Adjusting the pressure of the Roots blower requires changing the system resistance or adjusting the operating parameters of the blower. However, it should be noted that the Roots blower is a positive displacement blower and does not generate pressure on its own. The pressure is determined by the resistance of the backend system. The following are specific adjustment methods and precautions:
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**1、 The correct logic for regulating pressure**
The pressure (gauge pressure) of a Roots blower is essentially the result of gas overcoming system resistance, so adjusting the pressure needs to be done through:
1. * * Increase resistance * * → Increase pressure (such as closing a valve).
2. * * Reduce resistance * * → Reduce pressure (such as opening valves or cleaning pipelines).
**Important principle * *: Do not increase pressure by increasing the speed! Overpressure can cause motor overload or rotor damage.
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**2、 Common adjustment methods**
1. * * Export valve adjustment (most commonly used)**
-Boost operation:
Gradually close the outlet valve, the resistance increases, and the pressure gauge reading rises.
**Applicable scenario * *: Short term pressure adjustment (such as temporary process requirements).
**Risk * *: Overpressure may occur when the valve is fully closed, and it is necessary to cooperate with the valve (set to 1.1 times the rated pressure).
-* * Voltage reduction operation * *:
Open the outlet valve to reduce resistance and decrease pressure.
2. * * Bypass reflux regulation**
-Method: Add a bypass to the outlet pipeline to divert some of the gas back to the inlet.
**Advantages: Avoiding the risk of fully closing the valve and suitable for frequent adjustments.
**Disadvantage: Increased energy consumption (partial gas circulation work).
3. * * Variable frequency speed regulation (indirect regulation)**
-* * Principle * *: Reduce speed → Reduce air volume → System resistance naturally decreases → Pressure decreases.
**Applicable scenario * *: occasions where both air volume and pressure need to be adjusted simultaneously (such as changes in aeration tank requirements).
**Restrictions * *:
-The speed shall not be lower than the rated value of 30 (to avoid insufficient lubrication of the rotor).
-Boosting is ineffective: Increasing the speed only increases the air volume. If the system resistance remains unchanged, the pressure remains unchanged.
4. Replace the rotor or adjust the clearance**
-* * Applicable situation * *:
-The wear of the rotor leads to significant internal leakage (the pressure cannot meet the standard).
-Need to change the pressure range for a long time (such as replacing with a larger flow model).
-* * Operation * *:
Adjust the rotor clearance to 0.15~0.20mm (requires professional personnel to do so).
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**3、 Adjustment schemes in different scenarios**
|* * Requirement scenario * * | * * Recommended method * * | * * Precautions * *|
|--------------------|---------------------------|----------------------------------|
|Temporary small boost | Close the outlet valve | Monitor current ≤ rated value|
|Long term voltage reduction operation | Variable frequency to reduce speed | Avoid low speed (>30 rated)|
|High pressure stability requirement | Replacement of two-stage Roots blower | Special design required for pressure>0.8 Bar|
|Leakage leads to insufficient pressure | Inspect rotor/pipeline seals | Prioritize checking flange gaskets and shaft seals|
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**4、 Operation example**
**Goal * *: Increase the outlet pressure of the fan from 0.4 Bar to 0.5 Bar.
1. * * Steps * *:
-Observe the pressure gauge and slowly rotate the outlet valve handwheel (turn down).
-Pause every 15 ° adjustment and record changes in pressure and current.
-Stop when the pressure reaches 0.5 Bar and confirm that the current does not exceed the nameplate value.
2. * * Exception Handling * *:
-If the current approaches the rated value, stop regulating the valve and check if the system is blocked.
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**5、 Strictly prohibit operation**
1. Adjusting the intake valve may cause negative pressure intake of the fan and damage the seal.
2. * * Disassemble valve operation * *: Equipment cannot be protected when overpressure occurs.
3. * * Overspeed operation * *: Motor overload and increased rotor wear.
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**6、 The relationship between pressure regulation and energy consumption**
-Valve regulation energy consumption:
Closing the valve will increase energy consumption (useless work is converted into heat).
-Variable frequency regulation energy consumption:
Reducing the speed can save energy (power ∝ speed 3), but it needs to match the system characteristics.
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**Summary**
-* * Short term adjustment * *: Control with outlet valve (the fastest).
-* * Long term optimization * *: Variable frequency speed regulation or replacement of fan model.
-The fundamental principle is that the pressure of the Roots blower is determined by the system, and the essence of regulation is to change the resistance.
-Red line: Under certain circumstances, the pressure must not exceed the calibrated value on the nameplate!
If the pressure is abnormal and cannot be adjusted, it is recommended to check for pipeline blockage, rotor wear, or instrument failure.
