Insufficient pressure of Roots blower is a common fault, which may be caused by equipment problems, insufficient system resistance, or improper operation. The following is a detailed analysis of the reasons and solutions:
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**1、 Equipment related reasons**
1. * * Rotor wear or excessive clearance**
-Performance: The air volume has significantly decreased and the noise has increased.
-Reason: Long term operation has caused the gap between the rotor and the housing to exceed 0.25mm (standard 0.15~0.20mm), resulting in severe gas leakage.
-* * Resolve * *:
Use a feeler gauge to check the gap and adjust or replace the rotor.
Two blade fans require paired replacement of rotors to maintain a 90 ° phase difference.
2. * * Belt slippage/coupling failure**
-Performance: The motor speed is normal, but the fan speed has decreased.
-Reason: Belt looseness, aging, or poor alignment of the coupling.
-* * Resolve * *:
Belt drive: Adjust the tension (press down to 10-15mm).
Direct connection type: Use a dial gauge to calibrate coaxiality (deviation ≤ 0.05mm).
3. Motor or frequency converter malfunction**
-Performance: Abnormal current and non compliant speed.
-Reason: unstable voltage, incorrect parameters of the frequency converter, or damage to the motor winding.
-* * Resolve * *:
Check the rated speed of the motor (such as 2900rpm) and set the matching frequency of the frequency converter.
Measure the balance of three-phase current, if the deviation is greater than 10, the motor needs to be repaired.
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**2、 System pipeline issues**
1. Pipeline leakage or valve not tightly closed**
-Performance: The pressure gauge fluctuates greatly and there is an airflow sound at the flange.
-* * Reason * *: Damaged flange gasket, valve leakage, or pipeline weld cracking.
-* * Resolve * *:
Apply soapy water to check for leaks, replace gaskets or repair welding.
Manually close the valve and test the pressure recovery.
2. * * Filter/muffler blockage**
-Performance: Import negative pressure increases, motor current increases.
-Reason: Dust or oil stains blocking the filter element or silencing cotton.
-* * Resolve * *:
Clean or replace the filter (must be handled when the pressure difference is greater than 10kPa).
Check if the internal structure of the muffler has collapsed.
3. * * Low system demand pressure**
-Performance: The pressure gauge reading is low, but the air volume meets the process requirements.
-Reason: The actual resistance is less than the rated pressure of the fan (such as a short pipeline or a fully open valve).
-* * Resolve * *:
Artificially increasing resistance (such as closing the outlet valve) to test the fan's capacity.
Re calculate the system resistance and replace with a lower pressure model if necessary.
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**3、 Operation and environmental factors**
1. * * Medium change**
-Performance: Pressure fluctuates with temperature or gas composition.
-* * Reason * *:
-High temperature air has low density and pressure drops (for every 10 ℃ increase, the pressure drops by about 3).
-Transporting humid air or corrosive gases can cause internal rusting.
-* * Resolve * *:
Install gas coolers or devices.
Choose a fan with anti-corrosion coating.
2. * * Valve misoperation**
-Performance: The pressure cannot be increased and the valve continues to exhaust.
-Reason: Valve spring failure or set value too low.
-* * Resolve * *:
Test the valve popping pressure (should be 1.1 times the rated pressure).
Replace the damaged valve.
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**4、 Fault diagnosis process**
```mermaid
graph TD
A [Low pressure] -->B {Check air volume}
B -->| Normal air volume | C [Insufficient system resistance]
B -->| Decreased air volume | D {Check speed}
D -->| Low speed | E [Belt/motor issue]
D -->| Normal speed | F [Rotor wear or leakage]
C -->G [Pipeline Leakage/Valve Opening]
F -->H [Detecting rotor clearance]
```
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**5、 Preventive measures**
1. * * Regular maintenance * *:
-Check the belt/coupling monthly and measure the rotor clearance quarterly.
2. * * Monitoring instruments * *:
-Install import and export pressure gauges and record changes in pressure differential.
3. * * System Design * *:
-Reduce the number of right angle elbows in pipeline layout and match the air volume with filter selection.
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**6、 Urgent handling**
If production does not allow shutdown:
**Temporary plan * *: Close the outlet valve until the pressure meets the standard (monitor current ≤ rated value).
**Risk Warning: Long term pressure holding operation will shorten the lifespan of the fan!
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**Summary**
Insufficient pressure is often caused by leakage, insufficient speed, or unreasonable system design. Prioritize checking the sealing and speed of the pipeline, and then inspect the internal wear of the equipment. If the problem is complex, it is recommended to contact the manufacturer to provide performance curve comparison with measured data.
