Roots blower and ordinary blower (taking centrifugal blower as an example) have essential differences in structure, working principle, and application scenarios. Here is a detailed comparison between the two:
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**1、 Overview of Core Differences**
|* * Comparison item * * | * Roots blower * * | * * Ordinary centrifugal blower * *|
|------------------|-------------------------------|-------------------------------|
|* * Working principle * * | Volumetric (rotor meshing to transport gas) | Kinetic (impeller centrifugal force to accelerate gas)|
|* * Compression characteristics * * | No internal compression, pressure generated by system resistance | Dynamic compression, pressure converted from impeller kinetic energy|
|* * Flow pressure relationship * * | Flow is constant and independent of pressure | Flow decreases significantly with increasing pressure|
|* * Efficiency * * | 50~70 (applicable for low pressure) | 70~85 (better for medium and high pressure)|
|* * Noise * * | Large (80-95dB, high-frequency pulsation) | Small (65-80dB, continuous airflow)|
|* * Structural complexity * * | Simple (rotor+gear) | More complex (volute+impeller+guide vane)|
|* * Maintenance cost * * | Low (adjustable gap) | Medium (requires dynamic balance correction)|
|* * Typical pressure range * * | 0.1~1.0 bar (single-stage) | 0.1~1.5 bar|
|* * Price * * | Lower | Higher (under the same traffic)|
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**2、 Comparison of working principles**
**1. Roots blower (positive displacement)**
-* * Working process * *:
Two three leaf or two leaf rotors rotate through synchronous gear meshing, pushing gas from the inlet to the outlet.
**Features * *:
-The gas volume remains constant within the chamber without any compression process.
-The pressure is determined by the resistance of the backend system.
**2. Centrifugal fan (kinetic energy type)**
-* * Working process * *:
The motor drives the impeller to rotate, and the gas is accelerated by centrifugal force and then decelerated and expanded through the volute, converting kinetic energy into static pressure.
**Features * *:
-The pressure is proportional to the square of the impeller speed.
-Easy to surge at low flow rates (avoid operating at low flow rates).
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**3、 Differences in performance curves**
|* * Features * * | * Roots blower * * | * * Centrifugal blower * *|
|------------------|-------------------------------|-------------------------------|
|* * Flow pressure curve * * | Vertical line (constant flow) | Steep drop curve (sudden decrease in flow at high pressure)|
|* * Zone Range * * | Wide (60~rated flow) | Narrow (to match operating conditions)|
|Overload capacity * * | Strong (can withstand short-term overpressure) | Weak (overpressure is prone to surge)|
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**4、 Selection Guide**
**Priority selection of Roots blower**
-Constant flow rate is required (such as aeration in wastewater treatment).
-Transporting dusty/humid gases (with strong resistance to dirt and stains).
-Low pressure and high flow rate (≤ 0.5 bar, such as pneumatic conveying).
**Priority selection of centrifugal fans**
-Medium to high pressure demand (ventilation system>0.8 bar).
-* * Clean gas * * (dust content in the medium<50mg/m3).
-Space is limited (centrifugal fan structure is more compact).
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**5、 Maintenance comparison**
|* * Project * * | * Roots blower * * | * * Centrifugal blower * *|
|----------------|--------------------------|--------------------------|
|* * Daily maintenance * * | Check gear oil, adjust rotor clearance | Clean impeller, check bearing vibration|
|* * Overhaul cycle * * | 3-5 years (gear/bearing replacement) | 5-8 years (impeller dynamic balance correction)|
|Common faults: rotor collision, gear wear, impeller dust accumulation, and bearing overheating|
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**6、 Classic application scenarios**
-Roots blower:
-Oxygen supply for aeration tank in sewage treatment plant.
-Flour mill pneumatic conveying system.
-Vacuum packaging machine (reverse connection use).
-* * Centrifugal fan * *:
-Ventilation and air exchange in factory workshops.
-Boiler combustion system induced draft.
-Air conditioning system provides air supply.
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**7、 Economic comparison**
|* * Cost item * * | * Roots blower * * | * * Centrifugal blower * *|
|------------------|--------------------|--------------------|
|* * Procurement cost * * | Low (simple structure) | High (precision impeller)|
|* * Operating energy consumption * * | High (applicable to low pressure) | Low (medium high pressure)|
|* * Maintenance cost * * | Low | Medium|
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**Summary**
-Roots blower: Suitable for low-pressure scenarios with stable flow and dirt resistance, but with low energy efficiency and high noise.
-* * Centrifugal fan * *: Suitable for variable operating conditions of medium and high pressure, clean gas * *, with higher efficiency.
Select comprehensively based on pressure requirements, medium characteristics, and operating time. If specific selection suggestions are needed, further analysis of operating parameters can be provided!
