**The consequences and countermeasures of Roots blower reversal**
The Roots blower is designed as a unidirectional rotating device. If it reverses direction (running in the opposite direction to the calibration direction), it can cause a series of serious consequences, even leading to equipment damage. The following is a detailed analysis:
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**1、 Typical consequences of reversal**
|* * Fault type * * | * * Specific manifestations * * | * * Potential losses * *|
|--------------------|-----------------------------------------------------------------------------|-----------------------------------------------------------------------------|
|* * Damage caused by rotor collision * * | The meshing relationship of the synchronous gear is disrupted, resulting in direct contact between the two rotors and wear, deformation, or even fracture of the impeller| Need to replace the rotor assembly (cost up to 30-50% of the total machine price)|
|* * Gear system failure * * | Gear tooth breakage or misalignment leads to transmission failure| Synchronous gears are scrapped and need to be replaced in pairs (single replacement is strictly prohibited)|
|* * Bearing overload * * | Abnormal stress causes the bearing to heat up and get stuck| The bearing seat deforms, resulting in damage to the shaft neck|
|* * Performance zeroing * * | The airflow is reversed, the exhaust port becomes the intake port, and the system cannot establish pressure| Process interruption affects production continuity|
|Sealing leakage * * | Oil seal/mechanical seal fails due to reverse force, resulting in lubricating oil leakage| Chain failures caused by contaminated media or poor lubrication|
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**2、 Common reasons for reversal**
1. * * Power phase sequence error * * (L1/L2/L3 sequence is reversed when wiring three-phase motors).
2. Cross installation of belts (only for belt drive models).
3. * * The steering was not verified after repair * * (started directly after replacing the motor or gear).
4. * * Inverter parameter error * * (reverse output phase sequence setting).
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**3、 How to determine if the fan is reversing**
1. * * Visual inspection**
-The casing or motor is marked with a rotation direction arrow (such as * * CW * * clockwise/* * CWW * * counterclockwise).
2. Airflow testing**
-After starting with a jog, place your hand on the exhaust port:
-* * Normal * *: Strong airflow is emitted.
-* * Reverse * *: Inhalation or no airflow.
3. * * Abnormal noise monitoring**
-When reversing, there is usually a metallic friction sound (abnormal rotor engagement).
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**4、 Emergency handling steps**
1. * * Immediately shut down and cut off power * * to prevent continuous damage.
2. * * Swap the phase sequence of the power supply * * (any three-phase motor can swap two phase lines).
3. * * Check * *:
-Manually turn the disc to confirm if the rotor is stuck.
-Check if the gear meshing marks are aligned.
4. * * No load trial operation * *:
-After the jog test turns correctly, gradually load to the rated working condition.
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**5、 Preventive measures**
1. * * First start-up must check the steering * * (after installation or repair).
2. * * Install a phase sequence protector * * (automatically blocks reverse power supply).
3. Belt drive verification: Ensure that the belt is parallel and not crossed.
4. * * Operation training * *: Emphasize the hazards of reversal and standardize the start stop process.
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**6、 Special note: Reversible Roots blower**
-* * Customized models * *: A very small number of models support forward and reverse rotation, but must meet the following requirements:
-The rotor profile is symmetrical (such as a two blade profile).
-The lubrication system is suitable for bidirectional operation.
-Ordinary Roots blowers are strictly prohibited from reversing**
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**Summary**
-Reverse rotation=equipment killer: Short term reverse rotation can cause chain damage to the rotor, gears, and bearings.
-Correction cost is high: Maintenance costs may exceed 50% of the new machine price.
-Prevention is better than maintenance: eliminate risks through phase sequence protection and standardized operation.
If you notice a reversal accompanied by abnormal noise, it is recommended to stop the machine and contact a professional for maintenance to avoid secondary damage!
