
|* * Comparison item * * | * Roots blower * * | * * Ordinary centrifugal blower * *|
|------------------|-----------------------------|-----------------------------|
|* * Working principle * * | Volumetric (rotor engagement squeezing gas) | Kinetic (impeller rotation accelerating gas)|
|* * Flow characteristics * * | Flow is constant and independent of pressure | Flow decreases with increasing pressure|
|* * Pressure range * * | Medium and low pressure (9.8~98 kPa) | Low pressure (<10 kPa) or high pressure (>100 kPa)|
|Efficiency * * | 60~75 | 70~90 (narrow zone)|
|* * Noise * * | Large (85-100 dB) | Small (70-85 dB)|
|* * Medium adaptability * * | Can handle dusty/humid gases | Only suitable for clean gases|
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**2、 Differences in working principles**
**1. Roots blower**
-* * Volumetric Conveyor * *:
By the reverse rotation of two parallel rotors, gas is "wrapped" from the inlet and pushed to the outlet, without internal compression, and pressure is established by system resistance.
**Features * *:
-The flow rate is only proportional to the speed (variable frequency speed regulation is effective)
-The outlet pressure depends on the pipeline resistance
**2. Centrifugal fan**
-* * Kinetic Energy Conversion * *:
The high-speed rotation of the impeller allows the gas to gain kinetic energy, which is then converted into static pressure energy after being expanded by the volute.
**Features * *:
-Flow rate is inversely proportional to pressure (flow rate decreases as system resistance increases)
-The pressure is determined by the impeller diameter and speed
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**3、 Performance Curve Comparison**
|* * Features * * | * Roots blower * * | * * Centrifugal blower * *|
|------------------|----------------------------|----------------------------|
|Flow pressure curve |! [Roots Curve]（ https://example.com/roots_curve ）Constant flow rate, variable pressure |! [Centrifugal Curve]（ https://example.com/centrifugal_curve ）The flow rate decreases with increasing pressure|
|Area Range | Wide (60-75 Efficiency Range Wide) | Narrow (Area Only ± 10 Design Points)|
|Starting characteristics | Requires no-load starting (prevents overcurrent) | Can start under voltage|
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**4、 Application scenario selection**
**Prioritize choosing Roots blower**
-* * Stable flow required * *: such as sewage treatment aeration and pneumatic conveying
-* * Medium and low pressure demand * *: 0.1~0.5 bar pressure range
-* * Complex medium * *: gas containing a small amount of dust and high humidity
**Prioritize centrifugal fans**
-* * High flow and low pressure * *: such as ventilation and air exchange (flow rate>300 m3/min)
-High pressure demand: Multi stage centrifugal fans can reach over 1.0 MPa
-* * Clean gas * *: requires high cleanliness of the medium
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**5、 Comparison of key parameters for selection**
|* * Parameters * * | * Roots blower * * | * * Centrifugal blower * *|
|------------------|----------------------------|----------------------------|
|Flow regulation method | Only capable of variable frequency speed regulation | Adjustable valve/speed joint control|
|Allow medium viscosity | Almost no effect | Efficiency drops sharply when viscosity>30cP|
|Maintenance complexity | Low (only gear/bearing maintenance) | Medium (requires regular dynamic balance calibration)|
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**6、 Cost and lifespan**
|* * Project * * | * Roots blower * * | * * Centrifugal blower * *|
|------------------|----------------------------|----------------------------|
|Purchasing cost | relatively high (20-30% more expensive for the same traffic) | relatively low|
|Operating energy consumption | Medium (constant flow characteristic) | Low (zone)|
|Design lifespan | 8-10 years (rotor 50000 hours) | 10-15 years (impeller 100000 hours)|
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**7、 Typical Industry Applications**
**Roots blower**
-* * Sewage treatment * *: Aeration oxygen supply (requires gas volume of 0.8 Nm3/ton · minute)
-Aquaculture: fish pond oxygenation (pressure 20-40 kPa)
-Vacuum Packaging: Auxiliary Vacuum Extraction (-30~-50 kPa)
**Centrifugal fan**
-HVAC system: Building ventilation (flow rate>1000 m3/min)
-Boiler induced draft: High temperature flue gas transportation (300-400 ℃)
-* * Dust removal equipment * *: Large flow dust collection
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**8、 Warning of selection errors**
1. Misunderstanding of High Voltage:
-When the pressure of the Roots blower is greater than 98 kPa, the efficiency drops sharply, and a screw blower should be selected.
2. * * Misconceptions about traffic * *:
-Centrifugal fans are prone to surge at low flow rates and should be avoided in this condition.
3. Misunderstanding of Media:
-Fiber containing media will wrap around the centrifugal impeller, so only Roots blowers can be used.
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**Summary**
-The essential difference is that Roots blower is a volumetric fixed flow device, while centrifugal blower is a kinetic variable flow device.
-* * Selection principle * *:
-To ensure stable traffic, choose Roots
-To * * rate/high pressure * * → select centrifugation
-* * Mixed scheme * *: Some scenarios require parallel use (such as Roots providing basic flow and centrifugal peak adjustment).
It is recommended to conduct a comprehensive evaluation based on the characteristics of the medium, pressure requirements, and operating costs, and refer to the manufacturer's performance curve for selection.
