Roots blower is a type of volumetric gas delivery equipment that uses two or more interlocked rotors to rotate inside the casing, achieving forced gas delivery. Its name comes from the inventor Roots Brothers, and the following is a detailed analysis of its core principles and characteristics:
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**1、 Basic working principle**
1. * * Structural composition**
-* * Rotor (impeller) * *: Usually a two blade or three blade type, it maintains synchronous and reverse rotation through precision gears.
-* * Chassis * *: Closed cavity, forming a closed working chamber with the rotor.
-Import and Export: Gas is sucked in from the inlet and pushed to the outlet through the rotor.
2. * * Working process**
-* * Inhalation stage * *: When the rotor disengages, the chamber volume increases, creating negative pressure to suck in gas.
-Transport stage: The rotor rotates to seal the gas inside the chamber.
-Exhaust stage: The rotor meshes again, compresses the chamber volume, and the gas is forcibly discharged.
-* * Key feature * *: No internal compression (pressure determined by backend system resistance), flow rate proportional to speed.
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**2、 Core Features**
|* * Features * * | * * Description * *|
|----------------|-------------------------------------------------------------------------|
|* * Forced delivery * * | Stable flow rate, not affected by pressure changes (suitable for constant flow demand)|
|* * Non lubricating design * * | Transporting gas without oil pollution (applicable to the food/pharmaceutical industry)|
|* * Simple structure * * | No valves, few friction parts, low maintenance costs|
|* * Energy saving * * | Three leaf insulation efficiency can reach over 70%|
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**3、 Comparison of main types**
|* * Type * * | * * Two blade Roots blower * * | * * Three blade Roots blower * *|
|----------------|----------------------------------|----------------------------------|
|* * Impeller shape * * | Straight or involute | Spiral twisted blade type|
|* * Noise * * | High (85-95dB) | Low (75-85dB)|
|Pulse rate * * | 8~12 | 3~5|
|* * Applicable pressure * * | ≤ 98kPa | ≤ 147kPa (high pressure type)|
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**4、 Typical application areas**
1. * * Environmental Protection Engineering * *: Sewage Treatment Aeration (Three Leaf Low Noise Required).
2. * * Industrial conveying * *: Pneumatic conveying of particles (with two blade type for better wear resistance).
3. * * Vacuum system * *: Negative pressure suction (such as vacuum packaging).
4. Chemical metallurgy: Gas circulation, blast furnace blowing.
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**5、 Key parameters for selection**
1. * * Flow rate * *: 0.5~300m3/min (increase by 10 margins according to operating conditions).
2. * * Pressure * *: 9.8~98kPa (conventional), high pressure type can reach 147kPa.
3. * * Power * *:$ P=\ frac {Q × Δ P} {60 η} $(where η is 0.6~0.75).
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**6、 Difference from centrifugal fan**
|* * Comparison item * * | * Roots blower * * | * * Centrifugal blower * *|
|--------------|-------------------------------|-------------------------------|
|* * Working principle * * | Volumetric | Kinetic energy|
|* * Flow characteristics * * | Constant flow (flow remains basically unchanged when pressure changes) | Flow decreases significantly with increasing pressure|
|* * Efficiency * * | Medium high (50~75) | High (80~90, but narrow range)|
|* * Applicable pressure * * | Medium and low pressure (<150kPa) | Wide range (up to several hundred kPa)|
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**7、 Precautions for use**
1. * * Strictly prohibit overpressure * *: Valves must be installed at the outlet (set to 1.1 times the working pressure).
2. * * Startup Requirements * *: Start with no load and gradually increase the voltage.
3. * * Maintenance points * *:
-Replace gear oil every 2000 hours
-Regularly check the impeller clearance (radial 0.15~0.4mm)
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Roots blower, with its structural reliability and flow stability, has become a key equipment for industrial gas transportation. When selecting, the two blade or three blade type should be chosen based on pressure, medium characteristics, and noise requirements.
